STS-121 facts for kids

Quick facts for kids
STS-121

Fossum and Sellers on the end of Discovery's Orbiter Boom Sensor System during the mission's first EVA
Mission type	ISS logistics
Operator	NASA
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	Steven W. Lindsey Mark E. Kelly Michael E. Fossum Lisa M. Nowak Stephanie D. Wilson Piers J. Sellers
Launching	Thomas A. Reiter
Start of mission
Launch date	4 July 2006, 18:37:55 (2006-07-04UTC18:37:55Z) UTC
Launch site	Kennedy LC-39B
End of mission
Landing date	17 July 2006, 13:14:43 (2006-07-17UTC13:14:44Z) UTC
Landing site	Kennedy SLF Runway 15
Orbital parameters
Reference system	Geocentric
Regime	Low Earth
Perigee	352.8 kilometres (219.2 mi)
Apogee	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. Space Shuttle program ← STS-114 STS-115 →

STS-121 was a special NASA Space Shuttle mission in 2006. The mission used the Space Shuttle Discovery (also known as Space Shuttle Discovery). Its main goals were to test new safety methods and repair tools. These were very important after the Columbia disaster in 2003. The mission also delivered supplies and equipment to the International Space Station (ISS). A German astronaut, Thomas Reiter from the European Space Agency (ESA), also joined the ISS crew during this flight.

After two delays because of bad weather, Discovery launched successfully on July 4, 2006. This was at 2:37:55 PM EDT. It was the only time a Space Shuttle launched on Independence Day. The mission lasted for 13 days. It landed back at the Kennedy Space Center on July 17, 2006, at 9:14:43 AM EDT.

STS-121 was also called ISS Assembly Mission ULF 1.1. It was seen as a "Return to Flight" test mission. This was because it followed safety recommendations from the Columbia accident report. Its success helped NASA restart regular Space Shuttle flights to build the ISS.

Meet the STS-121 Crew

Position	Launching astronaut	Landing astronaut
Commander	Steven W. Lindsey Fourth spaceflight
Pilot	Mark E. Kelly Second spaceflight
Mission Specialist 1	Michael E. Fossum First spaceflight
Mission Specialist 2	Lisa M. Nowak Only spaceflight
Mission Specialist 3	Stephanie D. Wilson First spaceflight
Mission Specialist 4	Piers J. Sellers Second spaceflight
Mission Specialist 5	Thomas A. Reiter, ESA Expedition 13 Second and last spaceflight ISS Flight Engineer	None

Mission Goals and Preparations

The STS-121 mission aimed to continue testing new tools and ways to check and fix the heat shield. This shield protects the shuttle from extreme heat when it re-enters Earth's atmosphere. Making it safer was a top priority after the Columbia accident. The mission also brought more supplies and cargo to the International Space Station for its future growth.

NASA decided that two test flights were needed after the Columbia accident. This was because many safety tests were added. The STS-121 mission was originally planned for Columbia to fix the Hubble Space Telescope. But after the disaster, the mission name became available again. Discovery was chosen for this important second test flight.

The launch of STS-121 was delayed until July 2006. This was due to issues with foam debris and engine sensors from the previous mission, STS-114. On May 12, 2006, Discovery was moved to the Vehicle Assembly Building. Here, it was attached to its External Tank and Solid Rocket Boosters. It then moved to Launch Pad 39B on May 19, 2006.

Equipment Delivered to the ISS

The mission delivered over 2 tons of cargo to the ISS. This included important items for scientific experiments and station operations.

Key Items for the Space Station

• Minus Eighty Degree Laboratory Freezer for ISS (MELFI): This special freezer can hold samples at very cold temperatures, like -80°C. It was built in France and has four separate drawers. Scientists use it to store and transport samples for experiments.
• European Modular Cultivation System (EMCS): This system is for biological experiments. It's like a small greenhouse with two centrifuges. Each centrifuge can hold four experiment cartridges.
• New Oxygen Generation System: This device was a test for future long-duration missions to the Moon and Mars. It helps create oxygen for the astronauts. It was designed to support a crew of six people in the future.
• New Cycling Machine (CEVIS): This Danish-built exercise bike helps astronauts stay fit in space. It has a special system to reduce vibrations.
• Replacement Heat Exchanger: This part helps control the air temperature inside the ISS.

All these items were installed in the Destiny Laboratory Module. The shuttle also carried an Integrated Cargo Carrier with other parts for the station's mobile transporter system.

Mission Timeline: A Day-by-Day Journey

The Space Shuttle Discovery was docked to the ISS for most of the mission. During this time, the Leonardo Multi Purpose Logistics Module (MPLM) was connected to the station. This allowed the crew to move equipment, supplies, and experiments between the shuttle and the ISS.

Three spacewalks were planned for the mission. The third spacewalk depended on having enough supplies. The crew also had "Get Ahead" tasks if they finished their main work early. They even had a day off to explore the ISS, take photos, and talk to the press.

Launch Attempts and Liftoff

The first launch attempt on July 1, 2006, was delayed due to thunderstorms. NASA also took special steps to keep turkey vultures away from the launch area. This was because of a close call during the STS-114 mission.

The second launch attempt on July 2 was also scrubbed due to bad weather. Finally, on July 4, 2006, at 2:37:55 PM EDT, Space Shuttle Discovery launched successfully. It was the first time a US Space Shuttle launched on Independence Day.

During launch, NASA used many cameras to watch for falling foam from the external tank. No large pieces were seen falling off. About 23 minutes into the flight, astronaut Michael Fossum saw some debris floating near the shuttle. It was later found to be strips of ice that had formed on an engine nozzle.

Inspecting the Shuttle in Space

On its way to the ISS, the crew used a 50-foot-long Orbiter Boom Sensor System (OBSS). This boom had lasers and a camera to check the shuttle's underside for damage. They paid close attention to the wings.

Inspections found a small piece of material called a "gap filler" sticking out from the left wing. This was not a major concern. They also found bird droppings on the right wing, which were still there after landing, though charred!

Docking with the Space Station

Before docking, the shuttle did a special flip maneuver. This allowed the ISS crew to take photos of Discovery's heat shield. The docking with the ISS went smoothly. Thomas Reiter officially became part of the International Space Station Expedition 13 crew after docking.

The Leonardo module was then connected to the station's Unity module. The crew also did more detailed checks of the shuttle's heat shield while it was docked. Sensors on the wing picked up six small impacts, but none were strong enough to cause damage.

Spacewalks: Working Outside the Station

• Spacewalk 1: Michael Fossum and Piers Sellers did a 7.5-hour spacewalk. They tested using the OBSS (the long boom) as a work platform for potential shuttle repairs. They found it to be very stable. Fossum had a small issue with his safety tether, but it was quickly fixed. They also worked on a cable cutter on the ISS's mobile transporter.
• Spacewalk 2: Sellers and Fossum performed another spacewalk, lasting 6 hours and 47 minutes. They installed a spare pump module and replaced a cable reel for the station's Mobile Transporter rail car. They also continued moving cargo between the shuttle, the ISS, and the Leonardo module.
• Spacewalk 3: This final spacewalk by Sellers and Fossum showed how to repair the shuttle's heat shield. They worked on damaged samples of heat shield material brought into space. They used a special material called NOAX (Non-Oxide Adhesive Experimental). Sellers accidentally lost a spatula during this spacewalk, but it floated away and was not a danger.

Life in Space and Landing Prep

The crew had a day off after their busy spacewalks and cargo transfers. Michael Fossum even received a call from the Governor of Texas, Rick Perry.

The Leonardo module, now filled with returned experiments and trash, was moved back into Discovery's cargo bay. Astronauts Stephanie Wilson and Lisa Nowak used the Canadarm2 robotic arm for this. They also used the arm and boom to inspect the shuttle's wings for any damage from space debris.

Before landing, there was a small leak concern in one of the shuttle's auxiliary power units (APUs). These units provide power for landing. After tests, mission controllers were confident it was safe to use for re-entry.

Returning Home

Space Shuttle Discovery undocked from the ISS after a 9-day stay. This happened over the Pacific Ocean. Pilot Mark Kelly flew Discovery to a point above the station before moving away.

The crew did final inspections of the shuttle's right wing and nose cap for any damage. They also checked all systems needed for landing.

Discovery was cleared for landing after a final check of its heat shield. It landed successfully on schedule at 9:14:43 AM EDT at Kennedy Space Center's Shuttle Landing Facility. One small issue was that the right air data probe briefly failed to deploy, but it started working on its own.

After landing, the crew and NASA officials said that Discovery's windows would be replaced. This was so engineers could study small imperfections that appeared during the mission. They also announced that the Space Shuttle Program was "back in business."

Wake-up Calls: Songs from Home

A fun tradition for NASA spaceflights is playing a special song to wake up the crew each day. These songs are often chosen by their families and have a special meaning.

Images for kids

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  Discovery arrives at the launch pad, for STS-121.

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  Discovery is moved from the Orbiter Processing Facility (OPF) to the Vehicle Assembly Building (VAB) for STS-121.

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  Launch of STS-121 on 4 July 2006

• 

  Integrated Cargo Carrier (ICC) for STS-121

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  Lightweight Multi-Purpose Experiment Support Structure Carrier (LMC) with TPS Repair Box

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  On launch day, the STS-121 crew walks to the traditional AstroVan en route to the launch pad.

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  Piers Sellers during the third spacewalk of STS-121.

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  Discovery landing at Kennedy Space Center.

See also

In Spanish: STS-121 para niños