NASA prepares for Boeing Starliner's uncrewed return to Earth

Sept. 5 (UPI) -- The beleaguered Boeing Starliner spacecraft that took two NASA astronauts to the International Space Station will attempt to make its uncrewed return to Earth on Friday evening, the company has announced.

NASA on Thursday issued a timeline and a set of criteria for the Starliner's departure from the ISS and return to Earth.

The space capsule has faced a host of issues since well before its launch, and continued to experience problems even after arriving at the ISS, which ultimately culminated in Boeing making a deal with competitor SpaceX to bring the astronauts back home in February.

The June 5 mission was scheduled to last eight days. Instead, astronauts Butch Wilmore and Suni Williams will spend eight months in space.

"Mission managers will complete a series of operational and weather checks before the spacecraft undocks from the orbital complex," NASA said in a release.

Following the undocking from the ISS, the Starliner will fire a series of departure rockets allowing the capsule to reach its landing site in as little as six hours, pending weather and wind conditions. If those are not optimal, Starliner will try again between 24 and 31 hours later.

"Once clear to proceed, Starliner executes its deorbit burn, which lasts approximately 60 seconds, slowing it down enough to re-enter Earth's atmosphere and committing the spacecraft to its targeted site," NASA said. "Immediately after the deorbit burn, Starliner repositions for service module disposal, which will burn up during re-entry over the southern Pacific Ocean."

Scientists are prepared for a plasma buildup on the craft, causing it to reach 3,000 degrees Fahrenheit and resulting in a possible four-minute gap in communications with ground crews.

Once it re-enters Earth's atmosphere, Starliner will jettison its heat shield at approximately 30,000 feet exposing a series of drags and parachutes which will start the initial slowdown of the craft. At 3,000 feet, Starliner will jettison an additional heat shield and a half dozen inflatable landing bags will be deployed.

The Starliner will be traveling at 4 mph when it touches down, NASA said.

"The NASA and Boeing landing and recovery team is stationed at a holding zone near Starliner's intended landing site," NASA said. "After landing, a series of five teams move in toward the spacecraft in a sequential order."

Those crews are scheduled to "sniff" the capsule for any combustible fuels that did not burn off on re-entry. Another team will then check electrical ground and yet another crew will move in to provide power and cooling to the unit even though there will be no one in it.

NASA was forced to reduce by half the size of its planned crew SpaceX Crew-9 mission to the International Space Station in order to accommodate the return of Wilmore and Williams.

The space agency announced the decision Friday to send only NASA astronaut Nick Hague and Roscosmos cosmonaut Aleksandr Gorbunov aboard the mission, which will launch no earlier than Sept. 24.

Boeing's Starliner spacecraft has remained stalled at the ISS because of issues with its propulsion system that have led to safety concerns after its initial flight.

NASA decided Aug. 24 to return Starliner from the space station uncrewed due to those safety concerns.

"While we've changed crew before for a variety of reasons, downsizing crew for this flight was another tough decision to adjust to given that the crew has trained as a crew of four," NASA Chief Astronaut Joe Acaba said in the agency's statement last week.

Once the Starliner lands and checks out with ground crews, the capsule will be transported to Boeing facilities at NASA's Kennedy Space Center in Florida for refurbishment ahead of its next flight.