Boeing Starliner facts for kids

Quick facts for kids
Boeing Starliner

Boeing Starliner Spacecraft 2 approaching the ISS in May 2022, during Orbital Flight Test 2
Manufacturer	Boeing Defense, Space & Security
Country of origin	United States
Operator	Boeing Defense, Space & Security
Applications	ISS crew transport
Specifications
Spacecraft type	Capsule
Design life	60 hours (free flight) 7 months (docked)
Payload capacity	To ISS: 4 crew and 100 kg (220 lb) cargo
Crew capacity	Up to 7
Volume	11 m3 (390 cu ft)
Regime	Low Earth orbit
Dimensions
Length	5.03 m (16.5 ft) (Capsule and SM)
Diameter	4.56 m (15 ft)
Production
Status	Active
Built	3
Operational	2
Retired	1
Maiden launch	Uncrewed: December 20, 2019 Crewed: June 5, 2024
Configuration
Exploded view of the Starliner A: Crew capsule, B: Service module 1: Nosecone, 2: Parachute compartment cover, 3: Crew access hatch, 4: RCS thrusters for re-entry, 5: Airbags, 6: Heat shield, 7: NASA Docking System, 8: Parachutes, 9: Window, 10: Umbilical, 11: Radiators, 12: "Doghouse" with RCS and OMAC thrusters, 13: Propellant tanks, 14: Roll control thruster, 15: RS-88 engines for launch escape, 16: Solar panels

The Boeing Starliner (also called CST-100) is a special spacecraft. It is made to carry astronauts to and from the International Space Station (ISS). It can also travel to other places in low Earth orbit.

Boeing built the Starliner as part of NASA's Commercial Crew Program. This program helps private companies create spacecraft for NASA. The Starliner has two main parts: a reusable crew capsule and a part called a service module that is used only once.

The Starliner is a bit bigger than the SpaceX Crew Dragon. It can carry up to seven people, but NASA usually plans to send no more than four. It can stay connected to the ISS for up to seven months. The Starliner launches into space on an Atlas V N22 rocket from Cape Canaveral Space Launch Complex 41 in Florida.

NASA gave Boeing a contract in 2014 to build and operate the Starliner. The Starliner was supposed to be ready by 2017. However, it has faced many delays due to problems with how it was managed and engineered.

The first test flight without a crew, called the Orbital Flight Test, happened in December 2019. It had some problems, so a second test flight was needed in May 2022. During the Crew Flight Test in June 2024, the Starliner's small engines (thrusters) had issues when it was getting close to the ISS. NASA decided it was too risky to bring the astronauts back to Earth on that spacecraft. So, the Starliner landed without a crew in September 2024.

How the Starliner Was Developed

Building a Starliner in 2018.

After the Space Shuttle program ended, NASA wanted new ways to send astronauts to space. Instead of building and owning all spacecraft, NASA decided to try something new. They asked private companies to build and operate spacecraft. NASA would then buy rides on these spacecraft, like a customer. To help companies get started, NASA offered money for them to develop new vehicles.

Boeing has a long history of building things for space. They helped build parts of the Saturn V rockets and the Lunar Roving Vehicles used on the Moon. They have also been a main contractor for the US Orbital Segment of the ISS since 1993. Because of their experience, Boeing was a strong choice to compete for these new space contracts.

In 2010, Boeing introduced its design for NASA's Commercial Crew Program. They called it the CST-100. Boeing received money from NASA to help develop the Starliner. They hoped it would be ready to fly by 2015.

In 2011, NASA let Boeing use a special building at the Kennedy Space Center. This building, called Orbiter Processing Facility-3, was used to build and test the Starliner. Over the next few years, NASA gave Boeing more money to continue developing the spacecraft.

NASA was going to choose a company for the main Commercial Crew Transportation Capability (CCtCap) contract in 2014. Boeing wanted to be the only company chosen. Many people at NASA trusted Boeing because of their past work and safety record.

However, William H. Gerstenmaier, who was in charge of human space exploration at NASA, wanted more than one company. He believed that having two companies would create competition and provide a backup if one had problems. He convinced NASA to get more money so they could choose two companies.

On September 16, 2014, NASA announced that both Boeing and SpaceX would get contracts to build crewed spacecraft. Boeing received $4.2 billion for the Starliner, and SpaceX received $2.6 billion for their Crew Dragon. To get all the money, each company had to complete several tests. These included an escape test, an uncrewed test flight, a crewed test flight, and six missions to the ISS. NASA would not pay for failed tests and only had to buy two crewed missions from each company at first.

How the Starliner Works

Currently operational crewed orbital spacecraft

The Starliner's main body at the former Orbiter Processing Facility in 2011.

Testing a Starliner model in a wind tunnel in 2011.

The name CST-100 was first used in 2010. "CST" stands for Crew Space Transportation. The "100" refers to the Kármán line, which is an unofficial boundary of space about 100 kilometers (62 mi) above Earth. The Starliner's design uses ideas from Boeing's work on NASA's Apollo, Space Shuttle, and ISS programs.

The Starliner spacecraft, showing the capsule and service module.

The Starliner has a reusable capsule and a service module that is used once and then thrown away. It is designed for missions to low Earth orbit. The capsule can hold seven people or a mix of crew and cargo. For NASA missions to the ISS, it will carry four astronauts and some cargo. The Starliner capsule can be used up to ten times. Boeing plans to use two main capsules for all its missions. Each flight uses a new service module, which helps the spacecraft move and provides power. The Starliner also has Wi-Fi and tablet computers for the crew.

The Starliner uses the NASA Docking System to connect to the ISS. Before its second uncrewed test flight (OFT-2), Boeing added a special cover under the nose of the Starliner. This cover protects the docking port when the capsule comes back through Earth's atmosphere.

The capsule has a special heat shield to protect it from the extreme heat during re-entry. Solar panels on the back of the service module provide electricity for the spacecraft.

There is also a 1.78 m (5.8 ft) structure called an aeroskirt. This part helps the rocket fly steadily and smoothly during launch.

The Starliner has 64 engines (thrusters) made by Aerojet Rocketdyne:

• 12 small thrusters on the capsule help steer it when it comes back into the atmosphere.
• 52 thrusters on the service module help control the spacecraft during most of the flight.
• 20 larger thrusters, called OMAC thrusters, are used to change the spacecraft's orbit.
• 4 very powerful RS-88 engines are used for a launch escape system. This system can quickly pull the capsule away from the rocket if there is a problem during launch.

The Starliner capsule is designed to land on land, not in the ocean. This is a first for a crewed capsule launched from the United States. After re-entering the atmosphere, three parachutes slow the capsule down to about 4 miles per hour (350 ft/min; 1.8 m/s). Just before landing, six airbags inflate to cushion the impact. There are four main landing spots, mostly in the Western United States. This allows the service module to be dropped over the Pacific Ocean, where it burns up safely. Boeing says there are about 450 landing chances each year across all five sites.

NASA chose four experienced astronauts to help Boeing and SpaceX with their designs. These astronauts were also supposed to be the first to fly on the new spacecraft. One astronaut, Doug Hurley, found that the Boeing engineers were not as open to feedback as the SpaceX engineers. He later chose not to fly on Starliner. Hurley and another astronaut, Bob Behnken, flew the first crewed flight of the Crew Dragon. Astronaut Sunita Williams flew on the Starliner's Crew Flight Test, but she returned to Earth on a Crew Dragon because of Starliner's thruster problems.

The Starliner program has cost Boeing a lot of money, more than $2 billion by early 2025.

After the problems during the Crew Flight Test, NASA Administrator Bill Nelson said that Boeing's CEO, Kelly Ortberg, promised to keep the Starliner program going. However, some financial experts wondered if Boeing would keep investing in a program that was losing money. In October, The Wall Street Journal reported that Boeing was thinking about selling some of its space programs, including Starliner. As of early 2025, NASA and Boeing have not announced plans for the next Starliner flight.

Testing the Starliner

Testing of Starliner parts began in 2011, and tests with actual spacecraft started in 2019.

Escape and Drop Tests

An Erickson Skycrane helicopter (front) and the Starliner (back) in 2012. The helicopter dropped the capsule from about 7,000 feet (2,000 m) to test its parachutes and airbags.

A close-up of Starliner's six airbags during a drop test.

In September 2011, Boeing finished tests to check its airbag landing system. These airbags are under the Starliner's heat shield. They inflate with nitrogen and oxygen gas just before landing. Tests were done in the Mojave Desert to see how the airbags would work in different wind conditions.

In April 2012, Boeing dropped a Starliner model over the Nevada desert. This test successfully checked the craft's three main landing parachutes from 3,400 m (11,200 ft) high.

In 2016, Boeing announced delays to its test schedule. They needed to make the spacecraft lighter, fix air flow issues during launch, and meet new software rules from NASA. The first uncrewed Orbital Flight Test was then planned for spring 2019. The first crewed flight (Boe-CFT) was set for summer 2019.

A serious problem happened during a hot-fire test in June 2018. A design flaw caused a leak of toxic fuel, leading to a fireball. Boeing told NASA about the problem but tried to keep it quiet, even from the astronauts involved.

In November 2019, a pad abort test took place. The capsule launched away from its pad, but one of its three parachutes did not open. However, the landing was still considered safe, and the test was a success.

First Uncrewed Orbital Flight Test

The top and bottom parts of Boeing Starliner Spacecraft 3 Calypso being joined together at Kennedy Space Center in June 2018.

Boeing Starliner Spacecraft 3 Calypso landed at White Sands Missile Range in New Mexico after its uncrewed Orbital Flight Test in December 2019.

The first uncrewed Boeing Orbital Flight Test (OFT) launched on December 20, 2019. It carried a test dummy named "Rosie the Rocketeer" and a toy. The mission almost ended in disaster and was called a partial failure.

After launch, the spacecraft's clock was off by 11 hours. This caused its thrusters to fire for too long, using up too much fuel. Because of this, the Starliner could not reach the ISS. Another software error was found later that could have caused the service module and capsule to crash into each other.

The spacecraft landed safely at White Sands Missile Range in New Mexico two days after launch. After it landed, NASA astronaut Sunita Williams named the spacecraft Calypso, after a famous research ship.

After the mission, Boeing admitted they had not tested the entire mission from start to finish. They had only tested smaller parts. This led to the software errors. NASA was also criticized for not making Boeing do a full end-to-end test.

The investigation into the flight made many suggestions for Boeing and NASA to improve.

Second Uncrewed Orbital Flight Test

Boeing Starliner Spacecraft 2 before landing at White Sands Missile Range in New Mexico after OFT-2 in May 2022.

Because the first test flight did not meet its goals, Boeing decided to fly a second uncrewed mission, called Boeing Orbital Flight Test 2 (OFT-2). Boeing paid for this extra test flight.

In August 2021, problems were found with 13 valves in the spacecraft's propulsion system. The spacecraft had to be taken off its rocket and returned to the factory. It was later discovered that moisture had caused corrosion in the valves. Boeing decided to replace the entire service module.

The OFT-2 mission finally launched on May 19, 2022. It again carried Rosie the Rocketeer. Two of the main thrusters failed during the flight, and some smaller thrusters also had issues during docking. Despite these problems, the spacecraft was able to use its other thrusters to compensate.

On May 22, 2022, the capsule successfully docked with the International Space Station. On May 25, 2022, the capsule returned to Earth and landed successfully. During re-entry, one of the navigation systems briefly lost contact with GPS satellites, but this was not a major issue.

Third Orbital Flight Test (Crewed)

Boeing Starliner Spacecraft 3 Calypso launching on the Crew Flight Test atop an Atlas V rocket.

Boeing Starliner Spacecraft 3 Calypso docked to the ISS during the Crew Flight Test.

The Starliner's crewed flight test was meant to be its last test before it started regular service. This test would send two astronauts to the ISS for about a week. However, the capsule's thrusters had problems when docking with the ISS. Even after months of testing, NASA could not fully understand why the thrusters failed. Because of this, NASA decided it was too risky to bring the astronauts back to Earth on the Starliner. So, the Starliner returned without a crew.

This launch faced many delays, including issues with parachutes and wiring. These delays pushed the launch back to mid-2024.

A launch attempt on May 6, 2024, was stopped due to a problem with the rocket. Then, a helium leak in the service module caused more delays. Another attempt on June 1 was stopped because of a computer problem on the ground. Finally, Starliner successfully launched on June 5, 2024.

Once in orbit and approaching the ISS, the Starliner's thrusters showed problems. Five of them were considered damaged, and five helium leaks were found. The astronauts were still able to safely dock the capsule to the ISS.

A team from NASA and Boeing spent weeks trying to figure out why the thrusters malfunctioned. They did tests on the ground and with the astronauts in space. They found that a Teflon seal could deform due to heat, causing the thrusters to degrade. However, they could not fully recreate the problem on the Starliner in orbit.

NASA decided it was too risky to bring the astronauts back on the Starliner. Boeing, however, said they were confident in the Starliner and believed it was safe for the astronauts to return on it.

Starliner landed safely in the White Sands Missile Range in New Mexico on September 7, 2024. During its re-entry, it had two new technical problems. There was a brief issue with its navigation system, and one of the 12 thrusters used to steer the capsule during re-entry failed to ignite.

NASA will review all the mission data to decide what else needs to be done for the Starliner to be fully approved. NASA Administrator Bill Nelson said that Boeing's CEO has promised to continue the Starliner program.

Boeing officials canceled a planned news conference after the landing and refused to answer questions from journalists.

Commercial Use of Starliner

An artist's drawing of a Boeing Starliner connecting to the ISS.

Under the Commercial Crew Program, Boeing owns and operates the Starliner capsules. This means Boeing can offer other commercial flights if they do not get in the way of NASA missions. While SpaceX has already sold private commercial flights, Boeing has not yet.

The agreement allows Boeing to sell seats for space tourists on ISS flights. However, because ISS missions are usually long, this is unlikely to happen often.

In 2021, Blue Origin, Boeing, and Sierra Nevada Corporation announced plans for a commercial space station called Orbital Reef. This station could be visited by both the Starliner and Sierra Nevada's Dream Chaser spacecraft.

Launch Vehicle

The Starliner was designed to work with several different rockets, including the Atlas V, Delta IV, Falcon 9, and Vulcan Centaur.

For its test flights and up to six future missions, the Starliner is expected to fly on the Atlas V. However, the company that operates the Atlas V stopped making the rocket in 2024. The rockets that have already been made are set aside for customers, including the six needed for the remaining Starliner flights.

The Starliner's future after these flights is uncertain. The Delta IV rocket is retired, and no more are available. The Falcon 9 is owned by SpaceX, which is a competitor. The Vulcan Centaur rocket has not yet been approved for human spaceflight, and Boeing would have to pay for those tests.

Atlas V Configuration

For Starliner launches, the Atlas V rocket uses a special setup called the N22 configuration. Most other Atlas V launches use a nose cone and a single-engine upper stage. The N22 setup does not use a nose cone. Instead, it has two solid rocket boosters (SRBs) and a Dual Engine Centaur second stage, which has two engines.

The Starliner is the only crewed spacecraft launched by the Atlas V.

While newer Atlas V launches use different solid rocket boosters, these are not approved for human spaceflight. So, crewed Starliner missions use older, human-rated boosters.

The Dual Engine Centaur was brought back for Starliner missions. Its two engines help the rocket fly a smoother path. This reduces the forces astronauts feel and allows the capsule to escape safely at any time if there is a problem.

Launch Path

After launch, the rocket goes through several steps. It passes through max q (the point of highest air pressure), drops its solid rocket boosters, and then the Centaur upper stage fires. The nosecone and aeroskirt are also dropped.

About 15 minutes after lift-off, the Starliner spacecraft separates from the Centaur. It is on a suborbital path, meaning it is almost fast enough to orbit Earth but not quite. This suborbital path is unusual for satellites but similar to how the Space Shuttle and Space Launch System launch. It ensures that if the spacecraft fails to reach orbit, it will come back to Earth in a controlled way.

After separating, the Starliner's own thrusters on its service module fire for about 45 seconds. This final push puts the spacecraft into orbit, allowing it to continue its journey to the International Space Station.

List of Starliner Spacecraft

As of 2020, Boeing planned to have three Starliner capsules. Each capsule could be reused up to ten times after about six months of work. However, in August 2020, Boeing decided to use only two capsules for all planned Starliner missions.

S/N	Name	Type	Status	Flights	Flight time	Total flight time	Notes	Cat.
S1	None	Prototype	Retired	1	1m 19s (PAT)	1m 19s	This prototype was used only for the pad abort test.
S2	TBA	Crew	Active	1	5d 23h 54m (OFT-2)	5d 23h 54m	Completed the OFT-2 flight.
S3	Calypso	Crew	Active	2	2d 1h 22m (OFT) 93d 13h 9m (CFT)	95d 14h 31m	Named after Jacques Cousteau's ship RV Calypso. It was the first Starliner to orbit during OFT and the first to carry a crew to space during CFT.

List of Starliner Flights

This list includes only missions that have been completed or are planned. Dates are in UTC. For future events, the dates are the earliest possible times and might change.

NASA has only ordered three Starliner flights once the capsule is fully approved. They have the option to buy up to six operational flights. However, it is unclear if that many missions can happen before the ISS is planned to be retired in 2030.

See also

In Spanish: CST-100 Starliner para niños

• List of crewed spacecraft
• Orion (spacecraft)
• SpaceX Dragon 2, another human-rated capsule spacecraft
• Dream Chaser, a human-rated spaceplane being developed
• Orel, a human-rated spacecraft being developed in Russia
• Mengzhou, a human-rated spacecraft being developed in China