Fiery Success: NASA and Boeing’s Starliner Hot Fire Thruster Test Yields Impressive Results

Boeing’s Starliner spacecraft that launched NASA’s Crew Flight Test astronauts Butch Wilmore and Suni Williams to the International Space Station is pictured docked to the Harmony module’s forward port. This long-duration photograph was taken at night from the orbital complex as it soared 258 miles above western China. Credit: NASA

NASA and Boeing engineers completed a hot fire test of the Starliner spacecraft’s reaction control system jets, with astronauts Butch Wilmore and Suni Williams on board.

The test evaluated 27 of the spacecraft’s 28 jets, checking thruster performance and helium leak rates, showing positive preliminary results.

Starliner Spacecraft Test Overview

On July 27, engineering teams with NASA and Boeing completed a hot fire test of the Starliner spacecraft’s reaction control system jets to evaluate the spacecraft’s propulsion system. NASA astronauts Butch Wilmore and Suni Williams, assigned to the agency’s Boeing Crew Flight Test, were seated inside the docked spacecraft during the test as part of preparations before their return aboard Starliner from the International Space Station.

The test involved firing 27 of the spacecraft’s 28 jets for short bursts, moving through them one at a time to check thruster performance and helium leak rates. Preliminary results show all the tested thrusters are back to preflight levels based on thrust and chamber pressure.

Boeing’s Starliner spacecraft that launched NASA’s Crew Flight Test astronauts Butch Wilmore and Suni Williams to the International Space Station is pictured docked to the Harmony module’s forward port. This view is from a window on the SpaceX Dragon Endeavour spacecraft docked to the port adjacent to the Starliner. Credit: NASA

Helium Manifolds and Thruster Performance

As part of the test configuration, all helium manifolds, which control and direct the flow of helium, were opened allowing engineers to continue evaluation of Starliner’s helium supply and leak rates. The teams verified Starliner continues to show the margin needed to support a return trip from the station. Following the test, the helium manifolds were closed and will remain closed until Starliner activates its propulsion system ahead of undocking. Teams also will verify the helium leak rate before Starliner undocks.

Teams are reviewing data from the docked hot fire test and the recent ground testing of a Starliner thruster at NASA’s White Sands Test Facility in New Mexico before holding an agency return readiness review. Following this agency-level review, NASA and Boeing will select a target return date.

NASA’s Boeing Crew Flight Test astronauts (from top) Butch Wilmore and Suni Williams pose for a portrait inside the vestibule between the forward port on the International Space Station’s Harmony module and Boeing’s Starliner spacecraft. Credit: NASA

Astronauts’ Ongoing Activities

While ground teams work to finalize Starliner’s return to Earth, Wilmore and Williams continue to work alongside the Expedition 71 crew, assisting with science investigations and maintenance activities. On July 29, Wilmore and Williams entered their spacecraft and checked its water systems, called down to Boeing mission personnel for a conference, and put on their space suits long enough to perform a pressure test. Wilmore started his morning in the Harmony module, assembling the BioServe centrifuge as Williams reviewed procedures for operating the Astrobee free-flying robotic assistants.