Starliner

Meet Starliner, Boeing’s crew capsule developed for NASA’s Commercial Crew Program.

Boeing is one of two companies building commercial human spaceflight vehicles for NASA and will be the second to fly astronauts. Starliner is designed to carry up to seven people to and from the International Space Station on missions lasting up to six months. Boeing also plans to use it for private astronaut flights to the ISS and for independent free-flying orbital missions.

The Starliner capsule, named Calypso, can operate autonomously or be manually controlled.

Tech Specs

Launch mass: 13000 kg

Crew capacity: Up to 7

Diameter: 4.56 m (15.0 ft)

Length: 5.03 m (16.5 ft)

Design life: 60 hours (free flight). 210 days (docked)

Flight Heritage

First Flight

On December 20, 2019, Boeing’s Starliner launched in its first uncrewed orbital test (OFT-1) aboard a ULA Atlas V rocket. After separation, a software error caused Starliner’s Mission Elapsed Timer (MET) to sync incorrectly with the Atlas V booster (about 11 hours early), leading to a mis-timed orbital insertion burn, which used extra fuel and prevented rendezvous with the ISS.

During the flight, another software bug was discovered in the service module disposal sequence: an incorrect valve-mapping in the thruster control code that, if left uncorrected, could have caused the service module to bump back into the crew module after separation. There was also an intermittent space-to-ground communications issue that limited control from Mission Control.

After orbit testing, Starliner performed a deorbit burn, separated its service module, and reentered. It landed on December 22, 2019, at White Sands Space Harbor, New Mexico. A software patch was uploaded during flight to correct the disposal-sequence error, allowing for a safe separation and landing.

NASA and Boeing conducted a joint investigation and identified three key anomalies: the MET error, the service module disposal bug, and the intermittent communications link. The mission was shorter than planned and its failure to dock with the ISS led to a decision to perform a second uncrewed test flight.

Second Flight

On May 19, 2022, Boeing conducted Orbital Flight Test-2 (OFT-2), the second uncrewed test of the Starliner spacecraft, launching on a ULA Atlas V at 6:54 p.m. EDT. The capsule carried no crew, only the instrumented test device Rosie, and was flown to validate end-to-end systems after earlier issues prevented a previous launch attempt.

Starliner reached orbit but experienced two failed service-module thrusters during the insertion burn; backups compensated and the spacecraft continued toward the International Space Station. It performed automated approach and rendezvous procedures and docked on May 20, about 24 hours after launch.

The spacecraft stayed docked for several days, carrying NASA cargo to the ISS. Upon departure it completed four separation burns, then executed its deorbit sequence. After jettisoning the service module, the crew module reentered using its heat shield, parachutes, and airbags, landing at White Sands Space Harbor, New Mexico, on May 25, 2022, at 6:49 p.m. EDT. The mission lasted roughly six days and met NASA’s major test objectives, including ascent, docking, undocking, deorbit, and recovery performance.

Thrid Flight
On June 5, 2024, Boeing’s Starliner lifted off on its first crewed flight, the CFT, from Cape Canaveral at 10:52 a.m. EDT, carried by a ULA Atlas V rocket. Onboard were two NASA astronauts: Barry “Butch” Wilmore and Sunita “Suni” Williams, both veteran test pilots.

After roughly a 25-hour flight, Starliner docked to the International Space Station, connecting at the forward port of the Harmony module on June 6, 2024, at around 1:34 p.m. EDT. Once at the station, Wilmore and Williams carried out a series of manual and automated control tests to validate Starliner’s handling and systems.

However, the mission ran into technical problems: during docking, five of the 28 reaction-control thrusters failed to behave normally, though four were later reactivated. In addition, throughout the mission, Boeing and NASA detected helium leaks in the thruster system, both issues raised serious safety concerns about using Starliner to bring the crew back.

Because of that, NASA made a decision: instead of returning Wilmore and Williams in Starliner, the spacecraft (named Calypso) undocked autonomously from the ISS on September 6, 2024, with no crew onboard. After undocking, additional thruster tests were run, and though one of the twelve thrusters on the crew module failed during testing, redundancy remained.

Starliner performed a deorbit burn later that night (around 11:17 p.m. EDT), and safely landed at White Sands Space Harbor, New Mexico, early on September 7, 2024, concluding the mission.

Because of the unresolved thruster and helium issues, NASA opted to bring the two astronauts back on a SpaceX Dragon capsule instead. They returned on the Crew-9 Dragon in March 2025.

Courtesy of NASA, Boeing, and ULA.

A ULA Atlas V rocket will launch astronauts to the International Space Station (ISS) aboard Boeing’s CST-100 Starliner capsule. The Starliner will be launched from Space Launch Complex-41 at Cape Canaveral Space Force Station on Florida’s Space Coast.

Specs

Height: 58.3 m (191 ft) with payload fairing, 52.4 m (172 ft) with Starliner

Diameter: 3.81 m (12.5 ft)

Mass: 590,000 kg (1,300,000 lb)

Stages: 2

Dual-Engine Centaur: For CST-100 Starliner missions, the Centaur upper stage uses two RL10A-4-2 engines for additional thrust to accommodate the Starliner and shape the ascent trajectory toward the Space Station.

Launch Vehicle Adapter (LVA) and Aeroskirt: The LVA attaches the Starliner capsule to the Atlas V rocket and connects to the Centaur upper stage. The aeroskirt extends the Starliner’s aerodynamic surface, improving stability and performance during launch.

The Atlas V rocket is configured uniquely for the Starliner missions, without a payload fairing and with a special aeroskirt at the base of the Starliner. This configuration is designated as N22, which indicates no payload fairings ("N"), two solid rocket motors ("2"), and two engines on the Centaur upper stage ("2"). The dual-engine Centaur upper stage, which provides extra thrust for Starliner, is exclusively used for these missions. Although this variant is specific to Starliner, the dual-engine Centaur has flown more than 160 times on previous Atlas V versions with a single-engine configuration.

The launch of Starliner requires a more gradual ascent than typical Atlas V missions. This is done to ensure the safety of the Starliner and its future crews, allowing them to abort the mission at any point during launch if necessary. The Emergency Detection System (EDS) is in place to monitor various launch vehicle parameters, assessing the health of the rocket. Should any issues arise, the EDS can send an abort signal, allowing the Starliner to safely escape.

Photo courtesy of ULA

Space Launch Complex 41 (SLC-41) is a significant launch site located at Cape Canaveral Space Force Station (CCSFS) in Florida. Originally built in the 1960s, SLC-41 was designed to support the Titan III and Titan IV rocket programs. Throughout its history, the pad has been used for various missions, including the deployment of military and reconnaissance satellites. A notable launch from SLC-41 was the Cassini spacecraft mission, which began its journey to Saturn in 1997.

In the early 2000s, SLC-41 was repurposed to support the Atlas V rocket, operated by United Launch Alliance (ULA). This transition involved extensive upgrades to the pad’s infrastructure and the installation of new ground support equipment to accommodate the Atlas V. These modifications ensured that SLC-41 could meet the requirements of modern space missions.

Under ULA’s management, SLC-41 has hosted a range of important launches, including the Mars Science Laboratory mission, which successfully landed the Curiosity rover on Mars in August 2012, and the launch of GPS III satellites, enhancing global positioning capabilities. The pad has also supported Boeing's CST-100 Starliner capsule, which is part of NASA’s Commercial Crew Program. The Starliner capsule, designed to transport astronauts to and from the International Space Station, has been launched from SLC-41 to support crewed missions.

Looking to the future, SLC-41 is set to support ULA’s Vulcan Centaur rocket. The Vulcan Centaur is intended to replace the Atlas V and Delta IV rockets, marking a new era in ULA’s launch capabilities with enhanced performance and cost-efficiency. The pad’s infrastructure will be further updated to accommodate this next-generation rocket.

ISS - Harmony forward

The Harmony module, also known within NASA as Node-2, was launched to the ISS in October 2007 on the STS-120 mission of Shuttle Discovery.

Harmony serves as the gateway between the U.S. scientific and living modules and ESA's Columbus laboratory and JAXA’s Kibo lab complex.

The module is equipped with two docking ports for U.S. crew (Dragon and Starliner) and cargo (Dragon) spacecraft and also has one berthing port that can be used for either Northrop Grumman's Cygnus or Japan's HTV cargo crafts.

Photo: The Harmony module, with the forward docking port visible. Credit: NASA

Boeing’s Starliner spacecraft will land at White Sands Missile Range’s Space Harbor in New Mexico.

Boeing’s Orbital Flight Test-2 (OFT-2) was Starliner’s second uncrewed flight test to the International Space Station as part of NASA's Commercial Crew Program. OFT-2 serves as an end-to-end test of the system's capabilities.

About four hours after departing the space station, Starliner touched down in New Mexico which tested the end-to-end capabilities of the crew-capable spacecraft. The landing followed a deorbit burn, separation of the spacecraft’s service module, and successful deployment of its three main parachutes and six airbags.

Image and caption: NASA

Download the Supercluster app to track spacecraft traffic and view crewmembers aboard the International Space Station and China’s Tiangong Space Station.

Alternatively, you can use the web version of our Stations Dashboard on Supercluster's website.

We now track "Arrivals and Departures" for both stations through a new "Timetable" feature, covering crew rotations and cargo resupply missions.

You can also switch between the ISS and Tiangong to see their relative positions over Earth on our mini-map.

A recent update allows users to enable push alerts for notifications when space stations pass over their location.

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