Tag: Voyager 1

Engineers reactivate thrusters on Voyager-1 that have been out of commission since 2004

11:58 am

The Voyager missions
The routes the Voyager spacecraft have
taken since launch. Not to scale.

Because of an anticipated pause in communications due to upgrade work on the antennas of NASA’s Deep Space Network — used to communicate with interplanetary missions — the engineers operating the two Voyager spacecraft that are now in interstellar space after almost a half century of travel have improvised a repair that reactivated thrusters on Voyager-1 that were deemed inoperable in 2004.

Since then the spacecraft had been dependent solely on its backup thrusters. The engineers wanted the spacecraft to have two sets of thrusters again in case something went wrong during that pause in communications, running from May 2025 to February 2026.

The repair required getting two heaters switched back on, and carried with it the risk of an explosion that would destroy Voyager-1. The command to reactivate the heaters was sent on March 20, 2025, and two days later (after the command traveled at the speed of light for 23 hours to reach Voyager-1 and then 23 hours to return) the spacecraft signaled that all was well and that the heaters and thrusters were now working again.

Both Voyagers are expected to run out of power sometime in the next two years. The goal now is try to make both last at least until 2027, so that they will mark a full half century of operation since their launch in 1977.

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Engineers turn off one more instrument on each Voyager spacecraft

3:57 pm

The Voyager missions
The routes the Voyager spacecraft have
taken since launch. Not to scale.

Due to continuing reductions in the power generated by their nuclear energy sources (after a half century of operation) engineers have now turned off one more science instrument on each Voyager spacecraft in order to extend the spacecrafts’ life as long as possible.

Mission engineers at NASA’s Jet Propulsion Laboratory in Southern California turned off the cosmic ray subsystem experiment aboard Voyager 1 on Feb. 25 and will shut off Voyager 2’s low-energy charged particle instrument on March 24. Three science instruments will continue to operate on each spacecraft. The moves are part of an ongoing effort to manage the gradually diminishing power supply of the twin probes.

Even with this action, the future lifespan of both spacecraft is very limited. It is expected the savings in power will allow both to last about a year longer, well into 2026. In order to keep the Voyagers operating as long as into the 2030s mission engineers are now working up a timeline for shutting down the remaining instruments in a step-by-step manner. In that long run the goal won’t be science gathering but engineering. Can humans keep a spacecraft operating for more than a half century at distances billions of miles away?

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Engineers restore Voyager-1 after communications issue

9:20 am

The Voyager missions
The routes the Voyager spacecraft have
taken since launch.

Engineers have now manged to resume normal communications with the Voyager-1 interplanetary probe after it had shut down its main communications channel last month due to low power levels.

Earlier this month, the team reactivated the X-band transmitter and then resumed collecting data the week of Nov. 18 from the four operating science instruments. Now engineers are completing a few remaining tasks to return Voyager 1 to the state it was in before the issue arose, such as resetting the system that synchronizes its three onboard computers.

The X-band transmitter had been shut off by the spacecraft’s fault protection system when engineers activated a heater on the spacecraft. Historically, if the fault protection system sensed that the probe had too little power available, it would automatically turn off systems not essential for keeping the spacecraft flying in order to keep power flowing to the critical systems. But the probes have already turned off all nonessential systems except for the science instruments. So the fault protection system turned off the X-band transmitter and turned on the S-band transmitter, which uses less power.

The S-band transmitter had not been used since 1981, so it took awhile for ground engineers to find the very weak signal. Once found however it was possible to recover operations, though those operations will likely continue for only another year or two. The spacecraft’s power supply is expected to finally run out sometime in ’26 or ’27.

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New issue with Voyager-1

9:41 am

The Voyager missions
The routes the Voyager spacecraft have
taken since launch.

According to a NASA report yesterday, engineers are dealing with a new technical problem that has occurred Voyager-1, flying out beyond the edge of the solar system.

On Oct. 16, the flight team sent a command to turn on one of the spacecraft’s heaters. While Voyager 1 should have had ample power to operate the heater, the command triggered the fault protection system. The team learned of the issue when the Deep Space Network couldn’t detect Voyager 1’s signal on Oct. 18.

The spacecraft typically communicates with Earth using what’s called an X-band radio transmitter, named for the specific frequency it uses. The flight team correctly hypothesized that the fault protection system had lowered the rate at which the transmitter was sending back data. This mode requires less power from the spacecraft, but it also changes the X-band signal that the Deep Space Network needs to listen for. Engineers found the signal later that day, and Voyager 1 otherwise seemed to be in a stable state as the team began to investigate what had happened.

Then, on Oct. 19, communication appeared to stop entirely. The flight team suspected that Voyager 1’s fault protection system was triggered twice more and that it turned off the X-band transmitter and switched to a second radio transmitter called the S-band. While the S-band uses less power, Voyager 1 had not used it to communicate with Earth since 1981. It uses a different frequency than the X-band transmitters signal is significantly fainter. The flight team was not certain the S-band could be detected at Earth due to the spacecraft’s distance, but engineers with the Deep Space Network were able to find it.

Though communications with the spacecraft continue, no data can be downloaded and work is essentially suspended while engineers troubleshoot why Voyager-1 kept initiating its fault system.

It is amazing that communications were still possible using the S-band after more than forty years. I would bet that no engineers from then still work at the Deep Space Network. Kudos to the engineers there now for finding the signal.

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Engineers successfully switch thrusters on Voyager-1

9:14 am

The Voyager missions
The routes the Voyager spacecraft have
taken since launch.

Because of an increasing number of clogged thrusters on the almost half-century old Voyager-1 spacecraft, now flying just beyond the heliosphere of the solar system, engineers needed to switch thrusters recently, and successfully did so in a complex dance of engineering.

They had to switch from one thruster, in which a fuel line has become increasingly clogged in the last few years due to age, to an another thruster in a different system. The switch however required other careful preparations, since Voyager-1’s nuclear power supply has dropped to a point where they have been forced to shut down almost all operations. Thus, the thrusters are not getting heated as they once were, and turning on the replacement thruster in this condition could damage it.
» Read more

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Voyager-1 now returning science data from all working instruments

8:59 am

Engineers have now resumed full science operations on Voyager-1, presently more 15 billion miles from Earth, after computer issues shut the spacecraft down in November 2023.

The team partially resolved the issue in April when they prompted the spacecraft to begin returning engineering data, which includes information about the health and status of the spacecraft. On May 19, the mission team executed the second step of that repair process and beamed a command to the spacecraft to begin returning science data. Two of the four science instruments returned to their normal operating modes immediately. Two other instruments required some additional work, but now, all four are returning usable science data.

The four instruments study plasma waves, magnetic fields, and particles. Voyager 1 and Voyager 2 are the only spacecraft to directly sample interstellar space, which is the region outside the heliosphere — the protective bubble of magnetic fields and solar wind created by the Sun.

Voyager-2 is 12 billion miles from Earth. Both spacecraft are using what are the longest continously running computers ever built, having been turned on 47 years ago. Both spacecraft however do not have much longer to live, despite the recent fixes. The nuclear power source for both no longer provides enough power to run all their instruments, and will run down completely sometime in 2026, as expected, when operations will finally cease.

The spacecraft however will continue to fly out into interstellar space. In 40,000 years or so Voyager-1 will get within 1.6 light years of the star Gliese 445 in the constellation Camelopardalis, while at the same time Voyager 2 will pass 1.7 light-years from the star Ross 248 in the constellation Andromeda.

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Two of Voyager-1’s four instruments resume science operations

9:15 am

Engineers have resumed getting science data from two of Voyager-1’s four instruments for the first time since in November 2023, when corrupted computer memory caused the spacecraft to send only incoherent data.

The plasma wave subsystem and magnetometer instrument are now returning usable science data. As part of the effort to restore Voyager 1 to normal operations, the mission is continuing work on the cosmic ray subsystem and low energy charged particle instrument. (Six additional instruments aboard Voyager 1 are either no longer working or were turned off after the probe’s flyby of Saturn.)

Engineers hope to begin getting good data the other two instruments in the next few weeks.

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Voyager-1 back on line after software patch works

9:09 am

For the first time since November, Voyager-1 is sending data back to Earth coherently, after engineers figured out a way to isolate a corrupted computer chip.

The team discovered that a single chip responsible for storing a portion of the FDS memory — including some of the FDS computer’s software code — isn’t working. The loss of that code rendered the science and engineering data unusable. Unable to repair the chip, the team decided to place the affected code elsewhere in the FDS memory. But no single location is large enough to hold the section of code in its entirety.

So they devised a plan to divide the affected code into sections and store those sections in different places in the FDS. To make this plan work, they also needed to adjust those code sections to ensure, for example, that they all still function as a whole. Any references to the location of that code in other parts of the FDS memory needed to be updated as well.

The software patch was sent to the spacecraft on April 18, 2024, taking 22.5 hours to get there. It then took 22.5 hours for a response. On April 20th they received a confirmation that the patch had worked. Over the next few weeks more patches will be sent to Voyager-1 to allow it to resume sending science data back to Earth.

Both Voyager-1 and Voyager-2 were launched almost a half century ago, in 1977, and both are now more than more than 15 billion miles from Earth, traveling in interstellar space. Their computers are also the longest continuously running operating systems. Both only have a little more than two years left in their nuclear power supply, which was always expected to run out of power about a half century after launch. That both have continued to function for that entire time is a magnificent testament to the engineers who designed them.

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Voyager-1 still out of commission

8:05 am

Though engineers have now confirmed the cause of the computer problem that has prevented Voyager-1 from sending back readable data, a fix has not yet been attempted and the spacecraft remains in safe mode.

In early March, the team issued a “poke” command to prompt the spacecraft to send back a readout of the FDS [Flight Data Subsystem] memory, which includes the computer’s software code as well as variables (values used in the code that can change based on commands or the spacecraft’s status). Using the readout, the team has confirmed that about 3% of the FDS memory has been corrupted, preventing the computer from carrying out normal operations.

The team suspects that a single chip responsible for storing part of the affected portion of the FDS memory isn’t working. Engineers can’t determine with certainty what caused the issue. Two possibilities are that the chip could have been hit by an energetic particle from space or that it simply may have worn out after 46 years.

Although it may take weeks or months, engineers are optimistic they can find a way for the FDS to operate normally without the unusable memory hardware, which would enable Voyager 1 to begin returning science and engineering data again.

Considering that Voyager-1’s power supply will run out sometime in 2026, after almost a half century of operation, the engineers really don’t have that much time to fix the problem and resume science operations.

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Engineers report progress in restoring proper communications with Voyager-1

9:51 am

According to a NASA update yesterday, software engineers for the Voyager-1 spacecraft now beyond the edge of the solar system have managed to decipher the garbled data the spacecraft’s computers have been sending back to Earth since November 2023, and are in the process of analyzing that data with the hope of restoring full understandable communications.

The source of the issue appears to be with one of three onboard computers, the flight data subsystem (FDS), which is responsible for packaging the science and engineering data before it’s sent to Earth by the telemetry modulation unit.

On March 3, the Voyager mission team saw activity from one section of the FDS that differed from the rest of the computer’s unreadable data stream. The new signal was still not in the format used by Voyager 1 when the FDS is working properly, so the team wasn’t initially sure what to make of it. But an engineer with the agency’s Deep Space Network, which operates the radio antennas that communicate with both Voyagers and other spacecraft traveling to the Moon and beyond, was able to decode the new signal and found that it contains a readout of the entire FDS memory.

This new readable data was the result of a command sent two days before, suggesting that engineers are on the right track. Because Voyager-1 is so far away, 15 billion miles, it takes 22.5 hours for any command to be sent to the spacecraft, and another 22.5 hours for ground controllers to get a response. This long lag time has slowed the effort to fix the problem, but this new success suggests that a full recovery is possible.

That recovery is going to be relatively short-lived, no matter what. The nuclear-powered power sources for both Voyager spacecraft, flying since 1977, are expected to finally run out of power sometime in 2026, after almost a half century of operation. Moreover, the computers on both Voyagers are the longest continuously running computers in history.

The engineering achievement of both is astonishing.

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Computer problem on Voyager-1 remains unsolved

9:54 am

Engineers remain baffled over a computer issue that has prevented the receipt of any data since November 2023 from Voyager-1, floating some 15 billion miles away just outside the solar system in interstellar space.

In November, the data packages transmitted by Voyager 1 manifested a repeating pattern of ones and zeros as if it were stuck, according to NASA. Dodd said engineers at JPL have spent the better part of three months trying to diagnose the cause of the problem. She said the engineering team is “99.9 percent sure” the problem originated in the FDS [Flight Data Subsystem], which appears to be having trouble “frame syncing” data.

So far, the ground team believes the most likely explanation for the problem is a bit of corrupted memory in the FDS. However, because of the computer hangup, engineers lack detailed data from Voyager 1 that might lead them to the root of the issue. “It’s likely somewhere in the FDS memory,” Dodd said. “A bit got flipped or corrupted. But without the telemetry, we can’t see where that FDS memory corruption is.”

Since November the only signal received from Voyager-1 is a carrier signal that simply tells engineers the spacecraft is alive. Though the effort continues to try to fix the spacecraft, the odds of bringing it back to life are becoming slim, especially because its power supply will run out in 2026 at the very latest. Even if they manage to fix the issue now, the spacecraft has only a short time left regardless.

Considering the computers on this spacecraft, as well as its twin Voyager-2, have been operating continuously for almost a half century since their launch in 1977, their failure now is nothing to be ashamed of. The engineers that built both did well, to put it mildly.

As for Voyager-1’s future, even dead it will fly on into interstellar space, eventually getting within 1.5 light years of a star in the constellation Camelopardalis.

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Voyager-1 has computer issues

9:03 am

According to the Voyager-1 science team, the probe has developed a problem with one of its three onboard computers, called the flight data system (FDS), that is preventing it from sending back useable data.

Among other things, the FDS is designed to collect data from the science instruments as well as engineering data about the health and status of the spacecraft. It then combines that information into a single data “package” to be sent back to Earth by the TMU. The data is in the form of ones and zeros, or binary code. Varying combinations of the two numbers are the basis of all computer language.

Recently, the TMU began transmitting a repeating pattern of ones and zeros as if it were “stuck.” After ruling out other possibilities, the Voyager team determined that the source of the issue is the FDS. This past weekend the team tried to restart the FDS and return it to the state it was in before the issue began, but the spacecraft still isn’t returning useable data.

Engineers are trouble-shooting the problem, and expect it will take several weeks at best to identify and then fix the issue. The 22-hour travel time for communications to reach the spacecraft, now beyond the edge of the solar system more than 15 billion miles away, means that it will at minimum take about two days to find out if a transmitted fix works.

As the spacecraft was launched in 1977, most of the engineers now working on it were not even born then, and must deal with a technology that was designed before personal computers, no less smart phones, even existed. Like the entire 1960s space race, the two Voyager craft now beyond the solar system were built by engineers using slide rules.

Voyager-2 also had problems in August that engineers were able to fix, so the prognosis here is not bad.

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The same region on Ganymede, as seen by Voyager-1 in 1979 and Juno in 2021

11:30 am

Ganymede compared between Voyager-1 and Juno
Click for full image.

When the Jupiter orbiter Juno did a close pass of the moon Ganymede on June 7, 2021, it took four pictures, covering regions mostly photographed for the first time by Voyager-1 in its close fly-by in 1979.

Scientists have now published the data from this new fly-by. Though Juno’s higher resolution pictures revealed many new details when compared with the Voyager-1 images from four decades earlier, the scientists found no changes. The comparison image, figure 2 of their paper, is to the right, reduced and sharpened to post here.

A flicker comparison between the registered JunoCam and Voyager reprojected mosaics revealed no apparent new impact features. Given the high albedo of fresh craters on Ganymede, with high albedo ejecta deposits two or three times the diameter of the craters themselves, we argue that new craters as small as 250 m diameter would be detectable in images at these 1 km per pixel scales. Extrapolating Ganymede cratering rates from Zahnle et al. (2003) below 1 km, the probability of JunoCam observing a new crater over 12.2 million km2 in 42 years is 1 in 1500, consistent with none being observed.

In other words, at these resolutions finding no new impacts is not a surprise.

Of the new features detected, the Juno images could see more details in the bright rays emanating from the crater Tros (in the lower center of both images), and thus found “…terrain boundaries previously mapped as ‘undivided’ or as ‘approximate’, several large craters, and 12 paterae newly identified in this region.”

Paterae resemble craters but are thought to be a some form of volcanic caldera. Their geological origin however is not yet completely understood.

The paper’s conclusion is actually the most exciting:

The insight gained from this handful of images makes it likely in our opinion that new observations from the upcoming JUICE and Europa Clipper missions will revolutionize our understanding of Ganymede.

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After 50 years Edward Stone retires as the project scientist for Voyagers 1 and 2

8:23 am

Edward Stone, the only project scientist the interstellar spacecraft Voyagers 1 and 2 have ever known, has now retired after 50 years service.

Stone accepted scientific leadership of the historic mission in 1972, five years before the launch of its two spacecraft, Voyager 1 and Voyager 2. Under his guidance, the Voyagers explored the four giant planets and became the first human-made objects to reach interstellar space, the region between the stars containing material generated by the death of nearby stars.

Until now, Stone was the only person to have served as project scientist for Voyager, maintaining his position even while serving as director of NASA’s Jet Propulsion Laboratory in Southern California from 1991 to 2001. JPL manages the Voyager mission for NASA. Stone retired from JPL in 2001 but continued to serve as the mission’s project scientist.

The new Voyager project scientist however is not new to the project.

Linda Spilker will succeed Stone as Voyager’s project scientist as the twin probes continue to explore interstellar space. Spilker was a member of the Voyager science team during the mission’s flybys of Jupiter, Saturn, Uranus, and Neptune. She later became project scientist for NASA’s now-retired Cassini mission to Saturn, and rejoined Voyager as deputy project scientist in 2021.

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Engineers fix problem that caused data to arrive garbled from Voyager-1

9:00 am

By switching computers on Voyager-1 — now in interstellar space and having recently celebrated its 45th anniversary since launch — engineers were able to prevent data from coming back garbled from the spacecraft.

Earlier this year, the probe’s attitude articulation and control system (AACS), which keeps Voyager 1’s antenna pointed at Earth, began sending garbled information about its health and activities to mission controllers, despite operating normally. The rest of the probe also appeared healthy as it continued to gather and return science data.

The team has since located the source of the garbled information: The AACS had started sending the telemetry data through an onboard computer known to have stopped working years ago, and the computer corrupted the information.

Suzanne Dodd, Voyager’s project manager, said that when they suspected this was the issue, they opted to try a low-risk solution: commanding the AACS to resume sending the data to the right computer.

The switch worked. The mystery now is figuring out why the AACS started using that long-decommissioned computer, which could indicate another computer or software issue elsewhere in the spacecraft.

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Puzzling telemetry from Voyager-1 suggests problem

9:49 am

Engineers are puzzling over strange operational data coming from Voyager-1, launched in 1977 and now in interstellar space more than 14 billion miles away, that suggests a technical problem but also makes no sense.

The engineering team with NASA’s Voyager 1 spacecraft is trying to solve a mystery: The interstellar explorer is operating normally, receiving and executing commands from Earth, along with gathering and returning science data. But readouts from the probe’s attitude articulation and control system (AACS) don’t reflect what’s actually happening onboard.

The AACS controls the 45-year-old spacecraft’s orientation. Among other tasks, it keeps Voyager 1’s high-gain antenna pointed precisely at Earth, enabling it to send data home. All signs suggest the AACS is still working, but the telemetry data it’s returning is invalid. For instance, the data may appear to be randomly generated, or does not reflect any possible state the AACS could be in.

The issue hasn’t triggered any onboard fault protection systems, which are designed to put the spacecraft into “safe mode” – a state where only essential operations are carried out, giving engineers time to diagnose an issue. Voyager 1’s signal hasn’t weakened, either, which suggests the high-gain antenna remains in its prescribed orientation with Earth.

Figuring out what has happened is made more difficult by distance. It takes about 20 hours for signals to get from Voyager-1 to Earth, even at the speed of light. Thus, any attempted fix will arrive almost two days after it first occurred, at the soonest.

Both Voyager-1 and Voyager-2 are still operating, though at significantly reduced power. It is expected that sometime in the next few years their nuclear power sources will finally be unable to produce enough power to keep them functioning. If so, both spacecraft will have survived the maximum time predicted when launched.

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Interstellar space, as seen by both Voyager spacecraft

11:36 am

Today a suite of new science papers were published outlining what scientists learned when Voyager 2 joined Voyager 1 in interstellar space last November.

The Sun’s heliosphere is like a ship sailing through interstellar space. Both the heliosphere and interstellar space are filled with plasma, a gas that has had some of its atoms stripped of their electrons. The plasma inside the heliosphere is hot and sparse, while the plasma in interstellar space is colder and denser. The space between stars also contains cosmic rays, or particles accelerated by exploding stars. Voyager 1 discovered that the heliosphere protects Earth and the other planets from more than 70% of that radiation.

The data also shows that Voyager 2, which exited the heliosphere somewhat perpendicular to its direction of travel, is still in the transitional zone between the heliosphere and interstellar space. Voyager 1 exited out the head of the heliosphere, so its transitional zone was compressed and shorter.

The real achievement of these results however is that they were obtainable at all. For both spacecraft to be functioning so well after forty years in space, and able to get their data back to Earth from distances more than 11 billion miles, is a true testament to the grand engineering that went into their design and construction.

They built well in the mid-twentieth century.

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Engineers adjust Voyagers 1 & 2 because of steadily dropping power

6:35 pm

In recognition that the available power on both Voyager 1 and Voyager 2 continues to drop due to the age of the spacecraft, engineers have decided to make some major changes in how they operate both spacecraft.

For example, to save power on Voyager 2 they have turned off the heaters for the instrument that confirmed last year that the spacecraft had entered interstellar space. Even so, the instrument is still functioning and sending back data. It is expected it will continue to work for some time before finally succumbing to the cold of deep space.

They have also decided to reactivate the back-up thrusters on Voyager 2, just as they did with Voyager 1 in 2017.

Another challenge that engineers have faced is managing the degradation of some of the spacecraft thrusters, which fire in tiny pulses, or puffs, to subtly rotate the spacecraft. This became an issue in 2017, when mission controllers noticed that a set of thrusters on Voyager 1 needed to give off more puffs to keep the spacecraft’s antenna pointed at Earth. To make sure the spacecraft could continue to maintain proper orientation, the team fired up another set of thrusters on Voyager 1 that hadn’t been used in 37 years.

Voyager 2’s current thrusters have started to degrade, too. Mission managers have decided to make the same thruster switch on that probe this month. Voyager 2 last used these thrusters (known as trajectory correction maneuver thrusters) during its encounter with Neptune in 1989.

It is thirty years since those thusters on Voyager 2’s were used. If they work it will be an incredible testament to the engineers who designed both spacecraft.

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Voyager 1 fires thrusters not used in 37 years

3:30 pm

Because Voyager 1’s primary attitude thrusters are beginning to show wear (after forty years in space), engineers decided to experiment using a different set of thrusters not used since the spacecraft flew past Saturn in 1980, and found that they worked!

In the early days of the mission, Voyager 1 flew by Jupiter, Saturn, and important moons of each. To accurately fly by and point the spacecraft’s instruments at a smorgasbord of targets, engineers used “trajectory correction maneuver,” or TCM, thrusters that are identical in size and functionality to the attitude control thrusters, and are located on the back side of the spacecraft. But because Voyager 1’s last planetary encounter was Saturn, the Voyager team hadn’t needed to use the TCM thrusters since November 8, 1980. Back then, the TCM thrusters were used in a more continuous firing mode; they had never been used in the brief bursts necessary to orient the spacecraft.

…On Tuesday, Nov. 28, 2017, Voyager engineers fired up the four TCM thrusters for the first time in 37 years and tested their ability to orient the spacecraft using 10-millisecond pulses. The team waited eagerly as the test results traveled through space, taking 19 hours and 35 minutes to reach an antenna in Goldstone, California, that is part of NASA’s Deep Space Network.

Lo and behold, on Wednesday, Nov. 29, they learned the TCM thrusters worked perfectly — and just as well as the attitude control thrusters.

They figure these back-up thrusters will allow them to extend the mission by two or three years. The test also went so well that they now plan to do the same test on Voyager 2, which has still not entered interstellar space.

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Hubble takes a look at both Voyagers’ interstellar path

10:43 am

Using the Hubble Space Telescope astronomers have taken a peek at the interstellar material that the two Voyager spacecraft will travel through as they move out and leave the solar system in the coming decades.

Voyager 1 is 13 billion miles from Earth, making it the farthest human-made object ever built. In about 40,000 years, after the spacecraft will no longer be operational and will not be able to gather new data, it will pass within 1.6 light-years of the star Gliese 445, in the constellation Camelopardalis. Its twin, Voyager 2, is 10.5 billion miles from Earth, and will pass 1.7 light-years from the star Ross 248 in about 40,000 years.

For the next 10 years, the Voyagers will be making measurements of interstellar material, magnetic fields, and cosmic rays along their trajectories. Hubble complements the Voyagers’ observations by gazing at two sight lines along each spacecraft’s path to map interstellar structure along their star-bound routes. Each sight line stretches several light-years to nearby stars. Sampling the light from those stars, Hubble’s Space Telescope Imaging Spectrograph measured how interstellar material absorbed some of the starlight, leaving telltale spectral fingerprints.

Hubble found that Voyager 2 will move out of the interstellar cloud that surrounds the solar system in a couple thousand years. The astronomers, based on Hubble data, predict that the spacecraft will spend 90,000 years in a second cloud before passing into a third interstellar cloud.

This is very clever science. It allows data from Hubble to complement the data from the two Voyager spacecraft to better understand the interstellar regions that surround our solar system.

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Voyager 1 might not have left the solar system

11:56 pm

The uncertainty of science: Two scientists dispute the finding this year that Voyager 1 has entered interstellar space.

Voyager has yet to detect what scientists long predicted would be the calling card of interstellar space: a shift in the direction of the magnetic field. Scientists had expected the probe to encounter particles under the influence of the interstellar magnetic field draped over the outer shell of the heliosphere, inducing an abrupt shift. But the direction has remained stubbornly constant, and researchers can’t explain why. “This whole region is a lot messier than anyone dreamed of,” Christian says.

It’s a bit too messy for George Gloeckler and Lennard Fisk, Voyager scientists at the University of Michigan in Ann Arbor. They wondered whether the magnetic field and particle density conditions measured by Voyager could exist within the heliosphere. In a paper accepted for publication in Geophysical Research Letters, Gloeckler and Fisk argue that the outer heliosphere could allow an influx of galactic particles from beyond the bubble that would explain the density measurements.

The researchers’ analysis includes a way to definitively test the idea: If Voyager 1 is within the heliosphere, Gloeckler and Fisk note, then it should still be at the mercy of the sun’s magnetic field. If that were the case, within a year or so, Voyager should detect a 180-degree flip in the field’s direction, a regular occurrence caused by the sun’s rotation. “If that happens,” Gloeckler says, “Len and I will have a big celebration.”

I suspect that both sides are right, and that the transition into interstellar space is simply very complex. Some data will say the spacecraft is outside the solar system, while other data will say it is inside.

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Voyager 1’s future.

9:08 am

Voyager 1’s future.

Voyager 1 has enough nuclear fuel to keep doing science through to 2025, and then it will be dead, adrift. On its current trajectory, the probe should eventually end up within 1.5 light years of a star in Camelopardalis, a northern constellation that looks like a cross between a giraffe and a camel. No one knows if there are any planets around that star, nor if aliens will be in residence by the time the probe arrives. “But if they are there, maybe they will capture Voyager 1,” says mission scientist Tom Krimigis of Johns Hopkins University in Baltimore, Maryland.

In addition to the above silliness, the article gives a good summary of the real data that Voyager 1 is sending back about interstellar space.

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NASA has announced a press conference for later today about the Voyager spacecraft.

9:26 am

NASA has announced a press conference for later today about the Voyager spacecraft.

The rumors are that all the scientists involved with this data from this spacecraft now finally agree that Voyager has left the solar system. More to come.

The rumors were true: NASA has confirmed that Voyager 1 is out of the solar system and in interstellar space, and has been since last summer.

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Scientists today published a new model that suggests that Voyager 1 actually entered interstellar space in July of last year.

9:28 am

Ad astra: Scientists today published a new model that suggests that Voyager 1 actually left the solar system and entered interstellar space in July of last year.

In describing on a fine scale how magnetic field lines from the sun and magnetic field lines from interstellar space can connect to each other, they conclude Voyager 1 has been detecting the interstellar magnetic field since July 27, 2012. Their model would mean that the interstellar magnetic field direction is the same as that which originates from our sun.

Other models envision the interstellar magnetic field draped around our solar bubble and predict that the direction of the interstellar magnetic field is different from the solar magnetic field inside. By that interpretation, Voyager 1 would still be inside our solar bubble.

This new model might very well explain the conflicting data received from the spacecraft, some of which said it was out of the solar system and some of which said it was not.

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Voyager 1 has found the edge of the solar system to be far more complex than predicted by scientists.

8:44 am

The uncertainty of science: Voyager 1 has found the edge of the solar system to be far more complex than predicted by scientists.

Scientists had assumed that Voyager 1, launched in 1977, would have exited the solar system by now. That would mean crossing the heliopause and leaving behind the vast bubble known as the heliosphere, which is characterized by particles flung by the sun and by a powerful magnetic field.

The scientists’ assumption turned out to be half-right. On Aug. 25, Voyager 1 saw a sharp drop-off in the solar particles, also known as the solar wind. At the same time, there was a spike in galactic particles coming from all points of the compass. But the sun’s magnetic field still registers, somewhat diminished, on the spacecraft’s magnetometer. So it’s still in the sun’s magnetic embrace, in a sense.

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