The spacecraft, built by Maxar Space Systems, will operate its electric thrusters for the equivalent of three months between now and November to keep the mission on track for arrival at asteroid Psyche in 2029.
“Through comprehensive testing and analysis, the team narrowed down the potential causes to a valve that may have malfunctioned in the primary line,” NASA said in a statement Friday. “The switch to the identical backup propellant line in late May restored full functionality to the propulsion system.”
The next waypoint on Psyche’s voyage will be a flyby of Mars in May 2026. Officials expect Psyche to keep that date, which is critical for using Mars’ gravity to slingshot the spacecraft deeper into the Solar System, eventually reaching the asteroid belt about four years from now.
NASA’s Psyche spacecraft takes a spiral path to the asteroid Psyche, as depicted in this graphic that shows the path from above the plane of the planets, labeled with key milestones of the prime mission. Credit: NASA/JPL-Caltech
At Psyche, the spacecraft will enter orbit and progressively move closer to the asteroid, using a suite of sensors to map its surface, measure its shape, mass, and gravity field, and determine its elemental composition. Observations through telescopes suggest Psyche is roughly 140 miles (226 kilometers) in diameter, or about the width of Massachusetts. But it’s likely not spherical in shape. Scientists describe its shape as more akin to a potato.
Potatoes come in lots of shapes, and researchers won’t know exactly what Psyche looks like until NASA’s asteroid explorer arrives in 2029. Psyche will be the first metallic, or M-type, asteroid visited by any spacecraft, and scientists are eager to study an object that’s largely made of metals—probably iron, nickel, and perhaps some rarer elements— instead of rocky minerals.
With the Psyche spacecraft’s plasma thrusters back in action, these goals of NASA’s billion-dollar science mission remain achievable.
“The mission team’s dedication and systematic approach to this investigation exemplifies the best of NASA engineering,” said Bob Mase, Psyche project manager at JPL, in a statement. “Their thorough diagnosis and recovery, using the backup system, demonstrates the value of robust spacecraft design and exceptional teamwork.”
But there’s still a lingering concern whatever problem caused the valve to malfunction in the primary fuel line might also eventually affect the same kind of valve in the backup line.
“We are doing a lot of good proactive work around that possible issue,” wrote Lindy Elkins-Tanton, Psyche’s principal investigator at Arizona State University, in a post on X.
If signed into law as written, the White House’s proposal to slash nearly 25 percent from NASA’s budget would have some dire consequences.
It would cut the agency’s budget from $24.8 billion to $18.8 billion. Adjusted for inflation, this would be the smallest NASA budget since 1961, when the first American launched into space.
The proposed funding plan would halve NASA’s funding for robotic science missions and technology development next year, scale back research on the International Space Station, turn off spacecraft already exploring the Solar System, and cancel NASA’s Space Launch System rocket and Orion spacecraft after two more missions in favor of procuring lower-cost commercial transportation to the Moon and Mars.
The SLS rocket and Orion spacecraft have been targets for proponents of commercial spaceflight for several years. They are single-use, and their costs are exorbitant, with Moon missions on SLS and Orion projected to cost more than $4 billion per flight. That price raises questions about whether these vehicles will ever be able to support a lunar space station or Moon base where astronauts can routinely rotate in and out on long-term expeditions, like researchers do in Antarctica today.
Reusable rockets and spaceships offer a better long-term solution, but they won’t be ready to ferry people to the Moon for a while longer. The Trump administration proposes flying SLS and Orion two more times on NASA’s Artemis II and Artemis III missions, then retiring the vehicles. Artemis II’s rocket is currently being assembled at Kennedy Space Center in Florida for liftoff next year, carrying a crew of four around the far side of the Moon. Artemis III would follow with the first attempt to land humans on the Moon since 1972.
The cuts are far from law
Every part of Trump’s budget proposal for fiscal year 2026 remains tentative. Lawmakers in each house of Congress will write their own budget bills, which must go to the White House for Trump’s signature. A Senate bill released last week includes language that would claw back funding for SLS and Orion to support the Artemis IV and Artemis V missions.
Comet 311P/PanSTARRS was observed by the Hubble Space Telescope in 2013 with a set of six comet-like tails radiating from its main body. This object, also called P/2013 P5, is known as an active asteroid. Credit: NASA, ESA, and D. Jewitt (UCLA)
Tianwen-2’s mothership, with 11 scientific instruments, will commence the second phase of its mission after dropping off the asteroid specimens at Earth. The probe’s next journey will bring it near an enigma in the asteroid belt, named 311P/PanSTARRS, in the mid-2030s. This object is one in a rare class of objects known as active asteroids or main-belt comets, small worlds that have tails and comas like comets but loiter in orbits most commonly associated with asteroids. Tianwen-2 will be the first mission to see such an object up close.
Stepping into the Solar System
Until the last few years, China’s space program has primarily centered on the Moon as a destination for scientific exploration. The Moon remains the main target for China’s ambitions in space, with the goal of accomplishing a human lunar landing by 2030. But the country is looking farther afield, too.
With the Tianwen-1 mission in 2021, China became the second country to achieve a soft landing on Mars. After Tianwen-2, China will again go to Mars with the Tianwen-3 sample return mission, slated for launch in 2028.
China is looking at launching Tianwen-4 around 2029 to travel to Jupiter and enter orbit around Callisto, one of its four largest moons. In the 2030s, China’s roadmap includes a mission to return atmospheric samples from Venus to Earth, a Mars research station, and a probe to Neptune.
Meanwhile, NASA has sent spacecraft to study every planet in the Solar System and currently has spacecraft at or on the way to the Moon, Mars, Jupiter, a metal asteroid, and to interstellar space. Another US science mission, Dragonfly, is scheduled for launch in 2028 on a daring expedition to Saturn’s moon Titan.
But NASA’s science division is bracing for severe budget cuts proposed by President Donald Trump. In planetary science, the White House’s budget blueprint calls for canceling a joint US-European Mars Sample Return mission and several other projects, including the DAVINCI mission to Venus.
An illustration depicts a NASA spacecraft approaching the metal-rich asteroid Psyche. Though there are no plans to mine Psyche, such asteroids are being eyed for their valuable resources. Credit: NASA/JPL-Caltech/ASU
Each electric thruster on Psyche generates just 250 milli-newtons of thrust, roughly equivalent to the weight of three quarters. But they can operate for months at a time, and over the course of a multi-year cruise, these thrusters provide a more efficient means of propulsion than conventional rockets.
The plasma thrusters are reshaping the Psyche spacecraft’s path toward its destination, a metal-rich asteroid also named Psyche. The spacecraft’s four electric engines, known as Hall effect thrusters, were supplied by a Russian company named Fakel. Most of the other components in Psyche’s propulsion system—controllers, xenon fuel tanks, propellant lines, and valves—come from other companies or the spacecraft’s primary manufacturer, Maxar Space Systems, in California.
The Psyche mission is heading first for Mars, where the spacecraft will use the planet’s gravity next year to slingshot itself into the asteroid belt, setting up for arrival and orbit insertion around the asteroid Psyche in August 2029.
Psyche launched in October 2023 aboard a SpaceX Falcon Heavy rocket on the opening leg of a six-year sojourn through the Solar System. The mission’s total cost adds up to more than $1.4 billion, including development of the spacecraft and its instruments, the launch, operations, and an experimental laser communications package hitching a ride to deep space with Psyche.
Psyche, the asteroid, is the size of Massachusetts and circles the Sun in between the orbits of Mars and Jupiter. No spacecraft has visited Psyche before. Of the approximately 1 million asteroids discovered so far, scientists say only nine have a metal-rich signature like Psyche. The team of scientists who put together the Psyche mission have little idea of what to expect when the spacecraft gets there in 2029.
Metallic asteroids like Psyche are a mystery. Most of Psyche’s properties are unknown other than estimates of its density and composition. Predictions about the look of Psyche’s craters, cliffs, and color have inspired artists to create a cacophony of illustrations, often showing sharp spikes and grooves alien to rocky worlds.
In a little more than five years, assuming NASA gets past Psyche’s propulsion problem, scientists will supplant speculation with solid data.
More data will likely reduce the chance of an impact to zero. If not, we have options.
Discovery images of asteroid 2024 YR4. Credit: ATLAS
Something in the sky captured the attention of astronomers in the final days of 2024. A telescope in Chile scanning the night sky detected a faint point of light, and it didn’t correspond to any of the thousands of known stars, comets, and asteroids in astronomers’ all-sky catalog.
The detection on December 27 came from one of a network of telescopes managed by the Asteroid Terrestrial-impact Last Alert System (ATLAS), a NASA-funded project to provide warning of asteroids on a collision course with Earth.
Within a few days, scientists gathered enough information on the asteroid—officially designated 2024 YR4—to determine that its orbit will bring it quite close to Earth in 2028, and then again in 2032. Astronomers ruled out any chance of an impact with Earth in 2028, but there’s a small chance the asteroid might hit our planet on December 22, 2032.
How small? The probability has fluctuated in recent days, but as of Thursday, NASA’s Center for Near Earth Object Studies estimated a 1.9 percent chance of an impact with Earth in 2032. The European Space Agency (ESA) put the probability at 1.8 percent. So as of now, NASA believes there’s a 1-in-53 chance of 2024 YR4 striking Earth. That’s about twice as likely as the lifetime risk of dying in a motor vehicle crash, according to the National Safety Council.
These numbers are slightly higher than the probabilities published last month, when ESA estimated a 1.2 percent chance of an impact. In a matter of weeks or months, the number will likely drop to zero.
No surprise here, according to ESA.
“It is important to remember that an asteroid’s impact probability often rises at first before quickly dropping to zero after additional observations,” ESA said in a press release. The agency released a short explainer video, embedded below, showing how an asteroid’s cone of uncertainty shrinks as scientists get a better idea of its trajectory.
Refining the risk
Scientists estimate that 2024 YR4 is between 130 to 300 feet (40 and 90 meters) wide, large enough to cause localized devastation near the impact site. The asteroid responsible for the Tunguska event of 1908, which leveled some 500 square miles (1,287 square kilometers) of forest in remote Siberia, was probably about the same size. The meteor that broke apart in the sky over Chelyabinsk, Russia, in 2013 was about 20 meters wide.
Astronomers use the Torino scale for measuring the risk of potential asteroid impacts. Asteroid 2024 YR4 is now rated at Level 3 on this scale, meaning it merits close attention from astronomers, the public, and government officials. This is the second time an asteroid has reached this level since the scale’s adoption in 1999. The other case happened in 2004, when asteroid Apophis briefly reached a Level 4 rating until further observations of the asteroid eliminated any chance of an impact with the Earth in 2029.
In the unlikely event that it impacts the Earth, an asteroid the size of 2024 YR4 could cause blast damage as far as 30 miles (50 kilometers) from the location of the impact or airburst if the object breaks apart in the atmosphere, according to the International Asteroid Warning Network (IAWN), established in the aftermath of the Chelyabinsk event.
The asteroid warning network is affiliated with the United Nations. Officials activate the IAWN when an asteroid bigger than 10 meters has a greater than 1 percent chance of striking Earth within the next 20 years. The risk of 2024 YR4 meets this threshold.
The red points on this image show the possible locations of asteroid 2024 YR4 on December 22, 2032, as projected by a Monte Carlo simulation. As this image shows, most of the simulations project the asteroid missing the Earth. Credit: ESA/Planetary Defense Office
Determining the asteroid’s exact size will be difficult. Scientists would need deep space radar observations, thermal infrared observations, or imagery from a spacecraft that could closely approach the asteroid, according to the IAWN. The asteroid won’t come close enough to Earth for deep space radar observations until shortly before its closest approach in 2032.
Astronomers need numerous observations to precisely plot an asteroid’s motion through the Solar System. Over time, these observations will reduce uncertainty and narrow the corridor the asteroid will follow as it comes near Earth.
Scientists already know a little about asteroid 2024 YR4’s orbit, which follows an elliptical path around the Sun. The orbit brings the asteroid inside of Earth’s orbit at its closest point to the Sun and then into the outer part of the asteroid belt when it is farthest from the Sun.
But there’s a complication in astronomers’ attempts to nail down the asteroid’s path. The object is currently moving away from Earth in almost a straight line. This makes it difficult to accurately determine its orbit by studying how its trajectory curves over time, according to ESA.
It also means observers will need to use larger telescopes to see the asteroid before it becomes too distant to see it from Earth in April. By the end of this year’s observing window, the asteroid warning network says the impact probability could increase to a couple tens of percent, or it could more likely drop back below the notification threshold (1 percent impact probability).
“It is possible that asteroid 2024 YR4 will fade from view before we are able to entirely rule out any chance of impact in 2032,” ESA said. “In this case, the asteroid will likely remain on ESA’s risk list until it becomes observable again in 2028.”
Planetary defenders
This means that public officials might need to start planning what to do later this year.
For the first time, an international board called the Space Mission Planning Advisory Group met this week to discuss what we can do to respond to the risk of an asteroid impact. This group, known as SMPAG, coordinates planning among representatives from the world’s space agencies, including NASA, ESA, China, and Russia.
The group decided on Monday to give astronomers a few more months to refine their estimates of the asteroid’s orbit before taking action. They will meet again in late April or early May or earlier if the impact risk increases significantly. If there’s still a greater than 1 percent probability of 2024 YR4 hitting the Earth, the group will issue a recommendation for further action to the United Nations Office for Outer Space Affairs.
So what are the options? If the data in a few months still shows that the asteroid poses a hazard to Earth, it will be time for the world’s space agencies to consider a deflection mission. NASA demonstrated its ability to alter the orbit of an asteroid in 2022 with a first-of-its-kind experiment in space. The mission, called DART, put a small spacecraft on a collision course with an asteroid two to four times larger than 2024 YR4.
The kinetic energy from the spacecraft’s death dive into the asteroid was enough to slightly nudge the object off its natural orbit around a nearby larger asteroid. This proved that an asteroid deflection mission could work if scientists have enough time to design and build it, an undertaking that took about five years for DART.
Italy’s LICIACube spacecraft snapped this image of asteroids Didymos (lower left) and Dimorphos (upper right) a few minutes after the impact of DART on September 26, 2022. Credit: ASI/NASA
A deflection mission is most effective well ahead of an asteroid’s potential encounter with the Earth, so it’s important not to wait until the last minute.
Fans of Hollywood movies know there’s a nuclear option for dealing with an asteroid coming toward us. The drawback of using a nuclear warhead is that it could shatter one large asteroid into many smaller objects, although recent research suggests a more distant nuclear explosion could produce enough X-ray radiation to push an asteroid off a collision course.
Waiting for additional observations in 2028 would leave little time to develop a deflection mission. Therefore, in the unlikely event that the risk of an impact rises over the next few months, it will be time for officials to start seriously considering the possibility of an intervention.
Even without a deflection, there’s plenty of time for government officials to do something here on Earth. It should be possible for authorities to evacuate any populations that might be affected by the asteroid.
The asteroid could devastate an area the size of a large city, but any impact is most likely to happen in a remote region or in the ocean. The risk corridor for 2024 YR4 extends from the eastern Pacific Ocean to northern South America, the Atlantic Ocean, Africa, the Arabian Sea, and South Asia.
There’s an old joke that dinosaurs went extinct because they didn’t have a space program. Whatever happens in 2032, we’re not at risk of extinction. However, occasions like this are exactly why most Americans think we should have a space program. A 2019 poll showed that 68 percent of Americans considered it very or extremely important for the space program to monitor asteroids, comets, or other objects from space that could strike the planet.
In contrast, about a quarter of those polled placed such importance on returning astronauts to the Moon or sending people to Mars. The cost of monitoring and deflecting asteroids is modest compared to the expensive undertakings of human missions to the Moon and Mars.
From taxpayers’ point of view, it seems this part of NASA offers the greatest bang for their buck.
Stephen Clark is a space reporter at Ars Technica, covering private space companies and the world’s space agencies. Stephen writes about the nexus of technology, science, policy, and business on and off the planet.
“We want to have the quickest, cheapest way to get these 30 samples back.”
This photo montage shows sample tubes shortly after they were deposited onto the surface by NASA’s Perseverance Mars rover in late 2022 and early 2023. Credit: NASA/JPL-Caltech/MSSS
For nearly four years, NASA’s Perseverance rover has journeyed across an unexplored patch of land on Mars—once home to an ancient river delta—and collected a slew of rock samples sealed inside cigar-sized titanium tubes.
These tubes might contain tantalizing clues about past life on Mars, but NASA’s ever-changing plans to bring them back to Earth are still unclear.
On Tuesday, NASA officials presented two options for retrieving and returning the samples gathered by the Perseverance rover. One alternative involves a conventional architecture reminiscent of past NASA Mars missions, relying on the “sky crane” landing system demonstrated on the agency’s two most recent Mars rovers. The other option would be to outsource the lander to the space industry.
NASA Administrator Bill Nelson left a final decision on a new mission architecture to the next NASA administrator working under the incoming Trump administration. President-elect Donald Trump nominated entrepreneur and commercial astronaut Jared Isaacman as the agency’s 15th administrator last month.
“This is going to be a function of the new administration in order to fund this,” said Nelson, a former Democratic senator from Florida who will step down from the top job at NASA on January 20.
The question now is: will they? And if the Trump administration moves forward with Mars Sample Return (MSR), what will it look like? Could it involve a human mission to Mars instead of a series of robotic spacecraft?
The Trump White House is expected to emphasize “results and speed” with NASA’s space programs, with the goal of accelerating a crew landing on the Moon and sending people to explore Mars.
NASA officials had an earlier plan to bring the Mars samples back to Earth, but the program slammed into a budgetary roadblock last year when an independent review team concluded the existing architecture would cost up to $11 billion—double the previous cost projection—and wouldn’t get the Mars specimens back to Earth until 2040.
This budget and schedule were non-starters for NASA. The agency tasked government labs, research institutions, and commercial companies to come up with better ideas to bring home the roughly 30 sealed sample tubes carried aboard the Perseverance rover. NASA deposited 10 sealed tubes on the surface of Mars a couple of years ago as insurance in case Perseverance dies before the arrival of a retrieval mission.
“We want to have the quickest, cheapest way to get these 30 samples back,” Nelson said.
How much for these rocks?
NASA officials said they believe a stripped-down concept proposed by the Jet Propulsion Laboratory in Southern California, which previously was in charge of the over-budget Mars Sample Return mission architecture, would cost between $6.6 billion and $7.7 billion, according to Nelson. JPL’s previous approach would have put a heavier lander onto the Martian surface, with small helicopter drones that could pick up sample tubes if there were problems with the Perseverance rover.
NASA previously deleted a “fetch rover” from the MSR architecture and instead will rely on Perseverance to hand off sample tubes to the retrieval lander.
An alternative approach would use a (presumably less expensive) commercial heavy lander, but this concept would still utilize several elements NASA would likely develop in a more traditional government-led manner: a nuclear power source, a robotic arm, a sample container, and a rocket to launch the samples off the surface of Mars and back into space. The cost range for this approach extends from $5.1 billion to $7.1 billion.
Artist’s illustration of SpaceX’s Starship approaching Mars. Credit: SpaceX
JPL will have a “key role” in both paths for MSR, said Nicky Fox, head of NASA’s science mission directorate. “To put it really bluntly, JPL is our Mars center in NASA science.”
If the Trump administration moves forward with either of the proposed MSR plans, this would be welcome news for JPL. The center, which is run by the California Institute of Technology under contract to NASA, laid off 955 employees and contractors last year, citing budget uncertainty, primarily due to the cloudy future of Mars Sample Return.
Without MSR, engineers at the Jet Propulsion Laboratory don’t have a flagship-class mission to build after the launch of NASA’s Europa Clipper spacecraft last year. The lab recently struggled with rising costs and delays with the previous iteration of MSR and NASA’s Psyche asteroid mission, and it’s not unwise to anticipate more cost overruns on a project as complex as a round-trip flight to Mars.
Ars submitted multiple requests to interview Laurie Leshin, JPL’s director, in recent months to discuss the lab’s future, but her staff declined.
Both MSR mission concepts outlined Tuesday would require multiple launches and an Earth return orbiter provided by the European Space Agency. These options would bring the Mars samples back to Earth as soon as 2035, but perhaps as late as 2039, Nelson said. The return orbiter and sample retrieval lander could launch as soon as 2030 and 2031, respectively.
“The main difference is in the landing mechanism,” Fox said.
To keep those launch schedules, Congress must immediately approve $300 million for Mars Sample Return in this year’s budget, Nelson said.
NASA officials didn’t identify any examples of a commercial heavy lander that could reach Mars, but the most obvious vehicle is SpaceX’s Starship. NASA already has a contract with SpaceX to develop a Starship vehicle that can land on the Moon, and SpaceX founder Elon Musk is aggressively pushing for a Mars mission with Starship as soon as possible.
NASA solicited eight studies from industry earlier this year. SpaceX, Blue Origin, Rocket Lab, and Lockheed Martin—each with their own lander concepts—were among the companies that won NASA study contracts. SpaceX and Blue Origin are well-capitalized with Musk and Amazon’s Jeff Bezos as owners, while Lockheed Martin is the only company to have built a lander that successfully reached Mars.
This slide from a November presentation to the Mars Exploration Program Analysis Group shows JPL’s proposed “sky crane” architecture for a Mars sample retrieval lander. The landing system would be modified to handle a load about 20 percent heavier than the sky crane used for the Curiosity and Perseverance rover landings. Credit: NASA/JPL
The science community has long identified a Mars Sample Return mission as the top priority for NASA’s planetary science program. In the National Academies’ most recent decadal survey released in 2022, a panel of researchers recommended NASA continue with the MSR program but stated the program’s cost should not undermine other planetary science missions.
Teeing up for cancellation?
That’s exactly what is happening. Budget pressures from the Mars Sample Return mission, coupled with funding cuts stemming from a bipartisan federal budget deal in 2023, have prompted NASA’s planetary science division to institute a moratorium on starting new missions.
“The decision about Mars Sample Return is not just one that affects Mars exploration,” said Curt Niebur, NASA’s lead scientist for planetary flight programs, in a question-and-answer session with solar system researchers Tuesday. “It’s going to affect planetary science and the planetary science division for the foreseeable future. So I think the entire science community should be very tuned in to this.”
Rocket Lab, which has been more open about its MSR architecture than other companies, has posted details of its sample return concept on its website. Fox declined to offer details on other commercial concepts for MSR, citing proprietary concerns.
“We can wait another year, or we can get started now,” Rocket Lab posted on X. “Our Mars Sample Return architecture will put Martian samples in the hands of scientists faster and more affordably. Less than $4 billion, with samples returned as early as 2031.”
Through its own internal development and acquisitions of other aerospace industry suppliers, Rocket Lab said it has provided components for all of NASA’s recent Mars missions. “We can deliver MSR mission success too,” the company said.
Rocket Lab’s concept for a Mars Sample Return mission. Credit: Rocket Lab
Although NASA’s deferral of a decision on MSR to the next administration might convey a lack of urgency, officials said the agency and potential commercial partners need time to assess what roles the industry might play in the MSR mission.
“They need to flesh out all of the possibilities of what’s required in the engineering for the commercial option,” Nelson said.
On the program’s current trajectory, Fox said NASA would be able to choose a new MSR architecture in mid-2026.
Waiting, rather than deciding on an MSR plan now, will also allow time for the next NASA administrator and the Trump White House to determine whether either option aligns with the administration’s goals for space exploration. In an interview with Ars last week, Nelson said he did not want to “put the new administration in a box” with any significant MSR decisions in the waning days of the Biden administration.
One source with experience in crafting and implementing US space policy told Ars that Nelson’s deferral on a decision will “tee up MSR for canceling.” Faced with a decision to spend billions of dollars on a robotic sample return or billions of dollars to go toward a human mission to Mars, the Trump administration will likely choose the latter, the source said.
If that happens, NASA science funding could be freed up for other pursuits in planetary science. The second priority identified in the most recent planetary decadal survey is an orbiter and atmospheric probe to explore Uranus and its icy moons. NASA has held off on the development of a Uranus mission to focus on the Mars Sample Return first.
Science and geopolitics
Whether it’s with robots or humans, there’s a strong case for bringing pristine Mars samples back to Earth. The titanium tubes carried by the Perseverance rover contain rock cores, loose soil, and air samples from the Martian atmosphere.
“Bringing them back will revolutionize our understanding of the planet Mars and indeed, our place in the solar system,” Fox said. “We explore Mars as part of our ongoing efforts to safely send humans to explore farther and farther into the solar system, while also … getting to the bottom of whether Mars once supported ancient life and shedding light on the early solar system.”
Researchers can perform more detailed examinations of Mars specimens in sophisticated laboratories on Earth than possible with the miniature instruments delivered to the red planet on a spacecraft. Analyzing samples in a terrestrial lab might reveal biosignatures, or the traces of ancient life, that elude detection with instruments on Mars.
“The samples that we have taken by Perseverance actually predate—they are older than any of the samples or rocks that we could take here on Earth,” Fox said. “So it allows us to kind of investigate what the early solar system was like before life began here on Earth, which is amazing.”
Fox said returning Mars samples before a human expedition would help NASA prioritize where astronauts should land on the red planet.
In a statement, the Planetary Society said it is “concerned that NASA is again delaying a decision on the program, committing only to additional concept studies.”
“It has been more than two years since NASA paused work on MSR,” the Planetary Society said. “It is time to commit to a path forward to ensure the return of the samples already being collected by the Perseverance rover.
“We urge the incoming Trump administration to expedite a decision on a path forward for this ambitious project, and for Congress to provide the funding necessary to ensure the return of these priceless samples from the Martian surface.”
China says it is developing its own mission to bring Mars rocks back to Earth. Named Tianwen-3, the mission could launch as soon as 2028 and return samples to Earth by 2031. While NASA’s plan would bring back carefully curated samples from an expansive environment that may have once harbored life, China’s mission will scoop up rocks and soil near its landing site.
“They’re just going to have a mission to grab and go—go to a landing site of their choosing, grab a sample and go,” Nelson said. “That does not give you a comprehensive look for the scientific community. So you cannot compare the two missions. Now, will people say that there’s a race? Of course, people will say that, but it’s two totally different missions.”
Still, Nelson said he wants NASA to be first. He said he has not had detailed conversations with Trump’s NASA transition team.
“I think it was a responsible thing to do, not to hand the new administration just one alternative if they want to have a Mars Sample Return,” Nelson said. “I can’t imagine that they don’t. I don’t think we want the only sample return coming back on a Chinese spacecraft.”
Stephen Clark is a space reporter at Ars Technica, covering private space companies and the world’s space agencies. Stephen writes about the nexus of technology, science, policy, and business on and off the planet.
Notably, the Dragonfly launch was one of the first times United Launch Alliance has been eligible to bid its new Vulcan rocket for a NASA launch contract. NASA officials gave the green light for the Vulcan rocket to compete head-to-head with SpaceX’s Falcon 9 and Falcon Heavy after ULA’s new launcher had a successful debut launch earlier this year. With this competition, SpaceX came out on top.
A half-life of 88 years
NASA’s policy for new space missions is to use solar power whenever possible. For example, Europa Clipper was originally supposed to use a nuclear power generator, but engineers devised a way for the spacecraft to use expansive solar panels to capture enough sunlight to produce electricity, even at Jupiter’s vast distance from the Sun.
But there are some missions where this isn’t feasible. One of these is Dragonfly, which will soar through the soupy nitrogen-methane atmosphere of Titan. Saturn’s largest moon is shrouded in cloud cover, and Titan is nearly 10 times farther from the Sun than Earth, so its surface is comparatively dim.
The Dragonfly mission, seen here in an artist’s concept, is slated to launch no earlier than 2027 on a mission to explore Saturn’s moon Titan. Credit: NASA/JHUAPL/Steve Gribben
Dragonfly will launch with about 10.6 pounds (4.8 kilograms) of plutonium-238 to fuel its power generator. Plutonium-238 has a half-life of 88 years. With no moving parts, RTGs have proven quite reliable, powering spacecraft for many decades. NASA’s twin Voyager probes are approaching 50 years since launch.
The Dragonfly rotorcraft will launch cocooned inside a transit module and entry capsule, then descend under parachute through Titan’s atmosphere, which is four times denser than Earth’s. Finally, Dragonfly will detach from its descent module and activate its eight rotors to reach a safe landing.
Once on Titan, Dragonfly is designed to hop from place to place on numerous flights, exploring environments rich in organic molecules, the building blocks of life. This is one of NASA’s most exciting, and daring, robotic missions of all time.
After launching from NASA’s Kennedy Space Center in Florida in July 2028, it will take Dragonfly about six years to reach Titan. When NASA selected the Dragonfly mission to begin development in 2019, the agency hoped to launch the mission in 2026. NASA later directed Dragonfly managers to target a launch in 2027, and then 2028, requiring the mission to change from a medium-lift to a heavy-lift rocket.
Dragonfly has also faced rising costs NASA blames on the COVID-19 pandemic and supply chain issues and an in-depth redesign since the mission’s selection in 2019. Collectively, these issues caused Dragonfly’s total budget to grow to $3.35 billion, more than double its initial projected cost.
Enlarge/ A “selfie” photo of China’s Zhurong rover and the Tianwen-1 landing platform on Mars in 2021.
China plans to launch two heavy-lift Long March 5 rockets with elements of the Tianwen-3 Mars sample return mission in 2028, the mission’s chief designer said Thursday.
In a presentation at a Chinese space exploration conference, the chief designer of China’s robotic Mars sample return project described the mission’s high-level design and outlined how the mission will collect samples from the Martian surface. Reports from the talk published on Chinese social media and by state-run news agencies were short on technical details and did not discuss any of the preparations for the mission.
Public pronouncements by Chinese officials on future space missions typically come true, but China is embarking on challenging efforts to explore the Moon and Mars. China aims to land astronauts on the lunar surface by 2030 in a step toward eventually building a Moon base called the International Lunar Research Station.
Liu Jizhong, chief designer of the Tianwen-3 mission, did not say when China could have Mars samples back on Earth. In past updates on the Tianwen-3 mission, the launch date has alternated between 2028 and 2030, and officials previously suggested the round-trip mission would take about three years. This would suggest Mars rocks could return to Earth around 2031, assuming an on-time launch in 2028.
NASA, meanwhile, is in the middle of revamping its architecture for a Mars sample return mission in cooperation with the European Space Agency. In June, NASA tapped seven companies, including SpaceX and Blue Origin, to study ways to return Mars rocks to Earth for less than $11 billion and before 2040, the cost and schedule for NASA’s existing plan for Mars sample return.
That is too expensive and too long to wait for Mars sample return, NASA Administrator Bill Nelson said in April. Mars sample return is the highest priority for NASA’s planetary science division and has been the subject of planning for decades. The Perseverance rover currently on Mars is gathering several dozen specimens of rock powder, soil, and Martian air in cigar-shaped titanium tubes for eventual return to Earth.
This means China has a shot at becoming the first country to bring pristine samples from Mars back to Earth, and China doesn’t intend to stop there.
“If all the missions go as planned, China is likely to become the first country to return samples from Mars,” said Wu Weiren, chief designer of China’s lunar exploration program, in a July interview with Chinese state television. “And we will explore giant planets, such as Jupiter. We will also explore some of the asteroids, including sample return missions from an asteroid, and build an asteroid defense system.”
The asteroid sample return mission is known as Tianwen-2, and is scheduled for launch next year. Tianwen means “questions to heaven.”
China doesn’t have a mission currently on Mars gathering material for its Tianwen-3 sample return mission. The country’s first Mars mission, Tianwen-1, landed on the red planet in May 2021 and deployed a rover named Zhurong. China’s space agency hasn’t released any update on the rover since 2022, suggesting it may have succumbed to the harsh Martian winter.
So, the Tianwen-3 mission must carry everything it needs to land on Mars, collect samples, package them for return to Earth, and then launch them from the Martian surface back into space. Then, the sample carrier will rendezvous with a return vehicle in orbit around Mars. Once the return spacecraft has the samples, it will break out of Mars orbit, fly across the Solar System, and release a reentry capsule to bring the Mars specimens to the Earth.
All of the kit for the Tianwen-3 mission will launch on two Long March 5 rockets, the most powerful operational launcher in China’s fleet. One Long March 5 will launch the lander and ascent vehicle, and another will propel the return spacecraft and Earth reentry capsule toward Mars.
Liu, Tianwen-3’s chief designer, said an attempt to retrieve samples from Mars is the most technically challenging space exploration mission since the Apollo program, according to China’s state-run Xinhua news agency. Liu said China will adhere to international agreements on planetary protection to safeguard Mars, Earth, and the samples themselves from contamination. The top scientific goal of the Tianwen-3 mission is to search for signs of life, he said.
Tianwen-3 will collect samples with a robotic arm and a subsurface drill, and Chinese officials previously said the mission may carry a helicopter and a mobile robot to capture more diverse Martian materials farther away from the stationary lander.
Liu said China is open to putting international payloads on Tianwen-3 and will collaborate with international scientists to analyze the Martian samples the mission returns to Earth. China is making lunar samples returned by the Chang’e 5 mission available for analysis by international researchers, and Chinese officials have said they anticipate a similar process to loan out samples from the far side of the Moon brought home by the Chang’e 6 mission earlier this year.
Enlarge/ This artist’s concept shows the possible appearance of ESA’s RAMSES spacecraft, which will release two small CubeSats for additional observations at Apophis.
For nearly 20 years, scientists have known an asteroid named Apophis will pass unusually close to Earth on Friday, April 13, 2029. But most officials at the world’s space agencies stopped paying much attention when updated measurements ruled out the chance Apophis will impact Earth anytime soon.
Now, Apophis is again on the agenda, but this time as a science opportunity, not as a threat. The problem is there’s not much time to design, build and launch a spacecraft to get into position near Apophis in less than five years. The good news is there are designs, and in some cases, existing spacecraft, that governments can repurpose for missions to Apophis, a rocky asteroid about the size of three football fields.
Scientists discovered Apophis in 2004, and the first measurements of its orbit indicated there was a small chance it could strike Earth in 2029 or in 2036. Using more detailed radar observations of Apophis, scientists in 2021 ruled out any danger to Earth for at least the next 100 years.
“The three most important things about Apophis are: It will miss the Earth. It will miss the Earth. It will miss the Earth,” said Richard Binzel, a professor of planetary science at MIT. Binzel has co-chaired several conferences since 2020 aimed at drumming up support for space missions to take advantage of the Apophis opportunity in 2029.
“An asteroid this large comes this close only once per 1,000 years, or less frequently,” Binzel told Ars. “This is an experiment that nature is doing for us, bringing a large asteroid this close, such that Earth’s gravitational forces and tidal forces are going to tug and possibly shake this asteroid. The asteroid’s response is insightful to its interior.”
It’s important, Binzel argues, to get a glimpse of Apophis before and after its closest approach in 2029, when it will pass less than 20,000 miles (32,000 kilometers) from Earth’s surface, closer than the orbits of geostationary satellites.
“This is a natural experiment that will reveal how hazardous asteroids are put together, and there is no other way to get this information without vastly complicated spacecraft experiments,” Binzel said. “So this is a once-per-many-thousands-of-years experiment that nature is doing for us. We have to figure out how to watch.”
This week, the European Space Agency announced preliminary approval for a mission named RAMSES, which would launch in April 2028, a year ahead of the Apophis flyby, to rendezvous with the asteroid in early 2029. If ESA member states grant full approval for development next year, the RAMSES spacecraft will accompany Apophis throughout its flyby with Earth, collecting imagery and other scientific measurements before, during, and after closest approach.
The challenge of building and launching RAMSES in less than four years will serve as good practice for a potential future real-world scenario. If astronomers find an asteroid that’s really on a collision course with Earth, it might be necessary to respond quickly. Given enough time, space agencies could mount a reconnaissance mission, and if necessary, a mission to deflect or redirect the asteroid, likely using a technique similar to the one demonstrated by NASA’s DART mission in 2022.
“RAMSES will demonstrate that humankind can deploy a reconnaissance mission to rendezvous with an incoming asteroid in just a few years,” said Richard Moissl, head of ESA’s planetary defense office. “This type of mission is a cornerstone of humankind’s response to a hazardous asteroid. A reconnaissance mission would be launched first to analyze the incoming asteroid’s orbit and structure. The results would be used to determine how best to redirect the asteroid or to rule out non-impacts before an expensive deflector mission is developed.”
Shaking off the cobwebs
In order to make a 2028 launch feasible for RAMSES, ESA will reuse the design of a roughly half-ton spacecraft named Hera, which is scheduled for launch in October on a mission to survey the binary asteroid system targeted by the DART impact experiment in 2022. Copying the design of Hera will reduce the time needed to get RAMSES to the launch pad, ESA officials said.
“Hera demonstrated how ESA and European industry can meet strict deadlines and RAMSES will follow its example,” said Paolo Martino, who leads ESA’s development of Ramses, which stands for the Rapid Apophis Mission for Space Safety.
ESA’s space safety board recently authorized preparatory work on the RAMSES mission using funds already in the agency’s budget. OHB, the German spacecraft manufacturer that is building Hera, will also lead the industrial team working on RAMSES. The cost of RAMSES will be “significantly lower” than the 300-million-euro ($380 million) cost of the Hera mission, Martino wrote in an email to Ars.
“There is still so much we have yet to learn about asteroids but, until now, we have had to travel deep into the Solar System to study them and perform experiments ourselves to interact with their surface,” said Patrick Michel, a planetary scientist at the French National Center for Scientific Research, and principal investigator on the Hera mission.
“For the first time ever, nature is bringing one to us and conducting the experiment itself,” Michel said in a press release. “All we need to do is watch as Apophis is stretched and squeezed by strong tidal forces that may trigger landslides and other disturbances and reveal new material from beneath the surface.”
Assuming it gets the final go-ahead next year, RAMSES will join NASA’s OSIRIS-APEX mission in exploring Apophis. NASA is steering the spacecraft, already in space after its use on the OSIRIS-REx asteroid sample return mission, toward a rendezvous with Apophis in 2029, but it won’t arrive at its new target until a few weeks after its close flyby of Earth. The intricacies of orbital mechanics prevent a rendezvous with Apophis any earlier.
Observations from OSIRIS-APEX, a larger spacecraft than RAMSES with a sophisticated suite of instruments, “will deliver a detailed look of what Apophis is like after the Earth encounter,” Binzel said. “But until we establish the state of Apophis before the Earth encounter, we have only one side of the picture.”
Enlarge/ At its closest approach, asteroid Apophis will closer to Earth than the ring of geostationary satellites over the equator.
Scientists are also urging NASA to consider launching a pair of mothballed science probes on a trajectory to fly by Apophis some time before its April 2029 encounter with Earth. These two spacecraft were built for NASA’s Janus mission, which the agency canceled last year after the mission fell victim to launch delays with NASA’s larger Psyche asteroid explorer. The Janus probes were supposed to launch on the same rocket as Psyche, but problems with the Psyche mission forced a delay in the launch of more than one year.
Despite the delay, Psyche could still reach its destination in the asteroid belt, but the new launch trajectory meant Janus would be unable to visit the two binary asteroids scientists originally wanted to explore with the probes. After spending nearly $50 million on the mission, NASA put the twin Janus spacecraft, each about the size of a suitcase, into long-term storage.
At the most recent workshop on Apophis missions in April, scientists heard presentations on more than 20 concepts for spacecraft and instrument measurements at Apophis.
They included an idea from Blue Origin, Jeff Bezos’s space company, to use its Blue Ring space tug as a host platform for multiple instruments and landers that could descend to the surface of Apophis, assuming research institutions have enough time and money to develop their payloads. A startup named Exploration Laboratories has proposed partnering with NASA’s Jet Propulsion Laboratory on a small spacecraft mission to Apophis.
“At the conclusion of the workshop, it was my job to try to bring forward some consensus, because if we don’t have some consensus on our top priority, we may end up with nothing,” Binzel said. “The consensus recommendation for ESA was to more forward with RAMSES.”
Workshop participants also gently nudged NASA to use the Janus probes for a mission to Apophis. “Apophis is a mission in search of a spacecraft, and Janus is a spacecraft in search of a mission,” Binzel said. “As a matter of efficiency and basic logic, Janus to Apophis is the highest priority.”
A matter of money
But NASA’s science budget, and especially funding for its planetary science vision, is under stress. Earlier this week, NASA canceled an already-built lunar rover named VIPER after spending $450 million on the mission. The mission had exceeded its original development cost by greater than 30 percent, prompting an automatic cancellation review.
The funding level for NASA’s science mission directorate this year is nearly $500 million less than last year’s budget, and $900 million below the White House’s budget request for fiscal year 2024. Because of the tight budget, NASA officials have said, for now, they are not starting development of any new planetary science missions as they focus on finishing projects already in the pipeline, like the Europa Clipper mission, the Dragonfly quadcopter to visit Saturn’s moon Titan, and the Near-Earth Object (NEO) Surveyor telescope to search for potentially hazardous asteroids.
Enlarge/ These grainy radar views of asteroid Apophis were captured using radars at NASA’s Goldstone Deep Space Communications Complex in California and Green Bank Telescope in West Virginia.
NASA has asked the Janus team to look at the feasibility of launching on the same rocket as NEO Surveyor in 2027, according to Dan Scheeres, the Janus principal investigator at the University of Colorado. With such a launch in 2027, Janus could capture the first up-close images of Apophis before RAMSES and OSIRIS-APEX get there.
“This is something that we’re currently presenting in some discussions with NASA, just to make sure that they understand what the possibilities are there,” Scheeres said in a meeting last week of the Small Bodies Advisory Group, which represents the asteroid science community.
“These spacecraft are capable of performing future scientific flyby missions to near-Earth asteroids,” Scheeres said. “Each spacecraft has a high-quality Malin visible imager and a thermal infrared imager. Each spacecraft has the ability to track and image an asteroid system through a close, fast flyby.”
“The scientific return from an Apophis flyby by Janus could be one of the best opportunities out there,” said Daniella DellaGiustina, lead scientist on the OSIRIS-APEX mission from the University of Arizona.
Binzel, who has led the charge for Apophis missions, said there is also some symbolic value to having a spacecraft escort the asteroid by Earth. Apophis will be visible in the skies over Europe and Africa when it is closest to our planet.
“When 2 billion people are watching this, they are going to ask, ‘What are our space agencies doing?’ And if the answer is, ‘Oh, we’ll be there. We’re getting there,’ which is OSIRIS-APEX, I don’t think that’s a very satisfying answer,” Binzel said.
“As the international space community, we want to demonstrate on April 13, 2029, that we are there and we are watching, and we are watching because we want to gain the most knowledge and the most understanding about these objects that is possible, because someday it could matter,” Binzel said. “Someday, our detailed knowledge of hazardous asteroids would be among the most important knowledge bases for the future of humanity.”
