HISTORY WRITTEN FOR CBS NEWS AND USED WITH PERMISSION
Space station commander Chris Cassidy and Robert Behnken plan to float outside on Friday for the first of up to four spacewalks necessary to complete replacement of old batteries in the lab’s solar power system. NASA managers hope to get the job done in time for Behnken and crewmate Douglas Hurley to return to Earth aboard their Crew Dragon capsule around August 2, officials said Wednesday.
When the SpaceX capsule took off on a SpaceX Falcon 9 rocket on May 30, NASA managers had not specified a return date. But flight controllers are now “watching the landing in early August,” Steve Stich, manager of NASA’s Commercial Crew Program, told reporters during a preview conference call of the spacewalk.
“The earliest would be around August 2,” he added. “We are working on those opportunities with the space station program.”
A splash in early August for the SpaceX capsule would give engineers time to thoroughly evaluate the spacecraft’s first pilot test flight, known as Demo 2, before clearing the decks for a full-length operational mission with four astronauts. in mid-September. That flight is known as the Crew-1 mission.
“Right now, we think we need around six weeks of time to review all the landing and decoupling data, and then go through the review process to get to the Crew One launch,” Stich said. “So there is some sort of six-week iron bar, so to speak, between the Demo-2 landing and the Crew-1 launch, and that will be a factor as we look at the Crew-1 release dates. later”.
Since docking at the space station the day after launch, Crew Dragon has spent most of its time off in a kind of electronic hibernation. But flight controllers wake him up every Wednesday to collect engineering data and evaluate his performance. So far, 25 days after its mission, the capsule is working almost perfectly.
A question mark during the flight was how the spacecraft’s solar cells could be affected by atomic oxygen in the space environment. Engineers expected its performance to degrade over time, but it turns out that the system has been operating above pre-flight predictions.
“The vehicle is working extremely well,” said Stich. “We are learning a lot about the vehicle. Nothing to worry about, learning to manage systems, heaters, and thermal performance as we go through changes in orbit. Also, we’ve been watching power generation (and) Dragon is generating more power than we expected. “
Hurley and Behnken will end their mission with NASA’s first ocean dip since the Apollo-Soyuz mission in 1975. Upon entering the flight, NASA focused on the landing zones off Cape Canaveral or Jacksonville with a backup site in the Gulf of Mexico near Pensacola.
Stich said mission managers are now evaluating additional sites outside of Panama City, Tallahassee, Tampa and Daytona Beach to provide more options in case of stormy tropical weather.
The Crew Dragon carries enough supplies on board for about three days of flight after leaving the space station. Stich said that depending on when the ship actually departs and which landing site is selected, the return trip home could be as short as six hours or could extend to a full day or even longer.
“It seems like the first opportunity to undock and go home would be around August 2,” Stich said. “We will have to see how EVA works.”
The space station’s four huge solar wings power eight electrical channels, which originally relied on 48 nickel-hydrogen batteries, six per power channel, to supply electricity when the station is not exposed to direct sunlight.
In a multi-year project, spacewalk astronauts have replaced 36 of the 48 oldest batteries, installing 18 smaller and more efficient lithium-ion power packs and adapter plates that complete the circuit instead.
Behnken and Cassidy, who launched into the station on April 9 aboard a Russian Soyuz spacecraft, plan two spacewalks, one on Friday and the second on Wednesday, to install three of the final six batteries and adapter plates in power channel 1B and store the six batteries to be replaced. Two more EVAs will be needed to install the final three batteries in channel 3B.
