NASA’s Pluto Spacecraft Begins New Mission at the Solar System’s Edge
New Horizons is about to wake up and study the Kuiper Belt, the universe and even Uranus and Neptune. But a new target to visit could trump them all
Only two spacecraft have ever left our solar system and lived to tell the tale. In 2012 and 2019, NASA’s Voyager 1 and 2 spacecraft respectively broke through the heliopause, the boundary at which our sun’s sphere of influence gives way to the interstellar medium. They have sent back remarkable riches from this distant location, humanity’s first foray into the limitless bounds beyond our solar system’s edge. In hot pursuit, however, is a far more advanced vehicle, sporting improved instruments, updated optics, and even a means to sample the interstellar medium itself. New Horizons was launched from Earth in 2006 on a mission to visit Pluto, arriving in 2015 and revealing incredible details during its all-too-brief flyby. The spacecraft has continued its cruise toward interstellar frontiers ever since. It has now begun its second extended mission, and is soon set to wake up from a deep hibernation, opening a wealth of new science opportunities in the outer solar system. “It takes a long time to get to where our spacecraft is,” says Alice Bowman, mission operations manager for New Horizons at the Johns Hopkins University Applied Physics Laboratory (JHUAPL) in Maryland. “When you have a spacecraft that is out in that part of the solar system, it is a huge asset to the scientific community. There are so many unique things that a spacecraft that is out that far can do. We definitely want to take advantage of that.”
For New Horizons, those “unique things” include unprecedented studies of the planets Uranus and Neptune, sampling of the local dust, studies of the background light in the universe, and more. The sum total will be a new phase of the mission that is “really unique and interdisciplinary in nature,” says Alan Stern, the lead on the mission at the Southwest Research Institute (SwRI) in Texas. In October, this two-year second extended mission officially began, but in 2023 it will pick up the pace as the spacecraft exits hibernation and begins its scientific program in earnest. “There were lots of good ideas for how to do things in astrophysics, heliophysics and planetary science,” Stern says. “We took the very best of those.” There is even, also, the tantalizing possibility of visiting another object in the Kuiper Belt, the region of asteroids and icy objects that lurks beyond Neptune, in which New Horizons has already visited one object—Arrokoth in 2019—after its Pluto encounter. Even without such a possibility, there was more than enough reason for NASA to extend the mission. “New Horizons is at a unique location in the solar system with an amazing suite of functioning instruments on-board,” says Becky McCauley Rench, New Horizons program scientist at NASA Headquarters in Washington, D.C. “[It] can provide valuable insights to the heliosphere and the solar wind, astronomical observations of the cosmic background radiation, and valuable data about Uranus and Neptune that can be applied to our knowledge about ice giant planets.”
Since June 1 the spacecraft has been in hibernation, with its major systems switched off to reserve power, while a gentle spin of five revolutions per minute keeps the spacecraft on course without using up its fuel. The spacecraft’s nuclear battery, degraded from its original design spec of 240 watts of power production, now makes about 200 watts, and there are about 11 kilograms of hydrazine fuel left of the 78 kilograms that were aboard when New Horizons launched. “We’re on an eighth of a tank,” Stern says. That makes operations difficult. “It is becoming more challenging,” Bowman says. “We have to be very judicious when we choose activities to do.” That is more than enough power and fuel, however, for the spacecraft’s operations to continue long into the future, perhaps the 2040s or even 2050s, when the spacecraft should have crossed the boundary into interstellar space. New Horizons is currently about 55 astronomical units (AU) from the sun, or 55 times the Earth-sun distance, some 65 AU short of that boundary and traveling outwards at about “three AU per year,” says Stern.
On March 1, the spacecraft will exit its hibernation mode, switching on its systems to truly begin its new extended mission (although some instruments have already been taking data while the rest of the spacecraft has been hibernating). In April, the spacecraft will cease to spin, allowing it to snap images of the planet Uranus. It will image both Uranus and Neptune again in the fall of 2023, and Uranus again in spring 2024. This will let astronomers track the motion of clouds as the planets rotate to better understand their energy balance as the sun shines upon them particularly when, in the fall of 2023, New Horizons will observe the planets edge-on while Hubble and other ground-based telescopes near-simultaneously observe their nearsides from Earth.
While the planets will only appear as dots of light to New Horizons, the spacecraft should be able to track the change in brightness of the planets that corresponds to observations from Hubble. “It doesn’t have to be exactly simultaneous, but we’re certainly folding in when Hubble can observe to the optimal time for New Horizons to observe,” says Will Grundy at Lowell Observatory in Arizona, a planetary scientist and co-investigator on the mission. Such studies, in turn, could prove useful for investigations of exoplanets in other solar systems. So far, ice giant planets like Uranus and Neptune have been found to be relatively common. By understanding what New Horizons can see in its limited observations of these planets compared to Hubble’s views, astronomers can extrapolate that to understand remote views of similar exoplanets, too. “It’ll get people really sharpening their pencils and figuring out what you can learn from that sort of observation,” Grundy says.
By pointing its cameras outward into deepest space, unhindered by light from the sun, New Horizons has already revealed something surprising about the universe, namely that the background visible light from all the stars and galaxies is about twice as bright as expected. Possible explanations include a smattering of faint galaxies, perhaps invisible to telescopes like Hubble but observable by the James Webb Space Telescope (JWST), or rogue stars drifting through the galaxy. “We’re going to be making even more precise measurements in 16 different directions,” says Stern, compared to just two directions previously. That should explain if the background light is spread evenly across the sky or focused in certain directions. The team will also do the same experiment in ultraviolet, “to rule some ideas ‘in’ or ‘out,’” Stern says.
New Horizons is also able to study its current region of space in more detail than could Voyager 1 and 2. The spacecraft is thought to be in a “desert” between an inner and outer Kuiper Belt region, in which the density of dust and objects is lower than average in the rest of the Kuiper Belt. A dust detector on the spacecraft should pick up a handful of dust impacts every year, and the electromagnetic pulse produced by those impacts should tell scientists how big the dust is and the amount of it, some of which may have resulted from objects colliding in the Kuiper Belt. “It’s a way of tasting the effect of Kuiper Belt collisions,” says Grundy. “Even small objects crash into each other, and we can detect that dust. It’s a way of telling the outermost extent of the Kuiper Belt.” New Horizons will also observe up to 10 or so other Kuiper Belt objects from afar, possibly resolving their shapes and sizes by working in tandem with ground-based telescopes, as well as looking for evidence of small accompanying moons.
As the spacecraft approaches the heliopause, it will also tell us more about how the properties of the sun’s heliosphere, its region of influence, are changing—taking measurements of the local plasma, charged particles and an influx of hydrogen gas from the interstellar medium. “We now have the opportunity of making a global map of the hydrogen distribution,” says Ralph McNutt, chief scientist for space science at JHUAPL and a co-investigator on New Horizons. “It’s part of the clue to how the overall heliosphere interacts with the interstellar medium on a large scale, and what the interstellar medium is doing to our home.” The hope, however, is that the spacecraft will remain operational and funded into the 2040s, when it should have reached the heliopause some 120 AU from Earth. “We think we’ve got enough power on board,” McNutt says.
Yet there is the constant possibility that all of these plans could change in an instant. Using the Subaru Telescope in Hawaii, the team continues to scour the Kuiper Belt for another object to visit, like Arrokoth. If a suitable candidate is found that could be reached by New Horizons, “we would drop the rest of the program to conserve fuel,” says Stern. “We were sent to do the Kuiper Belt.” No such target has yet been found, but the search continues. “If we can get a second Kuiper Belt object, that will trump everything,” says Stern. “If we can find one object that we can reach with the fuel supply, even if it’s four or five years from now, that will be the headliner.” But there is no guarantee of such an outcome. “The odds are not great because we’re through the densest part of the Kuiper Belt,” says Grundy. “It’s a long shot.”
In lieu of such a target being found, the team are also considering another high-profile task as part of its latest extended mission. The spacecraft could be directed to turn around and look back towards Earth, replicating the famous Pale Blue Dot image of our planet taken by Voyager 1 in 1990 from a distance of 40 AU. Stern says the team are currently investigating if this would be feasible. “The problem is we’re much further from the sun than Voyager was,” he says. That could make it too difficult to resolve Earth against the glare of the sun, while the brightness of the sun could potentially damage the spacecraft’s instruments. “We’re not going to burn out the cameras just to do it,” Stern says.
No other spacecraft will traverse this same region of space as New Horizons for decades. In the U.S. an effort led by McNutt called Interstellar Probe is currently being considered as a potential future project, but a decision by the National Academies’ Solar and Space Physics Decadal Survey is not expected until December 2024. While there have been no major updates to the project since the team published its proposal last year, there has been one major development, namely the successful first launch of the Space Launch System (SLS), earmarked as a potential launch vehicle for this ambitious mission. McNutt says his team has also spoken with other companies about possible alternative large rockets that could launch the mission, such as SpaceX’s Starship, which is expected to conduct its first orbital test flight by 2023. “We’re talking to them,” McNutt says. A separate interstellar mission from China, Interstellar Express, also appears to still be on track to launch later this decade.
For now, New Horizons is the only spacecraft barrelling towards the edge of the solar system, and it has two possible futures ahead of it. One is an interdisciplinary study of the outer solar system in a manner that will be unmatched for years to come. “We are going through the outer heliosphere where Voyager went but with vastly better instrumentation,” says Stern. “Our particle instruments are much more sensitive. We have a dust detector. And our ultraviolet spectrometer is being used to study the distribution of neutral hydrogen gas. Voyager just didn’t have the technology to do that.” The other is a diversion towards an as-yet undiscovered asteroid or comet lurking in the outer Kuiper Belt, an alluring but increasingly challenging possibility. “We don’t know how far the Kuiper Belt really extends,” Stern says. “We’re pulling out all the stops. If there’s something out there to get to, we will find it.”
Quelle: Scientific American
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Update: 18.03.2023
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New Horizons Pluto probe notches 3 new discoveries in outer solar system
New findings keep on coming from the mission's July 2015 Pluto flyby.
Pluto, as seen by NASA’s New Horizons spacecraft during its historic flyby of the dwarf planet in July 2015.(Image credit: NASA/JHUAPL/SwRI)
NASA's New Horizons probe flew by Pluto nearly eight years ago, but the epic encounter is still bearing scientific fruit.
New Horizons gave humanity its first up-close looks at Pluto on July 14, 2015, when the probe zoomed just 7,800 miles (12,500 kilometers) above the dwarf planet's frigid surface. The mission team is still analyzing the stockpile of data New Horizons gathered during the flyby — and still making intriguing discoveries, as new results show.
New Horizons researchers shared their latest findings on Tuesday (March 14) at the Lunar and Planetary Science Conference (LPSC) being held in Texas and virtually. Among the discoveries presented, one tied Pluto's puzzling flip to its ice-filled basin, another found interesting but puzzling landscapes on the dwarf planet's surface, and a third unveiled the building blocks that formed the snowman-like object Arrokoth, which New Horizons flew by on Jan. 1, 2019.
Pluto's flip tied to Sputnik Planitia
While scientists know that Pluto, like Earth, flipped on its side sometime in its past, Pluto's orientation before the flip and the degree to which it reoriented itself has not been well understood. Scientists who use New Horizons data to study Pluto's geologic past hope to find clues that explain this event.
Now, a group of researchers has attributed Pluto's flip to the formation of Sputnik Planitia, a 620-mile-wide (1,000 km) basin that makes up half of the iconic heart-shaped region on Pluto. Researchers previously knew that Sputnik, which is filled with nitrogen ice, played a profound role in realigning the dwarf planet's surface.
Using images that New Horizons sent home from the 2015 flyby, they are now trying to trace the path of Pluto's flip. In doing so, they found parallel mountain ranges and deep valleys that form what they think is a global tectonic system. These features are more than 186 miles (300 km) wide and span a similar distance from Pluto's north pole.
However, the fact that Pluto changed its orientation in the past reveals that none of the terrains scientists now see is in its original location.
"We can't really explain that in Pluto's current configuration," Oliver White, a New Horizons co-investigator at the SETI (Search for Extraterrestrial Intelligence) Institute in California, said during a presentation Tuesday at LPSC. Instead, these features likely existed along Pluto's equator early on and migrated to their current locations nearer the poles because of the flip, he said.
White's team also found that Pluto's subsurface ocean likely provided some push to Sputnik and helped shift a bulk of the dwarf planet's mass toward its equator.
The line in red reflects the system of valleys and mountain ranges that scientists think migrated from Pluto's equator to their current positions near its poles. (Image credit: James Tuttle Keane (JPL/Caltech)/NASA/Johns Hopkins APL/SwRI
Massive knife-like methane ice deposits extend to Pluto's far side
In addition to helping scientists study ancient landscapes on Pluto, New Horizons data is providing clues about its more recent features.
The spacecraft had previously spotted massive methane deposits near Pluto's equator, many as tall as Earth's skyscrapers. Scientists announced Tuesday that they had a new line of evidence suggesting that these knife-like landforms also extend to the far side of Pluto — beyond what New Horizons was able to see during its 2015 flyby.
"The discovery of these features just adds to our understanding of the processes that shape Pluto and other icy planets in our solar system and highlights the complexity, dynamic nature and diversity of planetary surfaces like Pluto's," Ishan Mishra, a postdoctoral researcher at NASA's Jet Propulsion Laboratory in California, said in a statement(opens in new tab).
On Earth, such pillars are called penitentes; they are made of water ice and stretch for just a few meters. On Pluto, however, these features primarily exist on the highest points on its surface and soar for hundreds of meters. At such heights, methane freezes out of Pluto's wispy atmosphere in cold weather and evaporates back into its gaseous state during warmer spells.
The team behind the latest study used images snapped by the Long Range Reconnaissance Imager (LORRI) onboard New Horizons, and studied how the light reflected from surfaces changes with different viewing angles.
Doing so, they found similar methane absorption features on the far side of Pluto, thanks to the surfaces being "rougher than average roughness of Pluto," Mishra said during his presentation. Such "bladed" terrains are likely one of the most common landforms on Pluto, he added.
New Horizons scientists are seeing evidence that so-called bladed terrain — a direct response of the landscape to Pluto's changing climate, marked in red on this map — extends across much of the planet. (Image credit: NASA/Johns Hopkins APL/SwRI
Piecing together Arrokoth's long-ago merger
On Jan. 1, 2019, New Horizons passed a small object in the Kuiper Belt called Arrokoth, which looks like a partially flattened snowman. Located 4 billion miles (6.6 billion km) from Earth, it became the farthest object ever explored by a spacecraft. It is also the most primitive, thanks to its distance from the sun that keeps in a "deep freeze."
Arrokoth is a gentle fusion of two objects that once orbited each other. The larger of the two lobes, called Wenu, is itself a pile of 12 rocks huddled around a bigger slab, scientists announced on Tuesday. The latest findings show that Wenu formed not as a whole, but by pieces of rock that already existed in the outer reaches of the solar system.
"This is surprising, and a new piece in the puzzle of how planetesimals — building blocks of the planets — like Arrokoth and other Kuiper Belt objects come together," New Horizons principal investigator Alan Stern, from the Southwest Research Institute in Colorado, said in a statement(opens in new tab).
Early in the history of the solar system, millions of kilometer-sized icy objects made up a vast, donut-shaped region at its edge called the Kuiper Belt. A few of them amalgamated to form Wenu, Stern said, but these tiny objects did not merge at high speeds, which explains why Wenu is elongated the way it is. (When objects merge at high speeds, their spin throws away material, forming circular bodies.) Since the rocks have retained their shape even after merging, Stern's team estimates that they would have been traveling less than 1 meter per second when they coalesced.
Previous research showed that Wenu tidally interacted with the smaller of the two objects; both lost some angular momentum by ejecting material and eventually merged to form today's Arrokoth.
The individual rocks look like "Lego pieces" and have similar sizes, compositions and colors, all of which tell us "something very important about the formation of Arrokoth," Stern said during his presentation at the conference.
Stern's team found that each of Arrokoth's 12 rocks are more than 3 miles (5 km) wide. Given that Wenu is only 6 miles (10 km) thick, scientists think the 12 rocks clustered around Wenu's equator make up a bulk of its body and also extend to its far side, which wasn't seen by New Horizons.
Looking inward: A unique view of Uranus and Neptune
Scientists also announced on Tuesday that future New Horizons observations will include clicking color images of both Uranus and Neptune. From its distinct vantage point in the Kuiper Belt, the spacecraft will be well placed for observations that "can only be done by a spacecraft far beyond Uranus and Neptune," said Stern.
Spacecraft within the solar system can only see light reflected from the ice giants inward, or from their sides facing Earth. New Horizons, though, will be able to collect data about the light scattered from the far sides of the planets.
Unlike the test images it clicked in 2019, future observations will be taken as the planets rotate, scientists announced on Tuesday. They say the new images, despite being low resolution that show the two ice giants no clearer than pale blue dots, will help researchers understand more about how cloud structures evolve on the two ice giants.
On June 1, 2022, scientists put New Horizons "to sleep" to save fuel, and the spacecraft woke up from its 10-month hibernation on March 1. From the third week of April, scientists expect the spacecraft to begin studying distant Kuiper Belt objects as well as the two outer gas giants.
The observations about Uranus and Neptune are "going to be very exciting when they do come along," said Will Grundy, a New Horizons co-investigator from Lowell Observatory in Arizona. New Horizons researchers will collaborate with those working with the Hubble Space Telescope, he added.
"The science return is better than either spacecraft can provide on its own," Grundy said in a statement(opens in new tab). "It also sets the stage for observations of similar ice giant planets around other stars."
Quelle: SC
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Update: 6.05.2023
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Hard feelings over mission change for NASA’s Pluto spacecraft
US space agency plans to shift the New Horizons planetary probe to studying heliophysics, and some scientists don’t agree.
In the distant reaches of the Solar System, more than 8 billion kilometres from Earth, NASA’s New Horizons spacecraft is at the centre of a dispute over its future.
The craft, which snapped stunning images during humanity’s first visit to Pluto in 2015, is within a few years of exiting the Kuiper belt, the realm of frozen objects that orbit the Sun beyond Neptune. In addition to Pluto, it has flown past another Kuiper belt object called Arrokoth, but has not found a third object to visit before it leaves. So NASA now plans to repurpose the spacecraft mainly as a heliophysics mission, to study space weather and other phenomena that it can measure from its unique location in the Solar System.
But some are unhappy with the decision, and worry that planetary studies are being truncated too soon. “Scientifically, I just don’t feel that we’re at diminishing returns yet,” says Kelsi Singer, the mission’s project scientist at the Southwest Research Institute in Boulder, Colorado.
Shifting New Horizons from being a planetary explorer to an interstellar emissary echoes what the agency did with the twin Voyager spacecraft after they visited the outer planets in the 1980s. “We have this perfectly working spacecraft that’s in a unique area,” says Nicola Fox, head of NASA’s science mission directorate in Washington DC. The agency wants to get the “best use” out of it, she says, as well as “open it up to as many scientists from as many disciplines as are interested”.
A mission takeover?
No one disputes that New Horizons has made stunning discoveries in the Kuiper belt, which contains debris left over from the Solar System’s early history. The spacecraft has uncovered secrets of Pluto’s icy surface and revealed more about how the building blocks of planets might have come together. Its 2019 fly-by of Arrokoth, a 35-kilometre-long Kuiper belt object made of two chunks of stuck-together space rock, “taught us so much about fundamental properties of planetary formation — completely transformational”, says Michele Bannister, a planetary scientist at the University of Canterbury in Christchurch, New Zealand.
New Horizons visited the Kuiper belt object Arrokoth in 2019.Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Roman Tkachenko
Without another Kuiper belt object to fly by, the planetary science for New Horizons becomes harder to justify, some say. Tensions arose last year after NASA’s planetary science division conducted a ‘senior review’ of its operational missions, as it does every few years. A panel of scientists evaluated eight missions, including New Horizons, for their recent scientific performance and future promise.
That review rated New Horizons’ current science as “excellent/very good” if planetary science, astrophysics and heliophysics were all included. The rating slid to “very good/good” for planetary science alone, in part because the science team’s proposed studies of Kuiper belt objects were “unlikely to dramatically improve the state of knowledge”, the review said. (The mission’s science team disputes that conclusion.)
NASA used the review in its decision to shift the spacecraft to being managed as a heliophysics mission, says Lori Glaze, head of the agency’s planetary science division. “Because that’s where the strength lies — in the science that can be conducted from here forward,” she says.
NASA will fund the mission from its planetary science budget until 30 September 2024. After that, management could be taken over by the much smaller heliophysics division, potentially involving a new group of scientists. In March, NASA asked US researchers for ideas on what science New Horizons could do across all disciplines, “to gauge the level of interest of the wider science community in pursuing the next phase of science leadership for the mission, and to estimate appropriate annual costs”.
To the mission’s current science team, this amounts to a takeover. “There’s going to be a boarding party on the first of October next year,” says Alan Stern, the mission’s principal investigator, who is also at the Southwest Research Institute. Fox responds that the New Horizons team was invited to submit a proposal to lead the spacecraft’s science in the heliophysics division starting in October 2024, and that the researchers declined.
Full replacement of a mission’s science team is relatively rare, says Amanda Hendrix, a researcher at the Planetary Science Institute in Boulder, Colorado. “This is kind of new territory that we’re getting into.”
In a ‘unique position’
Now the question is what science can still be done with New Horizons, and how. Although its plutonium power source is waning with time, it has enough to last probably another quarter of a century.
The craft is currently in the outer part of the Kuiper belt (see ‘Out there’), about which little is known because it can’t be observed well from Earth. “New Horizons is in a very unique position, and there’s basically no other way to get this information,” Singer says.
Source: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
Among other studies, New Horizons has been taking repeated pictures of distant Kuiper belt objects, building up information on their shapes and surface properties. The spacecraft also analyses dust in the Kuiper belt — data that can shed light on how often space rocks smash into each other.
In recent years, the spacecraft has begun to broaden its focus. In astrophysics, New Horizons’ location allows it to study several types of background light that permeate the Solar System. And in heliophysics, ongoing and future studies are exploring the floods of charged particles emanating from the Sun. “It’s very valuable in conjunction with the two Voyagers,” says Stamatios Krimigis, a space physicist and the only scientist who has been involved with missions to all of the Solar System’s planets and Pluto.
New Horizons, which cost US$780 million to build, launch and fly past Pluto, currently costs NASA around $10 million annually. Both Fox and Glaze told Nature that the decision to shift the mission away from planetary science was not driven by budgetary issues, such as those that have delayed a Venus mission and raised concerns over the cost of Mars sample return.
Both also said that if a Kuiper belt object were found that New Horizons could reach, NASA would be open to discussing that, even if the mission had already been shifted to heliophysics. Stern and his team continue to look for a fly-by target in the time they have left.
Quelle: nature
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Debate rages about future of New Horizons
LAUREL, Md. — NASA and the science team for a spacecraft in the outer reaches of the solar system are locked in a dispute about the future of that mission and the science it can perform.
The uncertainty about the future of the New Horizons mission started last year when NASA reviewed a proposal from the mission’s science team for a second extended mission. The spacecraft, launched in 2006, flew by Pluto in 2015 and the Kuiper Belt object Arrokoth in early 2019, and will continue to traverse the Kuiper Belt through 2028.
The project team had proposed a multidisciplinary science mission for New Horizons, conducing a mix of astrophysics, heliophysics and planetary science research. The focus is “only things that can be done by dint of being at that great distance or in the Kuiper Belt,” said Alan Stern, principal investigator for New Horizons, at a meeting of the Outer Planets Assessment Group (OPAG) here May 3.
NASA, as part of the planetary science senior review that considered proposals from New Horizons and other spacecraft seeking extended missions, only approved funding for two years, rather than three as requested. The agency elected to fund New Horizons through fiscal year 2024 as part of the planetary science division, then have the mission compete in a separate senior review for the heliophysics division for fiscal year 2025 and beyond.
The agency’s rationale was that the planetary science that New Horizons could do was less compelling than astrophysics and heliophysics. The senior review gave the overall proposal a score of “excellent/very good”, the second-highest possible score, but the planetary portion was rated “very good/good”, two levels lower.
“The proposed Kuiper belt object (KBO) studies are unlikely to dramatically improve the state of knowledge,” the senior review report stated. New Horizons would be able to observe several KBOs at a distance, and at viewing angles not possible from the Earth, but the report concluded that those observations would not be competitive with ground-based observations.
“We think that this is shortsighted,” Stern said. “It was the only mission ever sent and the only mission planned to study the Kuiper Belt, and we’re still there.”
He said that while the mission was invited to submit a proposal to the heliophysics senior review, it has decided not to do so. His concern was that New Horizons would become an “infrastructure” mission for heliophysics without a dedicated science team but instead teams that run the spacecraft’s instruments. “I dub them ‘zombie’ teams.”
“Writing a proposal to walk the plank, if you will, writing a proposal for the entire science team to be disbanded, did not look like something that we wanted to do,” Stern said. “We were afraid that the proposal would be accepted.”
That puts the future of New Horizons after fiscal year 2024 in limbo. “We are in a quandary. I don’t know what we’re going to do about it,” said Curt Niebur, lead scientist for flight programs in NASA’s planetary science division, at the OPAG meeting. NASA had hoped the mission would accept the senior review outcome. “That path is broken.”
He acknowledges, though, there had been a “miscommunication” on NASA’s part about the ability of New Horizons to do planetary science, particularly if scientists find a Kuiper Belt object in range of the spacecraft for a close flyby. “Should a KBO be found, yes, let’s talk about it. Let’s see if it’s reachable,” he said. “Let’s continue the search and we’ll take that up at the time that we find it.”
However, another KBO flyby appears unlikely. “It’s a needle-in-a-haystack problem. We’re looking,” he said, efforts that have included upgrading an instrument on the Subaru Telescope in Hawaii to better look for targets. “The odds are against us.”
That search, he argued, would become impossible if NASA’s plans for New Horizon go forward. “I doubt we’ll get any telescope time in 2024 because the planetary portion of the mission is ending,” he said, as observatories decide to allocate telescope time to others.
In March, NASA issued a request for information for a potential “New Horizons Interstellar Mission” that would continue the mission after fiscal year 2024. It sought ideas for heliophysics and other science the mission could do in 2025 through 2027 “to gauge the level of interest of the wider science community in pursuing the next phase of science leadership for the mission” and the costs to do so.
The document stated that “mission operations would be terminated at the end of the second extended mission” at the end of fiscal year 2024, but both Niebur and Stern emphasized at the OPAG meeting that there are no plans by NASA to turn off the spacecraft.
“The senior review did not suggest that the mission be truncated,” Niebur said. “NASA is not suggesting we turn off New Horizons.”
“NASA is not planning to turn the spacecraft off, simply to terminate the planetary mission and to dismiss the planetary team,” Stern said.
“We need to finish the Kuiper Belt,” Stern said, “We finally got a spacecraft here. We’re going to leave the Kuiper Belt in a few years. Why so impatient over pennies out of the planetary budget?”
Some at the OPAG meeting suggested that a solution would require some improved cooperation among NASA’s science divisions, including perhaps a more equitable sharing of mission costs. “Meritorious science can be achieved in heliophysics, astrophysics and planetary science but science optimization will require creative problem solving and cross-divisional leadership,” the senior review report stated.
“The longer you explore space, the more cross-divisional it becomes,” said Pontus Brandt of the Applied Physics Lab, who joined the New Horizons science team last year to support heliophysics studies. “Nature doesn’t really care about divisions and we need to figure out how to support that.”
Quelle: SN
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Update: 27.08.2023
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NASA's New Horizons mission faces an uncertain future (op-ed)
Adrift in the Kuiper Belt?
For 17 years, the New Horizons spacecraft has hurtled at unprecedented speed through the solar system. Launched in 2006, it flew past Pluto in July 2015, returning the first close-up images of the planet and its moon. Then, in 2019, the probe reconnoitered the Kuiper Belt Object (KBO) Arrokoth. Both encounters returned astonishing images and a treasure trove of transformative data.
With its budget being trimmed for 2024, NASA is making some weighty decisions... and one includes drastically trimming New Horizons funds by replacing the current science staff with a new team in an effort to save about $3 million—a rounding error in terms of the planetary science budget.
The principal investigator of the mission from its earliest days, Dr. Alan Stern, is not happy about the situation. "New Horizons is the only spacecraft in the Kuiper Belt, and the only one currently planned to go there. We have valuable new Kuiper Belt observations, and a search for a new flyby target, still to complete every year until we leave the Belt. Quitting this exploration prematurely, after spending nearly $1 billion to get New Horizons to the Kuiper Belt, seems to many of us to be tragically mistaken, a poor use of taxpayer money, and a lost scientific opportunity that can never be recovered from."
Rod Pyle is a space historian and author who has created and offered executive leadership and innovation training at NASA's Johnson Space Center. Rod has received endorsements and recognition from the outgoing Deputy Director of NASA, Johnson Space Center's Chief Knowledge Officer for his work.
As it stands, New Horizons will exit the Kuiper Belt around 2028 and should continue operating until 2050. "The spacecraft continues flying in excellent health today, returning data from the outer reaches of the solar system and preparing for a possible encounter with another KBO. Recent events, however, threaten the continued progress of this Kuiper Belt mission," Stern added.
While we can expect cuts across a variety of NASA programs and missions, the current New Horizons budget is about on par with other long-serving veterans of deep space explorations, Voyagers 1 and 2. We're talking well under $10 million per year, which in government terms is a pittance ... especially when you consider the expense of getting the spacecraft where they are today. That is a sunk cost, and the potential, congoing science returns from the mission are the dividends.
When New Horizons flew past Pluto, it returned an unprecedented look at the previously mysterious world and its large moon, Charon. Previous to this, the best images of Pluto came from the Hubble Space Telescope and were mere smudges just a few pixels across. The imagery and data returned from New Horizons upended many assumptions about not just Pluto and Charon, but also about the outer solar system.
"New Horizons literally wrote the book on Pluto and its system of moons. Before New Horizons, almost nothing was known. Today the New Horizons spacecraft and team have made Pluto one of the best known worlds in the solar system," Stern said.
New Horizons' next adventure was in the Kuiper Belt, the region beyond Neptune's orbit which is filled with rock and ice left over from the earliest era of the solar system. Stern's team targeted the KBO 486958 Arrokoth, which turned out to be another golden opportunity.
"Arrokoth may have been more important than our discoveries at Pluto," Stern commented. "For decades, there have been two warring computer models about how planets got their start and planetesimal formation. One was through high-speed collisions in their orbit around the sun, and the other was through local collapse clouds with very gentle collisions." After a thorough examination of Arrokoth, the latter model was validated. "It turns out these objects collided at very low speeds, more like how you might walk into a wall as opposed to supersonic impacts. When we saw Arrokoth up close, we realized from its shape and general surface geology that it had been built through gentle accretion," he added. Only though direct observation could this argument have been settled.
If NASA ends up cutting funding to this modestly budgeted mission, a new team would be installed—presumably one with no direct experience in outer solar system operations—with the focus shifted to low-level data gathering about heliophysics, the distant plasma environment of the sun. This reduced mission would utilize just a small fraction of the spacecraft's ongoing science capability.
"We've been in flight for going on 18 years, and we have every prospect of flying as long as the Voyagers," now going on 46 years, Stern said. "At that point we would be well beyond Kuiper Belt exploration and into interstellar space." Notably, while the Voyagers are currently exploring that same interstellar region, they are doing so with ancient 1970s technology and instruments that are being shut down as they age out, with mission operations scheduled to be slimmed down until they cease within a decade or so. "New Horizons should be able to continue until at least the middle of the 21st century," Stern added, "with nearly state-of-the-art instrumentation that will be capable of shifting our view of interstellar space just as it has changed our understanding of Pluto and KBOs. But none of that justifies curtailing the current exploration of the Kuiper Belt."
With a nearly $1 billion spacecraft and modern suite of instruments at stake, it seems incredibly wasteful to ignore the vast trove of valuable, one-of-a-kind data that would be lost with a mission shift—data that includes Kuiper Belt clues about the very formation of our solar system.
Groups like the National Space Society and others have placed a petition, to be forwarded to NASA and Congress, on Change.org. Prominent voices supporting the continuation of the mission as currently implemented include famed rock musician and astrophysicist Sir Brian May, former NASA Deputy Administrator Lori Garver, and science communicator Bill Nye.
Only through public action will our voices be heard and the mission continued at its full capability. It may be many decades before another robotic craft is sent this way; perhaps longer. Your voice counts. Go to the Save New Horizons petition page to let NASA know that science matters.
