Dragon cargo ship departs space station and heads for Earth

SpaceX’s Cargo Dragon capsule departs the International Space Station Thursday. Credit: NASA TV/Spaceflight Now

A SpaceX cargo capsule undocked from the International Space Station Thursday and headed for splashdown in the Gulf of Mexico after a two-day delay to wait for Tropical Storm Elsa to clear the area.

Flying in autopilot mode, the Cargo Dragon capsule backed away from the space station’s Harmony module at 10:45 a.m. EDT (1445 GMT) Thursday as the complex sailed more than 250 miles over the South Atlantic Ocean.

The spacecraft fired thrusters to depart the vicinity of the space station, setting the stage for re-entry and splashdown in the Gulf of Mexico south of Tallahassee, Florida, at around 11:29 p.m. EDT Friday (0329 GMT Saturday).

The unpiloted supply ship spent 33 days at the space station since docking there June 5, two days after launch aboard a SpaceX Falcon 9 rocket from NASA’s Kennedy Space Center in Florida.

The mission set to end Friday is SpaceX’s 22nd round-trip cargo delivery flight to the space station since 2012. NASA has contracts with SpaceX and Northrop Grumman to fly commercial resupply missions to the station.

On the trip up to the space station, the Dragon capsule delivered more than 7,300 pounds (3,300 kilograms) of cargo, including experiments and upgraded solar arrays. Astronauts Shane Kimbrough and Thomas Pesquet installed and unfurled the roll-out solar arrays on three spacewalks last month.

After unpacking the ship’s pressurized cargo cabin, the station astronauts loaded some 5,300 pounds (2,400 kilograms) of research specimens, experiments, and other equipment for return to Earth, according to a NASA spokesperson.

A view of the return cargo packed inside SpaceX’s Dragon supply ship. Credit: Thomas Pesquet/ESA/NASA

Experiments coming back to Earth include a pharmaceutical investigation from Eli Lilly and Company looking at how gravity affects freeze-dried materials. On Earth, freeze-drying medications for long-term storage results in layers with structural differences, and scientists want to know whether specimens freeze-dried in microgravity on the space station have a different structure.

The Dragon capsule is also returning an experiment evaluating how gravity affects the structure, composition, and activity of oral bacteria. The data could help design treatments to combat oral diseases on long-term space missions to the moon and Mars, according to NASA.

Leah Cheshier, a NASA spokesperson, said the Dragon capsule is also returning to Earth with spacewalk equipment, including a pistol grip tool, torque wrench, cooling garments, water sampling kits, and spacesuit components, such as gloves.

“I want to say thanks to all the SpaceX and NASA teams and all the scientists, engineers, and researchers who have equipment on this vehicle,” Kimbrough said after the Dragon spacecraft departed the station Thursday. “It was a great vehicle. It kept us busy for this past month doing a bunch of great science.”

The Dragon spacecraft will jettison its disposable trunk section at 10:41 p.m. EDT Friday (0241 GMT Saturday). The unpressurized trunk hosts the ship’s power-generating solar arrays.

The capsule will fire its Draco thrusters at 10:45 p.m. EDT (0245 GMT) for a nine-minute deorbit burn to slow the craft’s velocity enough to drop back into the atmosphere.

After plunging through the atmosphere, with a heat shield to protect against scorching temperatures, the Dragon capsule will deploy four parachutes a few minutes before splashdown in the Gulf of Mexico at 11:29 p.m. EDT (0329 GMT).

SpaceX’s “Go Navigator” recovery ship will be standing by near the Dragon capsule’s splashdown zone south of Tallahassee. SpaceX crews will pull the spacecraft out of the sea and begin unpacking time-sensitive cargo, including experiment freezers to preserve sensitive samples returned from the space station.

The experiments will be ferried to shore via helicopter, allowing scientists to quickly begin analyzing the results.

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