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Voyager 2 Gets a Life-Extending Power Boost in Deep Space

NASA engineers have come up with a power-saving strategy to eke more time—and more science—out of the Voyager probes, humanity’s longest-running spacecraft , as they continue venturing into unexplored reaches of interstellar space.

And time is of the essence: Voyager 1 and 2 have been flying since 1977, and their power sources have been gradually fading, putting their instruments at risk. Out in the vast abyss of deep space, unfathomably far from our sun, solar power isn’t viable. That’s why engineers equipped each Voyager with a trio of radioisotope thermoelectric generators , or RTGs. These work by converting the heat from the decay of radioisotope fuel, plutonium-238, into electricity. They’re basically nuclear batteries—and they’re finally running out of juice, losing a predictable 4 watts per year. While the Voyagers don’t need that power for propulsion, it’s essential to their ability to collect scientific readings of far-flung charged particles and magnetic fields—so far, humanity’s only opportunity to sample that data in interstellar space.

A couple of years ago, NASA began exploring ways to keep the Voyagers’ instruments running as long as possible. The first move, in 2019, was to start turning off the heaters for the science instruments. That worked; the devices kept working despite temperatures dropping some 50 degrees Celsius, much colder than the conditions they’d been tested in. But it still wasn’t enough, so at the end of March, a NASA team initiated an energy-saving strategy on Voyager 2 that dips into some reserve power meant to protect systems from voltage spikes.

While this strategy does leave the craft more vulnerable, the risk of such spikes seems to be very low, says Suzanne Dodd, the Voyager project manager at NASA’s Jet Propulsion Laboratory in Southern California. Assuming all goes well, they’ll start similar voltage management on Voyager 1 as early as this fall. Altogether, Dodd thinks this could buy the probes’ science mission a few extra years. Voyager is still a mission of discovery, she says, and every piece of data the spacecraft obtain in interstellar space is valuable. “I continue to be amazed by these spacecraft and by the engineers who come up with clever ways to operate them,” says Dodd.

Now 45 years old, the Voyagers spent their first two decades flying through the solar system, snapping photos of Jupiter, Saturn, Uranus, and Neptune as they zoomed by. Voyager 1 also captured the iconic “ pale blue dot ” photograph of a tiny, distant Earth. As they kept going, they continued capturing data. They have long outlived their predecessors, Pioneer 10 and 11 , which were the first probes to fly by the gas giants but shut down more than 20 years ago. Both Voyagers have flown well beyond the Kuiper belt, a region hosting Pluto and other small, icy bodies. In 2012, Voyager 1 left the heliosphere, the protective bubble of particles and magnetic fields generated by the sun, beyond which lies the interstellar medium. Its twin followed six years later, at which point both were officially in interstellar territory, cruising at 35,000 miles per hour into the unknown.

Today, Voyager 1 is 159 astronomical units from home, and Voyager 2 is at 133 AU, traveling in a different direction. (1 AU is the distance between the Earth and sun, or about 93 million miles.) The spacecraft are surely showing signs of age—the team dealt with telemetry problems on Voyager 1 last year—but the cosmic workhorses are continuing on .

It’s not uncommon for NASA missions to far outlive their expected lifetimes, and to be granted extensions after achieving their main objectives. The Opportunity Mars rover rolled on for nearly 15 years , rather than three months. The Saturn-focused Cassini orbiter, which NASA operated in collaboration with the European Space Agency, persevered for 20 years instead of four. But the Voyagers surely take the cosmic cake. If the energy-conserving gambit of Dodd’s team works, the two could reach the unprecedented age of 50—with a “stretch goal” of reaching 200 AU around the year 2035.

But this will require sacrificing the science instruments one by one.

Voyager 2 still has five instruments humming along: a magnetometer, a plasma wave surveyor, a plasma science experiment, a cosmic ray detector, and a low-energy charged particle detector. The first two only take about 2W to run, and their electronics are in the body of the probe, so they’ll probably be the last to be shut down. The others are housed on the boom of the craft, where it’s frigid, and they use between 3 and  5 watts each, so turning each one of them off would buy another year of life.

Interstellar space might seem completely empty, but it’s not: There are still solar particles and magnetic phenomena to study. “The further we get from the sun, the more interesting it gets because we really don’t know what we might find. And having two Voyager spacecraft is like seeing through binoculars,” says Linda Spilker, the Voyager project scientist at JPL. For instance, astrophysicists expected that outside the heliosphere, the sun’s magnetic field would slowly rotate into the direction of the interstellar medium, and the Voyagers would be able to track that. But they’ve seen no such rotation yet, Spilker says, suggesting models of the magnetic fields need updating.

The spacecraft have also used their instruments to survey interstellar material and to detect radiation from a dazzlingly bright gamma-ray burst in another galaxy last October.

Missions based on newer probes will take advantage of Voyager’s ongoing solar science. As early as 2025, NASA plans to launch the Interstellar Mapping and Acceleration Probe (IMAP) to survey the heliosphere. The Voyagers are already well outside of the heliosphere, so the measurements from the distant probes can be compared to those from the much closer new one. “Having the Voyagers out there during IMAP will be really wonderful. As we’re seeing imaging with IMAP, the Voyagers are also going to be making valuable measurements locally,” says David McComas, a Princeton physicist who leads the IMAP collaboration. He likens it to doctors taking a CAT scan of a person’s brain for the big picture, plus a biopsy for detailed information.

The Voyagers aren’t done yet, but they already have an impressive legacy. That includes NASA’s New Horizons probe, which glided by Pluto in 2015 . Now 55 AU away from Earth, that spacecraft is probing the edge of the heliosphere with newer, better sensors than the Voyagers are equipped with, and it has already taken images of objects that hadn’t even been discovered when the Voyagers launched, like Pluto’s moons and a Kuiper Belt object called Arrokoth . “For all of us at New Horizons, the Voyager team, they are our heroes,” says Alan Stern, the collaboration’s principal investigator and a planetary scientist at the Southwest Research Institute. New Horizons is the only other distant human-made probe still operating, and it could last until 2050, Stern says. The team is now looking for a new target for a flyby.

Inspired by the Voyagers’ tremendous success, engineers are already designing next-generation spacecraft concepts, such as those that could be powered by lasers and lightsails and could one day whiz into our interstellar environs faster and farther than 1970s probes could. What advice should they glean from the Voyagers’ long and healthy lives? First, says Dodd, it’s useful to have plenty of fuel and redundant systems, because even robust instruments eventually fail. And it’s important to pass knowledge on, she says, in case the craft outlives the generation of engineers who designed it.

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July 1, 2022

21 min read

Record-Breaking Voyager Spacecraft Begin to Power Down

The pioneering probes are still running after nearly 45 years in space, but they will soon lose some of their instruments

By Tim Folger

NASA/JPL-Caltech

I f the stars hadn't aligned, two of the most remarkable spacecraft ever launched never would have gotten off the ground. In this case, the stars were actually planets—the four largest in the solar system. Some 60 years ago they were slowly wheeling into an array that had last occurred during the presidency of Thomas Jefferson in the early years of the 19th century. For a while the rare planetary set piece unfolded largely unnoticed. The first person to call attention to it was an aeronautics doctoral student at the California Institute of Technology named Gary Flandro.

It was 1965, and the era of space exploration was barely underway—the Soviet Union had launched Sputnik 1, the first artificial satellite, only eight years earlier. Flandro, who was working part-time at NASA's Jet Propulsion Laboratory in Pasadena, Calif., had been tasked with finding the most efficient way to send a space probe to Jupiter or perhaps even out to Saturn, Uranus or Neptune. Using a favorite precision tool of 20th-century engineers—a pencil—he charted the orbital paths of those giant planets and discovered something intriguing: in the late 1970s and early 1980s, all four would be strung like pearls on a celestial necklace in a long arc with Earth.

This coincidence meant that a space vehicle could get a speed boost from the gravitational pull of each giant planet it passed, as if being tugged along by an invisible cord that snapped at the last second, flinging the probe on its way. Flandro calculated that the repeated gravity assists, as they are called, would cut the flight time between Earth and Neptune from 30 years to 12. There was just one catch: the alignment happened only once every 176 years. To reach the planets while the lineup lasted, a spacecraft would have to be launched by the mid-1970s.

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READY FOR LAUNCH: Voyager 2 undergoes testing at NASA’s Jet Propulsion Laboratory before its flight ( left ). The spacecraft lifted off on August 20, 1977. Credit: NASA/JPL-Caltech

As it turned out, NASA would build two space vehicles to take advantage of that once-in-more-than-a-lifetime opportunity. Voyager 1 and Voyager 2, identical in every detail, were launched within 15 days of each other in the summer of 1977. After nearly 45 years in space, they are still functioning, sending data back to Earth every day from beyond the solar system's most distant known planets. They have traveled farther and lasted longer than any other spacecraft in history. And they have crossed into interstellar space, according to our best understanding of the boundary between the sun's sphere of influence and the rest of the galaxy. They are the first human-made objects to do so, a distinction they will hold for at least another few decades. Not a bad record, all in all, considering that the Voyager missions were originally planned to last just four years.

Early in their travels, four decades ago, the Voyagers gave astonished researchers the first close-up views of the moons of Jupiter and Saturn, revealing the existence of active volcanoes and fissured ice fields on worlds astronomers had thought would be as inert and crater-pocked as our own moon. In 1986 Voyager 2 became the first spacecraft to fly past Uranus; three years later it passed Neptune. So far it is the only spacecraft to have made such journeys. Now, as pioneering interstellar probes more than 12 billion miles from Earth, they're simultaneously delighting and confounding theorists with a series of unexpected discoveries about that uncharted region.

Their remarkable odyssey is finally winding down. Over the past three years NASA has shut down heaters and other nonessential components, eking out the spacecrafts' remaining energy stores to extend their unprecedented journeys to about 2030. For the Voyagers' scientists, many of whom have worked on the mission since its inception, it is a bittersweet time. They are now confronting the end of a project that far exceeded all their expectations.*

“We're at 44 and a half years,” says Ralph McNutt, a physicist at the Johns Hopkins University Applied Physics Laboratory (APL), who has devoted much of his career to the Voyagers. “So we've done 10 times the warranty on the darn things.”

The stars may have been cooperating, but at first, Congress wasn't. After Flandro's report, NASA drew up plans for a so-called Grand Tour that would send as many as five probes to the four giant planets and Pluto. It was ambitious. It was expensive. Congress turned it down. “There was this really grand vision,” says Linda Spilker, a JPL planetary scientist who started working on the Voyager missions in 1977, a few months before their launch. “Because of cost, it was whittled back.”

Congress eventually approved a scaled-down version of the Grand Tour, initially called Mariner Jupiter-Saturn 1977, or MJS 77. Two spacecraft were to be sent to just two planets. Nevertheless, NASA's engineers went about designing, somewhat surreptitiously, vehicles capable of withstanding the rigors of a much longer mission. They hoped that once the twin probes proved themselves, their itinerary would be extended to Uranus, Neptune, and beyond.

“Four years—that was the prime mission,” says Suzanne Dodd, who, after a 20-year hiatus from the Voyager team, returned in 2010 as the project manager. “But if an engineer had a choice to put in a part that was 10 percent more expensive but wasn't something that was needed for a four-year mission, they just went ahead and did that. And they wouldn't necessarily tell management.” The fact that the scientists were able to build two spacecraft, and that both are still working, is even more remarkable, she adds.

In terms of both engineering and deep-space navigation, this was new territory. The motto “Failure is not an option” hadn't yet been coined, and at that time it would not have been apt. In the early 1960s NASA had attempted to send a series of spacecraft to the moon to survey future landing sites for crewed missions. After 12 failures, one such effort finally succeeded.

GOLDEN RECORD: Each Voyager carries a golden record ( left ) of sounds and images from Earth in case the spacecraft are intercepted by an extraterrestrial civilization. Engineers put the cap on Voyager 1’s record before its launch ( right ). Credit: NASA/JPL-Caltech

“In those days we always launched two spacecraft” because the failure rate was so high, said Donald Gurnett, only partly in jest. Gurnett, a physicist at the University of Iowa and one of the original scientists on the Voyager team, was a veteran of 40 other space missions. He spoke with me a few weeks before his death in January. (In an obituary, his daughter Christina said his only regret was that “he would not be around to see the next 10 years of data returning from Voyager.”)

When the Voyagers were being built, only one spacecraft had used a gravity assist to reach another planet—the Mariner 10 probe got one from Venus while en route to Mercury. But the Voyagers would be attempting multiple assists with margins of error measured in tens of minutes. Jupiter, their first stop, was about 10 times farther from Earth than Mercury. Moreover, the Voyagers would have to travel through the asteroid belt along the way. Before Voyager there had been a big debate about whether spacecraft could get through the asteroid belt “without being torn to pieces,” McNutt says. But in the early 1970s Pioneer 10 and 11 flew through it unscathed—the belt turned out to be mostly empty space—paving the way for Voyager, he says.

To handle all these challenges, the Voyagers, each about the size of an old Volkswagen Beetle, needed some onboard intelligence. So NASA's engineers equipped the vehicles' computers with 69 kilobytes of memory, less than a hundred thousandth the capacity of a typical smartphone. In fact, the smartphone comparison is not quite right. “The Voyager computers have less memory than the key fob that opens your car door,” Spilker says. All the data collected by the spacecraft instruments would be stored on eight-track tape recorders and then sent back to Earth by a 23-watt transmitter—about the power level of a refrigerator light bulb. To compensate for the weak transmitter, both Voyagers carry 12-foot-wide dish antennas to send and receive signals.

“It felt then like we were right on top of the technology,” says Alan Cummings, a physicist at Caltech and another Voyager OG. “I'll tell you, what was amazing is how quickly that whole thing happened.” Within four years the MJS 77 team had built three spacecraft, including one full-scale functioning test model. The spacecraft were rechristened Voyager 1 and 2 a few months before launch.

Although many scientists have worked on the Voyagers over the decades, Cummings can make a unique claim. “I was the last person to touch the spacecraft before they launched,” he says. Cummings was responsible for two detectors designed to measure the flux of electrons and other charged particles when the Voyagers encountered the giant planets. Particles would pass through a small “window” in each detector that consisted of aluminum foil just three microns thick. Cummings worried that technicians working on the spacecraft might have accidentally dented or poked holes in the windows. “So they needed to be inspected right before launch,” he says. “Indeed, I found that one of them was a little bit loose.”

Credit: Graphic by Matthew Twombly and Juan Velasco (5W Infographic); Consultants: John Richardson (principal investigator, Voyager Plasma Science, Massachusetts Institute of Technology, Center for Space Research) and Merav Opher (professor, Department of Astronomy, Boston University)

Voyager 1 reached Jupiter in March 1979, 546 days after its launch. Voyager 2, following a different trajectory, arrived in July of that year. Both spacecraft were designed to be stable platforms for their vidicon cameras, which used red, green and blue filters to produce full-color images. They hardly spin at all as they speed through space—their rotational motion is more than 15 times slower than the crawl of a clock's hour hand, minimizing the risk of blurred images. Standing-room crowds at JPL watched as the spacecraft started transmitting the first pictures of Jupiter while still about three or four months away from the planet.

“In all of the main conference rooms and in the hallways, they had these TV monitors set up,” Spilker says. “So as the data came down line by line, each picture would appear on a monitor. The growing anticipation and the expectation of what we were going to see when we got up really, really close—that was tremendously exciting.”

Cummings vividly recalls the day he caught his first glimpse of Jupiter's third-largest moon, Io. “I was going over to a building on the Caltech campus where they were showing a livestream [of Voyager's images],” he says. “I walk in, and there's this big picture of Io, and it's all orange and black. I thought, okay, the Caltech students had pulled a prank, and it's a picture of a poorly made pizza.”

Io's colorful appearance was completely unexpected. Before the Voyagers proved otherwise, the assumption had been that all moons in the solar system would be more or less alike—drab and cratered. No one anticipated the wild diversity of moonscapes the Voyagers would discover around Jupiter and Saturn.

The first hint that there might be more kinds of moons in the heavens than astronomers had dreamed of came while the Voyagers were still about a million miles from Jupiter. One of their instruments—the Low-Energy Charged Particle [LECP] detector system—picked up some unusual signals. “We started seeing oxygen and sulfur ions hitting the detector,” says Stamatios Krimigis, who designed the LECP and is now emeritus head of the space department at Johns Hopkins APL. The density of oxygen and sulfur ions had shot up by three orders of magnitude compared with the levels measured up to that point. At first, his team thought the instrument had malfunctioned. “We scrutinized the data,” Krimigis says, “but there was nothing wrong.”

The Voyagers' cameras soon solved the mystery: Io had active volcanoes. The small world—it is slightly larger than Earth's moon—is now known to be the most volcanically active body in the solar system. “The only active volcanoes we knew of at the time were on Earth,” says Edward Stone, who has been the project scientist for the Voyager missions since 1972. “And here suddenly was a moon that had 10 times as much volcanic activity as Earth.” Io's colors—and the anomalous ions hitting Krimigis's detector—came from elements blasted from the moon's volcanoes. The largest of Io's volcanoes, known as Pele, has blown out plumes 30 times the height of Mount Everest; debris from Pele covers an area about the size of France.

The twin spacecraft took a grand tour through the giant planets of the solar system, passing by Jupiter ( 1 , 2 ) and Saturn ( 5 , 6 ) and taking the first close-up views of those planets’ moons. Jupiter’s satellite Europa ( 3 ), for instance, turned out to be covered with ice, and its moon Io ( 4 ) was littered with volcanoes—discoveries that came as a surprise to scientists who had assumed the moons would be gray and crater-pocked like Earth’s. Voyager 2 went on to fly by Uranus ( 7 ) and Neptune ( 8 ), and it is still the only probe to have visited there. Credit: NASA/JPL ( 1 , 2 , 4 , 5 , 6 , 8 ); NASA/JPL/USGS (3); NASA/JPL-Caltech ( 7 )

Altogether, the Voyagers took more than 33,000 photographs of Jupiter and its satellites. It felt like every image brought a new discovery: Jupiter had rings; Europa, one of Jupiter's 53 named moons, was covered with a cracked icy crust now estimated to be more than 60 miles thick. As the spacecraft left the Jupiter system, they got a farewell kick of 35,700 miles per hour from a gravity assist. Without it they would not have been able to overcome the gravitational pull of the sun and reach interstellar space.

At Saturn, the Voyagers parted company. Voyager 1 hurtled through Saturn's rings (taking thousands of hits from dust grains), flew past Titan, a moon shrouded in orange smog, and then headed “north” out of the plane of the planets. Voyager 2 continued alone to Uranus and Neptune. In 1986 Voyager 2 found 10 new moons around Uranus and added the planet to the growing list of ringed worlds. Just four days after Voyager 2's closest approach to Uranus, however, its discoveries were overshadowed when the space shuttle Challenger exploded shortly after launch. All seven of Challenger 's crew members were killed, including Christa McAuliffe, a high school teacher from New Hampshire who would have been the first civilian to travel into space.

Three years later, passing about 2,980 miles above Neptune's azure methane atmosphere, Voyager 2 measured the highest wind speeds of any planet in the solar system: up to 1,000 mph. Neptune's largest moon, Triton, was found to be one of the coldest places in the solar system, with a surface temperature of −391 degrees Fahrenheit (−235 degrees Celsius). Ice volcanoes on the moon spewed nitrogen gas and powdery particles five miles into its atmosphere.

Voyager 2's images of Neptune and its moons would have been the last taken by either of the spacecraft had it not been for astronomer Carl Sagan, who was a member of the mission's imaging team. With the Grand Tour officially completed, NASA planned to turn off the cameras on both probes. Although the mission had been extended with the hope that the Voyagers would make it to interstellar space—it had been officially renamed the Voyager Interstellar Mission—there would be no photo ops after Neptune, only the endless void and impossibly distant stars.

ERUPTION: The discovery of the volcano Pele, shown in this photograph from Voyager 1, confirmed that Jupiter’s moon hosts active volcanism. Credit: NASA/JPL/USGS

Sagan urged NASA officials to have Voyager 1 transmit one last series of images. So, on Valentine's Day in 1990, the probe aimed its cameras back toward the inner solar system and took 60 final shots. The most haunting of them all, made famous by Sagan as the “Pale Blue Dot,” captured Earth from a distance of 3.8 billion miles. It remains the most distant portrait of our planet ever taken. Veiled by wan sunlight that reflected off the camera's optics, Earth is barely visible in the image. It doesn't occupy even a full pixel.

Sagan, who died in 1996, “worked really hard to convince NASA that it was worth looking back at ourselves,” Spilker says, “and seeing just how tiny that pale blue dot was.”

Both Voyagers are now so far from Earth that a one-way radio signal traveling at the speed of light takes almost 22 hours to reach Voyager 1 and just over 18 to catch up with Voyager 2. Every day they move away by another three to four light-seconds. Their only link to Earth is NASA's Deep Space Network, a trio of tracking complexes spaced around the globe that enables uninterrupted communication with spacecraft as Earth rotates. As the Voyagers recede from us in space and time, their signals are becoming ever fainter. “Earth is a noisy place,” says Glen Nagle, outreach and communications manager at the Deep Space Network's facility in Canberra, Australia. “Radios, televisions, cell phones—everything makes noise. And so it gets harder and harder to hear these tiny whispers from the spacecraft.”

Faint as they are, those whispers have upended astronomers' expectations of what the Voyagers would find as they entered the interstellar phase of the mission. Stone and other Voyager scientists I spoke with cautioned me not to conflate the boundary of interstellar space with that of the solar system. The solar system includes the distant Oort cloud, a spherical collection of cometlike bodies bound by the sun's gravity that may stretch halfway to the closest star. The Voyagers won't reach its near edge for at least another 300 years. But interstellar space lies much closer at hand. It begins where a phenomenon called the solar wind ends.

Like all stars, the sun emits a constant flow of charged particles and magnetic fields—the solar wind. Moving at hypersonic speeds, the wind blows out from the sun like an inflating balloon, forming what astronomers call the heliosphere. As the solar wind billows into space, it pulls the sun's magnetic field along for the ride. Eventually pressure from interstellar matter checks the heliosphere's expansion, creating a boundary—preceded by an enormous shock front, the “termination shock”—with interstellar space. Before the Voyagers' journeys, estimates of the distance to that boundary with interstellar space, known as the heliopause, varied wildly.

“Frankly, some of them were just guesses,” according to Gurnett. One early guesstimate located the heliopause as close as Jupiter. Gurnett's own calculations, made in 1993, set the distance at anywhere from 116 to 177 astronomical units, or AU—about 25 times more distant. (One AU is the distance between Earth and the sun, equal to 93 million miles.) Those numbers, he says, were not very popular with his colleagues. By 1993 Voyager 1 already had 50 AU on its odometer. “If [the heliopause] was at 120 AU, that meant we had another 70 AU to go.” If Gurnett was right, the Voyagers, clipping along at about 3.5 AU a year, wouldn't exit the heliosphere for at least another two decades.

That prediction raised troubling questions: would the Voyagers—or the support of Congress—last that long? The mission's funding had been extended on the expectation that the spacecraft would cross the heliopause at about 50 AU. But the spacecraft left that milestone behind without finding any of the anticipated signs of interstellar transit. Astronomers had expected the Voyagers to detect a sudden surge in galactic cosmic rays—high-energy particles sprayed like shrapnel at nearly the speed of light from supernovae and other deep-space cataclysms. The vast magnetic cocoon formed by the heliosphere deflects most low-energy cosmic rays before they can reach the inner solar system. “[It] shields us from at least 75 percent of what's out there,” Stone says.

The Voyager ground team was also waiting for the spacecraft to register a shift in the prevailing magnetic field. The interstellar magnetic field, thought to be generated by nearby stars and vast clouds of ionized gases, would presumably have a different orientation from the magnetic field of the heliosphere. But the Voyagers had detected no such change.

Gurnett's 1993 estimates were prescient. Almost 20 years passed before one of the Voyagers finally made it to the heliopause. During that time the mission narrowly survived threats to its funding, and the Voyager team shrank from hundreds of scientists and engineers to a few dozen close-knit lifers. Most of them remain on the job today. “When you have such a long-lived mission, you start to regard people like family,” Spilker says. “We had our kids around the same time. We'd take vacations together. We're spanning multiple generations now, and some of the younger people on Voyager were not even born [when the spacecraft] launched.”

The tenacity and commitment of that band of brothers and sisters were rewarded on August 25, 2012, when Voyager 1 finally crossed the heliopause. But some of the data it returned were baffling. “We delayed announcing that we had reached interstellar space because we couldn't come to an agreement on the fact,” Cummings says. “There was lots of debate for about a year.”

Although Voyager 1 had indeed found the expected jump in plasma density—its plasma-wave detector, an instrument designed by Gurnett, inferred an 80-fold increase—there was no sign of a change in the direction of the ambient magnetic field. If the vehicle had crossed from an area permeated by the sun's magnetic field to a region where the magnetic field derived from other stars, shouldn't that switch have been noticeable? “That was a shocker,” Cummings says. “And that still bothers me. But a lot of people are coming to grips with it.”

When Voyager 2 reached the interstellar shoreline in November 2018, it, too, failed to detect a magnetic field shift. And the spacecraft added yet another puzzle: it encountered the heliopause at 120 AU from Earth—the same distance marked by its twin six years earlier. That did not jibe with any theoretical models, all of which said the heliosphere should expand and contract in sync with the sun's 11-year cycle. During that period the solar wind ebbs and surges. Voyager 2 arrived when the solar wind was peaking, which, if the models were correct, should have pushed the heliopause farther out than 120 AU. “It was unexpected by all the theorists,” Krimigis says. “I think the modeling, in terms of the findings of the Voyagers, has been found wanting.”

Now that the Voyagers are giving theorists some real field data, their models of the interaction between the heliosphere and the interstellar environment are becoming more complex. “The sort of general picture is that [our sun] emerged from a hot, ionized region” and entered a spotty, partly ionized area in the galaxy, says Gary Zank, an astrophysicist at the University of Alabama in Huntsville. The hot region likely formed in the aftermath of a supernova—some nearby ancient star, or perhaps a few, exploded at the end of its life and heated up the space, stripping electrons off their atoms in the process. The boundary around that region can be thought of as “kind of like the seashore, with all the water and the waves swirling and mixed up. We're in that kind of turbulent region ... magnetic fields get twisted up, turned around. It's not like the smooth magnetic fields that theorists usually like to draw,” although the amount of turbulence seen can differ depending on the type of observation. The Voyagers' data show little field variation at large scales but many small-scale fluctuations around the heliopause, caused by the heliosphere's influence on the interstellar medium. At some point, it is thought, the spacecraft will leave those roiling shoals behind and at last encounter the unalloyed interstellar magnetic field.

Or maybe that picture is completely wrong. A few researchers believe that the Voyagers have not yet left the heliosphere. “There is no reason for the magnetic fields in the heliosphere and the interstellar medium to have exactly the same orientation,” says Len A. Fisk, a space plasma scientist at the University of Michigan and a former NASA administrator. For the past several years Fisk and George Gloeckler, a colleague at Michigan and a longtime Voyager mission scientist, have been working on a model of the heliosphere that pushes its edge out by another 40 AU.

Most people working in the field, however, have been convinced by the dramatic uptick in galactic cosmic rays and plasma density the Voyagers measured. “Given that,” Cummings says, “it's very difficult to argue that we're not really in interstellar space. But then again, it's not like everything fits. That's why we need an interstellar probe.”

McNutt has been pushing for such a mission for decades. He and his colleagues at Johns Hopkins recently completed a nearly 500-page report outlining plans for an interstellar probe that would launch in 2036 and potentially could reach the heliosphere within 15 years, shaving 20 years off Voyager 1's flight time. And unlike the Voyager missions, the interstellar probe would be designed specifically to study the outer edge of the heliosphere and its environs. Within the next two years the National Academies of Sciences, Engineering, and Medicine will decide whether the mission should be one of NASA's priorities for the next decade.

An interstellar probe could answer one of the most fundamental questions about the heliosphere. “If I'm looking from the outside, what the devil does this structure look like?” McNutt asks. “We really don't know. It's like trying to understand what a goldfish bowl looks like from the point of view of the goldfish. We [need to] be able to see the bowl from the outside.” In some models, as the heliosphere cruises along at 450,000 mph, interstellar matter flows smoothly past it, like water around the bow of a ship, resulting in an overall cometlike shape. One recent computer model, developed by astronomer Merav Opher and her colleagues at Boston University, predicts that more turbulent dynamics give the heliosphere a shape like a cosmic croissant.

“You can start multiple fights at any good science conference about that,” McNutt says, “but it's going to take getting out there and actually making some measurements to be able to see what's going on. It would be nice to know what the neighborhood looks like.”

Some things outlive their purpose—answering machines, VCRs, pennies. Not the Voyagers—they transcended theirs, using 50-year-old technology. “The amount of software on these instruments is slim to none,” Krimigis says. “There are no microprocessors—they didn't exist!” The Voyagers' designers could not rely on thousands of lines of code to help operate the spacecraft. “On the whole,” Krimigis says, “I think the mission lasted so long because almost everything was hardwired. Today's engineers don't know how to do this. I don't know if it's even possible to build such a simple spacecraft [now]. Voyager is the last of its kind.”

It won't be easy to say goodbye to these trailblazing vehicles. “It's hard to see it come to an end,” Cummings says. “But we did achieve something really amazing. It could have been that we never got to the heliopause, but we did.”

Voyager 2 now has five remaining functioning instruments, and Voyager 1 has four. All are powered by a device that converts heat from the radioactive decay of plutonium into electricity. But with the power output decreasing by about four watts a year, NASA has been forced into triage mode. Two years ago the mission's engineers turned off the heater for the cosmic-ray detector, which had been crucial in determining the heliopause transit. Everyone expected the instrument to die.

“The temperature dropped like 60 or 70 degrees C, well outside any tested operating limits,” Spilker says, “and the instrument kept working. It was incredible.”

The last two Voyager instruments to turn off will probably be a magnetometer and the plasma science instrument. They are contained in the body of the spacecraft, where they are warmed by heat emitted from computers. The other instruments are suspended on a 43-foot-long fiberglass boom. “And so when you turn the heaters off,” Dodd says, “those instruments get very, very cold.”

How much longer might the Voyagers last? “If everything goes really well, maybe we can get the missions extended into the 2030s,” Spilker says. “It just depends on the power. That's the limiting point.”

TINY SPECK: Among Voyager 1’s last photographs was this shot of Earth seen from 3.8 billion miles away, dubbed the “Pale Blue Dot” by Voyager scientist Carl Sagan. Credit: NASA/JPL-Caltech

Even after the Voyagers are completely muted, their journeys will continue. In another 16,700 years, Voyager 1 will pass our nearest neighboring star, Proxima Centauri, followed 3,600 years later by Voyager 2. Then they will continue to circle the galaxy for millions of years. They will still be out there, more or less intact, eons after our sun has collapsed and the heliosphere is no more, not to mention one Pale Blue Dot. At some point in their travels, they may manage to convey a final message. It won't be transmitted by radio, and if it's received, the recipients won't be human.

The message is carried on another kind of vintage technology: two records. Not your standard plastic version, though. These are made of copper, coated with gold and sealed in an aluminum cover. Encoded in the grooves of the Golden Records , as they are called, are images and sounds meant to give some sense of the world the Voyagers came from. There are pictures of children, dolphins, dancers and sunsets; the sounds of crickets, falling rain and a mother kissing her child; and 90 minutes of music, including Bach's Brandenburg Concerto No. 2 and Chuck Berry's “Johnny B. Goode.”

And there is a message from Jimmy Carter, who was the U.S. president when the Voyagers were launched. “We cast this message into the cosmos,” it reads in part. “We hope someday, having solved the problems we face, to join a community of galactic civilizations. This record represents our hope and our determination, and our good will in a vast and awesome universe.”

*Editor’ Note (6/22/22): This paragraph was edited after posting to correct the description of when NASA began shutting down nonessential components of the Voyager spacecraft.

Tim Folger is a freelance journalist who writes for National Geographic , Discover , and other national publications.

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Voyager space mission turns 45 in unprecedented NASA success story

By Art Raymond

One revealing clue about how long NASA’s Voyager probes have been traveling through space can be found in the “high-tech” storage device both exploration craft use to store data — an eight-track tape.

While readers of a certain age will remember the jarring, mid-song-clunks of the first popular portable music medium, those who missed that particular joy were probably not around on Aug. 20, 1977, when the first of the twin Voyager probes launched from Cape Canaveral, Florida.

Voyager 2 launched that day, followed two weeks later by the liftoff of Voyager 1. Since that time, the two probes have captured stunning images in planetary flybys and are now venturing through interstellar space, still gathering and transmitting new information back to their home planet.

Exploring on borrowed time: No one is more stunned than NASA engineers that the Voyagers, originally expected to have a lifespan of five years, are still operational, albeit at a scaled down capacity to reserve their dwindling power supplies. In 2012, the Voyager program broke the record as NASA’s longest-lived space mission.

Operated by NASA’s Jet Propulsion Laboratory, the first destinations for both probes was Jupiter and Saturn after which Voyager 1 headed for the heliosphere and Voyager 2 went on to record close encounters with Uranus and Neptune. Both craft are now in interstellar space — a region where the sun’s constant flow of material and magnetic field stop affecting its surroundings — and transmitting data that’s solving some scientific mysteries and unveiling new ones. As of January of this year, Voyager 1 was 14.5 billion miles from Terra Prime.

“Today, as both Voyagers explore interstellar space, they are providing humanity with observations of uncharted territory,” said Linda Spilker, Voyager’s deputy project scientist at JPL in a report posted to the lab’s website this week . “This is the first time we’ve been able to directly study how a star, our Sun, interacts with the particles and magnetic fields outside our heliosphere, helping scientists understand the local neighborhood between the stars, upending some of the theories about this region, and providing key information for future missions.”

In case of alien encounters, drop the needle on this: Sounding a bit like the proud parents of overachieving children, the Jet Propulsion Laboratory points out that the Voyagers’ eight-track tape storage systems have about 3 million times less memory than modern cellphones and transmit data about 38,000 times slower than a 5G internet connection.

While the technology behind the probes’ data storage may sound a bit dusty, their on-board “message in a bottle,” should either of the probes encounter extraterrestrial life on their journeys, can be found on an even more aged relic of recording.

Each Voyager is carrying a  golden record  containing images of life on Earth, diagrams of basic scientific principles and audio that includes sounds from nature, greetings in multiple languages and music, according to the Jet Propulsion Laboratory. The gold-coated records serve as a cosmic handshake for anyone (or any thing) that might encounter the space probes and include “how to play” instructions. The Jet Propulsion Laboratory says at the rate gold decays in space and is eroded by cosmic radiation, the records will last more than a billion years.

The sound of silence approaches: The Voyager probes are powered by a  radioisotope thermoelectric generator  containing plutonium, which gives off heat that is converted to electricity, according to the Jet Propulsion Laboratory. As the plutonium decays, the heat output decreases and the Voyagers lose electricity.  To compensate , the Voyager team turned off all nonessential systems and some once considered essential, including heaters that protect the still-operating instruments from the frigid temperatures of space. The Jet Propulsion Laboratory says all five of the instruments that have had their heaters turned off since 2019 are still working, despite being well below the lowest temperatures they were ever tested at.

NASA expects Voyager 1 and Voyager 2 to run out of power — officially ending their decadeslong missions — sometime in the mid-2020s, according to UPI .

Once the probes go silent, NASA says the Voyager craft will begin their final mission — venturing deeper into space and serving as Earth “ambassadors” should they ever encounter another life form.

NASA’s Voyager Space Probe’s Reserve Power, And The Intricacies Of RTG-Based Power Systems

Launched in 1977, the Voyager 1 and 2 space probes have been operating non-stop for over 45 years, making their way from Earth to our solar system’s outer planets and beyond. Courtesy of the radioisotope thermoelectric generators (RTGs) which provided 470 W at launch, they are able to function in the darkness of Deep Space as well as they did within the confines of our Sun-lit solar system. Yet as nothing in the Universe is really infinite, so too do these RTGs wear out over time, both from natural decay of their radioactive source and from the degradation of the thermocouples.

Despite this gradual drop in power, NASA recently announced that Voyager 2 has a hitherto seemingly unknown source of reserve power that will postpone the shutdown of more science instruments for a few more years. The change essentially bypasses a voltage regulator circuit and associated backup power system, freeing up the power consumed by this for the scientific instruments which would otherwise have begun to shut down years sooner.

While this is good news in itself, it’s also noteworthy because the Voyager’s 45+ year old Multi-Hundred Watt (MHW) RTGs are the predecessor to the RTGs that are still powering the New Horizons probe after 17 years, and the Mars Science Laboratory (Curiosity) for over 10 years, showing the value of RTGs in long-term exploration missions.

Although the basic principle behind an RTG is quite simple, their design has changed significantly since the US put a SNAP-3 RTG on the Transit 4B satellite in 1961.

Need For Power

Even on Earth it can be tough to find a reliable source of power that will last for years or even decades, which is why NASA’s Systems for Nuclear Auxiliary Power ( SNAP ) development program produced RTGs intended for both terrestrial and space-based use, with the SNAP-3 being the first to make it to space. This specific RTG produced a mere 2.5 W, and the satellites also had solar panels and NiCd batteries. But as a space-based RTG test bed, SNAP-3 laid the groundwork for successive NASA missions.

The SNAP-19 provided the power (~30 W per RTG) for the Viking 1 and 2 landers, as well as Pioneer 10 and 11. Five SNAP-27 units provided the power for the Apollo Lunar Surface Experiments Packages ( ALSEP ) that were left on the Moon by the Apollo 12, 14, 15, 16, and 17 astronauts. Each SNAP-27 unit provided approximately 75 W at 30 VDC of power from its 3.8 kg plutonium-238 fuel rod that was rated for 1,250 W thermally. After ten years, a SNAP-27 still produces over 90% of its rated electrical power, allowing each ALSEP to transmit data on moonquakes and other information recorded by its instruments for as long as the power budget allows.

By the time the Apollo project’s support operations were wound down in 1977, the ALSEPs were left with only their transmitters turned on. Apollo 13’s SNAP-27 unit (attached to the outside of the lunar module) made a re-entry to Earth, where it still lies – intact – at the bottom of the Tonga Trench in the Pacific Ocean.

The relative inefficiency of RTGs was readily apparent even back then, with the SNAP-10A experiment demonstrating a compact 500 W fission reactor in an ion-drive satellite that readily outperformed the SNAP RTGs. Although much more powerful per unit volume and nuclear fuel, thermocouple-based RTGs do have the advantage of absolutely zero moving parts and only passive cooling requirements. This allows for them to be literally stuck on a space probe, satellite or vehicle with thermal radiation and/or convection providing the cold side for the thermocouple .

These thermocouples employ the Seebeck effect , the Peltier effect in reverse, to turn the thermal gradient between two dissimilar electrically conductive materials into essentially a generator. Much of the challenge with thermocouple-based RTGs has been to find the most efficient and durable composition. Although Rankine-, Brayton- and Stirling-cycle RTGs have also been experimented with, these have the distinct disadvantage of moving mechanical parts, requiring seals and lubrication.

When considering the 45+ year lifespan of the Voyager MHW-RTGs with their relatively ancient silicon-germanium (SiGe) thermocouples, the disadvantages of adding mechanical components should be obvious. Especially when considering the MHW RTG two generations of successors so far.

Not Your 1970s RTG

While Voyager’s MHW-RTG was developed specifically for the mission by NASA, its successor, the creatively titled general-purpose heat source ( GPHS ) RTG, was designed by General Electric’s Space Division and subsequently used on the Ulysses (1990 – 2009), Galileo (1989 – 2003), Cassini-Huygens (1997 – 2017) and New Horizons (2006 – ) missions. Each GPHS-RTG produces about 300 W of electrical power from 4,400 W thermal, using still similar silicon-germanium thermocouples.

An interesting sidenote here is that even the solar-powered Mars rovers include a radioisotope unit, although in the form of a radioisotope heater unit ( RHU ), with the Sojourner Rover having three of these RHUs, and Spirit & Opportunity eight RHUs each. These RHUs provide a constant source of heat that allows scarce electricity from solar panels and batteries to be used for duties other than running heaters.

Meanwhile, the currently active Mars rovers, Curiosity and its twin Perseverance, get both electrical power and heat from a single multi-mission radioisotope thermoelectric generator ( MMRTG ) unit. These RTGs use PbTe/TAGS thermoelectric couples, meaning lead/tellurium alloy for one side and tellurium (Te), silver (Ag), germanium (Ge) and antimony (Sb) for the other side of the couple. The MMRTG is rated for a lifespan of up to 17 years, but is likely to outperform its design specifications by a considerable margin like the MHW-RTGs and others have. The Pu-238 fuel with an MMRTG is contained in General Purpose Heat Source (GPHS) modules, which serve to protect the fuel from damage.

The main failure mode of the SiGe thermocouples was migration of the germanium over time, which causes sublimation. This was prevented in later designs by coating the SiGe thermocouples with silicon nitride. The PbTe/TAGS thermocouples should provide further stability in this regard, and the MMRTGs in Curiosity and Perseverance have served as real-world duration tests.

A Matter Of Fuel

The Voyager 1 and 2 probes are well out of reach for a big service and maintenance session, so NASA had to get creative to optimize power usage. Although the backup power circuit was perhaps considered a necessity back in the 1970s in case there were power fluctuations from any of the three RTGs on each space probe, there is enough real-life monitoring data to support the suggestion that it may be superfluous, barring alien influences.

With the nearly 46 years of data from the Voyager RTGs, we can see now that thermocouple stability is essential to maintain a constant power output, with the decay of the plutonium-238 fuel source significantly easier to model and predict. Now that with the MMRTG units we should have addressed many of the issues that caused degradation of the thermocouples over time. The only missing ingredient is the Pu-238 fuel.

Most of the Pu-238 that the US had originally came from the Savannah River Site ( SRS ) before this facility and its special reactors was shutdown in 1988. After this the US would import Pu-238 from Russia before the latter’s stocks would also begin to run low, leading to the awkward position of the US running out of what is one of the best radioactive isotopes to use in RTGs for long-duration missions. With a short half-life of 87.7 years and only alpha decay, Pu-238 is both rather benign to surrounding materials, while providing significant amounts of thermal power.

With only enough Pu-238 left for the two MMRTGs in the current Mars rovers and two more after these, the US has now restarted Pu-238 production. Although Pu-238 can be created via a few different ways, the preferred way appears to be to use stockpiled neptunium-237 and expose it to neutrons in fission reactors or similar neutron sources, to generate Pu-238 via neutron capture. According to NASA, about 1.5 kg of Pu-238 per year should be enough to satisfy demand for future space missions.

A Tiny Spacecraft In The Dark

Voyager 1 is currently at a distance of 159.14 AU (23.807 billion km) from Earth, and Voyager 2 is only marginally closer at 133.03 AU from Earth. As a project that has its roots in the Space Race and has ended up outliving not only many of its creators, but also the geopolitics of the time, it is perhaps one of the few human-made constants with which we can all identify in some fashion.

As carriers of the golden discs that contain the essence of humanity, extending the life of these spacecraft goes beyond merely the science they can perform, out in the darkness of Deep Space. With every year extra we may learn a bit more and see a bit more of what awaits humanity beyond the reaches of this rather ordinary, out of the way solar system.

45 thoughts on “ NASA’s Voyager Space Probe’s Reserve Power, And The Intricacies Of RTG-Based Power Systems ”

Never read a technical article that was as vague as this one! What have they done? Bypassed a voltage regulator to avoid it’s losses?

^ this, I was hoping for some sort of info on how they’ve done it, how the architecture of these things works (how do you software-reconfigure a power supply reliably?) that sort of thing.

agreed. feels like it was written by AI

I suspect the circuit is a “voltage regulator circuit”, no matter how regular or irregular it may be.

Most likely a few extra thermoelectric pairs that can be switched on if the system detects excess power draw from the instruments, otherwise unnecessary as excess voltage on the bus would stress the instruments’ own regulators more.

I was referring to a typo which has since been changed.

Still, I’d have thought they’d want all the thermoelectric units to be roughly equally sharing the job. Sounds like an interesting solution.

I was thinking that each unit has some extra “operational reserve”, but this is just speculation.

“Although Rankine-, Brayton- and Stirling-cycle RTGs have also been experimented with, these have the distinct disadvantage of moving mechanical parts, requiring seals and lubrication.”

I imagine with MEMS technology that issue could be dealt with.

https://hal.science/hal-03432187/document

From the description, it seems that the buffer was not intended to deal with the instability of the RTG, but to account for failures in the equipment which could drag the system voltage down, so it acts as a booster in case the computer detects a sagging voltage. Some extra thermoelectric pairs can be switched in and out as needed. This buys time to isolate the fault and shut the failing instrument down. If the extra power was on all the time, you would need an additional “regulator” device or devices to spend the excess power for the same point, which complicates matters and introduces another point of failure if it latches on.

Of course this now leaves the risk that the aging equipment can malfunction and draw more power, which would then pull the whole thing down.

That’s an explanation. I wonder if the extra power being unregulated does matter anymore. I mean, if the Voyagers are nowadays running “undervolted” anyway, the worst that could happen is that the extra therm. pairs increase the voltage levels to what used to be the normal voltage range. And since instruments are no longer being switched on/off all the time, the power draw should be quite constant. But I’m just a layman, of course.

That is the point. They’ve now run into the “operating reserve” of their power plant.

Probably spell check. Technical terms aren’t in it’s vocabulary. It’s one of those er/or words. There is no conserving the output for longer life from a RTG. If you start out with with a slowly decreasing voltage you would series regulate till the regulator voltage drop determines the useful life. Bypass the regulator and get that voltage drop back for more life. Maybe it’s a space hardened LM317 type. Even if it’s switched mode it still comes down to DC in DC out. Genius that there is a bypass mode which normally could fry things when new. Mid 70’s or older tech.

If you draw too much power out of an RTG, it cools down and the efficiency goes down after a while, giving you less power than expected, so switching the “booster” at the source instead of the regulator can give you more power temporarily than if you just bypass a regulator.

Besides, the linear regulator to spend the excess power also needs a cooling system with external radiators for any appreciable wattage, while you already got the cooling fins in the RTG to do the job. Every gram counts on a space craft.

We´ll hit the wall well before we´ll have any chance of extending beyond the solar system. At the fastest speed of even tomorrow´s technology it would still take a veeeery long time.

Just compare it to the speed we´re destroying our environment.

We all live in a shrinking capsule and the time is counted. The only spaceship we got to survive for the future is precisely the one we are walking on. And we´re wasting it, trying to dominate nature in any way we can instead of understanding we´re part of it.

We just don´t deserve this planet we have. A short-lived and short-sighted specie with the mind of a hunter-gatherer that will be just a fart on the geological scale, with a deep impact on the ecosystem.

I suppose one of the problems is that human kind has no other species for comparison. Thus it must learn from its own failures. At the very least, human kind has good intentions, also. The majority doesn’t want to be bad or destroy this planet. It’s rather incompetence that causes this dilemma. But even in the most pessimistic outcome, nature will recover. Maybe after human kind has vanished, at worst. This planet had recovered many times in the past millions of years.

incompetence is second, greed is first, by far. And third is numbness.

I´m not worried for nature, there a many many ways it will recover. The change speed we´re imposing on the planet is very brutal, and we won´t make it, but it´s unlikely life will disappear from the planet anytime soon. The recovery won´t be as fast as the demise, of course.

Hm. I suppose there’s some truth within. However, not all humans are alike. Natives and monks had been living in harmony with nature since ancient times, for example. If we’re lucky, some of them will remain and preserve things like music, art, fairy tales and mathematics. Those things deserve to be remembered.

Last but nit least, humans had a positive influence on animals, too. They learnt things like compassion and gratefulness, among other things. Some wild animals do seem to find our pet dogs to be trustworthy, for example. And some wild animals even go so far to approach passengers if they need help. Just think of the many firefighters who save animals. There surely are good people, but they don’t stand out as much as they deserve it.

“I´m not worried for nature, there a many many ways it will recover.”

We ARE “nature.” What effects on the planet we have are just as valid as any other species that evolved here and those effects are absolutely minimal despite the doomsday hype and anecdotes. Do as I have done and calculate the percent by weight of the oh so terrible plastic pollution of the oceans. There are so many leading zeros to the right of the decimal point it’s hilarious and shows why scientific notation exists. There’s a great meme of every human on the planet ground into meat ball placed in Central Park. It’s just under ONE kilometer in diameter.

The “we’re doomed” hype is just an attempt at more centralized CONTROL. Stop falling for it.

“The whole aim of practical politics is to keep the populace alarmed (and hence clamorous to be led to safety) by an endless series of hobgoblins, most of them imaginary.” – H.L. Mencken (1880-1956)

“It is simply no longer possible to believe much of the clinical research that is published, or to rely on the judgment of trusted physicians or authoritative medical guidelines. I take no pleasure in this conclusion, which I reached slowly and reluctantly over my two decades as editor of The New England Journal of Medicine.” – Marcia Angell (2009)

“The case against science is straightforward: much of the scientific literature, perhaps half, may simply be untrue. Afflicted by studies with small sample sizes, tiny effects, invalid exploratory analyses, and flagrant conflicts of interest, together with an obsession for pursuing fashionable trends of dubious importance, science has taken a turn towards darkness.” – Richard Horton, editor of The Lancet (2015)

Why Most Published Research Findings Are False John P. A. Ioannidis – 2005

https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.0020124

There is increasing concern that most current published research findings are false. The probability that a research claim is true may depend on study power and bias, the number of other studies on the same question, and, importantly, the ratio of true to no relationships among the relationships probed in each scientific field…Moreover, for many current scientific fields, claimed research findings may often be simply accurate measures of the prevailing bias. In this essay, I discuss the implications of these problems for the conduct and interpretation of research.

“There’s a great meme of every human on the planet ground into meat ball placed in Central Park. It’s just under ONE kilometer in diameter.”

[Reluctant Cannibal] does that make your mouth water? B^)

“The whole aim of practical politics is to keep the populace alarmed (and hence clamorous to be led to safety) by an endless series of hobgoblins, most of them imaginary.” – H.L. Mencken (1880-1956)

I’d love to learn more about those non-imaginary hobgoblins….

Winston, for endocrine disrupting chemicals (like many plastics) you don’t need high concentrations to drastically change biological systems. The whole POINT of hormones (the endocrine system) is that tiny amounts can have very very strong biological effects. So “lots of zeroes after the decimal point” isn’t itself any indication of safety. Not to mention, concentration gradients exist, especially in the ocean. So one area may have undetectable levels while another may be saturated. Add in some bioaccumulation and concentration up the food chain and ocean plastics are indeed bad news. No, the oceans won’t boil away or anything crazy like that, and I’m sure there’s a gross oversimplification that can be parroted to gloss over the problems. For example it’s easy to quote biological activity to claim that an area is teeming with life. If all that biological activity is toxic sludge it doesn’t really help the apex predators like you and me who rely on the food web.

Eh, I’m sure we’ll figure it out. No point in fretting over it. I dumped over 500 gallons of perfectly drinkable water down the drain today while I was testing a configuration on this piece of equipment I’m working on, lol.

Complacent optimism does not hold water in front of the scale of destruction we´re achieving down here. You pink-tainted glasses will start to crumble when your comfortable existence will be directly threatened. The world you´re living is the direct result of the frenetic exploitation of resources, and those shrink at fast speed. And everybody, no matter how they are comfortable now, will be impacted.

Pessimism is much worse, though. It doesn’t add anything meaningful to the matter.

It hurts moral, it puts people down, leads to resignation, stagnation, dead.

Think of what Einstein said, ‘I’d rather be an optimist and a fool than a pessimist and right.’

And that dude wasn’t just smart, but also wise and with lots of life experience. He enjoyed life as much as he could.

In German, there’s an old saying, apparently by E. Kästner, “Es gibt nichts Gutes, außer man tut es!” (There’s nothing good, except you do it.)

It means that it depends on us to make the world a good place, that everyone of us matters to do something good. And we can do it, if we really want to. It’s not too late until it’s too late. As long as people are around who care, there’s hope. We all must put aside our grief and pessimism and get going.

>> You pink-tainted glasses will start to crumble when your comfortable existence will be directly threatened.

When? Care to give a date? And, if that dates comes and goes and we’re still comfortable, then we’re agreed that you are wrong?

O you are one of those people who think space exploration is a waste, we should spend the money fixing this planet, right? Well we wouldn’t even know what we are doing to this planet without the satellites in space to measure things for us. At minimum the technological advancement from space far outweighs its cost

No, far from it. I just point out the discrepancy between space dreams and ticking biodiversity bomb and our poor management.

Complaining about humanity over and over alone doesn’t help, though. It just makes people give up and then they will mentally resign and nolonger care about environment. Which in turn makes you a part of the problem, rather than the solution. People who repeat those negative lines/point of views have a bad influence on others. Like a fire/virus that spreads.

Constructive criticism would be better, thus, I think. Let’s use our imagination to find a solution, rather than being creative at pointing out why things must fail. That energy would be better spent on creativity.

It’s always a good idea to the read a comment, and then reply only to the things that are actually said, instead of responding to your own imagination.

every time I take a walk outside I see what we have DONE to this planet. Every satellite or worse humans launching into space a little piece of Gaia dies.

It hasn’t done ANYTHING for mankind.Like zilch…

And to perpetuate the idea that space could safe mankind… we weren’t even able to save the bizon or the dodo…

that’s how silly things are.

I get yours and ono’s point and do agree in parts.

However, optimism is what can save the day. Human kind has the power to heal the planet.

In the pandemic, for example, when China made “a pause” and traffic/pollution was reduced, the air quality had quickly increased there.

Human kind can do a lot to save the planet.

a) It can turn salty water into drinking water by building desalination plants. b) It can bring extinct races back to life, researchers had collected seeds and DNA samples. c) Genetics can create plants that can live in though environments, like Mars. Or Earth, after the apocalypse. ;)

d) Cities could be restructured to feature a home for plants and animal life. Trees on the roofs, ivy plants on the housewalls, “central parks” in the hearts of the cities. Convection cooling in new buildings. Human imagination finds a way.

e) Cities under water. The seas are barely explored yet. Human kind might be able to use the vast resources without getting in the way with sea life. The thermal power down there is so vast, it should be sufficient for both sea life and humans.

Unfortunately, the insight might not occur until we’re at the verge of destruction. On the bright side, the good people who are willing to change have a chance to make it.

a) byproduct of desalination plants (brine) are rejected into seawater where it impacts water chemistry and ecosystems. It does not save the planet, and requires quite some energy to work. The benefit for humans it largely offset by the toll it take to underwater ecosystems. Oceans dead zones are already a problem https://oceanservice.noaa.gov/facts/deadzone.html b) seed banks can save some species, but many species of plants are in fact depends of other species (like one plant – one pollinator insect interaction). You´d get at most just one part of the puzzle. https://www.britishecologicalsociety.org/natural-seed-banks-cannot-protect-biodiversity-from-the-effects-of-climate-change/ c) genes interactions are VERY complex. While it´s true one can alter, splice, edit genes, we´re way way far to make genetic editing that is beneficial to environment. Might look good at first, but most of the time it bring a lot of unexpected consequences

e) The seas are barely explored yet, but much altered already, especially deep sea ecosystems that are very slow and very fragile are destructed as a massive scale. Just think how what proportion of the plastic waste that float (the visible part of the plasticberg) vs the plastic that sinks and destroys deep sea ecosystems. Those play a very important role, and we´re just starting to discover it. Cities under water are inept concept, that requires so so much resources and technologies to build, making these so much more wasteful than settlement on the surface.

Advanced species have probably mastered interstellar travel. If they´re observing us, it´s likely that seeing how much death and destruction we leave behind, they would be concerned to see us being able to escape our neighborhood and would likely consider us as a threat.

Same if we manage to build any superintelligence: it´s unlikely it would accept s a master: having an immature boss is at best no fun, but if you have no choice it´s pure hell.

That’s the Steven Hawking nonsense, I suppose? I was quite disillusioned in his late years. Poor dude.

No, I don’t think so. A sentient species so advanced wouldn’t harm humanity, since space faring species are rare in cosmic dimensions. They’d be above all unnecessary violence. Maybe they even faced the same troubles as us in their evolution.

They would rather observe us, try to proserve the diversity on this planet. Maybe get into contact with us if it’s the right moment in time.

Have a look at Star Trek, that’s more realistic than Hollywood’s invasion/instruction paranoia. Or let’s just think for ourselves instead of repeating nonse by some VIPs.

What’s also to consider, humanity is very young. We’re just learning to walk.

We’re certainly no threat in any way. We can barely leave earth orbit yet.

And except earth, all the other planets are dead rocks or gas giants.

With the exception of a few moons that might contain primitive bacteria and water ice.

We certainly don’t pollute anything, that’s utter nonsense.

It’s rather the contrary. Our probes might bring life into the universe, through the microbes that might travel with them. Seeds of life, so to say.

That’s also the reason why NASA and other space agencies are very carefully and rather burn up their probes into the atmospheres if gas giants like Jupiter: They try not to unresponsibly endanger possible, already existing life on those moons.

No idea where that “humanity is bad and pollutes everything” mentality comes from. Space is dead, no one cares out there.

Humans are the only known species that cares and worries about these things. We’re alife, we *are* life. It’s us who can spread life into the universe.

So please, stop being pessimistic. We have a problem here on earth, yes. And we must figure out a solution. Talking about guilt is no solution, it’s irrelevant, too. An open mind and optimism is tge key to find answers. Best regards.

Assuming there is alien life.

https://youtu.be/k_B9YP5nEWw

That’s nonsense. Satellites provide services that are essential for keeping our planet healthy: weather forecasting, and all kinds of land monitoring, for example. GPS makes travel more efficient. Communications satellites reduce the need to travel. I could go on.

The negative impact of spaceflight on our planet is currently about a million times smaller than the negative impact of commercial air travel on our planet.

The human condition is a simple to solve, neuter 50% of all newborns. Adjust % if needed. Overpopulation will be a thing of the past in 20-30 years. Promoting suicide as something noble and good will easily buy a few 100k less mouths to feed annually. Where there is a will, there is a way. I for one would happily see all the mexicants go, leaving the world to us mexicans.

I was thinking it was a simple shunt regulator to stop surges when a load was switched off. Can anyone post a link to a proper technical description of the system?

The Apollo 13’s SNAP-27 was not attached to the outside of the Lunar Module. A graphite cask containing the plutonium 238 fuel rod was. The fuel rod was removed from the cask and transferred to the generator during setup of the instruments on the lunar surface. The generator would not have survived re-entry, but the cask was designed to so that plutonium would not have been scattered in case of a launch failure.

People should check out the Dragonfly mission. It is a MMRTG powered octocopter which will fly on Titan, a moon of Saturn:

https://dragonfly.jhuapl.edu/

“The change essentially bypasses a voltage regulator circuit and associated backup power system,”

The real life version of how Star Trek fixes problems. “I’ve rerouted the plasma conduits but it won’t withstand another hit like that last one.” “Do we have phasers Mr. Scott?” “Aye, one phaser bank, Captain.” “That’s all we need. Mr. Sulu…”

Ha. My thoughts too xD

Enjoyed the article, thank you!

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Spacecraft 'Nuclear Batteries' Could Get a Boost from New Materials

A cutting-edge development in spacecraft power systems is a powerful material with an unfamiliar name: skutterudite.

No extension cord is long enough to reach another planet, and there's no spacecraft charging station along the way. That's why researchers are hard at work on ways to make spacecraft power systems more efficient, resilient and long-lasting.

"NASA needs reliable long-term power systems to advance exploration of the solar system," said Jean-Pierre Fleurial, supervisor for the thermal energy conversion research and advancement group at NASA's Jet Propulsion Laboratory, Pasadena, California. "This is particularly important for the outer planets, where the intensity of sunlight is only a few percent as strong as it is in Earth orbit."

A cutting-edge development in spacecraft power systems is a class of materials with an unfamiliar name: skutterudites (skut-ta-RU-dites). Researchers are studying the use of these advanced materials in a proposed next-generation power system called an eMMRTG, which stands for Enhanced Multi-Mission Radioisotope Thermoelectric Generator.

What is an RTG?

Radioactive substances naturally generate heat as they spontaneously transform into other elements. Radioisotope power systems make use of this heat as fuel to produce useful electricity for use in a spacecraft. The radioisotope power systems on NASA spacecraft today harness heat from the natural radioactive decay of plutonium-238 oxide.

The United States first launched a radioisotope thermoelectric generator (RTG) into space on a satellite in 1961. RTGs have powered NASA's twin Voyager probes since their launch in 1977; more than 10 billion miles (16 billion kilometers) away, the Voyagers are the most distant spacecraft from Earth and are still going. RTGs have enabled many other missions that have sent back a wealth of science results, including NASA's Mars Curiosity rover and the New Horizons mission, which flew by Pluto in 2015.

The new eMMRTG would provide 25 percent more power than Curiosity's generator at the start of a mission, according to current analyses. Additionally, since skutterudites naturally degrade more slowly that the current materials in the MMRTG, a spacecraft outfitted with an eMMRTG would have at least 50 percent more power at the end of a 17-year design life than it does today.

"Having a more efficient thermoelectric system means we'd need to use less plutonium. We could go farther, for longer and do more," Bux said.

What are skutterudites?

The defining new ingredients in the proposed eMMRTG are materials called skutterudites, which have unique properties that make them especially useful for power systems. These materials conduct electricity like metal, but heat up like glass, and can generate sizable electrical voltages.

Materials with all of these characteristics are hard to come by. A copper pot, for example, is an excellent conductor of electricity, but gets very hot quickly. Glass, on the other hand, insulates against heat well, but it can't conduct electricity. Neither of these properties are appropriate in a thermoelectric material, which converts heat into electricity.

"We needed to design high temperature compounds with the best mix of electrical and heat transfer properties," said Sabah Bux, a technologist at JPL who works on thermoelectric materials. "Skutterudites, with their complex structures composed of heavy atoms like antimony, allow us to do that."

RTGs in space

A team at JPL is working on turning skutterudites into thermocouples. A thermocouple is a device that generates an electrical voltage from the temperature difference in its components. Compared to other materials, thermocouples made of skutterudites need a smaller temperature difference to produce the same amount of useful power, making them more efficient.

In Curiosity's power system, the Multi Mission RTG (MMRTG), 768 thermocouples encircle a central can-like structure, all facing the same direction towards the heat source, at the center of the generator. The enhanced MMRTG (eMMRTG) would have the same number of thermocouples, but all would be made from skutterudite material instead of the alloys of tellurium currently used.

"Only minimal changes to the existing MMRTG design are needed to get these results," Fleurial said. A group of about two dozen people at JPL is dedicated to working on these advanced materials and testing the resulting thermocouple prototypes.

The new skutterudite-based thermocouples passed their first major NASA review in late 2015. If they pass further reviews in 2017 and 2018, the first eMMRTG using them could fly aboard NASA's next New Frontiers-class mission.

Earth-based applications of skutterudite

There are many potential applications for these advanced thermoelectric materials here on Earth.

"In situations where waste heat is emitted, skutterudite materials could be used to improve efficiency and convert that heat into useful electricity," said Thierry Caillat, project leader for the technology maturation project at JPL.

For example, exhaust heat from a car could be converted into electricity and fed back into the vehicle, which could be used to charge batteries and reduce fuel use. Industrial processes that require high temperatures, such as ceramic and glass processing, could also use skutterudite materials to make use of waste heat. In 2015, JPL licensed patents on these high-temperature thermoelectric materials to a company called Evident Technologies, Troy, New York.

"Over the last 20 years, the field of thermoelectrics has come into being and blossomed, especially at JPL," said Fleurial. "There's a lot of great science happening in this area. We're excited to explore the idea of taking these materials to space, and benefitting U.S. industry along the way."

JPL's work to develop higher-efficiency thermoelectric materials is carried out in partnership with the U.S. Department of Energy (DOE), Teledyne Energy Systems and Aerojet Rocketdyne, and is funded by NASA's Radioisotope Power System program, which is managed by NASA Glenn Research Center in Cleveland. The spaceflight hardware is produced by Teledyne Energy Systems and Aerojet Rocketdyne under a contract held by the DOE, which fuels, completes final assembly and owns the end item. Caltech manages JPL for NASA.

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NASA is keeping Voyager 2 going until at least 2026 by tapping into backup power

Emma Bowman

Artist's concept of NASA's Voyager spacecraft. After the Voyager 1 and its replica Voyager 2 launched in 1977, their power sources are slowly dying. NASA/JPL-Caltech hide caption

Artist's concept of NASA's Voyager spacecraft. After the Voyager 1 and its replica Voyager 2 launched in 1977, their power sources are slowly dying.

NASA's Voyager 2 spacecraft, which has been probing the outer bounds of the solar system for over 45 years, is running out of power. But a new plan aims to keep its interstellar mission alive for at least three more years.

The Voyager 2, first launched in 1977, has been helping scientists investigate faraway planets and understand how the heliosphere — the sun's outermost atmospheric bubble-like layer that traps particles and magnetic fields — protects Earth from its volatile interstellar environment.

With Voyager 2's power supply dwindling, NASA was about to shut down one of its five science instruments onboard the spacecraft. To keep it going, engineers had already sacrificed heaters and other nonessential parts that drained power. But engineers have now found a way to tap reserve power from a safety mechanism that regulates the spacecraft's voltage.

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"The move will enable the mission to postpone shutting down a science instrument until 2026, rather than this year," NASA's Jet Propulsion Laboratory said this past week.

Voyager 2 and its twin, Voyager 1 (launched the same year), are the only spacecraft to have ventured beyond the heliosphere.

Ed Stone, who was the chief scientist at NASA's Jet Propulsion Lab before he retired last year, has spent over half his life dedicated to the Voyager program. He oversaw the spacecrafts churn out one discovery after another as they explored Jupiter, Saturn, Uranus and Neptune.

"What it revealed was how complex and dynamic the solar system really is. Before Voyager, the only known active volcanoes were here on Earth," Stone told NPR in 2017 . "Then we flew by Jupiter's moon, Io, and it has 10 times the volcanic activity of earth. Before Voyager, the only known oceans in the solar system were here on Earth. Then we flew by another moon of Jupiter, Europa, which it turns out has a liquid water ocean beneath its icy crust."

Voyager 2 is 12.3 billion miles away from Earth and counting . Voyager 1, also facing an expiration date as it also loses power, is 14.7 billion miles away.

"The science data that the Voyagers are returning gets more valuable the farther away from the Sun they go, so we are definitely interested in keeping as many science instruments operating as long as possible," Linda Spilker, the Voyager program's project scientist at the Jet Propulsion Lab, said in a statement.

NASA, meanwhile, has been working to make sure the Voyagers' legacy doesn't end with a slow fizzle, with officials weighing expensive and complex proposals from several groups for a new, long-term probe.

NASA scientists add years to Voyager 2 power supply

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How do you extend the life of a satellite that's 45 years in on a more than 12 billion mile journey away from Earth? You review the schematics one more time and consider every component.

On Wednesday, NASA announced that scientists have done just that - determining a way to extend the life of Voyager 2 without shutting down any of the probe's scientific instruments.

“The science data that the Voyagers are returning gets more valuable the farther away from the Sun they go, so we are definitely interested in keeping as many science instruments operating as long as possible,” said Linda Spilker, Voyager’s project scientist at NASA’s Jet Propulsion Laboratory in Southern California, which manages the mission for NASA.

What: Voyager 2 power supply

When: Launched in 1977, the Voyager 2 spacecraft is more than 12 billion miles from Earth, using five science instruments to study interstellar space. 

The Power: Both Voyager probes power themselves with radioisotope thermoelectric generators (RTGs), which convert heat from decaying plutonium into electricity. The continual decay process means the generator produces slightly less power each year. So far, the declining power supply hasn’t impacted the mission’s science output, but to compensate for the loss, engineers have turned off heaters and other systems that are not essential to keeping the spacecraft flying.

Nothing left to turn off: Voyager 2 is essentially operating with an extra science instrument. Realizing there's nothing left to turn off on the probe without losing valuable data, scientists turned to what amounts to a voltage regulator that draws and stores a small amount of power. Utilizing that small reserve for science rather than voltage protection will allow scientists to extend the life of the probe. Voyager 1 is in a different situation because one of its instruments failed early in its mission and the probe therefore uses less power.

Aging equipment: Although Voyager 2's voltage will not be tightly regulated as a result, even after more than 45 years in flight, the electrical systems on both probes remain relatively stable, minimizing the need for a safety net. The engineering team is also able to monitor the voltage and respond if it fluctuates too much. If the new approach works well for Voyager 2, the team may implement it on Voyager 1 as well.

“Variable voltages pose a risk to the instruments, but we’ve determined that it’s a small risk, and the alternative offers a big reward of being able to keep the science instruments turned on longer,” said Suzanne Dodd, Voyager’s project manager at JPL. “We’ve been monitoring the spacecraft for a few weeks, and it seems like this new approach is working.”

Rob Landers  is a veteran multimedia journalist for the USA Today Network of Florida. Contact Landers at 321-242-3627 or  [email protected] . Instagram:  @ByRobLanders   Youtube :  @florida_today

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A High-Energy Proton Beam Could Finally Connect Us to Proxima Centauri

This propulsion system may speed up the future of interstellar travel.

• The closest star to Earth, Proxima Centauri (PC), is still about 8000 times further away from us than Pluto.
• Propelling a probe to PC will require a much higher cruising speed than we can currently achieve in order to get useful data.
• The solution could be a proton beam, made diffraction-proof by complex algorithms.

But it’s still about 1600 times closer to us than the closest non-Sun star, Proxima Centauri (PC). It could be that the PC system is humanity’s best candidate for true habitation of a second planet, which has made it the subject of interest for decades. But at 25 trillion miles away, it’s more than a little bit out of our current reach. After all, it took Voyager 50 years to get as far away as it is.

So, in order to ever probe Proxima Centauri and its handful of exoplanets , we need a new craft-powering paradigm. And because a probe is very tiny—Voyager is about 1,500 pounds, compared to the Space Shuttle’s 4.5 million pounds at takeoff—it could be a good way to experiment with interplanetary and interstellar propulsion ideas.

In 2018, NASA’s experimental NASA Innovative Advanced Concepts (NIAC) group published a report by scientist Chris Limbach on a proton beam propulsion system . The proposed proton beam is called PROCSIMA: Photon-paRticle Optically Coupled Soliton Interstellar Mission Accelerator.

A beam might seem wild compared to the fairly routine-sounding nuclear battery that powers Voyager 1. Of course, when the Voyager crafts were being constructed in the 70s, that was also quite ‘far out’—but it worked. And while still theoretical, the beam also has benefits very grounded in real life. “Beam concepts are unique in that their propulsion capability principally derives from the separation of power and propulsion subsystems from the spacecraft itself,” Limbach wrote, “thereby liberating the propulsion dynamics from the rocket equation.”

In other words, all of the work of propulsion is being done on Earth, where the proton beam is based. As a result, the calculations around the probe spacecraft itself become less complex. Think about the probe like a baseball. For a baseball, your body swinging the bat is the propulsion system. That’s very different from a baseball you only hold in your hand until it can fly on the same trajectory but under its own power, which is the idea behind most propulsion systems. (That’s a complicated baseball that would win the science fair for sure.)

This, Limbach explains in the paper, is all pretty much old news. But something has stopped people from using Earth beams. Yes, they save complexity, but beams by nature end up diffracting—functionally the light beam equivalent of dissolving—over long distances until they’re no longer effective. That means the probe could only be powered for a certain distance before it would be on its own.

Limbach’s breakthrough in the paper, he explains, is a way to keep that beam tight, even over trillions of miles. And while Star Trek and other science fiction sometimes depicts outer space as cluttered with close-by objects, the truth is that our local space is quite empty, with a clear path from here to Proxima Centauri.

Limbach’s paper is an exploration and review of existing knowledge, with his original ideas intended to spark discussion of next steps into self-guiding (and non-diffracting) particle beams. They’re not without their own high complexity, he explains, but moving that complexity to Earth means no one will find it miraculous when the system is repaired during the probe’s journey.

“These studies did not reveal any ‘show-stoppers,’” Limbach concludes—just promising ideas that need more exploration . And as we think more and more about traveling to outer space, perhaps that work will seem more urgent again.

Caroline Delbert is a writer, avid reader, and contributing editor at Pop Mech. She's also an enthusiast of just about everything. Her favorite topics include nuclear energy, cosmology, math of everyday things, and the philosophy of it all. 

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Way out in interstellar space, Voyager 1 is roaming where no human has ever been, revealing secrets of our universe more than 15 billion miles away. Today, the story of its nearly 50-year journey through space and the scientists trying to keep it with us.

Voyager 1 launched on Sept. 5, 1977, during the height of the space age. In the decades since, this unmanned spacecraft has ventured to the outer edges of our universe, sending back one-of-a-kind images and exploring realms that humans will probably never reach. 

Voyager 1 is now more than 15 billion miles away in interstellar space, still collecting data and sending it back to Earth. But late last year, Voyager 1 faced its biggest crisis yet. It went silent and stopped communicating. In the months that followed, scientists at NASA launched an all-hands-on-deck effort to find a solution.  

Today on “Post Reports,” science reporter Joel Achenbach on Voyager’s journey through space, its fragile future and the desperate effort to keep it with us. We hear from Linda Spilker, project scientist for Voyager 1, and David Cummings, a member of a “tiger team” at NASA’s Jet Propulsion Laboratory.   

Today’s show was produced by Elana Gordon. It was edited by Peter Bresnan and mixed by Sean Carter. Thanks to Stephen Smith.  

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Where are they now.

• frequently asked questions
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The identical Voyager spacecraft are three-axis stabilized systems that use celestial or gyro referenced attitude control to maintain pointing of the high-gain antennas toward Earth. The prime mission science payload consisted of 10 instruments (11 investigations including radio science).

The command computer subsystem (CCS) provides sequencing and control functions The CCS contains fixed routines such as command decoding and fault detection and corrective routines, antenna pointing information, and spacecraft sequencing information.

The Attitude and Articulation Control Subsystem (AACS) controls spacecraft orientation, maintains the pointing of the high gain antenna towards Earth, controls attitude maneuvers, and positions the scan platform.

Uplink communications is via S-band (16-bits/sec command rate) while an X-band transmitter provides downlink telemetry at 160 bits/sec normally and 1.4 kbps for playback of high-rate plasma wave data. All data are transmitted from and received at the spacecraft via the 3.7 meter high-gain antenna (HGA).

Electrical power is supplied by three Radioisotope Thermoelectric Generators (RTGs). The current power levels are about 249 watts for each spacecraft. As the electrical power decreases, power loads on the spacecraft must be turned off in order to avoid having demand exceed supply. As loads are turned off, some spacecraft capabilities are eliminated.

3D Model : Click (or touch) and drag to interact with this 3D model of the Voyager spacecraft.

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NCM battery problem

• Thread starter RAYMOND LAWRENCE
• Start date Jul 9, 2021

RAYMOND LAWRENCE

• Jul 9, 2021

I have a Moscow Plus, the battery will not switch on either on or off the bike, the charger shows fully charged.  

Active Member

It's dirty contacts on the battery button, I always open it up and clean it with electronics contact cleaner.  

Hi, thanks for the thought,tried it but but made no difference, also checked the fuse,that was ok  

Well-Known Member

Hmm? Could be a broken contact ´in´ the battery? You might want to talk to the seller about a return. How many kliks?  

• Jul 10, 2021

Thanks for the reply, it is a bit strange as it was working but has developed a fault whilst not being used,which is why the dirty switch contacts made sense. I removed the top of the battery and sprayed switch cleaner over the switch area and checked the fuse,which was ok. The problem is ebike battery companies just want to rebuild the battery with new cells and do not want to get involved with the control unit. I purchased the bike direct from Leon cycles with a one year warranty on the battery,which has now expired,, but it is easier to contact the Pope than them.  

RAYMOND LAWRENCE said: I removed the top of the battery and sprayed switch cleaner over the switch area Click to expand...

Hi, thanks for the reply, I did spray in all spaces around the switch including above the contacts between switch and case, but I will give it another go. Interesting metaphore by the way.  

Hi, I am using an electrical contact cleaner, the switch is not an enclosed unit as you have shown, I can get the spray behind the button onto the circuit board it operates on. I fear that it is a component failure on the pcb.  

The button on the board is a simple momentary on short. If you feel confident, short where you think the button does the contacting. Hard paper clip is preferred over wire, as the wire may dance around and touch other unintended areas.  

Sorry to here the franchise you bought from is unresponsive. the store in seattle near me has been very helpful. They are currently offering a new 13ah for $300, & 16ah for $400. Still, I think you should be entitled to a replacement free or at least a signifigant discount if the failure is in the circuit board or cell connections.  

So if I understand correctly: 1) Battery was working before, you had ended a ride and fully charged the battery but it then it stopped working 2) Battery does not power the bike 3) Pressing the on/off button on the battery does nothing. Did you try long pressing for 15-20sec? 4) No LED's on the battery at all 5) You've opened the battery and checked both fuses. There's a 15a-20a discharge fuse at the top and a 5a charge fuse at the bottom (usually). Does the USB port work? My feeling is it's the discharge fuse but you say you've checked it. I think it's time to get a multimeter (are you comfy with that sort of thing). Check the power on the discharge port at the top. Anything? If you can carefully probe the charge port (BE CAREFUL, use a 2.1mm barrel connector from an old wall wart to make a plug to use to test with) what is the voltage there? Opening the top of the battery can you trace wires back from the discharge connector to the fuse then to the BMS. Check for voltage everyone along that path you can and let us know what you find. Post some pics of the BMS and wiring at the top of the battery  

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