Plagued with delays due to engineering issues, Starliner remains tethered to the ground.

Boeing and its customer, NASA, are now dealing with a helium leak from one of the capsule's reaction control system thrusters in the spacecraft’s service module. Helium was previously detected by Starliner’s sensors while it was on the launch pad in early May, but was within the determined limit. 

Starliner was scheduled for its inaugural crewed flight on May 6th but was called off due to an issue with a pressure valve on the Atlas’ Centaur upper stage. The flight was slated to carry veteran NASA Astronauts Barry “Butch” Wilmore and Sunita “Suni” Williams to the International Space Station.

The Atlas V and Starliner spacecraft were rolled back to the ULA’s Vertical Integration Facility (VIF) at Space Launch Complex-41 at Cape Canaveral Space Force Station in Florida to replace the problematic valve and carry out additional checks. Boeing conducted several pressure tests of the Starliner’s service module and said that the leak would not pose a significant risk to the flight, adding that it is sealed effectively across the entire service module. 

Helium is crucial to Starliner as it pressurizes its propulsion system, powering the 28 Orbital Maneuvering and Attitude Control (OMAC) thrusters and the reaction control system. These systems are essential for orienting and maneuvering the spacecraft in orbit, docking with the International Space Station, and to begin de-orbiting procedures to return to Earth.

NASA and Boeing teams are currently working to ensure that Starliner retains the performance it needs to rendezvous and dock to the ISS while maintaining the redundancy it requires for a crewed launch. Additionally, NASA says that the Commercial Crew Program and International Space Station Program will review data and procedures before making a final determination to proceed with the launch, which is now set for June 1st.

Technical issues with Starliner aren’t new. During the Starliner’s first uncrewed flight in December 2019, the spacecraft couldn’t place itself into a stable orbit shortly after separation from Atlas V as an internal error with the timekeeping caused it to perform a sequence of maneuvers at the wrong time, deviating from its planned trajectory. NASA and the Boeing team forgoed the planned rendezvous and docking with the ISS but focused on getting the capsule back and demonstrating the capsule reentry and landing operations. It successfully touched down at its landing zone at the US Army’s White Sands Missile Range in New Mexico, becoming the first American orbital crewed capsule to land in the US.

Hoping to correct issues from the first flight, Starliner was just hours away from returning to orbit for the second time in August 2021 before its teams experienced issues with the valves onboard its service module. 13 of the 24 oxidizer valves that carried propellant for in-orbit propulsion and reaction control systems did not work as expected. It took Boeing months to identify the source of the issue, citing excess water and humidity reacting with the oxidizer and the Teflon seals of the valves, causing them to corrode and get stuck. The company had to extensively study and redesign the valves, implementing serious changes to the service module.

With corrections in place, Starliner launched for the second time in May 2022. During its orbital insertion burn, two of its OMAC thrusters failed to fire as expected. The first thruster failed after only one second. Its backup thruster immediately fired and continued for 25 seconds before it too failed. Tertiary backup group kicked up and the spacecraft was able to place itself in orbit and made its way to the orbiting laboratory. Starliner docked to the ISS and spent 4 days before landing back at the White Sands in New Mexico.

This upcoming third flight, with a crew onboard, intends to build on lessons from the first two test flights and plans to test several systems before certification for operational use.

Starliner is launched atop the Atlas V, a veteran rocket that has launched to orbit 99 times successfully, having propelled NASA’s Curiosity and Perseverance Rover to Mars, New Horizons spacecraft to Pluto, multiple Earth observation satellites for NASA and national security payloads for the Department of Defense. For Starliner missions, the Atlas V variant consists of two solid rocket boosters and a Centaur upper stage with dual engine configuration, consisting of two Aerojet Rocketdyne RL-10 engines, as opposed to the conventional single-engine setup. This dual-engine configuration, once standard on all Atlas missions for decades, became less common as the performance of the RL-10 engines improved. However, this setup is crucial for Starliner as it allows for a flight trajectory that enables a crew ejection capability during the entire powered flight in the event of failure.  

Flying onboard the inaugural Starliner mission are veteran NASA astronauts Barry "Butch" Wilmore as the Commander and Sunita "Suni" Williams as the Pilot. Both astronauts, former Navy test pilots, are highly experienced in testing unknown equipment. Their extensive spaceflight experience and lessons learned have led them to pilot the sixth-ever crewed spacecraft developed and flown in the US. Suni Williams will also mark a milestone as the first woman to fly on the first crewed flight of an orbital spacecraft.

"I don't think either one of us ever dreamed that we'd be associated with the first flight of a brand-new spacecraft,” said Butch during a press conference. Butch was inducted into NASA’s Astronaut Corps in 2000. He has flown aboard Space Shuttle Atlantis on STS-129 and the Russian Soyuz spacecraft for Expedition 41/42, accumulating 178 days in space and conducting four spacewalks.

Suni Williams, selected as a NASA astronaut in 1998, is an Ohio native who has participated in Expedition 14/15 and 32/33. She has flown aboard Space Shuttle Discovery for the STS-116 mission and the Russian Soyuz. Williams served as the commander of Expedition 33 and performed three spacewalks during that stint and totaling 7 during her spaceflight career.

Suni and Butch have been integral to the development of the Starliner, having been involved since the project's inception and playing an active role in the design of several onboard systems. Their extensive piloting experience in the Navy has been crucial in shaping the spacecraft.

“That background of understanding test acquisition was required to certify various components ... [and] the vital importance of making sure that in an integrated fashion, everything works as planned. That's been invaluable for the process," Wilmore noted.

Initially, NASA astronauts Nicole Mann, along with Suni Williams, and Boeing astronaut Chris Ferguson were assigned to this mission. However, subsequent delays led to Nicole being reassigned to SpaceX’s Crew-5 and Ferguson being replaced by Barry Wilmore due to family reasons.

Starliner’s Crewed Flight Test is set to pave the way for operational missions that will transport four astronauts to the ISS for six-month durations, pending a comprehensive review of the test data. Following a successful conclusion of these tests, NASA’s Commercial Crew Program will transition from its developmental phase to an operational phase, where SpaceX and Boeing will alternate launching missions to the ISS.

The first operational mission for Starliner, named Boeing Starliner-1, is scheduled to launch no earlier than early 2025. Commanded by NASA Astronaut Scott Tingle with Michael Finkle serving as the Pilot, the crew will also include Canadian Astronaut Joshua Kutryk and Japanese Astronaut Kimiya Yui as mission specialists.

Steve Stich, Program Manager of the Commercial Crew Program, noted that while the upcoming updates to Starliner are not groundbreaking, they are significant enhancements that will be implemented by the first operational mission, incorporating feedback from the Crewed Flight Test. "Boeing has plans to do various updates, and one of them they’re going to put in place for Starliner-1 is an improved capability to land in winds. They’ve also got an upgrade to some of the structures that hold the airbags," said Stich during the launch readiness press conference. "For Starliner-1, we’ll [also] have the capability to dock and undock from the Zenith port and also perform port relocation operations."

Currently, Starliner can only dock on the forward facing port, located at the Harmony module of the ISS, previously occupied by SpaceX’s Crew Dragon Endeavour. To make way for Starliner, the crew of Crew-8 conducted the autonomous port relocation operations, shifting the dragon spacecraft to the IDA port located towards the Zenith. Supercluster tracks all traffic and crew movements at both the International Space Station and China's Tiangong Space Station on our Stations Dashboard available here and on the Supercluster App.

With the operational phase of Starliner, NASA will gain access to two independently developed and launched crewed spacecrafts for the International Space Station, adding a layer of redundancy to ensure the United States always maintains the capability to launch humans into orbit. "We are really excited to have this second transportation system up and available to us," remarked Stich. This level of redundancy was always a strategic goal of the Commercial Crew Program, aiming to secure continuous human presence on the ISS and maintain operational capabilities even if one spacecraft encounters safety or other issues.

"We've seen in the past the importance, I think, of having this dissimilar redundancy, [because] it's always tough to fly into space," Stich added, emphasizing the foundational objectives of NASA’s Commercial Crew Program.

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