A reusable Falcon 9 rocket sent the capsule into space at 5:07 p.m. before returning to a landing pad several miles from its launch location in Cape Canaveral.
This time around the capsule was loaded up with roughly 6,000 pounds of supplies and equipment, including experiments to study the cardiovascular systems of fruit flies in low gravity and bone loss in mice aboard the ISS.
Once secured, the crew will begin to unload the 1,700 kilograms of pressurized cargo, while an additional 1,600 kilograms of unpressurised material will be unpacked from Dragon's trunk using the station's robotic arm.
Saturday was a historic launch date for SpaceX and NASA, with the Dragon being the first of its kind to be relaunched, coinciding with the 100th launch from the Launch Complex 39A at Kennedy Space Center. SpaceX launched its first recycled booster two months ago and plans to reuse another booster this coming month.
The first stage of that Falcon 9 then came back to Earth for a science fiction-looking landing at a pad in Cape Canaveral, Florida.
"The majority of this Dragon has been in space before", he said during a prelaunch news conference earlier this week.More news: London attacks: Two of the three killers identified
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He said the entire industry is interested in 'this whole notion of reuse, ' first realized with the space shuttles. It also marked the first time that SpaceX has launched a spaceship that has been used on a previous mission to the space station.
The Dragon capsule actually contained many of its original parts.
Reusing a spacecraft also marks another huge step forward in SpaceX's efforts to bring down the cost of spaceflight. Unlike the Dragon, the Cygnus is not created to survive re-entry and it will burn up when it falls back into the atmosphere.
SpaceX says it could re-fly as many as six used Falcon 9s before the end of 2017.
SpaceX has been hauling station supplies for NASA for five years, both up and down. "We expect to increase the amount of reflight as (NASA's contracts with SpaceX) proceed".
The Falcon 9 lifts off from Kennedy Space Center. That way, the company can at some point shut down production of the vehicle and focus on the production of another spacecraft: the upgraded Dragon. The station was zooming over Oman in the Persian Gulf when the Falcon took flight.