The last time America had a capability to launch humans into space from US soil was back when the space shuttle – more formally the Space Transportation System – was still flying. However, the last shuttle flight was concluded on July 21st, 2011, when the shuttle Atlantis, with a career spanning 25 years and 33 flights into space that clocked-up 306 days, 14 hours, 12 minutes, 43 seconds in orbit, touched down at the shuttle Landing Facility at Kennedy Space Centre, Florida.
At that time, it was expected there would be just a four-year pause between the end of STS-135, the 135th shuttle flight, and the inception of a new generation of human-rated launch systems: the Boeing CST-100 Starliner, the SpaceX Crew Dragon and NASA’s own Orion system. However, development of these vehicles has been such that almost double that amount of time has passed.
But on Saturday, March 2nd, 2019, the United States did take a major step in it trek to resume a home-grown capability to launch people into space, with the successful first orbital launch of Crew Dragon.
Crew Dragon is a human-rated, reusable capsule system developed from the highly successful SpaceX Dragon cargo capsule currently used to fly supplies and equipment to and from the International Space Station (ISS). Officially designated Crew Dragon 2, it is designed to launch atop the Falcon 9 Block 5 launcher, and will operate alongside the Cargo Dragon 2, as the backbone of SpaceX’s involvement in ISS support activities. In addition, there are plans in hand to use Crew Dragon in commercial flights to the planned Bigelow Commercial Space Station, should that come to pass.
Once operational. it will be capable of flying up to seven crew into space, although for ISS flights, Crew Dragon will likely fly with a maximum of four crew, as NASA would like to use the added payload mass and volume ability to carry pressurised cargo to / from the ISS. Also, NASA initially do not want to use the Crew Dragon’s Super Draco motors for anything else but a propulsive assist right before final touchdown, otherwise relying on parachutes for the majority of the descent post-mission, limiting the all-up mass the capsule can bring back.
For the first orbital flight of the system – referred to as demonstration flight 1 (DM1), the Dragon 2 launched without a human crew – although it does carry an instrumented mannequin named “Ripley” after the iconic character played by Sigourney Weaver in the Alien(s) film franchise. Also on board is a small payload from NASA which the vehicle will deliver to the ISS, and a “high-tech” zero-gee indicator intended to show people watching the launch live stream the moment the vehicle achieved orbit.
Lift-off occurred precisely on time at 07:29 GMT – there was no extended window, so a failure to meet the launch time would have seen the flight postponed until March 5th, 2019. The first stage carried the vehicle through the denser part of the atmosphere, rapidly accelerating it.
Just over 2 minutes following launch, the nine first stage Merlin engines shut down, allowing the stage to separate. This continued to cost upwards as the single, vacuum-adjusted Merlin on the second stage fired, pushing it and the attached Crew Dragon on up towards orbit.
Reaching the termination point of its flight, the Falcon’s first stage carried out a series of manoeuvres that allowed it to re-ignite three of its motors in what is referred to as the “burn back” manoeuvres, designed to orient the stage for re-entry into the denser part of the atmosphere and cushion it through that re-entry phase.
These manoeuvres are a common part of Falcon 9 flights when the first stage is to be recovered post-flight. Such was the case here when, some 10 minutes after launch, the first stage made a successful landing on the SpaceX Autonomous Drone Landing Ship Of Course I Still Love You. Minutes later, the motor on the Falcon’s upper stage shut down, and the Crew Dragon separated from the stage.
Once in orbit, the Crew Dragon tested its Draco thrusters and opened its nose cone to reveal the forward docking port as it commenced a gentle “chase” to catch the ISS, gradually raising its altitude in the process.
Docking with the station began at 10:51 GMT on Sunday, March 3rd, more than 400 km (248 mi) above the Earth’s surface north of New Zealand, 27 hours after launch. The spacecraft made an initial “soft capture” with the docking port on the station’s Harmony module, the docking mechanisms then pulled Dragon into a firm “hard capture” with the station about 10 minutes later.
Prior to docking the Crew Dragon closed to a distance of 150m from the station before halting its forward motion and then backing away again to 180m, testing its ability to move away from the station in the event of a problem. Once docked, a further series of checks were performed to “safe” the vehicle, prior to the hatches between it and the ISS being opened at 13:30 GMT. As a further precaution, Russian cosmonaut Oleg Kononenko and Canadian David Saint-Jacques wore gas masks to guard against any internal leaks of gas in the capsule when they first entered. After they had carried out atmospheric readings, NASA astronaut Anne McClain joined Saint-Jacques in starting to unload more than 180 kg of cargo included in the flight.
During the unloading, Saint-Jacques knocked the “high-tech” zero gee plushy, sending it carooming around the capsule, prompting mission control to observe, “Can you tell we’re in microgravity?”
The Dragon will remain docked with the ISS through until Friday, March 8th, after which it will depart for a return to Earth, bringing a small amount of cargo with it. The capsule should splash down in the Atlantic Ocean at around 13:45 GMT that day, after a parachute descent through the atmosphere.
If all goes according to plan, the capsule used in this test (C201), will make a second uncrewed flight in June 2019, when it will be used to conduct an in-flight abort test, using its Draco motors to push it free of its Falcon 9 launcher to simulate what would happen in the event of a real booster malfunction. Following that flight, and assuming there are no further issues, the second demonstration flight (DM2) should take place in July 2019, when NASA astronauts Bob Behnken and Doug Hurley, both veterans of the space shuttle, will fly to the ISS aboard Crew Dragon C203, where they will remain for 2 weeks before making a return to Earth.
Assuming that flight (Demonstration Mission 2) is successful, Crew Dragon should then be cleared to start flying crews to and from the ISS at the end of 2019.
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