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

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.

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.

The crew of STS-95, including John Glenn (top centre), onboard Space Shuttle Discovery.  Glenn became the oldest person to go into space at the age of 77, returning to space over 36 years after his first mission, the longest gap between missions for any astronaut.

The crew of STS-95, including John Glenn (top centre), onboard Space Shuttle Discovery.  Glenn became the oldest person to go into space at the age of 77, returning to space over 36 years after his first mission, the longest gap between missions for any astronaut.

NASA astronaut Pam Melroy during training for STS-92, her first space mission.

NASA astronaut Pam Melroy during training for STS-92, her first space mission.

Crew of STS-91, the final space shuttle mission to Mir

Crew of STS-91, the final space shuttle mission to Mir

Discovery deploys her parachute as STS-85 ends with a landing on the runway at Kennedy Space Center.

Discovery deploys her parachute as STS-85 ends with a landing on the runway at Kennedy Space Center.

STS-82 was the second servicing mission to the Hubble Space Telescope

STS-82 was the second servicing mission to the Hubble Space Telescope

Mission Specialist Carl Meade drifts over Discovery’s playload bay in a test of the SAFER backpack during STS-64.

Mission Specialist Carl Meade drifts over Discovery’s playload bay in a test of the SAFER backpack during STS-64.

Toothbrush and toothpaste floating in microgravity during STS-70

Toothbrush and toothpaste floating in microgravity during STS-70

STS-53 crew

STS-53 crew