Sign up for CNN’s Science of Miracles newsletter. Explore the universe with news of fascinating discoveries, scientific breakthroughs and more.
CNN
–
The final attempt at the inaugural crewed launch of Boeing’s Starliner spacecraft is on track for Wednesday after a computer glitch halted the countdown just moments before liftoff on Saturday.
The historic mission, called the Crew Flight Test, is set to launch at 10:52 a.m. ET from the Cape Canaveral Space Force Station in Florida. The event will be streamed live on NASA’s website, with coverage beginning at 6:45 a.m. ET.
Veteran NASA astronauts Butch Wilmore and Suni Williams will be the first crew to board the Starliner, propelled to orbit atop an Atlas V rocket built by United Launch Alliance, a joint venture between Boeing and Lockheed Martin.
The long-awaited flight was 3 minutes and 50 seconds into liftoff Saturday afternoon when an automatic hold triggered by the ground launch sequencer, or computer that launches the rocket. The crews safely ejected the astronauts from the capsule, and Williams and Wilmore returned to the crew quarters as fuel was drained from the rocket.
Joe Raedle/Getty Images
Boeing’s Starliner spacecraft lands atop a United Launch Alliance Atlas V rocket at the Cape Canaveral Space Force Station in Florida on May 31.
United Launch Alliance technicians and engineers evaluated the ground support equipment over the weekend, examining three large computers housed inside a shelter at the base of the launch pad. Each computer is identical, providing triple redundancy to ensure the safe launch of manned missions.
“Imagine a big rack that is a big computer where the functions of the computer as a controller are separated separately on individual cards or printed circuit boards,” said Tory Bruno, president and CEO of United Launch Alliance, during a press conference on Saturday. . “They’re all independent, but together, it’s an integrated controller.”
The cards inside the computers are responsible for various key systems that must occur before launch, such as loosening the bolts on the base of the rocket so it can be removed after launch.
During the last four minutes before launch, all three computers must communicate and agree with each other. But during Saturday’s countdown, a card on one of the computers was six seconds slower to respond than the other two computers, indicating something was wrong and triggering an automatic hold, according to Bruno.
Over the weekend, engineers evaluated computers, power supplies, and network communication between computers. The team isolated the problem to a single ground power supply inside one of the computers, which provides power to the computer cards responsible for key countdown events — including the refueling valves for the rocket’s upper stage, according to a separate update from NASA.
Starliner crews reported no signs of physical damage to the computer, which they removed and replaced with a spare. Meanwhile, mission specialists continue to analyze the damaged power unit to better understand what went wrong.
Other computers and their cards were also evaluated, and all of them are functioning normally as expected, according to the ULA team.
The Starliner mission management team reviewed the computer replacement troubleshooting steps that were taken, and they agreed that Starliner will “go” for launch on Wednesday, according to an update from NASA.
“I greatly appreciate the work of the NASA, Boeing and ULA teams over the past week,” Steve Stich, manager of NASA’s Commercial Crew Program, said in a statement. “In particular, the ULA team worked hard to quickly learn more about these issues, keep our NASA and Boeing teams informed, and advocate for this next effort. We will continue to do it step by step.”
Mission teams had successfully worked through several other issues that arose earlier in the countdown to Saturday’s launch attempt. These problems included a loss of data from the ground valves responsible for refilling the second, or upper, stage of the Atlas V rocket with liquid oxygen and hydrogen before liftoff.
Both the liquid oxygen and hydrogen used to fuel the rocket boil off as the rocket lands on the pad before launch, so refueling continues until liftoff. After assessing the issue, the mission teams switched to a redundant system for valve data and were able to restart the process.
Weather conditions are 90% favorable for a Wednesday morning launch, with the only concern being cumulus clouds, according to the US Air Force’s 45th Weather Squadron. If the launch doesn’t happen on Wednesday, there is another possibility at 10:29 a.m. Thursday, according to NASA.
If Starliner successfully lifts off, astronauts will spend just over 24 hours traveling to the International Space Station.
Joe Skipper/Reuters
Veteran NASA astronauts Butch Wilmore (left) and Suni Williams are seen Saturday before the second Starliner launch attempt.
After docking, Williams and Wilmore will spend eight days living in the orbiting laboratory, joining the seven astronauts and cosmonauts already on board. Both will continue to test the functionality of the Starliner spacecraft while it is docked at the space station and then return home with the same capsule. It is expected to parachute into a landing at one of several designated locations throughout the southwestern United States.
Meanwhile, the two astronauts remain in quarantine to protect their health before launch, and they are practicing procedures and simulations ahead of the historic flight, according to NASA.