Sunita Williams and Barry “Butch” Wilmore must have breathed a sigh of relief when they opened the hatch and floated into the International Space Station (ISS) on June 6, 2024. It was the first time the Starliner spacecraft they arrived on had carried humans.
Starliner was built by aerospace giant Boeing and was the second commercial spacecraft to carry astronauts to the ISS, following Crew Dragon, built by Elon Musk’s SpaceX company. SpaceX has already completed eight crewed flights to the space station.
NASA’s decision more than a decade ago to turn crew transportation over to private companies like SpaceX and Boeing was seen as a bold move. The private space sector is now thriving, with fully private flights to Earth orbit already underway and plans for commercially funded space stations in the pipeline.
Wilmore and Williams had expected to return to Earth on Starliner eight days after arriving at the ISS. Little did they know that more than two months later, they would still be there, waiting for a detailed analysis from NASA and Boeing to determine if it was safe to send them back on Starliner.
On August 24, the U.S. space agency announced that it did not have enough confidence to send the two astronauts back to the Boeing spacecraft. So, what does this mean for the two astronauts and for the future of commercial space travel?
First of all, Williams and Wilmore are not in danger. They are safe on the ISS, with enough food, clean water and air. They are now expected to stay on the ISS for eight months and return next year in a Crew Dragon spacecraft.
This planned Dragon flight, called Crew-9, is scheduled to launch in September and return in February 2025. It will now carry only two astronauts to the ISS instead of the planned four, to make room for the two unexpected crew members on the return flight.
The fact that such an option is available is a triumph for commercial spaceflight. SpaceX has become a reliable choice for NASA to bring its astronauts to the ISS. In addition to eight crew rotation flights to date, SpaceX has launched more than 20 unmanned resupply missions to the ISS since 2012.
Read more: Astronauts stuck on International Space Station after more problems with Boeing’s troubled Starliner
After losing 14 astronauts in two Space Shuttle disasters—Challenger in 1986 and Columbia in 2003—NASA could no longer afford more deadly accidents amid a bleak financial landscape. So NASA Administrator Bill Nelson decided that Starliner would not return astronauts to Earth.
Starliner’s first crewed flight to the ISS took place on June 5, 2024, after two uncrewed test flights. The latter mission was plagued by helium leaks—discovered both before launch and during flight—and faulty thrusters, the engines used to maneuver Starliner through space. Helium is used to push propellant into Starliner’s thrusters, so these defects could have compromised maneuvers to approach and dock with the ISS.
Critical functions
The correct functioning of the thrusters is also crucial to ensuring that the Starliner crew module, the part of the spacecraft in which astronauts travel, enters the Earth’s atmosphere at a safe angle. If the spacecraft re-enters too steeply, it could break up at a speed of 17,500 miles per hour. If it re-enters too shallowly, it could blast off the atmosphere and back into space.
For most of the mission, the crew module is attached to a service module that provides power and houses the thrusters. Problems with the thrusters in Starliner’s service module were discovered during the unmanned test flight in 2022, which nevertheless successfully docked with the ISS.
This followed an initial test flight in 2019 that failed due to a combination of an onboard bell error and confused communications. In both cases, the crew module landed in one piece on Earth.
With astronauts on board, however, NASA officials weren’t taking any chances. Starliner’s unmanned return, scheduled for early September, will allow engineers on Earth to once again monitor the behavior of the thrusters. They’ll also be watching for potential problems with helium leaks. These are fairly common in rockets because helium atoms are so small that they don’t stick to other atoms very well—meaning they can squeeze through small pores with relative ease.
Unfortunately, the service module separates from the crew module during reentry and burns up in the atmosphere, so it is not possible to inspect the thrusters on the ground.
Competitive field
Boeing was awarded US$4.2 billion (£3.2 billion) by NASA’s Commercial Crew Program in 2014 and spent a decade completing its first – ill-fated – crewed mission to the ISS, using a United Launch Alliance Atlas V rocket. SpaceX – awarded a US$2.6 billion (£2 billion) contract by the same NASA program – managed to accomplish the feat faster, cheaper (at least for NASA) and more extensively.
SpaceX has also been able to routinely bring the first-stage boosters of its Falcon 9 rocket back to the ground from space, landing them upright on a ship in the ocean using engines.
The Falcon 9 consists of two powered sections: the first-stage booster carries the rocket’s second stage to a predetermined altitude and speed. By recovering the first stage, it can be reused, reducing launch costs. Before SpaceX incorporated reuse technology, rocket stages were generally discarded.
The company is also developing Starship, a massive spacecraft capable of carrying people or cargo on missions to the Moon or Mars, and the most powerful rocket ever built.
With other private companies like Sierra Space and Blue Origin (the space company of Amazon founder Jeff Bezos) also making big moves into the human spaceflight sector, Boeing faces stiff competition. The company has also faced heavy criticism following two fatal crashes of Boeing 737 Max planes and a door that flew off during a Boeing 737 Max 9 flight.
However, SpaceX got some unwelcome news on August 28 when a returning Falcon first-stage booster collapsed and exploded. The Federal Aviation Administration has now grounded all of its Falcon 9 rockets, one of which is scheduled to deliver Crew-9 to the ISS in September.
Above all, NASA’s decision to prioritize the safety of Williams and Wilmore and to work with a commercial partner to find a solution is another example of giving the private space industry the confidence needed to grow commercial human spaceflight.
It sends a message to everyone that trying something new doesn’t necessarily have to be reckless. In that sense, it’s a triumph of wisdom and prudence.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Jacco van Loon does not work for, is not an advisor to, owns no shares in, or receives financial support from any company or organization that would benefit from this article. He has also disclosed no relevant affiliations beyond his academic appointment.