The shadows of Piers Sellers and Mike Fossum are visible against Discovery’s payload bay door during an EVA on STS-121.

The shadows of Piers Sellers and Mike Fossum are visible against Discovery’s payload bay door during an EVA on STS-121.

Crew of STS-121 after landing

Crew of STS-121 after landing

Launch of STS-9, John Young’s sixth and final spaceflight

Launch of STS-9, John Young’s sixth and final spaceflight

Space Shuttle Challenger is rolled over from the OPF to the VAB in preparation for STS-8.

Space Shuttle Challenger is rolled over from the OPF to the VAB in preparation for STS-8.

Docking Module in the cargo bay of Space Shuttle Atlantis, ready to be attached to Mir during STS-74.

Docking Module in the cargo bay of Space Shuttle Atlantis, ready to be attached to Mir during STS-74.

Not the official crew photo of STS-61-C, the first space mission for current NASA Administrator Charles Bolden and the first of seven space missions for Franklin Chang-Diaz, who was also the first naturalised US citizen to go into space.

Not the official crew photo of STS-61-C, the first space mission for current NASA Administrator Charles Bolden and the first of seven space missions for Franklin Chang-Diaz, who was also the first naturalised US citizen to go into space.

Atlantis touches down on the dry desert lakebed at Edwards AFB at the end of STS-51-J, her first space mission.

Atlantis touches down on the dry desert lakebed at Edwards AFB at the end of STS-51-J, her first space mission.

STS-51-G was the first spaceflight of Shannon Lucid, the only space mission to include a Saudi crewmember, and the first shuttle mission to draw all of its crew from shuttle era astronaut groups.

STS-51-G was the first spaceflight of Shannon Lucid, the only space mission to include a Saudi crewmember, and the first shuttle mission to draw all of its crew from shuttle era astronaut groups.

Crew of STS-51-F - the second mission (of six) for Story Musgrave (centre back), the only astronaut to serve on missions aboard all five space-bound shuttle orbiters.

Crew of STS-51-F - the second mission (of six) for Story Musgrave (centre back), the only astronaut to serve on missions aboard all five space-bound shuttle orbiters.

STS-51-D crew portrait, including Senator Jake Garn (back row, right). Garn was severely incapacitated with space sickness during the mission, which led to the notation of the Garn Scale for measuring the severity of space sickness on astronauts in subsequent missions.

STS-51-D crew portrait, including Senator Jake Garn (back row, right). Garn was severely incapacitated with space sickness during the mission, which led to the notation of the Garn Scale for measuring the severity of space sickness on astronauts in subsequent missions.

Kathryn Sullivan during an EVA, STS-41-G, the first space mission to carry two women astronauts (Sullivan and Sally Ride). 

Kathryn Sullivan during an EVA, STS-41-G, the first space mission to carry two women astronauts (Sullivan and Sally Ride). 

Marsha Ivins, Kenneth Cockerell and Mark Polansky, photographed by colleagues during an EVA while Space Shuttle Atlantis was docked to the ISS during STS-98.

Marsha Ivins, Kenneth Cockerell and Mark Polansky, photographed by colleagues during an EVA while Space Shuttle Atlantis was docked to the ISS during STS-98.