In addition to efficiency, a nuclear-electric propulsion system has the benefit of using conventional plasma thrusters. But instead of using solar power to energize the thrusters’ xenon fuel, SR-1 will use electricity generated from a nuclear reactor.

“Our nuclear program, SR-1, is not about going and lobbying for billions of dollars to undertake a brand-new mission,” Isaacman said. “Honestly, we haven’t won the right to be able to do that after $20 billion worth of failed programs over time. This is why we’re taking hardware that we already have, a reactor that’s mostly built, fuel that’s mostly paid for over time.”

Gateway’s Power and Propulsion Element, seen here under construction last year, will form the centerpiece of the SR-1 Freedom mission.

Credit: Lanteris Space Systems

NASA officials did not disclose an estimated cost for the SR-1 mission.

After proving nuclear propulsion works, “then you can come back and maybe ask for more [funding] in the future when you show that it can be done,” Isaacman said.

“SR-1 Freedom primarily has that one new system, the reactor, on a spacecraft bus that already exists,” Sinacore said. “The timeline will match the need with the next Mars launch window in December 2028. Orbital mechanics does not negotiate, and the scope must bend around this deadline.”

There are still some hurdles that won’t be easy to jump. Readying any large space mission, especially one as novel as a nuclear propulsion demo, for launch in less than three years will require sharp focus, resistance to mission creep, and near-perfect execution. Sinacore laid out an ambitious timeline for SR-1, with mission design complete by June and large-scale assembly beginning at the start of 2028. If the mission misses a launch opportunity in late 2028, the next Earth-Mars alignment won’t happen until early 2031.

“We are not trying to do everything,” Sinacore said. “We are trying to do the hard thing, which is operate a coupled nuclear reactor, power conversion, and electric propulsion thruster system beyond Earth orbit for the first time ever.”

Although NASA will be the “prime integrator” for SR-1, actually launching radioactive fuel into space requires input from multiple federal agencies, including the Department of Energy. Any rocket selected to launch a nuclear-powered mission must undergo a special certification. SpaceX’s Falcon Heavy, which NASA originally booked to launch the Gateway core module, is undergoing a nuclear certification to launch NASA’s Dragonfly mission to Saturn’s moon Titan.

https://arstechnica.com/space/2026/03/here-is-nasas-plan-for-nuking-gateway-and-sending-it-to-mars/

But the Swift spacecraft will surely crash back to Earth, likely before the end of this year, without a reboost. That’s where Katalyst comes in. The company’s robotic servicing spacecraft, named Link, will attempt to rendezvous and dock with the Swift satellite, then raise its altitude to give the observatory a new lease on life.

That is, if everything goes according to plan.

Artist’s illustration of Katalyst’s Link spacecraft (top) approaching NASA’s Swift observatory (bottom).

Credit: Katalyst Space Technologies

Deadline looming

There are a few things you should know about this venture. First, Swift was never designed to be captured or reboosted in orbit. Second, this mission is the first time Katalyst will attempt to dock with another satellite in space. And third, NASA gave Katalyst a daunting timetable of just nine months to build, test, and launch the rescue mission before Swift’s altitude falls too low for a safe rendezvous.

“This is really technically ambitious,” said Ghonhee Lee, founder and CEO of Katalyst.

Launch is scheduled for June 1, and there’s little margin for error. By late summer or early fall, Swift will slip below 200 miles (320 kilometers), too low for Katalyst to have confidence in controlling its spacecraft. “It’s a lot of drag with two big spacecraft docking together, ” Lee said. “Originally, we thought we had more time.”

NASA’s goals are twofold: first, demonstrate an important capability for the future of space exploration, and second, save Swift from a fiery demise and continue its scientific observations.

“We realized that you can’t get 100 percent guaranteed success on this,” Lee said.

When Ars visited Katalyst in late February, technicians were heads-down at work stations, soldering parts, assembling solar panels, and preparing components for environmental testing. For a traditional government space mission, a project might be at this stage of manufacturing years before reaching the launch pad.

“This is not quite as mature as you would expect,” one company official said. “Keep in mind that we started this whole thing about five months ago, so we are making great progress by those standards.”

https://arstechnica.com/space/2026/03/a-unique-nasa-satellite-is-falling-out-of-orbit-this-team-is-trying-to-rescue-it/

Saleem Ali, an environmental systems scientist at the University of Delaware who also provides research and advice on critical metals to the United Nations, says that deep-sea mining should be part of discussions on the green transition. He coauthored a 2022 analysis, funded by The Metals Company, that compared mining waste from terrestrial deposits to that of seabed resources. (Ali says he has never received direct funding from The Metals Company.) For example, the analysis looked at the impact of terrestrial mine tailings on water pollution and local biodiversity, and at the anticipated pollution from nodule mining, such as seabed sediment kicked into the water column by harvesting machines. It suggests that both types of mining will have effects on biodiversity, but deep-sea mining could result in less waste and fewer risks for communities than terrestrial mining. The study cautions, however, that its conclusions are limited by “substantial uncertainty” regarding impacts of sediment plumes.

Ali adds that the International Seabed Authority has been collecting data for at least 30 years, which should be sufficient to develop rules and regulations to govern seabed mining even if it’s unclear what the long-term impacts are, and whether the environmental impacts are likely to be better or worse than mining on land.

“I’m not saying that we should go ahead with it. I’m saying that it deserves to be considered in this broad context of very difficult choices we have to make,” he says.

But opponents calling for moratoriums or bans note that the same study that The Metals Company refers to as evidence of quick recovery eventually reached more pessimistic conclusions from its data as a whole. “The effects of polymetallic nodule mining are likely to be long term,” the authors wrote, and the analyses “show considerable negative biological effects of seafloor nodule mining, even at the small scale of test mining experiments.” Scientists are concerned that deep-sea organisms, which are adapted to living in a dark, quiet, and sparsely populated environment, will not cope well with the noise and light disturbances from mining. The organisms will also be exposed to toxic metals and plumes of sediment that can interfere with feeding and breathing. The Metals Company did not respond to several requests for comment.

The seafloor of Clarion-Clipperton Zone is home to many creatures, some of which are shown here: anemone (top left), sea cucumber, Psychropotes longicauda (top right), sea urchin Plesiodiadema sp. (bottom right), and starfish (bottom left). The biology and ecology of these depths remain poorly understood, making it hard to know what the ecological impacts of deep-sea mining would be.

Credit: ROV TEAM / GEOMAR (CC-BY 4.0)

https://arstechnica.com/science/2026/03/mining-the-deep-ocean/

On Monday, a paper announcing that all four DNA bases had been found on an asteroid sparked a lot of headlines. But many of the headlines omitted a key word needed to put the discovery in context: “again.” The paper itself cited similar results dating back to 2011, and the ensuing years have seen various confirmations and more rigorous studies. The new work was less notable for showing that we had found these bases in Ryugu than for solving a previous mystery: earlier studies had failed to detect them there, despite their presence in many other asteroid samples.

Outside the headlines, though, the new work provides some interesting details, as it may answer an important question: how these bases got there in the first place. Understanding that better may be critical for getting a better picture of how the raw materials for life ended up on Earth in the first place.

Searching for bases

Let’s start with a description of what the researchers found. Both DNA and RNA, the two nucleic acids used by life, share a similar structure. That includes the backbone, a chain that alternates between sugars and phosphates that are all chemically linked together. While the specific sugar differs between DNA and RNA, the chain itself varies only in length; otherwise, the backbone of every DNA or RNA molecule is identical.

What gives nucleic acids the identity needed to carry genetic information are the bases. There are four (A, T, C, and G in DNA; A, U, C, and G in RNA), and one is always attached to each of the sugars in the backbone. The order of the bases along the backbone is what carries genetic information, enabling life as we know it. It’s been hypothesized that, before life evolved, the order of bases along RNA molecules determined the sorts of chemical reactions they could catalyze.

https://arstechnica.com/science/2026/03/we-keep-finding-the-raw-material-of-dna-in-asteroids-whats-it-telling-us/

The DOE spokesperson said its radiation standards “are aligned with Gold Standard Science… with a focus on protecting people and the environment while avoiding unnecessary bureaucracy.”

The department has already decided to abandon the long-standing radiation protection principle known as “ALARA”—the “As Low As Reasonably Achievable” standard—which directs anyone dealing with radioactive materials to minimize exposure.

It often pushes exposure well below legal thresholds. Many experts agreed that the ALARA principle was sometimes applied too strictly, but the move to entirely throw it out was opposed by many prominent radiation health experts.

Whether the agencies will actually change the legal thresholds for radiation exposure is an open question, said sources familiar with the deliberations.

Internal DOE documents arguing for changing dose rules cite a report produced at the Idaho National Laboratory, which was compiled with the help of the AI assistant Claude. “It’s really strange,” said Kathryn Higley, president of the National Council on Radiation Protection and Measurements, a congressionally chartered group studying radiation safety. “They fundamentally mistake the science.”

John Wagner, the head of the Idaho National Laboratory and the report’s lead author, acknowledged to ProPublica that the science over changing radiation exposure rules is hotly contested. “We recognize that respected experts interpret aspects of this literature differently,” he wrote. His analysis was not meant to be the final word, he said, but was “intended to inform debate.”

The impact of radiation levels at very low doses is hard to measure, so the US has historically struck a cautious note. Raising dose limits could put the US out of step with international standards.

For his part, Cohen has told the nuclear industry that he sees his job as making sure the government “is no longer a barrier” to them.

In June, he shot down the notion of companies putting money into a fund for workplace accidents. “Put yourself in the shoes of one of these startups,” he said. “They’re raising hundreds of millions of dollars to do this. And then they would have to go to their VCs and their board and say, listen, guys, we actually need a few hundred million dollars more to put into a trust fund?”

He also suggested that regulators should not fret about preparing for so-called 100-year events—disasters that have roughly a 1 percent chance of taking place but can be catastrophic for nuclear facilities.

“When SpaceX started building rockets, they sort of expected the first ones to blow up,” he said.

This story originally appeared on ProPublica.

ProPublica is a Pulitzer Prize-winning investigative newsroom. Read the original story here. Sign up for The Big Story newsletter to receive stories like this one in your inbox.

Pratheek Rebala and Kirsten Berg contributed research.

https://arstechnica.com/science/2026/03/doge-goes-nuclear-how-trump-invited-silicon-valley-into-americas-nuclear-power-regulator/

Those statements suggested the Space Force was likely to transfer the GPS slated to fly on the next Vulcan rocket to a different launch vehicle. That’s exactly what happened. On Friday, Space Systems Command confirmed that GPS III SV10 will now launch on SpaceX’s Falcon 9 rocket in late April. Read our earlier story on why the Space Force is so eager to launch GPS satellites.

Each GPS III satellite weighs more than four tons at launch. SpaceX’s Falcon 9 and Falcon Heavy rockets and ULA’s Vulcan are the only launchers certified by the Space Force to launch these types of missions. With an inventory of reusable boosters flying several times per week, SpaceX can fit new missions in on relatively short notice.

“With this change, we are answering the call for rapid delivery of advanced GPS capability while the Vulcan anomaly investigation continues,” said Col. Ryan Hiserote, director of the National Security Space Launch program. “We are once again demonstrating our team’s flexibility and are fully committed to leverage all options available for responsive and reliable launch for the nation.”

The first Vulcan rocket fires off its launch pad in Florida in January 2024.

Credit: United Launch Alliance

Fall from grace

This is not a good look for United Launch Alliance, once the US military’s sole launch provider. SpaceX began launching US national security missions in 2018 after winning the right to compete for military launch contracts with its Falcon 9 rocket. The company entered the military launch market after filing a lawsuit against the Air Force in 2014 protesting the Pentagon’s decision to award ULA a multibillion-dollar sole-source contract.

The military opened a series of launch contracts to the competition, and in 2020, it selected ULA for 60 percent and SpaceX for 40 percent of its missions up for awards through the end of 2023. Last year, Space Systems Command announced the winners of a follow-on competition covering launches through the end of the decade. This time, SpaceX won the majority of the contracts, with ULA relegated to second position. The Space Force added Blue Origin as a third launch provider.

The Pentagon has maintained a policy of assured access to space since the 1990s, when the military lost several expensive, high-priority payloads in launch failures. ULA was the only provider for these launches for more than a decade, with Atlas V and Delta IV rockets providing overlap in capability to deliver most, but not all, national security payloads to orbit. The Delta IV is now out of service, and the Atlas V is nearing retirement.

Today, SpaceX alone comes closest to providing assured access to space, despite ULA’s backlog of more than $8 billion in military launch contracts.

https://arstechnica.com/space/2026/03/spacex-swipes-yet-another-military-contract-from-united-launch-alliance/

When NASA’s Perseverance rover landed in Jezero Crater in 2021, its primary mission was to scour the remnants of a dried-up Martian lakebed for signs of ancient life. Scientists have been focused on the crater’s spectacular Western Delta, a fan-shaped geologic feature deposited by a river flowing into the basin billions of years ago. But now Perseverance’s ground-penetrating radar (called RIMFAX) detected what is likely another, even older river delta buried tens of meters beneath it.

“I think it’s a promising place to look for signs of biosignatures at depth,” says Emily L. Cardarelli. “Microbial life could have potentially developed in those types of environments.” Cardarelli, an astrobiologist at the University of California Los Angeles, led the team interpreting RIMFAX imagery.

Peeking underground

Perseverance’s RIMFAX, the Radar Imager for Mars Subsurface Experiment, continuously fires radar waves into the ground, acquiring soundings each time the rover traveled 10 centimeters. When these radio waves hit boundaries between different types of rock, ice, or sediment layers, some of the signal bounces back. The timing and intensity of these reflections allow scientists to construct a two-dimensional, vertical slice of the subsurface, much like a sonogram of the Martian crust.

During a campaign spanning from September 2023 to February 2024, or over 250 Martian sols, Perseverance drove across a geological zone known as the Margin unit. The Margin unit is an expansive deposit flanking the inner rim of Jezero’s inlet valley, occupying the space between the western fan deposits and the crater rim. It is rich in magnesium carbonates, which was one of the main reasons Jezero Crater has been chosen as the Perseverance’s landing site: on Earth, carbonates are exceptionally good at preserving the chemical fingerprint of life. “You can think of the Cliffs of Dover, for example, that are all carbonate—they have tons of fossils in them,” Cardarelli says.

https://arstechnica.com/science/2026/03/perseverances-radar-revealed-ancient-subsurface-river-delta-on-mars/

For more than 60 years, nearly every large rocket used some combination of the same liquid and solid propellants. Refined kerosene was favored for its easy handling and non-toxicity, hydrazine for its storability and simplicity, hydrogen for its efficiency, and solid fuels for their long shelf life and rapid launch capability.

About 15 years ago, rocket companies started serious development of large methane-fueled engines. SpaceX and Blue Origin now build the most powerful of these new engines—the Raptor and BE-4—each capable of generating more than half a million pounds of thrust. SpaceX’s Starship rocket and its enormous booster are powered by 39 Raptors, while Blue Origin’s New Glenn and United Launch Alliance’s Vulcan rockets use a smaller number of BE-4s on their booster stages.

Burning methane in combination with liquid oxygen, these “methalox” engines have several advantages. Methane is better suited for reusable engines because they leave less behind sooty residue than kerosene, which SpaceX uses on the Falcon 9 rocket. Methane is easier to handle than liquid hydrogen, which is prone to leaks and must be stored at staggeringly cold temperatures of around minus 423 degrees Fahrenheit (minus 253 degrees Celsius). Methane is also a cryogenic liquid, but it has a warmer temperature closer to that of liquid oxygen, between minus 260 and minus 297 degrees Fahrenheit (minus 162 to minus 183 degrees Celsius).

A Chinese rocket became the first methane-fueled launcher to reach orbit in 2023. In the United States, Rocket Lab, Stoke Space, and Relativity Space are also developing methane-fueled engines for their next-generation launch vehicles.

But rockets sometimes blow up. The US Space Force and NASA, the agencies responsible for range safety at America’s federally owned spaceports, want to better understand how the hazards from an exploding methalox rocket might differ from those of other launchers. This is important as launches become more routine, with companies foreseeing multiple flights per day from launch pads that are, in some cases, just 1 or 2 miles apart.

“We just don’t have the analysis on those to be able to say, ‘Hey, from a testing perspective, how small can we reduce the BDA and be safe?’” said Col. Brian Chatman, commander of the Eastern Range at Cape Canaveral Space Force Station in Florida, at a roundtable with reporters last year.

SpaceX’s 11th Starship flight climbs away from Starbase, Texas, in October 2025.

Credit: SpaceX

A fine idea

Launch pads for methalox rockets are now operational or under construction on government property at Kennedy Space Center and Cape Canaveral Space Force Station in Florida, Vandenberg Space Force Base in California, and NASA’s Wallops Flight Facility in Virginia. SpaceX currently launches Starship test flights from South Texas on private property. The Federal Aviation Administration has jurisdiction for public safety there.

https://arstechnica.com/space/2026/03/nasa-is-blowing-stuff-up-to-study-the-explosive-potential-of-methalox-rockets/

It took nearly a decade for most archaeologists to come around to the idea, but Monte Verde rewrote the story we thought we knew about how (and when) people first moved into, and spread throughout, the Americas. For once in the history of science, that statement isn’t just a headline-grabbing exaggeration—it was really that big a deal.

However, Surovell and his colleagues recently re-evaluated those dates and realized the site can’t be more than 8,000 years old. So what does that mean for the story it had helped re-write? Surprisingly little, it turns out.

Digging into the details

Surovell and his colleagues didn’t challenge the accuracy of the original radiocarbon dates. The bits of organic matter in the layer of sediment at the site are, they agree, around 14,500 years old. Instead, Surovell and his colleagues questioned whether that sediment layer actually covered the site 14,500 years ago or if it washed in later from a part of the riverbank laid down much earlier. In general, newer layers of sediment stack on top of older ones, but real-world geology is often messier than that, and that seems to be what happened at Monte Verde.

The archaeologists mapped the layers of sediment around the site: layers of sand and gravel left behind by glaciers 26,000 years ago, wood-laden silt from peaty marshes 15,000 to 13,000 years ago, a layer of volcanic debris that blanketed the whole region 11,000 years ago. And through it all, the channel cut by what’s now Chinchihuapi Creek, which carved its way through the volcanic layer and into the buried marshes beneath sometime between 11,700 and 7,600 years ago.

And that’s the complicated part, because the creek left older layers of sediment exposed on the hillsides along its banks. When it flooded, it scooped out some of that older sediment and deposited it on the floodplain, forming the ground where a group of around 20 or 30 ancient Chileans would eventually set up camp.

https://arstechnica.com/science/2026/03/an-early-indigenous-site-may-not-be-early-but-it-doesnt-really-matter/

Despite being declared the third-hottest year on record, 2025 was a relatively quiet year for climate disasters in the US. No major hurricanes made landfall, while the total number of acres burned in wildfires last year—a way of measuring the intensity of wildfire season—fell below the 10-year average.

But starting this week, the West is experiencing what looks to be a record-breaking heat wave, while forecasting models predict that a strong El Niño event is likely to emerge later this year. These two unrelated phenomena could set the stage for a long stretch of unpredictable and extreme weather reaching into next year, compounding the effects of a climate that’s getting hotter and hotter thanks to human activity.

First, there’s the heat. Beginning this week and heading into next, a massive ridge of high-pressure air will bring record-breaking temperatures to the American West. The National Weather Service predicts that temperature records across multiple states are set to be broken in dozens of locations, stretching as far east as Missouri and Tennessee. The NWS has issued heat warnings for parts of California, Arizona, and Nevada, as well as fire warnings for parts of Wyoming, Nebraska, South Dakota, and Colorado.

“This will be the single strongest ridge we’ve observed outside of summer in any month,” says Daniel Swain, a climate scientist at the University of California Agriculture and Natural Resources.

The other remarkable thing about this heat wave, Swain says, is just how long it’s going to last. “This is not a day or two of extreme heat,” he says. “We’ve already in some of these places been seeing record highs every day for a week, and we expect to see them every day for another at least seven to 10 days.” The later end of March will be much more intense, with temperatures in some places breaking April and May records. “There aren’t that many weather patterns that can result in an 85- or 90-degree temperature in San Francisco, Salt Lake City, and Denver in the same week.”

https://arstechnica.com/science/2026/03/the-us-is-looking-at-a-year-of-chaotic-weather/