artemis II

Rocket Report: Stoke is stoked; sovereignty is the buzzword in Europe

artemis II, european space agency, falcon 9, isar aerospace, launch, NASA, rocket lab, rocket report, Science, Space, space launch system, spacex, united launch alliance / Beth Washington / March 28, 2025

“The idea that we will be able to do it through America… I think is very, very doubtful.”

Stoke Space’s Andromeda upper stage engine is hot-fired on a test stand. Credit: Stoke Space

Welcome to Edition 7.37 of the Rocket Report! It’s been interesting to watch how quickly European officials have embraced ensuring they have a space launch capability independent of other countries. A few years ago, European government satellites regularly launched on Russian Soyuz rockets, and more recently on SpaceX Falcon 9 rockets from the United States. Russia is now non grata in European government circles, and the Trump administration is widening the trans-Atlantic rift. European leaders have cited the Trump administration and its close association with Elon Musk, CEO of SpaceX, as prime reasons to support sovereign access to space, a capability currently offered only by Arianespace. If European nations can reform how they treat their commercial space companies, there’s enough ambition, know-how, and money in Europe to foster a competitive launch industry.

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.

Isar Aerospace aims for weekend launch. A German startup named Isar Aerospace will try to launch its first rocket Saturday, aiming to become the first in a wave of new European launch companies to reach orbit, Ars reports. The Spectrum rocket consists of two stages, stands about 92 feet (28 meters) tall, and can haul payloads up to 1 metric ton (2,200 pounds) into low-Earth orbit. Based in Munich, Isar was founded by three university graduate students in 2018. Isar scrubbed a launch attempt Monday due to unfavorable winds at the launch site in Norway.

From the Arctic … Notably, this will be the first orbital launch attempt from a launch pad in Western Europe. The French-run Guiana Space Center in South America is the primary spaceport for European rockets. Virgin Orbit staged an airborne launch attempt from an airport in the United Kingdom in 2023, and the Plesetsk Cosmodrome is located in European Russia. The launch site for Isar is named Andøya Spaceport, located about 650 miles (1,050 kilometers) north of Oslo, inside the Arctic Circle. (submitted by EllPeaTea)

A chance for competition in Europe. The European Space Agency is inviting proposals to inject competition into the European launch market, an important step toward fostering a dynamic multiplayer industry officials hope one day will mimic that of the United States, Ars reports. The near-term plan for the European Launcher Challenge is for ESA to select companies for service contracts to transport ESA and other European government payloads to orbit from 2026 through 2030. A second component of the challenge is for companies to perform at least one demonstration of an upgraded launch vehicle by 2028. The competition is open to any European company working in the launch business.

Challenging the status quo … This is a major change from how ESA has historically procured launch services. Arianespace has been the only European launch provider available to ESA and other European institutions for more than 40 years. But there are private companies across Europe at various stages of developing their own small launchers, and potentially larger rockets, in the years ahead. With the European Launcher Challenge, ESA will provide each of the winners up to 169 million euros ($182 million), a significant cash infusion that officials hope will shepherd Europe’s nascent private launch industry toward liftoff. Companies like Isar Aerospace, Rocket Factory Augsburg, MaiaSpace, and PLD Space are among the contenders for ESA contracts.

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Rocket Lab launches eight satellites. Rocket Lab launched eight satellites Wednesday for a German company that is expanding its constellation to detect and track wildfires, Space News reports. An Electron rocket lifted off from New Zealand and completed deploying its payload of eight CubeSats for OroraTech about 55 minutes later, placing them into Sun-synchronous orbits at an altitude of about 341 miles (550 kilometers). This was Rocket Lab’s fifth launch of the year, and the third in less than two weeks.

Fire goggles … OroraTech launched three satellites before this mission, fusing data from those satellites and government missions to detect and track wildfires. The new satellites are designed to fill a gap in coverage in the afternoon, a peak time for wildfire formation and spread. OroraTech plans to launch eight more satellites later this year. Wildfire monitoring from space is becoming a new application for satellite technology. Last month, OroraTech partnered with Spire for a contract to build a CubeSat constellation called WildFireSat for the Canadian Space Agency. Google is backing FireSat, another constellation of more than 50 satellites to be deployed in the coming years to detect and track wildfires. (submitted by EllPeaTea)

Should Britain have a sovereign launch capability? A UK House of Lords special inquiry committee has heard from industry experts on the importance of fostering a sovereign launch capability, European Spaceflight reports. On Monday, witnesses from the UK space industry testified that the nation shouldn’t rely on others, particularly the United States, to put satellites into orbit. “The idea that we will be able to do it through America… certainly in today’s, you know, the last 50 days, I think is very, very doubtful. The UK needs access to space,” said Scott Hammond, deputy CEO of SaxaVord Spaceport in Scotland.

Looking inward … A representative from one of the most promising UK launch startups agreed. “Most people who are looking to launch are beholden to the United States solutions or services that are there,” said Alan Thompson, head of government affairs at Skyrora. “Without having our own home-based or UK-based service provider, we risk not having that voice and not being able to undertake all these experiments or be able to manifest ourselves better in space.” The UK is the only nation to abandon an independent launch capability after putting a satellite into orbit. The British government canceled the Black Arrow rocket in the early 1970s, citing financial reasons. A handful of companies, including Skyrora, is working to restore the orbital launch business to the UK.

This rocket engine CEO faces some salacious allegations. The Independent published what it described as an exclusive report Monday describing a lawsuit filed against the CEO of RocketStar, a New York-based company that says its mission is “improving upon the engines that power us to the stars.” Christopher Craddock is accused of plundering investor funds to underwrite pricey jaunts to Europe, jewelry for his wife, child support payments, and, according to the company’s largest investor, “airline tickets for international call girls to join him for clandestine weekends in Miami,” The Independent reports. Craddock established RocketStar in 2014 after financial regulators barred him from working on Wall Street over a raft of alleged violations.

Go big or go home … The $6 million lawsuit filed by former CEO Michael Mojtahedi alleges RocketStar “is nothing more than a Ponzi scheme… [that] has been predicated on Craddock’s ability to con new people each time the company has run out of money.” On its website, RocketStar says its work focuses on aerospike rocket engines and a “FireStar Fusion Drive, the world’s first electric propulsion device enhanced with nuclear fusion.” These are tantalizing technologies that have proven elusive for other rocket companies. RocketStar’s attorney told The Independent: “The company denies the allegations and looks forward to vindicating itself in court.”

Another record for SpaceX. Last Thursday, SpaceX launched a batch of clandestine SpaceX-built surveillance satellites for the National Reconnaissance Office from Vandenberg Space Force Base in California, Spaceflight Now reports. This was the latest in a series of flights populating the NRO’s constellation of low-Earth orbit reconnaissance satellites. What was unique about this mission was its use of a Falcon 9 first stage booster that flew to space just nine days prior with a NASA astronomy satellite. The successful launch broke the record for the shortest span between flights of the same Falcon 9 booster, besting a 13.5-day turnaround in November 2024.

A mind-boggling number of launches … This flight also marked the 450th launch of a Falcon 9 rocket since its debut in 2010, and the 139th within a 365-day period, despite suffering its first mission failure in nearly 10 years and a handful of other glitches. SpaceX’s launch pace is unprecedented in the history of the space industry. No one else is even close. In the last Rocket Report I authored, I wrote that SpaceX’s steamroller no longer seems to be rolling downhill. That may be the case as the growth in the Falcon 9 launch cadence has slowed, but it’s hard for me to see anyone else matching SpaceX’s launch rate until at least the 2030s.

Rocket Lab and Stoke Space find an on-ramp. Space Systems Command announced Thursday that it selected Rocket Lab and Stoke Space to join the Space Force’s National Security Space Launch (NSSL) program. The contracts have a maximum value of $5.6 billion, and the Space Force will dole out “task orders” for individual missions as they near launch. Rocket Lab and Stoke Space join SpaceX, ULA, and Blue Origin as eligible launch providers for lower-priority national security satellites, a segment of missions known as Phase 3 Lane 1 in the parlance of the Space Force. For these missions, the Space Force won’t require certification of the rockets, as the military does for higher-value missions in the so-called “Lane 2” segment. However, Rocket Lab and Stoke Space must complete at least one successful flight of their new Neutron and Nova rockets before they are cleared to launch national security payloads.

Stoked at Stoke … This is a big win for Rocket Lab and Stoke. For Rocket Lab, it bolsters the business case for the medium-class Neutron rocket it is developing for flights from Wallops Island, Virginia. Neutron will be partially reusable with a recoverable first stage. But Rocket Lab already has a proven track record with its smaller Electron launch vehicle. Stoke hasn’t launched anything, and it has lofty ambitions for a fully reusable two-stage rocket called Nova. This is a huge vote of confidence in Stoke. When the Space Force released its invitation for an on-ramp to the NSSL program last year, it said bidders must show a “credible plan for a first launch by December 2025.” Smart money is that neither company will launch its rockets by the end of this year, but I’d love to be proven wrong.

Falcon 9 deploys spy satellite. Monday afternoon, a SpaceX Falcon 9 took flight from Florida’s Space Coast and delivered a national security payload designed, built, and operated by the National Reconnaissance Office into orbit, Florida Today reports. Like almost all NRO missions, details about the payload are classified. The mission codename was NROL-69, and the launch came three-and-a-half days after SpaceX launched another NRO mission from California. While we have some idea of what SpaceX launched from California last week, the payload for the NROL-69 mission is a mystery.

Space sleuthing … There’s an online community of dedicated skywatchers who regularly track satellites as they sail overhead around dawn and dusk. The US government doesn’t publish the exact orbital parameters for its classified spy satellites (they used to), but civilian trackers coordinate with one another, and through a series of observations, they can produce a pretty good estimate of a spacecraft’s orbit. Marco Langbroek, a Dutch archeologist and university lecturer on space situational awareness, is one of the best at this, using publicly available information about the flight path of a launch to estimate when the satellite will fly overhead. He and three other observers in Europe managed to locate the NROL-69 payload just two days after the launch, plotting the object in an orbit between 700 and 1,500 kilometers at an inclination of 64.1 degrees to the equator. Analysts speculated this mission might carry a pair of naval surveillance spacecraft, but this orbit doesn’t match up well with any known constellations of NRO satellites.

NASA continues with Artemis II preps. Late Saturday night, technicians at Kennedy Space Center in Florida moved the core stage for NASA’s second Space Launch System rocket into position between the vehicle’s two solid-fueled boosters, Ars reports. Working inside the iconic 52-story-tall Vehicle Assembly Building, ground teams used heavy-duty cranes to first lift the butterscotch orange core stage from its cradle, then rotate it to a vertical orientation and lift it into a high bay, where it was lowered into position on a mobile launch platform. The 212-foot-tall (65-meter) core stage is the largest single hardware element for the Artemis II mission, which will send a team of four astronauts around the far side of the Moon and back to Earth as soon as next year.

Looking like a go … With this milestone, the slow march toward launch continues. A few months ago, some well-informed people in the space community thought there was a real possibility the Trump administration could quickly cancel NASA’s Space Launch System, the high-priced heavy-lifter designed to send astronauts from the Earth to the Moon. The most immediate possibility involved terminating the SLS program before it flies with Artemis II. This possibility appears to have been overcome by circumstances. The rockets most often mentioned as stand-ins for the Space Launch System—SpaceX’s Starship and Blue Origin’s New Glenn—aren’t likely to be cleared for crew missions for at least several years. The long-term future of the Space Launch System remains in doubt.

Space Force says Vulcan is good to go. The US Space Force on Wednesday announced that it has certified United Launch Alliance’s Vulcan rocket to conduct national security missions, Ars reports. “Assured access to space is a core function of the Space Force and a critical element of national security,” said Brig. Gen. Kristin Panzenhagen, program executive officer for Assured Access to Space, in a news release. “Vulcan certification adds launch capacity, resiliency, and flexibility needed by our nation’s most critical space-based systems.” The formal announcement closes a yearslong process that has seen multiple delays in the development of the Vulcan rocket, as well as two anomalies in recent years that were a further setback to certification.

Multiple options … This certification allows ULA’s Vulcan to launch the military’s most sensitive national security missions, a separate lot from those Rocket Lab and Stoke Space are now eligible for (as we report in a separate Rocket Report entry). It elevates Vulcan to launch these missions alongside SpaceX’s Falcon 9 and Falcon Heavy rockets. Vulcan will not be the next rocket that the company launches, however. First up is one of the company’s remaining Atlas V boosters, carrying Project Kuiper broadband satellites for Amazon. This launch could occur in April, although ULA has not set a date. This will be followed by the first Vulcan national security launch, which the Space Force says could occur during the coming “summer.”

Next three launches

March 29: Spectrum | “Going Full Spectrum” | Andøya Spaceport, Norway | 11: 30 UTC

March 29: Long March 7A | Unknown Payload | Wenchang Space Launch Site, China | 16: 05 UTC

March 30: Alpha | LM-400 | Vandenberg Space Force Base, California | 13: 37 UTC

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.

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As preps continue, it’s looking more likely NASA will fly the Artemis II mission

artemis, artemis II, human spaceflight, Kennedy Space Center, launch, moon, NASA, Science, Space, space launch system / Beth Washington / March 25, 2025

NASA’s existing architecture still has a limited shelf life, and the agency will probably have multiple options for transporting astronauts to and from the Moon in the 2030s. A decision on the long-term future of SLS and Orion isn’t expected until the Trump administration’s nominee for NASA administrator, Jared Isaacman, takes office after confirmation by the Senate.

So, what is the plan for SLS?

There are different degrees of cancellation options. The most draconian would be an immediate order to stop work on Artemis II preparations. This is looking less likely than it did a few months ago and would come with its own costs. It would cost untold millions of dollars to disassemble and dispose of parts of Artemis II’s SLS rocket and Orion spacecraft. Canceling multibillion-dollar contracts with Boeing, Northrop Grumman, and Lockheed Martin would put NASA on the hook for significant termination costs.

Of course, these liabilities would be less than the $4.1 billion NASA’s inspector general estimates each of the first four Artemis missions will cost. Most of that money has already been spent for Artemis II, but if NASA spends several billion dollars on each Artemis mission, there won’t be much money left over to do other cool things.

Other options for NASA might be to set a transition point when the Artemis program would move off of the Space Launch System rocket, and perhaps even the Orion spacecraft, and switch to new vehicles.

Looking down on the Space Launch System for Artemis II. Credit: NASA/Frank Michaux

Another possibility, which seems to be low-hanging fruit for Artemis decision-makers, could be to cancel the development of a larger Exploration Upper Stage for the SLS rocket. If there are a finite number of SLS flights on NASA’s schedule, it’s difficult to justify the projected $5.7 billion cost of developing the upgraded Block 1B version of the Space Launch System. There are commercial options available to replace the rocket’s Boeing-built Exploration Upper Stage, as my colleague Eric Berger aptly described in a feature story last year.

For now, it looks like NASA’s orange behemoth has a little life left in it. All the hardware for the Artemis II mission has arrived at the launch site in Florida.

The Trump administration will release its fiscal-year 2026 budget request in the coming weeks. Maybe then NASA will also have a permanent administrator, and the veil will lift over the White House’s plans for Artemis.

As preps continue, it’s looking more likely NASA will fly the Artemis II mission Read More »

NASA says Orion’s heat shield is good to go for Artemis II—but does it matter?

artemis, artemis II, bill nelson, human spaceflight, moon, NASA, orion, space launch system, Uncategorized / Kelly Newman / December 7, 2024

“We have since determined that while the capsule was dipping in and out of the atmosphere, as part of that planned skip entry, heat accumulated inside the heat shield outer layer, leading to gases forming and becoming trapped inside the heat shield,” said Pam Melroy, NASA’s deputy administrator. “This caused internal pressure to build up and led to cracking and uneven shedding of that outer layer.”

An independent team of experts concurred with NASA’s determination of the root cause, Melroy said.

NASA Administrator Bill Nelson, Deputy Administrator Pam Melroy, Associate Administrator Jim Free, and Artemis II Commander Reid Wiseman speak with reporters Thursday in Washington, DC. Credit: NASA/Bill Ingalls

Counterintuitively, this means NASA engineers are comfortable with the safety of the heat shield if the Orion spacecraft reenters the atmosphere at a slightly steeper angle than it did on Artemis I and spends more time subjected to higher temperatures.

When the Orion spacecraft climbed back out of the atmosphere during the Artemis I skip reentry, a period known as the skip dwell, NASA said heating rates decreased and thermal energy accumulated inside the heat shield’s Avcoat material. This generated gases inside the heat shield through a process known as pyrolysis.

“Pyrolysis is just burning without oxygen,” said Amit Kshatriya, deputy associate administrator of NASA’s Moon to Mars program. “We learned that as part of that reaction, the permeability of the Avcoat material is essential.”

During the skip dwell, “the production of those gases was higher than the permeability could tolerate, so as a result, pressure differential was created. That pressure led to cracks in plane with the outer mold line of the vehicle,” Kshatriya said.

NASA didn’t know this could happen because engineers tested the heat shield on the ground at higher temperatures than the Orion spacecraft encountered in flight to prove the thermal barrier could withstand the most extreme possible heating during reentry.

“What we missed was this critical region in the middle, and we missed that region because we didn’t have the test facilities to produce the low-level energies that occur during skip and dwell,” Kshatriya said Thursday.

During the investigation, NASA replicated the charring and cracking after engineers devised a test procedure to expose Avcoat heat shield material to the actual conditions of the Artemis I reentry.

So, for Artemis II, NASA plans to modify the reentry trajectory to reduce the skip reentry’s dwell time. Let’s include some numbers to help illustrate the difference.

The distance traveled by Artemis I during the reentry phase of the mission was more than 3,000 nautical miles (3,452 miles; 5,556 kilometers), according to Kshatriya. This downrange distance will be limited to no more than 1,775 nautical miles (2,042 miles; 3,287 kilometers) on Artemis II, effectively reducing the dwell time the Orion spacecraft spends in the lower heating regime that led to the cracking on Artemis I.

NASA’s inspector general report in May included new images of Orion’s heat shield that the agency did not initially release after the Artemis I mission. Credit: NASA Inspector General

With this change, Kshatriya said NASA engineers don’t expect to see the heat shield erosion they saw on Artemis I. “The gas generation that occurs during that skip dwell is sufficiently low that the environment for crack generation is not going to overwhelm the structural integrity of the char layer.”

For future Orion spaceships, NASA and its Orion prime contractor, Lockheed Martin, will incorporate changes to address the heat shield’s permeability problem.

Waiting for what?

NASA officials discussed the heat shield issue, and broader plans for the Artemis program, in a press conference in Washington on Thursday. But the event’s timing added a coat of incredulity to much of what they said. President-elect Donald Trump, with SpaceX founder Elon Musk in his ear, has vowed to cut wasteful government spending.

NASA says Orion’s heat shield is good to go for Artemis II—but does it matter? Read More »

NASA is stacking the Artemis II rocket, implying a simple heat shield fix

artemis, artemis II, human spaceflight, Kennedy Space Center, NASA, orion, Science, Space, space launch system, vehicle assembly building / 9u50fv / November 21, 2024

A good sign

The readiness of the Orion crew capsule, where the four Artemis II astronauts will live during their voyage around the Moon, is driving NASA’s schedule for the mission. Officially, Artemis II is projected to launch in September of next year, but there’s little chance of meeting that schedule.

At the beginning of this year, NASA officials ruled out any opportunity to launch Artemis II in 2024 due to several technical issues with the Orion spacecraft. Several of these issues are now resolved, but NASA has not released any meaningful updates on the most significant problem.

This problem involves the Orion spacecraft’s heat shield. During atmospheric reentry at the end of the uncrewed Artemis I test flight in 2022, the Orion capsule’s heat shield eroded and cracked in unexpected ways, prompting investigations by NASA engineers and an independent panel.

NASA’s Orion heat shield inquiry ran for nearly two years. The investigation has wrapped up, two NASA officials said last month, but they declined to discuss any details of the root cause of the heat shield issue or the actions required to resolve the problem on Artemis II.

These corrective options ranged from doing nothing to changing the Orion spacecraft’s reentry angle to mitigate heating or physically modifying the Artemis II heat shield. In the latter scenario, NASA would have to disassemble the Orion spacecraft, which is already put together and is undergoing environmental testing at Kennedy Space Center. This would likely delay the Artemis II launch by a couple of years.

In August, NASA’s top human exploration official told Ars that the agency would hold off on stacking the SLS rocket until engineers had a good handle on the heat shield problem. There are limits to how long the solid rocket boosters can remain stacked vertically. The joints connecting each segment of the rocket motors are certified for one year. This clock doesn’t actually start ticking until NASA stacks the next booster segments on top of the lowermost segments.

However, NASA waived this rule on Artemis I when the boosters were stacked nearly two years before the successful launch.

A NASA spokesperson told Ars on Wednesday that the agency had nothing new to share on the Orion heat shield or what changes, if any, are required for the Artemis II mission. This information should be released before the end of the year, she said. At the same time, NASA could announce a new target launch date for Artemis II at the end of 2025, or more likely in 2026.

But because NASA gave the “go” for SLS stacking now, it seems safe to rule out any major hardware changes on the Orion heat shield for Artemis II.

NASA is stacking the Artemis II rocket, implying a simple heat shield fix Read More »

It’s increasingly unlikely that humans will fly around the Moon next year

artemis II, ground systems, orion, Science, Space / 9u50fv / October 17, 2024

Don’t book your tickets for the launch of NASA’s Artemis II mission next year just yet.

We have had reason to doubt the official September 2025 launch date for the mission, the first crewed flight into deep space in more than five decades, for a while now. This is principally because NASA is continuing to mull the implications of damage to the Orion spacecraft’s heat shield from the Artemis I mission nearly two years ago.

However, it turns out that there are now other problems with holding to this date as well.

No schedule margin

A new report from the US Government Accountability Office found that NASA’s Exploration Ground Systems program—this is, essentially, the office at Kennedy Space Center in Florida responsible for building ground infrastructure to support the Space Launch System rocket and Orion—is in danger of missing its schedule for Artemis II.

During this flight a crew of four astronauts, commanded by NASA’s Reid Wiseman, will launch inside Orion on a 10-day mission out to the Moon and back. The spacecraft will follow a free-return trajectory, which is important, because if there is a significant problem with Orion spacecraft’s propulsion system, the trajectory of the vehicle will still carry it back to Earth. At their closest approach, the crew will come within about 6,500 miles (10,400 km) of the surface of the far side of the Moon.

The new report, published Thursday, finds that the Exploration Ground Systems program had several months of schedule margin in its work toward a September 2025 launch date at the beginning of the year. But now, the program has allocated all of that margin to technical issues experienced during work on the rocket’s mobile launcher and pad testing.

“Earlier in 2024, the program was reserving that time for technical issues that may arise during testing of the integrated SLS and Orion vehicle or if weather interferes with planned activities, among other things,” the report states. “Officials said it is likely that issues will arise because this is the first time testing many of these systems. Given the lack of margin, if further issues arise during testing or integration, there will likely be delays to the September 2025 Artemis II launch date.”

It’s increasingly unlikely that humans will fly around the Moon next year Read More »

Rocket delivered to launch site for first human flight to the Moon since 1972

artemis, artemis II, human spaceflight, Kennedy Space Center, NASA, Science, SLS core stage, Space, space launch system / Shannon Garcia / July 27, 2024

The central piece of NASA’s second Space Launch System rocket arrived at Kennedy Space Center in Florida this week. Agency officials intend to start stacking the towering launcher in the next couple of months for a mission late next year carrying a team of four astronauts around the Moon.

The Artemis II mission, officially scheduled for September 2025, will be the first voyage by humans to the vicinity of the Moon since the last Apollo lunar landing mission in 1972. NASA astronauts Reid Wiseman, Victor Glover, Christina Koch, and Canadian mission specialist Jeremy Hansen will ride the SLS rocket away from Earth, then fly around the far side of the Moon and return home inside NASA’s Orion spacecraft.

“The core is the backbone of SLS, and it’s the backbone of the Artemis mission,” said Matthew Ramsey, NASA’s mission manager for Artemis II. “We’ve been waiting for the core to get here because all the integrated tests and checkouts that we do have to have the core stage. It has the flight avionics that drive the whole system. The boosters are also important, but the core is really the backbone for Artemis. So it’s a big day.”

The core stage rolled off of NASA’s Pegasus barge at Kennedy early Wednesday, following a weeklong ocean voyage from New Orleans, where Boeing builds the rocket under contract to NASA.

Ramsey told Ars that ground teams hope to begin stacking the rocket’s two powerful solid rocket boosters on NASA’s mobile launcher platform in September. Each booster, supplied by Northrop Grumman, is made of five segments with pre-packed solid propellant and a nose cone. All the pieces for the SLS boosters are at Kennedy and ready for stacking, Ramsey said.

The SLS upper stage, built by United Launch Alliance, is also at the Florida launch site. Now, the core stage is at Kennedy. In August or September, NASA plans to deliver the two remaining elements of the SLS rocket to Florida. These are the adapter structures that will connect the core stage to the upper stage, and the upper stage to the Orion spacecraft.

A heavy-duty crane inside the cavernous Vehicle Assembly Building (VAB) will hoist each segment of the SLS boosters into place on the launch platform. Once the boosters are fully stacked, ground teams will lift the 212-foot (65-meter) core stage vertical in the transfer aisle running through the center of the VAB. A crane will then lower the core stage between the boosters. That could happen as soon as December, according to Ramsey.

Then comes the launch vehicle stage adapter, the upper stage, the Orion stage adapter, and finally, the Orion spacecraft itself.

Moving toward operations

NASA’s inspector general reported in 2022 that NASA’s first four Artemis missions will each cost $4.1 billion. Subsequent documents, including a Government Accountability Office report last year, suggest the expendable SLS core stage is responsible for at least a quarter of the cost for each Artemis flight.

The core stage for Artemis II is powered by four hydrogen-fueled RS-25 engines produced by Aerojet Rocketdyne. Two of the reusable engines for Artemis II have flown on the space shuttle, and the other two RS-25s were built in the shuttle era but never flew. Each SLS launch will put the core stage and its engines in the Atlantic Ocean.

Steve Wofford, who manages the stages office for the SLS program at NASA’s Marshall Space Flight Center, told Ars there are “no major configuration differences” between the core stages for Artemis I and Artemis II. The only minor differences involve instrumentation that NASA wanted on Artemis I to measure pressures, accelerations, vibrations, temperatures, and other parameters on the first flight of the Space Launch System.

“We are still working off some flight observations that we made on Artemis I, but no showstoppers,” Wofford said. “On the first article, the test flight, Artemis I, we really loaded it up. That’s a golden opportunity to learn as much as you can about the vehicle and the flight regime, and anchor all your models… As you progress, you need less and less of that. So Core Stage 2 will have less development flight instrumentation than Core Stage 1, and then Core Stage 3 will have less still.”

Rocket delivered to launch site for first human flight to the Moon since 1972 Read More »

NASA confirms “independent review” of Orion heat shield issue

artemis, artemis I, artemis II, human spaceflight, NASA, orion, Science, Space, victor glover / Shannon Garcia / May 9, 2024

Enlarge / The Orion spacecraft after splashdown in the Pacific Ocean at the end of the Artemis I mission.

NASA has asked a panel of outside experts to review the agency’s investigation into the unexpected loss of material from the heat shield of the Orion spacecraft on a test flight in 2022.

Chunks of charred material cracked and chipped away from Orion’s heat shield during reentry at the end of the 25-day unpiloted Artemis I mission in December 2022. Engineers inspecting the capsule after the flight found more than 100 locations where the stresses of reentry stripped away pieces of the heat shield as temperatures built up to 5,000° Fahrenheit.

This was the most significant discovery on the Artemis I, an unpiloted test flight that took the Orion capsule around the Moon for the first time. The next mission in NASA’s Artemis program, Artemis II, is scheduled for launch late next year on a test flight to send four astronauts around the far side of the Moon.

Another set of eyes

The heat shield, made of a material called Avcoat, is attached to the base of the Orion spacecraft in 186 blocks. Avcoat is designed to ablate, or erode, in a controlled manner during reentry. Instead, fragments fell off the heat shield that left cavities resembling potholes.

Investigators are still looking for the root cause of the heat shield problem. Since the Artemis I mission, engineers conducted sub-scale tests of the Orion heat shield in wind tunnels and high-temperature arcjet facilities. NASA has recreated the phenomenon observed on Artemis I in these ground tests, according to Rachel Kraft, an agency spokesperson.

“The team is currently synthesizing results from a variety of tests and analyses that inform the leading theory for what caused the issues,” said Rachel Kraft, a NASA spokesperson.

Last week, nearly a year and a half after the Artemis I flight, the public got its first look at the condition of the Orion heat shield with post-flight photos released in a report from NASA’s inspector general. Cameras aboard the Orion capsule also recorded pieces of the heat shield breaking off the spacecraft during reentry.

NASA’s inspector general said the char loss issue “creates a risk that the heat shield may not sufficiently protect the capsule’s systems and crew from the extreme heat of reentry on future missions.”

“Those pictures, we’ve seen them since they were taken, but more importantly… we saw it,” said Victor Glover, pilot of the Artemis II mission, in a recent interview with Ars. “More than any picture or report, I’ve seen that heat shield, and that really set the bit for how interested I was in the details.”

NASA confirms “independent review” of Orion heat shield issue Read More »

NASA still doesn’t understand root cause of Orion heat shield issue

artemis, artemis II, human spaceflight, Lockheed Martin, moon, NASA, orion, Space / Shannon Garcia / April 27, 2024

Flight rationale —

“When we stitch it all together, we’ll either have flight rationale or we won’t.”

Stephen Clark – Apr 27, 2024 12: 22 am UTC

NASA's Orion spacecraft descends toward the Pacific Ocean on December 11, 2021, at the end of the Artemis I mission. — Enlarge / NASA’s Orion spacecraft descends toward the Pacific Ocean on December 11, 2021, at the end of the Artemis I mission.

NASA

NASA officials declared the Artemis I mission successful in late 2021, and it’s hard to argue with that assessment. The Space Launch System rocket and Orion spacecraft performed nearly flawlessly on an unpiloted flight that took it around the Moon and back to Earth, setting the stage for the Artemis II, the program’s first crew mission.

But one of the things engineers saw on Artemis I that didn’t quite match expectations was an issue with the Orion spacecraft’s heat shield. As the capsule streaked back into Earth’s atmosphere at the end of the mission, the heat shield ablated, or burned off, in a different manner than predicted by computer models.

More of the charred material than expected came off the heat shield during the Artemis I reentry, and the way it came off was somewhat uneven, NASA officials said. Orion’s heat shield is made of a material called Avcoat, which is designed to burn off as the spacecraft plunges into the atmosphere at 25,000 mph (40,000 km per hour). Coming back from the Moon, Orion encountered temperatures up to 5,000° Fahrenheit (2,760° Celsius), hotter than a spacecraft sees when it reenters the atmosphere from low-Earth orbit.

Despite heat shield issue, the Orion spacecraft safely splashed down in the Pacific Ocean. Engineers discovered the uneven charring during post-flight inspections.

No answers yet

Amit Kshatriya, who oversees development for the Artemis missions in NASA’s exploration division, said Friday that the agency is still looking for the root cause of the heat shield issue. Managers want to be sure they understand the cause before proceeding with Artemis II, which will send astronauts Reid Wiseman, Victor Glover, Christina Koch, and Jeremy Hansen on a 10-day flight around the far side of the Moon.

This will be the first time humans fly near the Moon since the last Apollo mission in 1972. In January, NASA announced a delay in the launch of Artemis II from late 2024 until September 2025, largely due to the unresolved investigation into the heat shield issue.

“We are still in the middle of our investigation on the performance of the heat shield from Artemis I,” Kshatriya said Friday in a meeting with a committee of the NASA Advisory Council.

Engineers have performed sub-scale heat shield tests in wind tunnels and arc jet facilities to better understand what led to the uneven charring on Artemis I. “We’re getting close to the final answer in terms of that cause,” Kshatriya said.

NASA officials previously said it is unlikely they will need to make changes to the heat shield already installed on the Orion spacecraft for Artemis II, but haven’t ruled it out. A redesign or modifications to the Orion heat shield on Artemis II would probably delay the mission by at least a year.

Instead, engineers are analyzing all of the possible trajectories the Orion spacecraft could fly when it reenters the atmosphere at the end of the Artemis II mission. On Artemis I, Orion flew a skip reentry profile, where it dipped into the atmosphere, skipped back into space, and then made a final descent into the atmosphere, sort of like a rock skipping across a pond. This profile allows Orion to make more precise splashdowns near recovery teams in the Pacific Ocean and reduces g-forces on the spacecraft and the crew riding inside. It also splits up the heat load on the spacecraft into two phases.

The Apollo missions flew a direct reentry profile. There is also a reentry mode available called a ballistic entry, in which the spacecraft would fly through the atmosphere unguided.

Ground teams at NASA's Kennedy Space Center in Florida moved the Orion spacecraft for the Artemis II mission into an altitude chamber earlier this month. — Enlarge / Ground teams at NASA’s Kennedy Space Center in Florida moved the Orion spacecraft for the Artemis II mission into an altitude chamber earlier this month.

The charred material began flying off the heat shield in the first phase of the skip reentry. Engineers are looking at how the skip reentry profile affected the performance of the Orion heat shield. NASA wants to understand how the Orion heat shield would perform during each of the possible reentry trajectories for Artemis II.

“What we have the analysis teams off doing is saying, ‘OK, independent of what the constraints are going to be, what can we tolerate?” Kshatriya said.

Once officials understand the cause of the heat shield charring, engineers will determine what kind of trajectory Artemis II needs to fly on reentry to minimize risk to the crew. Then, managers will look at building what NASA calls flight rationale. Essentially, this is a process of convincing themselves the spacecraft is safe to fly.

“When we stitch it all together, we’ll either have flight rationale or we won’t,” Kshatriya said.

Assuming NASA approves the flight rationale for Artemis II, there will be additional discussions about how to ensure Orion heat shields are safe to fly on downstream Artemis missions, which will have higher-speed reentry profiles as astronauts return from landings on the Moon.

In the meantime, preparations on the Orion spacecraft for Artemis II continue at NASA’s Kennedy Space Center. The crew and service modules for Artemis II were mated together earlier this year, and the entire Orion spacecraft is now inside a vacuum chamber for environmental testing.

NASA still doesn’t understand root cause of Orion heat shield issue Read More »