With less than a month to go before NASA’s first crewed launch in nearly a decade, the space agency is still mulling over the details. On May 27, Bob Behnken and Doug Hurley will strap into their Crew Dragon spacecraft and blast off towards the International Space Station. During their stay, the duo will assist fellow NASA astronaut, Chris Cassidy, in maintaining the station as well as conducting several research experiments.
But how long the duo will remain on the station is still up in the air. NASA held a series of briefings on Friday, May 1, detailing the historic mission and how it would work. Hurley and Behnken will launch from Pad 39A at Kennedy Space Center at 4:32 p.m. EDT (20:32 UTC), and dock with the space station 24 hours later.
The exact length of that mission will be determined during their time in space. “It is a trade-off,” Kirk Shireman, NASA ISS program manager said during the news briefing, “between getting the spacecraft back quickly to complete its certification and providing additional crew time on the station for maintenance and research.”
The Demo-2 mission is a test flight. NASA and SpaceX will be using the mission to certify the Crew Dragon spacecraft for regular use to and from the station. So during this flight, the crew will try their hands at manual control and will test and monitor on boars systems during the significant phases of flight: launch, on orbit, and during re-entry.
Once the vehicle has completed its objectives successfully, it will be certified for a crewed flight. Currently, SpaceX is nearing completion on the next Dragon spacecraft, which will ferry four astronauts to the station for a long-duration mission. During the news briefings, SpaceX COO Gwynne Shotwell announced that the spacecraft for that mission is nearing completion and should arrive in Florida in the next couple of months.
Shireman said that the length of the Demo-2 mission was directly tied to that vehicle’s progress. “What we would like to do, from a station perspective, is to keep them on orbit as long as we can until that Crew-1 vehicle is just about ready to go, bring Demo-2 home, allow that certification work to be completed and launch Crew-1,” he said.
Steve Stich, NASA’s deputy manager of the commercial crew program, said that at minimum, the DM-2 crew would stay on orbit about a month. Their maximum stay would be no more than 119 days, due to the potential degradation of the Dragon spacecraft’s solar panels.
Solar panels are how spacecraft get their power while on orbit, and the sensitive components within the hardware degrade over time thanks to the harshness of the space environment. While it’s on orbit, ground control teams will “wake up” the spacecraft once a week to perform health checks and test the solar array’s performance.
“We would like to fly a mission that is as long as we need to for a test flight, but also support some of the space station program needs,” Stitch said.
Originally, Behnken and Hurley were expected to have a much shorter time on orbit. However, NASA officials said they started to explore the possibility of extending their mission six months ago to ensure there were enough astronauts onboard the space station to keep the orbital outpost in top shape. This year the agency is celebrating 20 years of continuous human presence on the space station, and NASA would like to ensure its continuation into the future.
To that end, Behnken and Hurley have spent significant time training to refresh themselves on station systems as well as prepare the potential spacewalks. A new shipment of batteries is scheduled to arrive on station a few days before Behnken and Hurley, and it’s possible that Behnken could be asked to conduct a spacewalk, along with Chris Cassidy.
The top priority for Behnken and Hurley will be to thoroughly check out the Crew Dragon’s systems, followed closely by relieving Chris Cassidy. “There’s a lot of work and activity that can be done in the U.S. segment; certainly more than one person can accomplish on their own,” Behnken explained during a later briefing.