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/

A little more than a month ago, SpaceX founder Elon Musk put down a marker of his intent to saturate low-Earth orbit with up to 1 million satellites. Its purpose? Provide always-on data center services around the planet.

Now, Amazon and Blue Origin founder Jeff Bezos has done something similar with a filing to the Federal Communications Commission of his own, proposing a constellation of up to 51,600 satellites operating in Sun-synchronous orbits at altitudes ranging from 500 to 1,800 km. Bezos’ space company, Blue Origin, sought the authority to do this and is calling the constellation “Project Sunrise.”

In its filing, Blue Origin argues that terrestrial AI-based data centers will face difficulties scaling up to meet computing demand.

“The insatiable demand for AI workloads has led to the rapid buildout of terrestrial data centers globally,” the filing states. “Space-based data centers will be a complement to terrestrial infrastructure by introducing a new compute tier that operates independently of Earth-based constraints.”

A gold rush for land in space

In addition to SpaceX and Blue Origin, Starcloud, a smaller company backed by Nvidia, has also filed an application for an orbital data center megaconstellation of 88,000 satellites.

The new filings for these massive constellations—which none of these companies are prepared to populate just yet with actual satellites—likely represent a gold rush of sorts. Although low-Earth orbit is very large, there are only a select few orbits that provide continuous or nearly continuous sunlight (most orbits have periods of darkness when the Earth is between the satellite and the Sun).

Like SpaceX, Blue Origin is targeting these special polar orbits.

Its application seeks to put satellites in orbital inclinations between 97 and 104 degrees. These are known, generally, as Terminator Sun-synchronous orbits because the satellites remain in essentially permanent sunlight year-round. There is limited real estate there, even in outer space, and these regulatory filings are claims by the space companies to this territory.

Make that three for Jeff

This would be Bezos’ third megaconstellation. Amazon finally began launching its first satellites for the Amazon Leo (formerly Project Kuiper) constellation last year. This is intended to compete with SpaceX’s Starlink constellation, which will provide global Internet from low-Earth orbit. Then, in January, Blue Origin announced plans to launch the TeraWave constellation in low-Earth and medium-Earth orbit to provide high-speed connectivity for enterprise customers.

https://arstechnica.com/space/2026/03/jeff-bezos-throws-his-hat-in-the-ring-for-an-orbital-data-center-megaconstellation-too/

Artemis II rocket to roll back out to the pad. Engineers are targeting 8 pm EDT on Thursday, March 19, to start rolling the Artemis II SLS (Space Launch System) rocket and Orion spacecraft to Launch Pad 39B at the agency’s Kennedy Space Center in Florida, the US space agency said. NASA’s crawler-transporter 2 will carry the 11-million-pound stack, including the mobile launcher, at about 1 mph along the four-mile route from Kennedy’s Vehicle Assembly Building to the launch pad. The journey can take up to 12 hours.

Astronauts enter quarantine again … Meanwhile, the Artemis II crew entered quarantine at 5 pm CDT Wednesday in Houston to ensure they stay healthy leading up to launch. NASA astronauts Reid Wiseman, Victor Glover, and Christina Koch, along with CSA (Canadian Space Agency) astronaut Jeremy Hansen will limit their exposure to others for the next week in Houston before flying to Kennedy approximately five days before launch. Both activities are key milestones on the way to a launch as early as Wednesday, April 1.

Booster 19 completes initial test campaign. The Super Heavy first stage that will be used for the 12th Starship flight test, Booster 19, completed an initial test campaign on the newly commissioned Pad 2 at Starbase, Texas, NASASpaceflight.com reports. Culminating in a short static firing of the rocket, the series of tests was a first for Pad 2, the new Block 3/V3 Super Heavy Booster, and for the upgraded Raptor 3 outside of single engine testing.

New and improved (?) rocket and pad … As the inaugural vehicle to undergo operations on this pad, Booster 19’s campaign served as both a booster qualification test and a commissioning milestone for the expanded launch infrastructure. Pad 2 features significant upgrades over Pad 1, most notably dual booster quick disconnects: one dedicated to liquid methane and another to liquid oxygen. This separation enables independent tank pressurization and more efficient loading, reducing risks associated with mixed propellants. After the static firing, SpaceX said the rocket performed well. Flight 12 is likely to occur no earlier than the second half of April.

Next three launches

March 20: Electron | Eight Days a Week | Māhia Peninsula, New Zealand | 16:10 UTC

March 20: Falcon 9 | Starlink 17-15 | Vandenberg Space Force Base, Calif. | 21:48 UTC

March 22: Soyuz 2.1a | Progress MS-33 | Baikonur Cosmodrome, Kazakhstan | 11:59 UTC

https://arstechnica.com/space/2026/03/rocket-report-canada-makes-a-major-move-us-space-force-says-actually-lets-be-hasty/

There was no commercial application for the P-51. The P-51 was there to be a fighter escort and sweep asset for air superiority missions. As operational concepts mature for space superiority, those operational concepts will drive a performance envelope for warfare that will be mutually exclusive of commercial applications. Not in all cases. There are spinoffs that can happen, to be clear, but we’re focused on getting the war-fighting technologies right, and we believe the market will support this thesis.

Ars: This is an interesting topic, the idea of developing doctrine and learning how to use new technologies in warfare. I read the first munition was dropped from an airplane in 1911, before World War I. It’s interesting to trace where the space domain is in that arc and compare it to how humans learned how to fight in the air.

Rogers: That’s what I spend most of my time thinking about. How are we going to use space systems for warfare in the future? We have all the applications for intelligence and missile warning and communications, but we’re just starting to think about space warfare, offense, and defense.

By the way, those decompose into different missions on the basis of the specific tactical tasks that need to be accomplished… That means that there are going to be, just like in every other domain, platforms that are purpose-built, that really only have a [military] function. There’s no other function for a guided bomb unit, a GBU, other than for warfare. The B-2 has no commercial application. Lockheed Martin doesn’t sell F-35 to United Airlines, right? That’s because the mission drives the design, so I’m just basically vehemently agreeing with you.

Ars: Is True Anomaly building sensors, weapons, or things for on-ship awareness? Or just the spacecraft bus?

Rogers: We are absolutely designing and building payloads. We hope to announce a few early payloads this year, but we really see ourselves as a full-stack mission solution provider across a wide variety of space superiority missions. We’re going to build a wide variety of sensors for different mission applications: optical sensors, active sensors, lidars, radars, you name it. We’ll leverage our existing supply base where we can, but for most missions, we’re going to provide the full stack of capability, payload, spacecraft, software, and then ops and sustainment, and tactics development and training as well.

https://arstechnica.com/space/2026/03/dogfighting-in-space-this-company-builds-satellites-for-high-tempo-engagement/

It may sound fanciful, but a Los Angeles-based company says it has conceived of a plan to fly out to a smallish, near-Earth asteroid, throw a large bag around it, and bring the body back to a “safe” gathering point near our planet.

The company, TransAstra, said Wednesday that an unnamed customer has agreed to fund a study of its proposed “New Moon” mission to capture and relocate an asteroid approximately the size of a house, with a mass of about 100 metric tons.

“We envision it becoming a base for robotic research and development on materials processing and manufacturing,” said Joel Sercel, chief executive officer of TransAstra. “Long term, instead of building space hardware on the ground and launching propellant up from the Earth, we could harvest it from raw materials in space.”

Lots of targets

Sercel said there are as many as 250 potential target asteroids, with a diameter of up to about 20 meters, that could be reached with reusable, robotic spacecraft over the next decade. He envisions aggregating dozens, and then hundreds, of small asteroids at the “New Moon” processing facility, which could potentially be located at the Earth-Sun L2 point, about 1.5 million km from Earth.

Such asteroids could provide water for use as propellant and minerals for everything from solar panels to radiation shielding. Various asteroids could be targeted for their content, such as C-type asteroids as a source of water or M-types for metals.

All of this may seem a little bit out there, and to some extent it is. That’s the point of the feasibility study, which Sercel said will be completed by May, which will further refine a mission plan and its trajectory and the spacecraft needed to fly it. If fully funded, the mission could rendezvous with an asteroid by as early as 2028 or 2029. TransAstra is working with the University of Central Florida, Purdue, and NASA’s Jet Propulsion Laboratory/Caltech to complete its analysis.

https://arstechnica.com/space/2026/03/a-private-space-company-has-a-radical-new-plan-to-bag-an-asteroid/

Robert Goddard, a Massachusetts-born physicist, launched the world’s first liquid-fueled rocket on this date 100 years ago.

It was not an overly impressive flight. The rocket, fueled by gasoline and liquid oxygen, rose just 41 feet into the air, and the flight lasted 2.5 seconds before it struck ice and snow.

Nevertheless, this rocket, named “Nell,” represented a historic achievement that would help launch the modern age of spaceflight. Three decades later, the first objects would begin to ride liquid-fueled rockets into space, followed shortly by humans. A little more than 40 years would pass before humans walked on the Moon.

To mark this historic moment, a few Ars staffers are sharing some of their most memorable launches. Please add yours in the comments below.

Space Shuttle Endeavour

In February 2010, I was lucky enough to attend the penultimate night launch of the shuttle program, STS-130. This mission was a major ISS assembly flight, carrying both Node 3 and Cupola to the ISS. This one had nothing to do with me—instead, I was there as a plus-one for my wife, who had worked on Node 3 at Boeing and who had been invited to witness the hardware she’d worked on finally fly.

The day before the launch was a whirlwind of private tours through various KSC locations—we got to see one of the Crawler-Transporters up close, and then we had a photo-op right next to pad 39-A, where Endeavour was staged and ready. We got to see the VAB, the Orbiter Processing Facility, and the Space Station Processing Facility. There was also a big team lunch with some of the ESA partners my wife had worked with (including a group of Italian engineers from Alenia who, being ever Italian, had brought along a lot of wine).

Laura and Lee Hutchinson, standing near LC-39A on February 6, 2010, with Endeavour staged in the background.

Credit: Lee Hutchinson

The launch was originally scheduled for 04:39 Eastern the next morning, February 7, which meant no sleep. After a brief post-tour evening rest, we were all herded onto buses from the hotel at about midnight and then transported with the other program guests to the Banana Creek launch viewing area, about four miles from LC-39A. The Banana Creek viewing area is attached to the Saturn V visitor’s center, so we spent the hours before launch perusing the exhibits and enjoying KSC’s fantastic collection of historic human spaceflight artifacts.

https://arstechnica.com/space/2026/03/a-century-after-the-first-rocket-launch-ars-staffers-pick-their-favorites/

NASA assessed 1-in-276 odds for loss of crew on the first flight of astronauts aboard SpaceX’s Crew Dragon in 2020. For Boeing’s Starliner in 2024, the probability was 1 in 295. You wouldn’t be wrong to question those numbers given the proven performance of Dragon and Starliner.

This chart from NASA’s Office of Safety and Mission Assurance describes the agency’s process for conducting probabilistic risk assessments.

Credit: NASA

So, what do the Artemis II astronauts make of all this?

The mission’s commander, Reid Wiseman, said the crew members were trying to prepare their families “honestly and openly” for the hazards of a circumlunar flight.

“I went on a walk with my kids, and I told them, ‘Here’s where the will is, here’s where the trust documents are, and if anything happens to me, here’s what’s going to happen to you,’” Wiseman said. “That is a part of this life. I actually wish more people in everyday life talked to their families that way because you never know what the next day is going to bring.”

Any sailor knows you can’t stay in the harbor forever. Test pilots and astronauts take calculated risks for a living.

“When you see numbers like Mach 39 at entry, when you see numbers like 38,000 miles, 250,000 miles, and 5 or 6 million pounds on the pad, those are just insane numbers,” Wiseman said. “These numbers, you don’t even comprehend. There’s risk in that. We don’t know what we don’t know right now, so we’ll go learn all that [on the mission].

Despite the unknowns, Wiseman is ready: “For me, I actually feel completely 100 percent bought in. When I get into Orion, it’s like climbing into my bed, and I’ll feel warm and tucked in.”

The formal risk matrix for Artemis II is similar to that of Artemis I, with MMOD again at the top of the list. Matt Ramsey, NASA’s Artemis II mission manager, told Ars in January that the Orion spacecraft’s environmental control and life support system, which didn’t fly with its full capability on Artemis I, is the second-highest risk for Artemis II. “Those two are my biggest worries,” said Ramsey, who has been with NASA since 2002.

https://arstechnica.com/space/2026/03/flying-to-the-moon-for-the-first-time-in-54-years-is-risky-but-how-risky/

Welcome to Edition 8.33 of the Rocket Report! NASA officials seem optimistic about launching the Artemis II mission next month, so confident that they will forgo another fueling test on the Space Launch System rocket to check the integrity of fickle seals in a liquid hydrogen loading line. The rocket will return to the launch pad next week, with liftoff targeted for April 1 at 6:24 pm EDT (22:24 UTC). NASA has six launch dates available in early April after the agency added April 2 to the launch period. April 1 and 2 each have launch windows that open before sunset, an added bonus for those of us who prefer a day launch, for purely aesthetic reasons.

As always, we welcome reader submissions. If you don’t want to miss an issue, please subscribe using the box below (the form will not appear on AMP-enabled versions of the site). Each report will include information on small-, medium-, and heavy-lift rockets, as well as a quick look ahead at the next three launches on the calendar.

Firefly’s Alpha rocket flies again. Firefly Aerospace’s Alpha rocket successfully returned to flight Wednesday, March 11, launching a technology demonstration mission more than 10 months after the rocket’s previous launch failed, Space News reports. The launch followed several delays and scrubbed launch attempts. The two-stage Alpha rocket lifted off from Vandenberg Space Force Base, California, and headed southwest over the Pacific Ocean, reaching orbit about eight minutes later. Firefly said the rocket’s upper stage later reignited its engine, demonstrating the restart capability required for some orbit insertion missions. This was the seventh flight of Firefly’s Alpha rocket, capable of hauling more than a ton of payload to low-Earth orbit.

Block II preview... The recent setbacks for Firefly’s Alpha program included a launch failure last April and a fire that destroyed a booster stage on the test stand. The Texas-based company billed this week’s flight as a purely demonstration mission to validate several upgrades for the Alpha Block II rocket configuration, which will debut on the next launch. The Block II will include a 7-foot (2-meter) increase to Alpha’s length, consolidated batteries and avionics built in-house, improved thermal protection systems, and stronger carbon-composite structures built with automated machinery. This week’s flight carried the rocket’s new in-house avionics suite and enhanced thermal protection system, Firefly said. “Flight 7 served as a critical opportunity to validate Alpha’s performance ahead of our Block II upgrade, and this team knocked it out of the park,” said Adam Oakes, Firefly’s vice president of launch. (submitted by EllPeaTea)

https://arstechnica.com/space/2026/03/rocket-report-pentagon-needs-more-missile-interceptors-artemis-ii-clears-review/

In addition to parrying with SpaceX over its proposed, vastly larger orbital data center constellation, Amazon is seeking some regulatory relief of its own. Most pressing for Amazon is a deadline to deploy half of its Amazon Leo constellation, intended to ultimately comprise 3,236 satellites, by July 30. The company will not meet this deadline, with only a little more than three months to go, and Amazon has requested an extension, asking for it to be moved to July 30, 2028.

Carr pulls up

On Wednesday, FCC Chairman Brendan Carr injected himself into the SpaceX-Amazon fracas over megaconstellations.

“Amazon should focus on the fact that it will fall roughly 1,000 satellites short of meeting its upcoming deployment milestone, rather than spending their time and resources filing petitions against companies that are putting thousands of satellites in orbit,” Carr said on X, the social media network owned by Musk.

There are arguments to be made in favor of both SpaceX and Amazon regarding their competing concerns. For example, SpaceX is likely to be able to greatly accelerate the rate at which it launches satellites with the forthcoming Starship rocket. So saying it will take centuries to put its data centers into space is not likely true.

However, it is valid to criticize SpaceX’s application for 1 million satellites, which is an extraordinary number of spacecraft that would completely change many things about low-Earth orbit. The SpaceX application did not contain critical information about the size, mass, and other details needed to evaluate the constellation for safety and other concerns.

It cannot be comfortable for Amazon and Bezos to see Carr weighing in so publicly and favorably on Musk’s side. Legally, Carr is allowed to have strongly held policy views. But he is not supposed to single out companies for preferential treatment.

https://arstechnica.com/space/2026/03/fcc-chair-blasts-amazon-after-it-criticizes-spacex-megaconstellation/

No one on the ground has ever been injured by falling space junk, but there are examples of space debris causing property damage.

NASA’s two Van Allen Probes launched into elliptical orbits ranging from a few hundred miles above Earth up to an apogee, or high point, of nearly 20,000 miles. The orbits are inclined 10 degrees to the equator, limiting the risk of injury or damage to a swath of the tropics. NASA ended the mission in 2019 when the satellites ran out of fuel.

At that time, NASA engineers expected the spacecraft to reenter the atmosphere in 2034. But higher-than-anticipated solar activity caused the atmosphere to swell outward, increasing atmospheric drag on the satellites beyond initial estimates, according to NASA. Van Allen Probe B is expected to reenter no earlier than 2030, with a similar risk to the public.

The two spacecraft were built by the Johns Hopkins University Applied Physics Lab. NASA said the mission made several major discoveries, including “the first data showing the existence of a transient third radiation belt, which can form during times of intense solar activity.”

Several NASA satellites have reentered the atmosphere without complying with the government’s risk standard. One of the satellites, the Rossi X-ray Timing Explorer, fell out of orbit in 2018 with a 1-in-1,000 chance of harming someone on the ground. No one was hurt. RXTE was launched in 1995, just four months before NASA issued its first standard on orbital debris mitigation and reentry risk management.

While NASA has exceeded its standards before, the US government is not a top offender when it comes to unmitigated reentry risks. China launched four heavy-lift Long March 5B rockets between 2020 and 2022, and left its massive core stages in orbit to fall back to Earth. The four abandoned rocket cores, each nearly 24 tons in mass, reentered the atmosphere uncontrolled. Two of them dropped wreckage on land—in the Ivory Coast and Borneo—but no injuries were reported.

https://arstechnica.com/space/2026/03/nasa-approved-a-safety-waiver-for-this-weeks-reentry-of-van-allen-probe/