BUSAN, South Korea — SpaceX will develop an upgraded version of its Dragon spacecraft for NASA to handle the departure of the International Space Station around the end of the decade.
At a July 17 briefing, NASA and SpaceX officials provided new details about the United States Deorbit Vehicle (USDV) spacecraft NASA selected SpaceX to build on June 26 under a contract worth up to $843 million. At the time of the announcement, neither the agency nor the company described the spacecraft’s design or specific capabilities.
The USDV will be based on SpaceX’s Dragon spacecraft, but with a redesigned, larger, multi-jet Draco trunk section. The spacecraft will have 46 Draco thrusters, 16 for attitude control and 30 to perform the maneuvers needed to lower the station’s orbit at the end of its life, said Sarah Walker, director of Dragon mission control at SpaceX.
The “enhanced” section of the trunk is twice as long as the regular one, she said, and will include engines, fuel tanks, power generation and other systems. It will hold six times more propellant than the current Dragon spacecraft, while generating and storing three to four times more power. “It’s almost a spaceship in itself,” she said.
NASA, which will own and operate the USDV after SpaceX builds it, will launch the vehicle to the ISS shortly after the station’s last crew arrives. Once the USDV arrives and is checked out, ISS controllers will allow the station’s orbit to naturally descend, with the final crew leaving once the station’s altitude, currently about 400 kilometers, reaches 330 kilometers.
The station’s orbit would continue to decay for about six months before NASA used the USDV for the station’s final controlled deorbit, targeting an open ocean region in a narrow corridor about 2,000 kilometers long. Dana Weigel, NASA’s ISS program manager, said NASA expects pieces of the station ranging in size from a microwave oven to a sedan to survive reentry and splash up in that corridor.
The USDV has an estimated mass of more than 30,000 kilograms, including 16,000 kilograms of propellant. “We have to be on a heavier class rocket,” Weigel said, rather than the Falcon 9 used today for Dragon missions. NASA independently procures the launch vehicle at least three years before launch.
“If there is an opportunity for SpaceX to launch a USDV, we’re happy to support it,” Walker said.
The only other company to offer a USDV was Northrop Grumman. According to NASA’s source selection statement, Northrop offered a vehicle priced “significantly higher” than SpaceX, with lower ratings for both mission suitability and past performance.
“I was really happy that we got proposals from companies that we did,” said Ken Bowersox, NASA’s associate administrator for space operations. “I would have expected a few more, to be honest, but I was very happy to get the ones we got.
Weigel added that NASA emphasized the flight legacy in its USDV request for proposals because of the high reliability needed to bring down the station safely. “I’m not at all surprised that our current transportation providers who are already flying and compatible with things like docking to the ISS” were in the running for the vehicle, she said. “I thought we’d get a few more, but it’s definitely not a surprise with the two we got.
Falcon 9 Anomaly Update
The briefing came nearly a week after Falcon 9 suffered an anomaly during the launch of a suite of Starlink satellites. A liquid oxygen leak in the rocket’s upper stage prevented the stage’s engine from performing a second burn and placed the satellites in very low perigee orbits.
The incident grounded the Falcon 9, although Weigel said that for now, NASA is moving forward with plans to launch the Cygnus cargo vehicle as soon as possible in early August on one Falcon 9, followed by a Crew-9 launch on another Falcon 9 by mid-August at the earliest.
SpaceX is investigating the anomaly in cooperation with the Federal Aviation Administration, which must give approval that the vehicle poses no risk to public safety before SpaceX can resume launches. “We have our own process outside of what the FAA does,” Weigel said, noting that NASA is included in the ongoing investigation.
“We maintain a close partnership with the FAA and with all of our customers, and it’s going really well,” Walker said. “The team has made tremendous progress in just these early days.
She said the company is working to complete an investigation to determine what impact, if any, they will have on the schedule for the upcoming ISS and other launches. “That’s our top priority right now,” she said. “As for Team Dragon, my team, we continue to prepare the nominal launch for a number of upcoming launches in our manifest.