After spending nearly a week connected to the International Space Station, SpaceX’s Dragon is ready to head home. Astronauts aboard the station have unloaded and repacked the private spacecraft -- the first to visit the ISS -- and will begin unberthing procedures tomorrow morning. Splashdown in the Pacific Ocean is scheduled for Thursday at 11:44AM EDT (15:44 UTC). If successful, Dragon's arrival will mark the first time an American spacecraft has returned from the ISS since space shuttle Atlantis in July 2011.
After Dragon’s hatch is closed, the vestibule connecting the vehicle to the station will be depressurized. Here is the schedule for the subsequent unberthing on Thursday morning:
- 2:30AM EDT (6:30 UTC) NASA TV coverage begins
- 4:05AM EDT (8:05 UTC) Canadarm2 unberths Dragon
- 5:35AM EDT (9:35 UTC) Dragon is released
Once floating free from the station, the Dragon will begin a series of burns to take it down the R-bar, the imaginary line connecting the ISS with the center of the Earth. The spacecraft will close its GNC (guidance, navigation and control) bay door, which contains the fixture Don Pettit grappled with Canadarm2 when the Dragon arrived.
The final challenge of SpaceX’s COTS (Commercial Orbital Transportation Services) demo flight will begin when the the Dragon initiates a de-orbit burn to reenter the Earth’s atmosphere. NASA flight director Holly Ridings said that the station crew has been told where to look for the resulting plasma trail, but since reentry will occur in daylight, it is unlikely the crew will witness the fiery show.
Here is the reentry timeline:
- 10:15AM EDT (14:15 UTC) NASA TV coverage begins
- 10:51AM EDT (14:51 UTC) Dragon initiates deorbit burn
- Trunk jettisoned
- Drogue chutes deployed
- Main chutes deployed
- 11:44AM EDT (15:44 UTC) Splashdown in Pacific Ocean (907 statute kilometers southwest of Los Angeles, California)
- Recovery of Dragon capsule at sea
- 2:00PM EDT (18:00 UTC) NASA TV coverage of Dragon mission status briefing
SpaceX mission director John Couluris said that SpaceX’s recovery vessels are operated by American Marine, which will operate out of Los Angeles. Although the forecast looks favorable for splashdown, the ships are equipped to recover the capsule in a variety of weather conditions. Couluris also said they have slightly higher operational constraints than the vessels used to recover NASA's Apollo capsules. The reentry has been timed so as to maximize the amount of daylight available for sea operations.
Once SpaceX delivers the Dragon’s cargo to NASA, they will have completed the necessary COTS milestones to begin official ISS resupply missions later this year. The next Falcon 9 rocket is already in Cape Canaveral, and its matching Dragon capsule is being processed in SpaceX’s Hawthorne plant.