NASA will determine SpaceX's first crewed mission duration based on several factors

Featured Image Source: SpaceX / NASA

The historic rocket flight that will return human spaceflight capabilities to the United States will take place in a couple of weeks. On May 27^th, veteran NASA Astronauts Robert Behnken and Douglas Hurley will lift off at 4:32 p.m. EDT. atop a Falcon 9 rocket, embarking on a voyage to the International Space Station (ISS) aboard SpaceX’s Crew Dragon spacecraft. It will SpaceX’s first crewed launch, known as Demo-2. The agency and SpaceX have been planning and preparing for the historic Demo-2 mission for years. Everything is ready, coordinated, and practiced. Though, the only detail that has not yet been established is the mission’s duration – how long will astronauts stay at the space station before heading back to Earth. NASA astronauts have been training to fly the new Crew Dragon spacecraft. Also, to conduct work at the orbiting laboratory that could involve extravehicular activity, spacewalks.  The station requires at least three crew members to maintain it. Currently, there is only one American astronaut, Chris Cassidy, at the laboratory. ISS needs a battery swap, a task that requires a spacewalk, which is why it is essential for NASA to send a crew to the space station because Cassidy cannot perform the spacewalk alone. “We currently are supporting the station with the bare minimum,” NASA administrator Jim Bridenstine said on Friday (May 1). “Without the presence of Behnken and Hurley, we otherwise would likely defer such an operation until additional NASA crew members are available.”

At the Demo-2 mission briefing (video above), Steve Stich, deputy manager of NASA's Commercial Crew Program, shared astronauts Behnken and Hurley could spend anywhere from 30 days to 119 days at the space station but the exact duration of the Demo-2 mission cannot be determined until they are already in space. “Really the decision point is, hey, is Dragon healthy? Is the vehicle performing well? The Dragon that's on orbit? And then we'll be looking ahead to that next mission, the Crew-1 flight, and looking at the vehicle readiness and trying to determine what's the smart thing to do relative to the mission duration,” he said. The Crew-1 mission, will be the second crewed flight launched from American soil aboard SpaceX’s Crew Dragon the craft is currently under development. So, the Demo-2 mission duration will be determined based on how well Crew Dragon operates in space, and how long the next craft takes to be ready for the next flight. Those are the factors NASA and SpaceX will base on to decide on a return flight date. “It's a little bit of a variable, but it's one that I think we can manage well,” Stich stated:

“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 and augment their crew capability to do science in other operations at the station.”

The Crew Dragon spacecraft developed for the Demo-2 mission cannot stay docked with the station for over 119 days. Stich explained it is because the craft’s solar arrays are not designed to support space environment for a longer period. “Any solar array in low Earth orbit tends to degrade a little bit over time,” Stich said. “It turns out the atmosphere has a little bit of oxygen in it, it's called atomic oxygen… So, there's a little bit of degradation in the ability for the cells itself to generate power. And the particular cells on the trunk for a Dragon, based on analysis capability, kind of a worst-case prediction, we think we can get about 120 days capability out of those.”

Source: SpaceX

Based on that timeframe, Crew Dragon could return with Behnken and Hurley aboard by the end of June, or later this year in September. It all depends on the factors mentioned. Upon return, Dragon will perform its first manned atmosphere reentry. The risky feat will consist of a parachute-assisted landing in the ocean to mark mission completion. Bridenstine had previously said it will take about one month to send the second crew to the space station because engineers will have to analyze the spacecraft's condition and data upon return. The next Dragon spacecraft for Crew 1, the operational mission, is under development to withstand 210 days in space and it will deploy a crew of four astronauts later this year.