Enlarge/ This photo of the International Space Station was captured by a crew member on a Soyuz spacecraft.
NASA/Roscosmos
A little more than two years ago, Dmitry Rogozin, the bellicose former head of Russia’s space agency, nearly brought the International Space Station partnership to its knees.
During his tenure as director general of Roscosmos, Rogozin was known for his bombastic social media posts and veiled threats to abandon the space station after Russia’s invasion of Ukraine. Russian President Vladimir Putin tersely dismissed Rogozin in July 2022 and replaced him with Yuri Borisov, a former deputy prime minister.
While the clash between Russia and Western governments over the war in Ukraine has not cooled, the threats against the International Space Station (ISS) ended. The program remains one of the few examples of cooperation between the US and Russian governments. Last year, Russia formally extended its commitment to the ISS to at least 2028. NASA and space agencies in Europe, Japan, and Canada have agreed to maintain the space station through 2030.
It’s this two-year disparity that concerns NASA officials plotting the final days of the ISS. NASA awarded SpaceX a contract in June to develop a deorbit vehicle based on the company’s Dragon spacecraft to steer the more than 450-ton complex toward a safe reentry over a remote stretch of ocean.
“We do have that uncertainty, 2028 through 2030, with Roscosmos,” said Robyn Gatens, director of the ISS program at NASA Headquarters, in a meeting of the agency’s advisory council this week. “We expect to hear from them over the next year or two as far as their follow-on plans, hoping that they also extend through 2030.”
Fighting through the tension
Roscosmos works in four-year increments, so Russia’s decision last year extended the country’s participation in the space station program from 2024 until 2028. Russian space officials know the future of the country’s space program is directly tied to the ISS. If Russia pulls out of the space station in 2028, Roscosmos will be left without much of a human spaceflight program.
There’s no chance Russia will have its own space station in low-Earth orbit in four years, so abandoning its role on the ISS would leave Russia’s Soyuz crew ferry spacecraft without a destination. Russian and Chinese leaders have fostered closer ties in space in recent years, but China’s Tiangong space station is inaccessible from Russia’s launch sites.
The US and Russian segments of the ISS depend on one another for critical functions. The US section generates most of the space station’s electricity and maintains the lab’s orientation without using precious rocket fuel. Russia is responsible for maintaining the station’s altitude and maneuvering the complex out of the path of space junk, although Northrop Grumman’s Cygnus cargo craft has also demonstrated an ability to boost the station’s orbit.
While Russia’s space program would feel the pain if Roscosmos made an early exit from the space station, the relationship between Russia and the West is volatile. US and European leaders may soon give Ukraine the green light to use Western-supplied weapons for attacks deep inside Russian territory. Putin said last week that this would be tantamount to war. “This will mean that NATO countries, the United States, and European countries are fighting Russia,” he said.
Enlarge/ Landspace’s reusable rocket test vehicle lifts off from the Jiuquan Satellite Launch Center on Wednesday, September 11, 2024.
Welcome to Edition 7.11 of the Rocket Report! Outside of companies owned by American billionaires, the most imminent advancements in reusable rockets are coming from China’s quasi-commercial launch industry. This industry is no longer nascent. After initially relying on solid-fueled rocket motors apparently derived from Chinese military missiles, China’s privately funded launch firms are testing larger launchers, with varying degrees of success, and now performing hop tests reminiscent of SpaceX’s Grasshopper and F9R Dev1 programs more than a decade ago.
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.
Landspace hops closer to a reusable rocket. Chinese private space startup Landspace has completed a 10-kilometer (33,000-foot) vertical takeoff and vertical landing test on its Zhuque-3 (ZQ-3) reusable rocket testbed, including a mid-flight engine reignition at near supersonic conditions, Aviation Week & Space Technology reports. The 18.3-meter (60-foot) vehicle took off from the Jiuquan launch base in northwestern China, ascended to 10,002 meters, and then made a vertical descent and achieved an on-target propulsive landing 3.2 kilometers (2 miles) from the launch pad. Notably, the rocket’s methane-fueled variable-thrust engine intentionally shutdown in flight, then reignited for descent, as engines would operate on future full-scale booster flybacks. The test booster used grid fins and cold gas thrusters to control itself when its main engine was dormant, according to Landspace.
“All indicators met the expected design” … Landspace hailed the test as a major milestone in the company’s road to flying its next rocket, the Zhuque-3, as soon as next year. With nine methane-fueled main engines, the Zhuque-3 will initially be able to deliver 21 metric tons (46,300 pounds) of payload into low-Earth orbit with its booster flying in expendable mode. In 2026, Landspace aims to begin recovering Zhuque-3 first-stage boosters for reuse. Landspace is one of several Chinese companies working seriously on reusable rocket designs. Another Chinese firm, Deep Blue Aerospace, says it plans a 100-kilometer (62-mile) suborbital test of a reusable booster soon, ahead of the first flight of its medium-class Nebula-1 rocket next year. (submitted by Ken the Bin)
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Isar Aerospace sets low bar for success on first launch. Daniel Metzler, CEO of German launch startup Isar Aerospace, stated that the first flight of the Spectrum rocket would be a success if it didn’t destroy the launch site, European Spaceflight reports. During an interview at the Handelsblatt innovation conference, Metzler was asked what he would consider a successful inaugural flight of Spectrum. “For me, the first flight will be a success if we don’t blow up the launch site,” explained Metzler. “That would probably be the thing that would set us back the most in terms of technology and time.” This tempering of expectations sounds remarkably similar to statements made by Elon Musk about SpaceX’s first flight of the Starship rocket last year.
In the catbird seat? … Isar Aerospace could be in a position to become the first in a new crop of European commercial launch companies to attempt its first orbital flight. Another German company, Rocket Factory Augsburg, recently gave up on a possible launch this year after the booster for its first launch caught fire and collapsed during a test at a launch site in Scotland. Isar plans to launch its two-stage Spectrum rocket, designed to carry up to 1,000 kilograms (2,200 pounds) of payload into low-Earth orbit, from Andøya Spaceport in Norway. Isar hasn’t publicized any schedule for the first flight of Spectrum, but there are indications the publicity-shy company is testing hardware at the Norwegian spaceport. (submitted by Ken the Bin)
FAA to introduce new orbital debris rules. The Federal Aviation Administration is moving ahead with efforts to develop rules for the disposal of upper stages as another Centaur upper stage breaks apart in orbit, Space News reports. The FAA released draft regulations on the matter for public comment one year ago, and the head of the agency’s commercial spaceflight division recently said the rules are a “high priority for our organization.” The rules would direct launch operators to dispose of upper stages in one of five ways, from controlled reentries to placement in graveyard or “disposal” orbits not commonly used by operational satellites. One change the FAA might make to the draft rules is to reduce the required timeline for an uncontrolled reentry of a disposed upper stage from no more than 25 years to a shorter timeline. “We got a lot of comments that said it should be a lot less,” said Kelvin Coleman, head of the FAA’s commercial spaceflight office. “We’re taking that into consideration.”
Upper stages are a problem … Several recent breakups involving spent upper stages in orbit have highlighted the concern that dead rocket bodies could create unnecessary space junk. Last month, the upper stage from a Chinese Long March 6A disintegrated in low-Earth orbit, creating at least 300 pieces of space debris. More recently, a Centaur upper stage from a United Launch Alliance Atlas V rocket broke apart in a much higher orbit, resulting in more than 40 pieces of debris. This was the fourth time one of ULA’s Centaur upper stages has broken up since 2018. (submitted by Ken the Bin)
Enlarge/ Boeing’s Starliner spacecraft after landing Friday night at White Sands Space Harbor, New Mexico.
Boeing
Boeing’s Starliner spacecraft sailed to a smooth landing in the New Mexico desert Friday night, an auspicious end to an otherwise disappointing three-month test flight that left the capsule’s two-person crew stuck in orbit until next year.
Cushioned by airbags, the Boeing crew capsule descended under three parachutes toward an on-target landing at 10: 01 pm local time Friday (12: 01 am EDT Saturday) at White Sands Space Harbor, New Mexico. From the outside, the landing appeared just as it would have if the spacecraft brought home NASA astronauts Butch Wilmore and Suni Williams, who became the first people to launch on a Starliner capsule on June 5.
But Starliner’s cockpit was empty as it flew back to Earth Friday night. Last month, NASA managers decided to keep Wilmore and Williams on the International Space Station (ISS) until next year after agency officials determined it was too risky for the astronauts to return to the ground on Boeing’s spaceship. Instead of coming home on Starliner, Wilmore and Williams will fly back to Earth on a SpaceX Dragon spacecraft in February. NASA has incorporated the Starliner duo into the space station’s long-term crew.
The Starliner spacecraft began the journey home by backing away from its docking port at the space station at 6: 04 pm EDT (22: 04 UTC), one day after astronauts closed hatches to prepare for the ship’s departure. The capsule fired thrusters to quickly back away from the complex, setting up for a deorbit burn to guide Starliner on a trajectory toward its landing site. Then, Starliner jettisoned its disposable service module to burn up over the Pacific Ocean, while the crew module, with a vacant cockpit, took aim on New Mexico.
After streaking through the atmosphere over the Pacific Ocean and Mexico, Starliner deployed three main parachutes to slow its descent, then a ring of six airbags inflated around the bottom of the spacecraft to dampen the jolt of touchdown. This was the third time a Starliner capsule has flown in space, and the second time the spacecraft fell short of achieving all of its objectives.
Not the desired outcome
“I’m happy to report Starliner did really well today in the undock, deorbit, and landing sequence,” said Steve Stich, manager of NASA’s commercial crew program, which manages a contract worth up to $4.6 billion for Boeing to develop, test, and fly a series of Starliner crew missions to the ISS.
While officials were pleased with Starliner’s landing, the celebration was tinged with disappointment.
“From a human perspective, all of us feel happy about the successful landing, but then there’s a piece of us that we wish it would have been the way we had planned it,” Stich said. “We had planned to have the mission land with Butch and Suni onboard. I think there are, depending on who you are on the team, different emotions associated with that, and I think it’s going to take a little time to work through that.”
Nevertheless, Stich said NASA made the right call last month when officials decided to complete the Starliner test flight without astronauts in the spacecraft.
“We made the decision to have an uncrewed flight based on what we knew at the time, and based on our knowledge of the thrusters and based on the modeling that we had,” Stich said. “If we’d had a model that would have predicted what we saw tonight perfectly, yeah, it looks like an easy decision to go say, ‘We could have had a crew tonight.’ But we didn’t have that.”
Boeing’s Starliner managers insisted the ship was safe to bring the astronauts home. It might be tempting to conclude the successful landing Friday night vindicated Boeing’s views on the thruster problems. However, he spacecraft’s propulsion system, provided by Aerojet Rocketdyne, clearly did not work as intended during the flight. NASA had the option of bringing Wilmore and Williams back to Earth on a different, flight-proven spacecraft, so they took it.
“It’s awfully hard for the team,” Stich said. “It’s hard for me, when we sit here and have a successful landing, to be in that position. But it was a test flight, and we didn’t have confidence, with certainty, of the thruster performance.”
Enlarge/ In this infrared view, Starliner descends under its three main parachutes moments before touchdown at White Sands Space Harbor, New Mexico.
NASA
As Starliner approached the space station in June, five of 28 control thrusters on Starliner’s service module failed, forcing Wilmore to take manual control as ground teams sorted out the problem. Eventually, engineers recovered four of the five thrusters, but NASA’s decision makers were unable to convince themselves the same problem wouldn’t reappear, or get worse, when the spacecraft departed the space station and headed for reentry and landing.
Engineers later determined the control jets lost thrust due to overheating, which can cause Teflon seals in valves to swell and deform, starving the thrusters of propellant. Telemetry data beamed back to the mission controllers from Starliner showed higher-than-expected temperatures on two of the service module thrusters during the flight back to Earth Friday night, but they continued working.
Ground teams also detected five small helium leaks on Starliner’s propulsion system soon after its launch in June. NASA and Boeing officials were aware of one of the leaks before the launch, but decided to go ahead with the test flight. Starliner was still leaking helium when the spacecraft undocked from the station Friday, but the leak rate remained within safety tolerances, according to Stich.
A couple of fresh technical problems cropped up as Starliner cruised back to Earth. One of 12 control jets on the crew module failed to ignite at any time during Starliner’s flight home. These are separate thrusters from the small engines that caused trouble earlier in the Starliner mission. There was also a brief glitch in Starliner’s navigation system during reentry.
Where to go from here?
Three NASA managers, including Stich, took questions from reporters in a press conference early Saturday following Starliner’s landing. Two Boeing officials were also supposed to be on the panel, but they canceled at the last minute. Boeing didn’t explain their absence, and the company has not made any officials available to answer questions since NASA chose to end the Starliner test flight without the crew aboard.
“We view the data and the uncertainty that’s there differently than Boeing does,” said Jim Free, NASA’s associate administrator, in an August 24 press conference announcing the agency’s decision on how to end the Starliner test flight. It’s unusual for NASA officials to publicly discuss how their opinions differ from those of their contractors.
Joel Montalbano, NASA’s deputy associate administrator for space operations, said Saturday that Boeing deferred to the agency to discuss the Starliner mission in the post-landing press conference.
Here’s the only quote from a Boeing official on Starliner’s return to Earth. It came in the form of a three-paragraph written statement Boeing emailed to reporters about a half-hour after Starliner’s landing: “I want to recognize the work the Starliner teams did to ensure a successful and safe undocking, deorbit, re-entry and landing,” said Mark Nappi, vice president and program manager of Boeing’s commercial crew program. “We will review the data and determine the next steps for the program.”
Nappi’s statement doesn’t answer one of the most important questions reporters would have asked anyone from Boeing if they participated in Saturday morning’s press conference: Does Boeing still have a long-term commitment to the Starliner program?
So far, the only indications of Boeing’s future plans for Starliner have come from second-hand anecdotes relayed by NASA officials. Boeing has been silent on the matter. The company has reported nearly $1.6 billion in financial charges to pay for previous delays and cost overruns on the Starliner program, and Boeing will again be on the hook to pay to fix the problems Starliner encountered in space over the last three months.
Montalbano said Boeing’s Starliner managers met with ground teams at mission control in Houston following the craft’s landing. “The Boeing managers came into the control room and congratulated the team, talked to the NASA team, so Boeing is committed to continue their work with us,” he said.
Enlarge/ Boeing’s Starliner spacecraft fires thrusters during departure from the International Space Station on Friday.
NASA
NASA isn’t ready to give up on Starliner. A fundamental tenet of NASA’s commercial crew program is to foster the development of two independent vehicles to ferry astronauts to and from the International Space Station, and eventually commercial outposts in low-Earth orbit. NASA awarded multibillion-dollar contracts to Boeing and SpaceX in 2014 to complete development of their Starliner and Crew Dragon spaceships.
SpaceX’s Dragon started flying astronauts in 2020. NASA would like to have another US spacecraft for crew rotation flights to support the ISS. If Boeing had more success with this Starliner test flight, NASA expected to formally certify the spacecraft for operational crew flights beginning next year. Once that happens, Starliner will enter a rotation with SpaceX’s Dragon to transport crews to and from the station in six-month increments.
Stich said Saturday that NASA has not determined whether the agency will require Boeing launch another Starliner test flight before certifying the spacecraft for regular crew rotation missions. “It’ll take a little time to determine the path forward, but today we saw the vehicle perform really well,” he said.
On to Starliner-1?
But some of Stich’s other statements Saturday suggested NASA would like to proceed with certifying Starliner and flying the next mission with a full crew complement of four astronauts. NASA calls Boeing’s first operational crew mission Starliner-1. It’s the first of at least three and potentially up to six crew rotation missions on Boeing’s contract.
“It’s great to have the spacecraft back, and we’re now focused on Starliner-1,” Stich said.
Before that happens, NASA and Boeing engineers must resolve the thruster problems and helium leaks that plagued the test flight this summer. Stich said teams are studying several ways to improve the reliability of Starliner’s thrusters, including hardware modifications and procedural changes. This will probably push back the next crew flight of Starliner, whether it’s Starliner-1 or another test flight, until the end of next year or 2026, although NASA officials have not laid out a schedule.
The overheating thrusters are located inside four doghouse-shaped propulsion pods around the perimeter of Starliner’s service module. It turns out the doghouses retain heat like a thermos—something NASA and Boeing didn’t fully appreciate before this mission—and the thrusters don’t have time to cool down when the spacecraft fires its control jets in rapid pulses. It might help if Boeing removes some of the insulating thermal blankets from the doghouses, Stich said.
The easiest method of resolving the problem of Starliner’s overheating thrusters would be to change the rate and duration of thruster firings.
“What we would like to do is try not to change the thruster. I think that is the best path,” Stich said. “There thrusters have shown resilience and have shown that they perform well, as long as we keep their temperatures down and don’t fire them in a manner that causes the temperatures to go up.”
There’s one thing from this summer’s test flight that might, counterintuitively, help NASA certify the Starliner spacecraft to begin operational flights with its next mission. Rather than staying at the space station for eight days, Starliner remained docked at the research lab for three months, half of the duration of a full-up crew rotation flight. Despite the setbacks, Stich estimated the test flight achieved about 85 to 90 percent of its objectives.
“There’s a lot of learning that happens in that three months that is invaluable for an increment mission,” Stich said. “So, in some ways, the mission overachieved some objectives, in terms of being there for extra time. Not having the crew onboard, obviously, there are some things that we lack in terms of Butch and Suni’s test pilot expertise, and how the vehicle performed, what they saw in the cockpit. We won’t have that data, but we still have the wealth of data from the spacecraft itself, so that will go toward the mission objectives and the certification.”
Enlarge/ Boeing’s Starliner spacecraft sits atop a United Launch Alliance Atlas V rocket before liftoff in June to begin the Crew Flight Test.
NASA is ready for Boeing’s Starliner spacecraft, stricken with thruster problems and helium leaks, to leave the International Space Station as soon as Friday, wrapping up a disappointing test flight that has clouded the long-term future of the Starliner program.
Astronauts Butch Wilmore and Suni Williams, who launched aboard Starliner on June 5, closed the spacecraft’s hatch Thursday in preparation for departure Friday. But it wasn’t what they envisioned when they left Earth on Starliner three months ago. Instead of closing the hatch from a position in Starliner’s cockpit, they latched the front door to the spacecraft from the space station’s side of the docking port.
The Starliner spacecraft is set to undock from the International Space Station at 6: 04 pm EDT (22: 04 UTC) Friday. If all goes according to plan, Starliner will ignite its braking rockets at 11: 17 pm EDT (03: 17 UTC) for a minute-long burn to target a parachute-assisted, airbag-cushioned landing at White Sands Space Harbor, New Mexico, at 12: 03 am EDT (04: 03 UTC) Saturday.
The Starliner mission set to conclude this weekend was the spacecraft’s first test flight with astronauts, running seven years behind Boeing’s original schedule. But due to technical problems with the spacecraft, it won’t come home with the two astronauts who flew it into orbit back in June, leaving some of the test flight’s objectives incomplete.
This outcome is, without question, a setback for NASA and Boeing, which must resolve two major problems in Starliner’s propulsion system—supplied by Aerojet Rocketdyne—before the capsule can fly with people again. NASA officials haven’t said whether they will require Boeing to launch another Starliner test flight before certifying the spacecraft for the first of up to six operational crew missions on Boeing’s contract.
A noncommittal from NASA
For over a decade, the space agency has worked with Boeing and SpaceX to develop two independent vehicles to ferry astronauts to and from the International Space Station (ISS). SpaceX launched its first Dragon spacecraft with astronauts in May 2020, and six months later, NASA cleared SpaceX to begin flying regular six-month space station crew rotation missions.
Officially, NASA has penciled in Starliner’s first operational mission for August 2025. But the agency set that schedule before realizing Boeing and Aerojet Rocketdyne would need to redesign seals and perhaps other elements in Starliner’s propulsion system.
No one knows how long that will take, and NASA hasn’t decided if it will require Boeing to launch another test flight before formally certifying Starliner for operational missions. If Starliner performs flawlessly after undocking and successfully lands this weekend, perhaps NASA engineers can convince themselves Starliner is good to go for crew rotation flights once Boeing resolves the thruster problems and helium leaks.
In any event, the schedule for launching an operational Starliner crew flight in less than a year seems improbable. Aside from the decision on another test flight, the agency also must decide whether it will order any more operational Starliner missions from Boeing. These “post-certification missions” will transport crews of four astronauts between Earth and the ISS, orbiting roughly 260 miles (420 kilometers) above the planet.
NASA has only given Boeing the “Authority To Proceed” for three of its six potential operational Starliner missions. This milestone, known as ATP, is a decision point in contracting lingo where the customer—in this case, NASA—places a firm order for a deliverable. NASA has previously said it awards these task orders about two to three years prior to a mission’s launch.
Josh Finch, a NASA spokesperson, told Ars that the agency hasn’t made any decisions on whether to commit to any more operational Starliner missions from Boeing beyond the three already on the books.
“NASA’s goal remains to certify the Starliner system for crew transportation to the International Space Station,” Finch said in a written response to questions from Ars. “NASA looks forward to its continued work with Boeing to complete certification efforts after Starliner’s uncrewed return. Decisions and timing on issuing future authorizations are on the work ahead.”
This means NASA’s near-term focus is on certifying Starliner so that Boeing can start executing its commercial crew contract. The space agency hasn’t determined when or if it will authorize Boeing to prepare for any Starliner missions beyond the three already on the books.
When it awarded commercial crew contracts to SpaceX and Boeing in 2014, NASA pledged to buy at least two operational crew flights from each company. The initial contracts from a decade ago had options for as many as six crew rotation flights to the ISS after certification.
Since then, NASA has extended SpaceX’s commercial crew contract to cover as many as 14 Dragon missions with astronauts, and SpaceX has already launched eight of them. The main reason for this contract extension was to cover NASA’s needs for crew transportation after delays with Boeing’s Starliner, which was originally supposed to alternate with SpaceX’s Dragon for human flights every six months.
Enlarge/ Boeing’s Starliner spacecraft is set to undock from the International Space Station on Friday evening.
NASA
Boeing’s Starliner spacecraft will gently back away from the International Space Station Friday evening, then fire its balky thrusters to rapidly depart the vicinity of the orbiting lab and its nine-person crew.
NASA asked Boeing to adjust Starliner’s departure sequence to get away from the space station faster and reduce the workload on the thrusters to reduce the risk of overheating, which caused some of the control jets to drop offline as the spacecraft approached the outpost for docking in June.
The action begins at 6: 04 pm EDT (22: 04 UTC) on Friday, when hooks in the docking mechanism connecting Starliner with the International Space Station (ISS) will open, and springs will nudge the spacecraft away its mooring on the forward end of the massive research complex.
Around 90 seconds later, a set of forward-facing thrusters on Starliner’s service module will fire in a series of 12 pulses over a few minutes to drive the spacecraft farther away from the space station. These maneuvers will send Starliner on a trajectory over the top of the ISS, then behind it until it is time for the spacecraft to perform a deorbit burn at 11: 17 pm EDT (03: 17 UTC) to target landing at White Sands Space Harbor, New Mexico, shortly after midnight EDT (10 pm local time at White Sands).
How to watch, and what to watch for
The two videos embedded below will show NASA TV’s live coverage of the undocking and landing of Starliner.
Starliner is leaving its two-person crew behind on the space station after NASA officials decided last month they did not have enough confidence in the spacecraft’s reaction control system (RCS) thrusters, used to make exact changes to the capsule’s trajectory and orientation in orbit. Five of the 28 RCS thrusters on Starliner’s service module failed during the craft’s rendezvous with the space station three months ago. Subsequent investigations showed overheating could cause Teflon seals in a poppet valve to swell, restricting the flow of propellant to the thrusters.
Engineers recovered four of the five thrusters after they temporarily stopped working, but NASA officials couldn’t be sure the thrusters would not overheat again on the trip home. NASA decided it was too risky for Starliner to come home with astronauts Butch Wilmore and Suni Williams, who launched on Boeing’s crew test flight on June 5, becoming the first people to fly on the commercial capsule. They will remain aboard the station until February, when they will return to Earth on a SpaceX Dragon spacecraft.
The original flight plan, had Wilmore and Williams been aboard Starliner for the trip home, called for the spacecraft to make a gentler departure from the ISS, allowing engineers to fully check out the performance of its navigation sensors and test the craft’s ability to loiter in the vicinity of the station for photographic surveys of its exterior.
“In this case, what we’re doing is the break-out burn, which will be a series of 12 burns, each not very large, about 0.1 meters per second (0.2 mph) and that’s just to take the Starliner away from the station, and then immediately start going up and away, and eventually it’ll curve around to the top and deorbit from above the station a few orbits later,” said Anthony Vareha, NASA’s flight director overseeing ISS operations during Starliner’s undocking sequence.
Astronauts won’t be inside Starliner’s cockpit to take manual control in the event of a major problem, so NASA managers want the spacecraft to get away from the space station as quickly as possible.
On this path, Starliner will exit the so-called approach ellipsoid, a 2.5-by-1.25-by-1.25-mile (4-by-2-by-2-kilometer) invisible boundary around the orbiting laboratory, about 20 to 25 minutes after undocking, NASA officials said. That’s less than half the time Starliner would normally take to leave the vicinity of the ISS.
“It’s a quicker way to get away from the station, with less stress on the thrusters,” said Steve Stich, NASA’s commercial crew program manager. “Essentially, once we open the hooks, the springs will push Starliner away and then we’ll do some really short thruster firings to put us on a trajectory that will take us above the station and behind, we’ll be opening to a nice range to where we can execute the deorbit burn.”
In the unlikely event of a more significant series of thruster failures, the springs that push Starliner away from the station should be enough to ensure there’s no risk of collision, according to Vareha.
“Then, after that, we really are going to just stay in some very benign attitudes and not fire the the thrusters very much at all,” Stich said.
Starliner will need to use the RCS thrusters again to point itself in the proper direction to fire four larger rocket engines for the deorbit burn. Once this burn is complete, the RCS thrusters will reorient the spacecraft to jettison the service module to burn up in the atmosphere. The reusable crew module relies on a separate set of thrusters during reentry.
Finally, the capsule will approach the landing zone in New Mexico from the southwest, flying over the Pacific Ocean and Mexico before deploying three main parachutes and airbags to cushion its landing at White Sands. Boeing and NASA teams there will meet the spacecraft and secure it for a road voyage back to Kennedy Space Center in Florida for refurbishment.
Meanwhile, engineers must resolve the causes of the thruster problems and helium leaks that plagued the Starliner test flight before it can fly astronauts again.
Enlarge/ Boeing’s Starliner spacecraft undocks from the International Space Station at the conclusion of an unpiloted test flight in May 2022.
NASA
NASA and Boeing are proceeding with final preparations to undock the Starliner spacecraft from the International Space Station next Friday, September 6, to head for landing at White Sands Space Harbor in southern New Mexico.
Astronauts Butch Wilmore and Suni Williams, who were supposed to return to Earth inside Starliner, will remain behind on the space station after NASA decided last week to conclude the Boeing test flight without its crew on board. NASA officials decided it was too risky to put the astronauts on Starliner after the spacecraft suffered thruster failures during its flight to the space station in early June.
Instead, Wilmore and Williams will come home on a SpaceX Dragon capsule no earlier than February, extending their planned stay on the space station from eight days to eight months. Flying on autopilot, the Starliner spacecraft is scheduled to depart the station at approximately 6: 04 pm EDT (22: 04 UTC) on September 6. The capsule will fire its engines to drop out of orbit and target a parachute-assisted landing in New Mexico at 12: 03 am EDT (04: 03 UTC) on September 7, NASA said in a statement Thursday.
NASA officials completed the second part of a two-day Flight Readiness Review on Thursday to clear the Starliner spacecraft for undocking and landing. However, there are strict weather rules for landing a Starliner spacecraft, so NASA and Boeing managers will decide next week whether to proceed with the return next Friday night or wait for better conditions at the White Sands landing zone.
Over the last few days, flight controllers updated parameters in Starliner’s software to handle a fully autonomous return to Earth without inputs from astronauts flying in the cockpit, NASA said. Boeing has flown two unpiloted Starliner test flights using the same type of autonomous reentry and landing operations. This mission, called the Crew Flight Test (CFT), was the first time astronauts launched into orbit inside a Starliner spacecraft, and was expected to pave the way for future operational missions to rotate four-person crews to and from the space station.
With the Starliner spacecraft unable to complete its test flight as intended, there are fundamental questions about the future of Boeing’s commercial crew program. NASA Administrator Bill Nelson said last week that Boeing’s new CEO, Kelly Ortberg, told him the aerospace company remained committed to Starliner. However, Boeing will be on the hook to pay for the cost of resolving problems with overheating thrusters and helium leaks that hamstrung the CFT mission. Boeing hasn’t made any public statements about the long-term future of the Starliner program since NASA decided to pull its astronauts off the spacecraft for its return to Earth.
Preparing for a contingency
NASA is clearly more comfortable with returning Wilmore and Williams to Earth inside SpaceX’s Dragon capsule, but the change disrupts crew operations at the space station. This week, astronauts have been reconfiguring the interior of a Dragon spacecraft currently docked at the outpost to support six crew members in the event of an emergency evacuation.
With Starliner leaving the space station next week, Dragon will become the lifeboat for Wilmore and Williams. If a fire, a collision with space junk, a medical emergency, or something else forces the crew to leave the complex, the Starliner astronauts will ride home on makeshift seats positioned under the four regular seats inside Dragon, where crews typically put cargo during launch and landing.
At least one of the Starliner astronauts would have to come home without a spacesuit to protect them if the cabin of the Dragon spacecraft depressurized on the descent. This has never happened on a Dragon mission before, but astronauts wear SpaceX-made pressure suits to mitigate the risk. The four astronauts who launched on Dragon have their suits, and NASA officials said a spare SpaceX suit already on the space station fit one of the Starliner astronauts, but they didn’t identify which one.
A pressure suit for the other Starliner crew member will launch on the next Dragon spacecraft—on the Crew-9 mission—set for liftoff on a SpaceX Falcon 9 rocket no earlier than September 24. Starliner’s troubles have also disrupted plans for the Crew-9 mission.
On Friday, NASA announced it would remove two astronauts from the Crew-9 mission, including its commander, Zena Cardman, who is a spaceflight rookie. Veteran astronaut Nick Hague will move from the pilot’s seat to take over as Crew-9 commander. Russian cosmonaut Aleksandr Gorbunov will join him.
NASA and Russia’s space agency, Roscosmos, have an agreement to launch Russian cosmonauts on Dragon missions and US astronauts on Russian Soyuz flights to the station. In exchange for NASA providing a ride for Gorbunov, NASA astronaut Don Pettit will fly to the space station on a Soyuz spacecraft next month.
The so-called “seat swap” arrangement ensures that, even if Dragon or Soyuz were grounded, there is always at least one US astronaut and one Russian cosmonaut on the station overseeing each partner’s segment of the outpost, maintaining propulsion, power generating, pointing control, thermal control, and other critical capabilities to keep the lab operational.
Enlarge/ A Starliner spacecraft mounted on top of an Atlas V rocket before an unpiloted test flight in 2022.
Ten years ago next month NASA announced that Boeing, one of the agency’s most experienced contractors, won the lion’s share of government money available to end the agency’s sole reliance on Russia to ferry its astronauts to and from low-Earth orbit.
At the time, Boeing won $4.2 billion from NASA to complete development of the Starliner spacecraft and fly a minimum of two, and potentially up to six, operational crew flights to rotate crews between Earth and the International Space Station (ISS). SpaceX won a $2.6 billion contract for essentially the same scope of work.
A decade later the Starliner program finds itself at a crossroads after Boeing learned it will not complete the spacecraft’s first Crew Flight Test with astronauts onboard. NASA formally decided Saturday that Butch Wilmore and Suni Williams, who launched on the Starliner capsule June 5, will instead return to Earth inside a SpaceX Crew Dragon spacecraft. Put simply, NASA isn’t confident enough in Boeing’s spacecraft after it suffered multiple thrusters failures and helium leaks on the way to the ISS.
So where does this leave Boeing with its multibillion contract? Can the company fulfill the breadth of its commercial crew contract with NASA before the space station’s scheduled retirement in 2030? It now seems that there is little chance of Boeing flying six more Starliner missions without a life extension for the ISS. Tellingly, perhaps, NASA has only placed firm orders with Boeing for three Starliner flights once the agency certifies the spacecraft for operational use.
Boeing’s bottom line
Although Boeing did not make an official statement Saturday on its long-term plans for Starliner, NASA Administrator Bill Nelson told reporters he received assurances from Boeing’s new CEO, Kelly Ortberg, that the company remains committed to the commercial crew program. And it will take a significant commitment from Boeing to see it through. Under the terms of its fixed price contract with NASA, the company is on the hook to pay for any expenses to fix the thruster and helium leak problems and get Starliner flying again.
Boeing has already reported $1.6 billion in charges on its financial statements to pay for delays and cost overruns on the Starliner program. That figure will grow as the company will likely need to redesign some elements in the spacecraft’s propulsion system to remedy the problems encountered on the Crew Flight Test (CFT) mission. NASA has committed $5.1 billion to Boeing for the Starliner program, and the agency has already paid out most of that funding.
Enlarge/ Boeing’s Starliner spacecraft, seen docked at the International Space Station through the window of a SpaceX Dragon spacecraft.
The next step for Starliner remains unclear, and we’ll assess that in more detail later in the story. Had the Starliner test flight ended as expected, with its crew inside, NASA targeted no earlier than August 2025 for Boeing to launch the first of its six operational crew rotation missions to the space station. In light of Saturday’s decision, there’s a high probability Starliner won’t fly with astronauts again until at least 2026.
Starliner safely delivered astronauts Butch Wilmore and Suni Williams to the space station on June 6, a day after their launch from Cape Canaveral Space Force Station, Florida. But five of the craft’s 28 reaction control system thrusters overheated and failed as it approached the outpost. After the failures on the way to the space station, NASA’s engineers were concerned Starliner might suffer similar problems, or worse, when the control jets fired to guide Starliner on the trip back to Earth.
On Saturday, senior NASA leaders decided it wasn’t worth the risk. The two astronauts, who originally planned for an eight-day stay at the station, will now spend eight months on the orbiting research lab until they come back to Earth with SpaceX.
If it’s not a trust problem, is it a judgement issue?
Boeing managers had previously declared Starliner was safe enough to bring Wilmore and Williams home. Mark Nappi, Boeing’s Starliner program manager, regularly appeared to downplay the seriousness of the thruster issues during press conferences throughout Starliner’s nearly three-month mission.
So why did NASA and Boeing engineers reach different conclusions? “I think we’re looking at the data and we view the data and the uncertainty that’s there differently than Boeing does,” said Jim Free, NASA’s associate administrator, and the agency’s most senior civil servant. “It’s not a matter of trust. It’s our technical expertise and our experience that we have to balance. We balance risk across everything, not just Starliner.”
The people at the top of NASA’s decision-making tree have either flown in space before, or had front-row seats to the calamitous decision NASA made in 2003 to not seek more data on the condition of space shuttle Columbia’s left wing after the impact of a block of foam from the shuttle’s fuel tank during launch. This led to the deaths of seven astronauts, and the destruction of Columbia during reentry over East Texas. A similar normalization of technical problems, and a culture of stifling dissent, led to the loss of space shuttle Challenger in 1986.
“We lost two space shuttles as a result there not being a culture in which information could come forward,” Nelson said Saturday. “We have been very solicitous of all of our employees that if you have some objection, you come forward. Spaceflight is risky, even at its safest, and even at its most routine. And a test flight by nature is neither safe nor routine. So the decision to keep Butch and Suni aboard the International Space Station and bring the Starliner home uncrewed is the result of a commitment to safety.”
Now, it seems that culture may truly have changed. With SpaceX’s Dragon spacecraft available to give Wilmore and Williams a ride home, this ended up being a relatively straightforward decision. Ken Bowersox, head of NASA’s space operations mission directorate, said the managers polled for their opinion all supported bringing the Starliner spacecraft back to Earth without anyone onboard.
However, NASA and Boeing need to answer for how the Starliner program got to this point. The space agency approved the launch of the Starliner CFT mission in June despite knowing the spacecraft had a helium leak in its propulsion system. Those leaks multiplied once Starliner arrived in orbit, and are a serious issue on their own that will require corrective actions before the next flight. Ultimately, the thruster problems superseded the seriousness of the helium leaks, and this is where NASA and Boeing are likely to face the most difficult questions moving forward.
Enlarge/ NASA astronauts Butch Wilmore and Suni Williams aboard the International Space Station.
Boeing’s previous Starliner mission, known as Orbital Flight Test-2 (OFT-2), successfully launched in 2022 and docked with the space station, later coming back to Earth for a parachute-assisted landing in New Mexico. The test flight achieved all of its major objectives, setting the stage for the Crew Flight Test mission this year. But the spacecraft suffered thruster problems on that flight, too.
Several of the reaction control system thrusters stopped working as Starliner approached the space station on the OFT-2 mission, and another one failed on the return leg of the mission. Engineers thought they fixed the problem by introducing what was essentially a software fix to adjust timing and tolerance settings on sensors in the propulsion system, supplied by Aerojet Rocketdyne.
That didn’t work. The problem lay elsewhere, as engineers discovered during testing this summer, when Starliner was already in orbit. Thruster firings at White Stands, New Mexico, revealed a small Teflon seal in a valve can bulge when overheated, restricting the flow of oxidizer propellant to the thruster. NASA officials concluded there is a chance, however small, that the thrusters could overheat again as Starliner departs the station and flies back to Earth—or perhaps get worse.
“We are clearly operating this thruster at a higher temperature, at times, than it was designed for,” said Steve Stich, NASA’s commercial crew program manager. “I think that was a factor, that as we started to look at the data a little bit more carefully, we’re operating the thruster outside of where it should be operated at.”
Enlarge/ A high-resolution commercial Earth-imaging satellite owned by Maxar captured this view of the International Space Station on June 7 with Boeing’s Starliner capsule docked at the lab’s forward port (lower right).
Senior NASA leaders, including the agency’s administrator, Bill Nelson, will meet Saturday in Houston to decide whether Boeing’s Starliner spacecraft is safe enough to ferry astronauts Butch Wilmore and Suni Williams back to Earth from the International Space Station.
The Flight Readiness Review (FRR) is expected to conclude with NASA’s most consequential safety decision in nearly a generation. One option is to clear the Starliner spacecraft to undock from the space station in early September with Wilmore and Williams onboard, as their flight plan initially laid out, or to bring the capsule home without its crew.
As of Thursday, the two veteran astronauts have been on the space station for 77 days, nearly 10 times longer than their planned stay of eight days. Wilmore and Williams were the first people to launch and dock at the space station aboard a Starliner spacecraft, but multiple thrusters failed and the capsule leaked helium from its propulsion system as it approached the orbiting complex on June 6.
That led to months of testing—in space and on the ground—data reviews, and modeling for engineers to try to understand the root cause of the thruster problems. Engineers believe the thrusters overheated, causing Teflon seals to bulge and block the flow of propellant to the small control jets, resulting in losing thrust. The condition of the thrusters improved once Starliner docked at the station when they weren’t repeatedly firing, as they need to do when the spacecraft is flying alone.
However, engineers and managers have not yet reached a consensus about whether the same problem could recur, or get worse, during the capsule’s journey back to Earth. In a worst-case scenario, if too many thrusters fail, the spacecraft would be unable to point in the proper direction for a critical braking burn to guide the capsule back into the atmosphere toward landing.
The suspect thrusters are located on Starliner’s service module, which will perform the deorbit burn and then separate from the astronaut-carrying crew module before reentry. A separate set of small engines will fine-tune Starliner’s trajectory during descent.
If NASA managers decide it’s not worth the risk, Wilmore and Williams would extend their stay on the space station until at least February of next year, when they would return to Earth inside a Dragon spacecraft provided by SpaceX, Boeing’s rival in NASA’s commercial crew program. This would eliminate the threat that thruster problems on the Starliner spacecraft might pose to the crew’s safety during the trip to Earth, but it comes with myriad side effects.
These effects include disrupting crew activities on the space station by bumping two astronauts off the next SpaceX flight, exposing Wilmore and Williams to additional radiation during their time in space, and dealing a debilitating blow to Boeing’s Starliner program.
If Boeing’s capsule cannot return to Earth with its two astronauts, NASA may not certify Starliner for operational crew missions without an additional test flight. In that case, Boeing probably wouldn’t be able to complete all six of its planned operational crew missions under a $4.2 billion NASA contract before the International Space Station is due for retirement in 2030.
FRR-eedom to speak
The Flight Readiness Review at NASA’s Johnson Space Center in Houston will begin Saturday morning. Ken Bowersox, a former astronaut and head of NASA’s Space Operations Mission Directorate, will chair the meeting. NASA Administrator Bill Nelson will participate, too. If there’s no unanimous agreement around the table at the FRR, a final decision on what to do could be elevated above Bowersox to NASA’s associate administrator, Jim Free or to Nelson.
“The agency flight readiness review is where any formal dissents are presented and reconciled,” NASA said in a statement Thursday. “Other agency leaders who routinely participate in launch and return readiness reviews for crewed missions include NASA’s administrator, deputy administrator, associate administrator, various agency center directors, the Flight Operations Directorate, and agency technical authorities.”
NASA has scheduled a press conference for no earlier than 1 pm ET (17: 00 UTC) Saturday to announce the agency’s decision and next steps, the agency said.
Lower-level managers will meet Friday in a so-called Program Control Board to discuss their findings and views before the FRR. At a previous Program Control Board meeting, managers disagreed on whether the agency was ready to sign off that the Starliner spacecraft was safe enough to return its astronauts to Earth.
There’s one new piece of information that engineers will brief to the Program Control Board on Friday:
“Engineering teams have been working to evaluate a new model that represents the thruster mechanics and is designed to more accurately predict performance during the return phase of flight,” NASA said. “This data could help teams better understand system redundancy from undock to service module separation. Ongoing efforts to complete the new modeling, characterize spacecraft performance data, refine integrated risk assessments, and determine community recommendations will fold into the agency-level review.”
Enlarge/ Boeing’s Starliner spacecraft, seen docked at the International Space Station through the window of a SpaceX Dragon spacecraft.
As soon as this week, NASA officials will make perhaps the agency’s most consequential safety decision in human spaceflight in 21 years.
NASA astronauts Butch Wilmore and Suni Williams are nearly 10 weeks into a test flight that was originally set to last a little more than one week. The two retired US Navy test pilots were the first people to fly into orbit on Boeing’s Starliner spacecraft when it launched on June 5. Now, NASA officials aren’t sure Starliner is safe enough to bring the astronauts home.
Three of the managers at the center of the pending decision, Ken Bowersox and Steve Stich from NASA and Boeing’s LeRoy Cain, either had key roles in the ill-fated final flight of Space Shuttle Columbia in 2003 or felt the consequences of the accident.
At that time, officials misjudged the risk. Seven astronauts died, and the Space Shuttle Columbia was destroyed as it reentered the atmosphere over Texas. Bowersox, Stich, and Cain weren’t the people making the call on the health of Columbia‘s heat shield in 2003, but they had front-row seats to the consequences.
Bowersox was an astronaut on the International Space Station when NASA lost Columbia. He and his crewmates were waiting to hitch a ride home on the next Space Shuttle mission, which was delayed two-and-a-half years in the wake of the Columbia accident. Instead, Bowersox’s crew came back to Earth later that year on a Russian Soyuz capsule. After retiring from the astronaut corps, Bowersox worked at SpaceX and is now the head of NASA’s spaceflight operations directorate.
Stich and Cain were NASA flight directors in 2003, and they remain well-respected in human spaceflight circles. Stich is now the manager of NASA’s commercial crew program, and Cain is now a Boeing employee and chair of the company’s Starliner mission director. For the ongoing Starliner mission, Bowersox, Stich, and Cain are in the decision-making chain.
All three joined NASA in the late 1980s, soon after the Challenger accident. They have seen NASA attempt to reshape its safety culture after both of NASA’s fatal Space Shuttle tragedies. After Challenger, NASA’s astronaut office had a more central role in safety decisions, and the agency made efforts to listen to dissent from engineers. Still, human flaws are inescapable, and NASA’s culture was unable to alleviate them during Columbia‘s last flight in 2003.
NASA knew launching a Space Shuttle in cold weather reduced the safety margin on its solid rocket boosters, which led to the Challenger accident. And shuttle managers knew foam routinely fell off the external fuel tank. In a near-miss, one of these foam fragments hit a shuttle booster but didn’t damage it, just two flights prior to Columbia‘s STS-107 mission.
“I have wondered if some in management roles today that were here when we lost Challenger and Columbia remember that in both of those tragedies, there were those that were not comfortable proceeding,” Milt Heflin, a retired NASA flight director who spent 47 years at the agency, wrote in an email to Ars. “Today, those memories are still around.”
“I suspect Stich and Cain are paying attention to the right stuff,” Heflin wrote.
The question facing NASA’s leadership today? Should the two astronauts return to Earth from the International Space Station in Boeing’s Starliner spacecraft, with its history of thruster failures and helium leaks, or should they come home on a SpaceX Dragon capsule?
Under normal conditions, the first option is the choice everyone at NASA would like to make. It would be least disruptive to operations at the space station and would potentially maintain a clearer future for Boeing’s Starliner program, which NASA would like to become operational for regular crew rotation flights to the station.
But some people at NASA aren’t convinced this is the right call. Engineers still don’t fully understand why five of the Starliner spacecraft’s thrusters overheated and lost power as the capsule approached the space station for docking in June. Four of these five control jets are now back in action with near-normal performance, but managers would like to be sure the same thrusters—and maybe more—won’t fail again as Starliner departs the station and heads for reentry.
Enlarge/ A Crew Dragon spacecraft is seen docked at the International Space Station in 2022. The section of the spacecraft on the left is the pressurized capsule, while the rear section, at right, is the trunk.
NASA
Sometime next year, SpaceX will begin returning its Dragon crew and cargo capsules to splashdowns in the Pacific Ocean and end recoveries of the spacecraft off the coast of Florida.
This will allow SpaceX to make changes to the way it brings Dragons back to Earth and eliminate the risk, however tiny, that a piece of debris from the ship’s trunk section might fall on someone and cause damage, injury, or death.
“After five years of splashing down off the coast of Florida, we’ve decided to shift Dragon recovery operations back to the West Coast,” said Sarah Walker, SpaceX’s director of Dragon mission management.
Public safety
In the past couple of years, landowners have discovered debris from several Dragon missions on their property, and the fragments all came from the spacecraft’s trunk, an unpressurized section mounted behind the capsule as it carries astronauts or cargo on flights to and from the International Space Station.
SpaceX returned its first 21 Dragon cargo missions to splashdowns in the Pacific Ocean southwest of Los Angeles. When an upgraded human-rated version of Dragon started flying in 2019, SpaceX moved splashdowns to the Atlantic Ocean and the Gulf of Mexico to be closer to the company’s refurbishment and launch facilities at Cape Canaveral, Florida. The benefits of landing near Florida included a faster handover of astronauts and time-sensitive cargo back to NASA and shorter turnaround times between missions.
The old version of Dragon, known as Dragon 1, separated its trunk after the deorbit burn, allowing the trunk to fall into the Pacific. With the new version of Dragon, called Dragon 2, SpaceX changed the reentry profile to jettison the trunk before the deorbit burn. This meant that the trunk remained in orbit after each Dragon mission, while the capsule reentered the atmosphere on a guided trajectory. The trunk, which is made of composite materials and lacks a propulsion system, usually takes a few weeks or a few months to fall back into the atmosphere and doesn’t have control of where or when it reenters.
Air resistance from the rarefied upper atmosphere gradually slows the trunk’s velocity enough to drop it out of orbit, and the amount of aerodynamic drag the trunk sees is largely determined by fluctuations in solar activity.
SpaceX and NASA, which funded a large portion of the Dragon spacecraft’s development, initially determined the trunk would entirely burn up when it reentered the atmosphere and would pose no threat of surviving reentry and causing injuries or damaging property. However, that turned out to not be the case.
In May, a 90-pound chunk of a SpaceX Dragon spacecraft that departed the International Space Station fell on the property of a “glamping” resort in North Carolina. At the same time, a homeowner in a nearby town found a smaller piece of material that also appeared to be from the same Dragon mission.
These events followed the discovery in April of another nearly 90-pound piece of debris from a Dragon capsule on a farm in the Canadian province of Saskatchewan. SpaceX and NASA later determined the debris fell from orbit in February, and earlier this month, SpaceX employees came to the farm to retrieve the wreckage, according to CBC.
Pieces of a Dragon spacecraft also fell over Colorado last year, and a farmer in Australia found debris from a Dragon capsule on his land in 2022.
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.”
Enlarge/ Boeing’s Strainer spacecraft is seen docked at the International Space Station in this picture taken July 3.
The astronauts who rode Boeing’s Starliner spacecraft to the International Space Station last month still don’t know when they will return to Earth.
Astronauts Butch Wilmore and Suni Williams have been in space for 51 days, six weeks longer than originally planned, as engineers on the groundwork through problems with Starliner’s propulsion system.
The problems are twofold. The spacecraft’s reaction control thrusters overheated, and some of them shut off as Starliner approached the space station June 6. A separate, although perhaps related, problem involves helium leaks in the craft’s propulsion system.
On Thursday, NASA and Boeing managers said they still plan to bring Wilmore and Williams home on the Starliner spacecraft. In the last few weeks, ground teams completed testing of a thruster on a test stand at White Sands, New Mexico. This weekend, Boeing and NASA plan to fire the spacecraft’s thrusters in orbit to check their performance while docked at the space station.
“I think we’re starting to close in on those final pieces of flight rationale to make sure that we can come home safely, and that’s our primary focus right now,” Stich said.
The problems have led to speculation that NASA might decide to return Wilmore and Williams to Earth in a SpaceX Crew Dragon spacecraft. There’s one Crew Dragon currently docked at the station, and another one is slated to launch with a fresh crew next month. Steve Stich, manager of NASA’s commercial crew program, said the agency has looked at backup plans to bring the Starliner crew home on a SpaceX capsule, but the main focus is still to have the astronauts fly home aboard Starliner.
“Our prime option is to complete the mission,” Stich said. “There are a lot of good reasons to complete this mission and bring Butch and Suni home on Starliner. Starliner was designed, as a spacecraft, to have the crew in the cockpit.”
Starliner launched from Cape Canaveral Space Force Station in Florida on June 5. Wilmore and Williams are the first astronauts to fly into space on Boeing’s commercial crew capsule, and this test flight is intended to pave the way for future operational flights to rotate crews of four to and from the International Space Station.
Once NASA fully certifies Starliner for operational missions, the agency will have two human-rated spaceships for flights to the station. SpaceX’s Crew Dragon has been flying astronauts since 2020.
Tests, tests, and more tests
NASA has extended the duration of the Starliner test flight to conduct tests and analyze data in an effort to gain confidence in the spacecraft’s ability to safely bring its crew home and to better understand the root causes of the overheating thrusters and helium leaks. These problems are inside Starliner’s service module, which is jettisoned to burn up in the atmosphere during reentry, while the reusable crew module, with the astronauts inside, parachutes to an airbag-cushioned landing.
The most important of these tests was a series of test-firings of a Starliner thruster on the ground. This thruster was taken from a set of hardware slated to fly on a future Starlink mission, and engineers put it through a stress test, firing it numerous times to replicate the sequence of pulses it would see in flight. The testing simulated two sequences of flying up to the space station, and five sequences the thruster would execute during undocking and a deorbit burn for return to Earth.
“This thruster has seen quite a bit of pulses, maybe even more than what we would anticipate we would see during a flight, and more aggressive in terms of two uphills and five downhills,” Stich said. “What we did see in the thruster is the same kind of thrust degradation that we’re seeing on orbit. In a number of the thrusters (on Starliner), we’re seeing reduced thrust, which is important.”
Starliner’s flight computer shut off five of the spacecraft’s 28 reaction control system thrusters, produced by Aerojet Rocketdyne, during the rendezvous with the space station last month. Four of the five thrusters were recovered after overheating and losing thrust, but officials have declared one of the thrusters unusable.
The thruster tested on the ground showed similar behavior. Inspections of the thruster at White Sands showed bulging in a Teflon seal in an oxidizer valve, which could restrict the flow of nitrogen tetroxide propellant. The thrusters, each generating about 85 pounds of thrust, consume the nitrogen tetroxide, or NTO, oxidizer and mix it with hydrazine fuel for combustion.
A poppet valve, similar to an inflation valve on a tire, is designed to open and close to allow nitrogen tetroxide to flow into the thruster.
“That poppet has a Teflon seal at the end of it,” Nappi said. “Through the heating and natural vacuum that occurs with the thruster firing, that poppet seal was deformed and actually bulged out a little bit.”
Stich said engineers are evaluating the integrity of the Teflon seal to determine if it could remain intact through the undocking and deorbit burn of the Starliner spacecraft. The thrusters aren’t needed while Starliner is attached to the space station.
“Could that particular seal survive the rest of the flight? That’s the important part,” Stich said.
