KENNEDY SPACE CENTER, Florida – As SpaceX prepares to launch its Crew Dragon spacecraft on its first test flight, the company and NASA acknowledge that there is still a lot of work to be done before the spacecraft is ready to go. carry astronauts.
At a briefing here on February 28, NASA and SpaceX officials announced plans to launch the Crew Dragon spacecraft on a test flight known as Demo-1 or DM-1, which will demonstrate the systems of this unmanned spaceship. The launch of the mission is scheduled on a Falcon 9 at 2:49 am east of March 2 from Launch Pad 39A, with an 80% chance that weather conditions will be acceptable.
One of the last hurdles that NASA and SpaceX had to overcome was a concern of Russia, one of the International Space Station's partners, about the risk that the space shuttle would run to the station if its computers did not work. correctly when approaching. Roscosmos issued a dissenting opinion on the flight software Crew Dragon during a flight readiness review on Feb. 22. NASA has subsequently endeavored to address these concerns.
"We agreed yesterday with Roscosmos about a protocol on this approach," said Joel Montalbano, NASA's ISS Program Manager. These included shutting down the station's hatches and preparing the crew of three ready to go to the Soyuz station docked at the station if Crew Dragon collided with the station due to a software failure, a scenario of which he described the probabilities. "
The Crew Dragon spacecraft approaches the ISS differently than the cargo version of Dragon, said Hans Koenigsmann, vice president of reliability of construction and flight systems at SpaceX. The Dragon cargo approaches the station from below until it is close enough to be captured by the robotic arm of the station. Crew Dragon will be positioned in front of the station and will move along the speed vector to dock at the station.
"It basically needs to actively accelerate and slow down to get to the station" with Crew Dragon's approach, he said. On the other hand, as the Dragon cargo approaches, "if you do nothing, you will slowly escape and get away from the station."
For the Demo-1 mission, Crew Dragon will approach within 150 meters of the station before the crew of the station issues a retreat order to bring it back to a distance of 180 meters. "All of this is part of the tests we are doing to ensure the safety of the space station," said Montalbano. The spacecraft will also stop at a distance of 20 meters for the final tests before berthing.
Crew Dragon's ability to safely dock at the station is just one of many tests that the spacecraft will undergo during a flight of approximately six days duration. "From NASA's point of view, we really want to see the performance in orbit and how the systems will work together," said Kathy Lueders, NASA's Commercial Program Program Manager.
"It's an invaluable exercise for us to learn in the space environment how these systems will work, and then to make sure these systems are ready for use when we send our crews over," she added.
The degree of closeness between Crew Dragon and the pilots is a subject of debate. Pat Forrester, head of the astronaut office at NASA, said it was "very exciting" to be back at the Kennedy Space Center before the launch of Demo-1. "It will be more exciting when we get back to the DM-2," said the crewed flight test. "While much progress has been made, there is still a lot of work to be done and we look forward to working with SpaceX as a team to achieve this."
Koenigsmann said that there was "still work to be done" on elements of Crew Dragon before the Demo-2 mission. The life support system will need to be strengthened for the Demo-2 mission, he said, as an example of change, and the software will be updated between the two missions.
"We have to work a lot of details, but in general it's the same vehicle," he said.
Another problem, reported for the first time during a briefing on 22 February, concerns Draco's thrusters of the spacecraft after the thermal vacuum tests. "As for the environment in which we expected this mission to be executed originally, the Dracos did not like this environment," said Lueders, with temperatures too low.
For Demo-1, the mission has been modified to avoid these low temperatures, including the approach of one day of the ISS after launch. In the end, heaters will be added to the thruster lines of the thruster so that this is not a problem for Demo-2, she said.
Other changes in the spacecraft probably depend on the outcome of Demo-1. Lueders said the spacecraft is heavily instrumented to measure its performance and that it will also ship a dummy – nicknamed "Ripley" according to the character of the Extraterrestrial movie franchise – to study the conditions that a human would experience on the spacecraft.
The launch of this Demo-2 mission is scheduled for July, according to NASA's current commercial flight test flight schedule, although most industry observers expect it to come back later in the year. year. Koenigsmann, asked if this July date was still feasible, said it would depend on changes to Crew Dragon after Demo-1.
"There is really a lot of ingenuity in both teams here," he said of NASA and SpaceX, citing as an example the short-term solution to the thruster problem. "For something similar, I would expect that we find a similar operational solution."