SpaceX's Dragon commercial cargo ship left the International Space Station and splashed down in the Pacific Ocean on Tuesday — capping off a day that also included a countdown (and scrub) for a SpaceX Falcon 9 rocket.
"Busy Tuesday," California-based SpaceX remarked in a tweet.
The Dragon disengaged without a hitch from its port on the space station's Harmony module, a month after it arrived with more than 2.5 tons of supplies and experiments.
During that time, the station's live-aboard crew unloaded all that cargo and filled the Dragon back up with 3,700 pounds (1,600 kilograms) of trash, equipment and experiments to be returned to Earth — including 17 student science projects. The round-trip cargo run was the fifth of 12 resupply missions covered under the terms of SpaceX's $1.6 billion contract with NASA.
The Dragon was released by the space station's robotic arm at 2:10 p.m. ET, freeing the uncrewed craft to go through a series of autonomous orbital maneuvers that led up to its splashdown off the coast of Baja California around 4:44 p.m. PT (7:44 p.m. ET).
After the capsule is picked up and placed on a recovery ship, it will be brought back to port in Long Beach, California, then shipped to Texas for processing.
Rocket launch put on hold
While one SpaceX team prepared for the Dragon's return, another team prepared for the launch of the DSCOVR satellite, also known as the Deep Space Climate Observatory, atop the Falcon 9.
The refrigerator-sized satellite's original mission — to observe Earth's full disk from a vantage point a million miles away — was suggested by Vice President Al Gore 17 years ago. Since then, its mission has shifted to focus on observations of solar storms.
DSCOVR's launch from Cape Canaveral Air Force Station in Florida had been held up for a couple of days due to a radar tracking glitch and weather concerns. On Tuesday, upper-level winds forced another postponement. Liftoff was reset for Wednesday.
Whenever it occurs, the DSCOVR launch will give SpaceX a second opportunity to try landing the Falcon 9's first stage on the deck of a drone ship in the Atlantic Ocean after stage separation.
SpaceX tried a similar maneuver last month when it launched the Dragon spaceship to the space station with a different Falcon 9, but it didn't quite work. A system of stabilizing grid fins ran out of hydraulic fluid just before landing. As a result, the rocket hit the deck off-kilter and exploded.
This time around, the trajectory is more challenging. In a tweet, SpaceX founder Elon Musk said the rocket stage would encounter two times the force and four times the heat as it makes its descent. "Plenty of hydraulic fluid, though," he added.