STS-121
 | This article needs more citations. (March 2025) |
 Fossum and Sellers on the end of Discovery's Orbiter Boom Sensor System during the mission's first EVA | |
| Names | Space Transportation System-121 |
|---|---|
| Mission type | ISS logistics |
| Operator | NASA |
| COSPAR ID | 2006-028A |
| SATCAT no. | 29251 |
| Mission duration | 12 days, 18 hours, 37 minutes, 54 seconds |
| Distance travelled | 8,500,000 kilometres (5,300,000 mi) |
| Orbits completed | 202 |
| Spacecraft properties | |
| Spacecraft | Space Shuttle Discovery |
| Launch mass | 121,092 kilograms (266,962 lb) |
| Crew | |
| Crew size | 7 up 6 down |
| Members | |
| Launching | |
| Start of mission | |
| Launch date | July 4, 2006, 18:37:55 UTC |
| Launch site | Kennedy, LC-39B |
| End of mission | |
| Landing date | July 17, 2006, 13:14:43 UTC |
| Landing site | Kennedy, SLF Runway 15 |
| Orbital parameters | |
| Reference system | Geocentric |
| Regime | Low Earth |
| Perigee altitude | 352.8 kilometres (219.2 mi) |
| Apogee altitude | 354.2 kilometres (220.1 mi) |
| Inclination | 51.6 degrees |
| Period | 91.6 minutes |
| Docking with ISS | |
| Docking port | PMA-2 (Destiny forward) |
| Docking date | 6 July 2006 14:52 UTC |
| Undocking date | 15 July 2006 10:08 UTC |
| Time docked | 8 days, 19 hours, 16 minutes |
 (L-R) Wilson, Fossum, Lindsey, Sellers, Kelly, Reiter, Nowak. | |
STS-121 was a 2006 Space Shuttle mission to the International Space Station (ISS) flown by Space Shuttle Discovery on its 32nd flight. The main purposes of the mission were to test new safety and repair techniques introduced following the Columbia disaster of February 2003 as well as to deliver supplies, equipment, and European Space Agency (ESA) astronaut Thomas Reiter to the ISS.[1] The European segment of the mission was called "Astrolab".[2]
After two weather-related delays, the shuttle successfully launched on Tuesday, July 4, 2006, at 14:37:55 EDT. It was the first and only shuttle launch on the United States' Independence Day. The mission lasted for 13 days before landing at the Kennedy Space Center on July 17, 2006, at 09:14:43 EDT.
STS-121 was also designated the ISS Assembly Mission ULF 1.1. As the mission followed on from STS-114 in carrying out the recommendations made in response to the Columbia Accident Investigation Board report, it was considered a Return to Flight test mission. Its successful launch and landing led NASA to fully resume regular Space Shuttle launches in the construction of the ISS.
Crew
[edit]| Position | Launching astronaut | Landing astronaut |
|---|---|---|
| Commander |  Steven LindseyFourth spaceflight | |
| Pilot | Mark Kelly Second spaceflight | |
| Mission Specialist 1 | Michael E. Fossum First spaceflight | |
| Mission Specialist 2 Flight Engineer |
Lisa Nowak Only spaceflight | |
| Mission Specialist 3 | Stephanie Wilson First spaceflight | |
| Mission Specialist 4 | Piers Sellers Second spaceflight | |
| Mission Specialist 5 |  Thomas Reiter, ESAExpedition 13 Second and last spaceflight ISS Flight Engineer |
None |
Crew notes
[edit]Thomas Reiter's position was previously planned to be filled by Sergey Volkov (Russia) before the launch of STS-121 was postponed until July 2006.
British-born astronaut Piers Sellers replaced Carlos Noriega who was originally scheduled to be on the STS-121 mission NASA announced on Thursday, July 15, 2004. This was due to an undisclosed, temporary medical condition.
The transfer of Reiter to the ISS returned the station to a three crew member staffing level. After the loss of Columbia and the grounding of the Shuttle fleet, only two people had been residing on the ISS.
Shuttle hardware
[edit]- External Tank: ET-119
- Solid Rocket Boosters: BI-126 & RSRM-93
- SSMEs: s/n 2045, 2051, 2056
- OMS engines: LP-01/35 RP-03/33
Crew seat assignments
[edit]| Seat[3] | Launch | Landing |  Seats 1–4 are on the flight deck. Seats 5–7 are on the mid-deck. |
|---|---|---|---|
| 1 | Lindsey | ||
| 2 | Kelly | ||
| 3 | Fossum | Wilson | |
| 4 | Nowak | ||
| 5 | Wilson | Fossum | |
| 6 | Sellers | ||
| 7 | Reiter | Unused | |
Mission background
[edit]During the STS-121 mission to the International Space Station (ISS), the crew of Space Shuttle Discovery continued to test new equipment and procedures for the inspection and repair of the thermal protection system that is designed to increase the safety of the Space Shuttles. It also delivered more supplies and cargo for future ISS expansion.
After the Columbia accident, NASA decided that two test flights would be required and that activities that were originally assigned to STS-114 would need to be divided into two missions because of the addition of post-Columbia safety tests. Before the accident, Columbia had been assigned to missions STS-118 and STS-121. The STS-118 mission, also an International Space Station flight, was at first reassigned to Discovery, but was later assigned to Space Shuttle Endeavour.
The STS-121 mission was originally to have sent Columbia to service the Hubble Space Telescope. However, that servicing mission was given another designation on the manifest before the disaster and the designation of STS-121 once again became available. Since STS-115 through STS-120 were already delegated to existing missions, NASA selected the lowest available mission designation for the second test flight. Hence, the mission following STS-114 is STS-121.
The STS-121 test flight mission was originally to be flown aboard Atlantis in September 2005, after Discovery flew STS-114, but a problem with the landing gear of Atlantis moved Discovery ahead to fly STS-121. After the return of Discovery to California following the completion of STS-114, scheduling again changed. Atlantis was moved up to fly the STS-115 mission (whose launch was planned for August 2006) and Discovery was to fly the STS-121 mission as originally planned. The launch of the STS-121 mission was delayed until July 2006 as well, due to an unresolved foam debris and the Engine Cut Off (ECO) sensor issue from STS-114.
On May 12, 2006, Discovery was moved from the Orbiter Processing Facility to the Vehicle Assembly Building, where it was mated to its External Tank and SRBs. Rollout to Pad 39B occurred on May 19, 2006, ahead of the planned launch, during the July 2006 launch window, which existed for about ten minutes each day between July 1 and 19.
Equipment delivered to the ISS
[edit] | This section needs more citations. (July 2026) |
Key items delivered, as part of over 2 tons of cargo included: Multi-Purpose Logistics Module (MPLM) Leonardo on its 4th flight, 7th MPLM overall, carrying:
- −80 °C Freezer
- This freezer is known as the Minus Eighty Degree Laboratory Freezer for ISS (MELFI). The French-built unit comprises four independent drawers which can be set to operate at different temperatures.[4] Initially, temperatures of −80, −26, and 4 °C (−112, −15, and 39 °F) will be used during in-orbit ISS operations. Both reagents and samples will be stored in the freezer. As well as storage, the freezer is designed to be used to transport samples to and from the ISS in a temperature controlled environment. The total capacity of the unit is 300 litres (79 US gal).[5]
- The European Modular Cultivation System (EMCS) for biological experiments.
- This consists of a gas tight incubator in which there are two centrifuges, each able to carry four experimental cartridges. Two "Ground controls"—exact copies of the equipment and experiments—will be run on the ground, one in Europe and one at NASA's Ames Research Center.
- New oxygen generation system
- This device is considered a test for an equipment design with potential for use on proposed future long durations to the Moon and Mars. The system will initially run below its maximum capacity, though it is designed for enabling the ISS to support a crew of six in the future. It will supplement the Russian-built Elektron system operating in the Zvezda module.
