Image copyright AFP Image caption Mr Hammack and the crew of the last SpaceX mission, Mr Halsted and Mr Andrews
A four-man American astronaut crew returned to Earth from the International Space Station in the latest delivery from Space Exploration Technologies (SpaceX).
Kevin Ford and Timothy Kopra, along with US Air Force Colonel Robert Hopkins and Russian Alexey Ovchinin, left behind the station on a SpaceX Dragon capsule in a “drop kick”.
It was the first delivery to the ISS after the end of the first US commercial spaceflight mission in 44 years.
On that mission, Cygnus spacecraft built by SpaceX safely returned to Earth last April.
In SpaceX’s resupply missions, it uses the larger Dragon capsule.
Image copyright Getty Images Image caption NASA astronaut Peggy Whitson is the longest-serving female space flight crew member
On December 21, the capsule was carrying a new pair of cosmonauts who will fly on the next resupply mission later this year.
The crew members shut off the propulsion system’s thrusters and the control panel’s red button, marking the end of a 200-day mission.
The International Space Station is a complex of research stations orbiting around Earth that are built by 15 countries for science research.
Russia currently supplies two-thirds of the ISS crew with its Soyuz spacecraft.
And the US supplies the rest of the crew members, known as the Expanded Space Crew Programme or ESC, by using the Falcon 9.
After just six manned missions of US cargo carriers during the Cold War, NASA has had very little operational cargo and crew vehicles and that’s only increased in recent years, said the BBC’s Ayan Adewusi.
What is SpaceX’s involvement in the COTS project?
Founded in 2002, SpaceX is led by Tesla founder Elon Musk.
It built the Falcon 9 booster that launched on October 19, which successfully launched the Crew Dragon capsule to the ISS, NASA’s fifth mission to the space station in two years.
Image copyright NASA Image caption SpaceX aims to make America the world’s space superpower once again
The goal of the commercial cargo programme was to get new vehicles and US companies doing unmanned tests for the space station and boost astronaut flights to the station.
SpaceX’s goal is to be able to launch a manned mission to the station next year and then 2020.
The Falcon 9’s maiden flight to the space station in June 2012 set up a two-way communication link with the station for the first time.
Since then, the company has successfully launched six cargo missions. The next is due to launch on 27 February 2019.
Image copyright SpaceX Image caption An image of the Falcon 9 rocket with the Crew Dragon capsule is displayed for the media at a news conference