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STS-114 was the "Return to Flight" Space Shuttle mission which launched Space Shuttle Discovery at 10:39 EDT (14:39 UTC), July 26, 2005. The launch, 907 days after the loss of Columbia, was approved despite unresolved fuel sensor anomalies in the external tank; those anomalies had prevented the shuttle from launching on July 13, its originally scheduled date.

The mission was completed on August 9, 2005. Due to the poor weather at Kennedy Space Center, Florida, the shuttle landed at Edwards Air Force Base, California, a secondary landing site.

The problem that resulted in the destruction of Columbia — debris separating from the external tank during ascent — unexpectedly recurred during the launch of Discovery. As a result, NASA decided on July 27 to postpone future shuttle flights pending additional modifications to the flight hardware.

Crew

Mission parameters

  • Mass:
    • Orbiter Liftoff: 121,483 kg
    • Orbiter Landing: 102,913 kg
  • Perigee: -
  • Apogee: 350.8 km
  • Inclination: 51.6°
  • Velocity: 27,661 km/h
  • Period: 91.6 min

    Mission highlights

    STS-114 marked the return to flight of the Space Shuttle after the Columbia disaster and was the second Shuttle flight with a female commander (Eileen Collins, who also commanded the STS-93 mission). The STS-114 mission was initially to be flown aboard the orbiter Atlantis, but NASA replaced it with Discovery after improperly installed gears were found in Atlantis' braking system. Seventeen years prior, Discovery had flown NASA's previous Return to Flight mission, STS-26.

    The STS-114 mission delivered supplies to the International Space Station. However, the major focus of the mission was testing and evaluating new Space Shuttle flight safety techniques, which included new inspection and repair techniques. The crewmembers used the new Orbital Boom Sensor System (OBSS) — a set of instruments on a 50-foot (15 m) extension attached to the Remote Manipulator System. The OBSS instrument package consists of visual imaging equipment and a Laser Dynamic Range Imager (LDRI) to detect problems with the shuttle's Thermal Protection System (TPS). The crew scanned the leading edges of the wings, the nose cap, and the crew compartment for damage, as well as other potential problem areas engineers wished to inspect based on video taken during lift-off.

    STS-114 was classified as Logistics Flight 1. Besides delivering supplies, the Shuttle replaced one of the ISS's Control Moment Gyroscopes. STS-114 also carried the Raffaello Multi-Purpose Logistics Module, built by the Italian Space Agency, and the External Stowage Platform-2. It was the last flight of Raffaello.

    The crew conducted three spacewalks while at the station. The first demonstrated repair techniques on the Shuttle's Thermal Protection System. During the second, the spacewalkers replaced the failed gyroscope. On the third, they installed the External Stowage Platform and repaired the shuttle, the first time repairs had been carried out during a spacewalk on the exterior of a spacecraft in flight. On August 1, it was announced protruding gap fillers on the front underside of the shuttle would be inspected and dealt with during the third spacewalk of the mission. The space walk was conducted on the morning of August 3. Robinson easily removed the two fillers with his fingers. Later on the same day, NASA officials said that they were looking closely at a thermal blanket located next to the commander's window on the port side of the orbiter. Published reports on August 4 said wind tunnel testing demonstrated that the orbiter is safe to re-enter with the billowed blanket. On July 30, NASA announced that STS-114 would be extended for one day, so that Discovery's crew could help the ISS crew maintain the station while the shuttle fleet is grounded. The extra day was also used to move more items from the shuttle to the ISS, as uncertainty mounted during the mission as to when a shuttle will next visit the station. The orbiter's arrival also gave the nearly 200-ton space station a free altitude boost of about 4,000 feet (1,220 meters). The station loses about 100 feet (30 meters) of altitude a day. *

    The shuttle hatch was closed the night before it undocked from the ISS. After undocking, the shuttle flew around the station to take photos.

    Atmospheric reentry and landing was originally planned for August 8, 2005, at Cape Canaveral, but unsuitable weather postponed the landing until the next day, then moved it to Edwards Air Force Base in California, where Discovery touched down at 8:11 AM EDT (5:11 AM PDT, 1211 UTC).

    Mission timeline

    This timeline is a summary. For a more detailed timeline, see NASA Timeline of Significant Mission Events.

    July 13, 2005

    • 11:55 EDT - The countdown clock was restarted after a programmed 3 hour hold.
    • 12:01 EDT - To loud applause and cheers, the crew entered the traditional AstroVan to make their way to the pad.
    • 12:30 EDT - The crew arrived at Pad 39B and proceeded into the White Room for boarding.
    • 13:32 EDT - Problem with LH2 fuel level sensor reported. Launch Director orders launch scrubbed.
    • 13:34 EDT - Crew egress began.
    • 13:59 EDT - Crew egress completed.

    July 14, 2005

    • 14:00 EDT - Technical meeting of Mission Management Team to discuss troubleshooting efforts following the draining of the External Tank (ET) the previous night.
    • 14:45 EDT - Press conference, earliest possible liftoff moved to Sunday, July 17. During this press conference it was confirmed that the preparations of Atlantis for the next scheduled flight STS-121 are not being delayed while troubleshooting the sensor problem on Discovery. This may impact the contingency planning for the mission.

    July 26, 2005

    • 08:08 EDT: Crew boarding complete.
    • 09:00 EDT: Shuttle hatch closed.
    • 09:24 EDT: T -20 minutes and holding.
    • 09:34 EDT: T -20 minutes and counting.
    • 09:45 EDT: T-9 minutes and holding.
    • 10:27 EDT: Launch Control reports go for launch
    • 10:30 EDT: T -9 minutes and counting.
    • 10:35 EDT: T -4 minutes, APU activation complete.
    • 10:39 EDT: Liftoff, shuttle has cleared the tower
    • 10:47 EDT: T +8 minutes, main engine shutdown and fuel tank separation as planned.

    July 28, 2005

    July 30, 2005

    • 05:46 EDT: T +03:19:07 Noguchi and Robinson begin first spacewalk
    • 12:36 EDT: T +04:02:57 Spacewalk completed successfully (duration 6 h 50 min)

    August 1, 2005

    • 04:44 EDT: T +05:18:05 Noguchi and Robinson begin second spacewalk to replace CMG
    • 11:14 EDT: T +06:00:35 Spacewalk completed successfully (duration 6 h 30 min)

    August 3, 2005

    • 04:48 EDT: T +07:18:09 Noguchi and Robinson begin third spacewalk. Robinson to remove two protruding gap fillers between thermal insulation tiles. Noguchi installs amateur radio satellite PCSAT2 along with an experiment to test solar cells.
    • 10:49 EDT: T +08:00:10 Spacewalk completed successfully (duration 6 h 1 min)

    August 6, 2005

    • 01:14 EDT: T+10:14:35 Orbiter crew bids farewell to ISS crew. Hatches between orbiter and ISS closed
    • 03:24 EDT: T+10:16:45 Orbiter undocks from ISS

    August 8, 2005

    • 03:20 EDT: T+12:16:41 Mission Control waves off the first of two landing opportunities for Space Shuttle Discovery due to low clouds over Kennedy Space Center
    • 05:04 EDT: T+12:18:25 Mission Control waves off the second landing attempt, delaying the landing for another day. Landing is now tentatively scheduled for 05:07 EDT August 9 at Kennedy Space Center. In the event of inclement weather in Florida, NASA will land Discovery at Edwards Air Force Base in California, or, as a last resort, White Sands, New Mexico.

    August 9, 2005

    • 03:12 EDT: T+13:16:33 Mission Control waves off the first landing opportunity for Discovery due to bad weather.
    • 05:03 EDT: T+13:18:24 Mission Control waves off the second landing opportunity due to thunderstorms within the 30 nautical-mile "safety zone" around KSC. Shuttle Discovery will now land at Edwards Air Force Base in California. The previous landing at Edwards Air Force Base was STS-111 on June 19, 2002. The last previous landing at Edwards was STS-48 on September 18, 1991.
    • 06:43 EDT: T+13:20:04 Capcom (Ken Ham), tells Discovery that "it's time to come home".
    • 07:06 EDT: T+13:20:27 Discovery begins its 2-minute, 42-second retrograde deorbit burn over the Western Indian Ocean to the north of Madagascar.
    • 07:09 EDT: T+13:20:30 Deorbit burn completed as planned, slowing the shuttle by 186 mi/h (300 km/h).
    • 07:28 EDT: T+13:20:49 APU are activated to power the shuttle's control surfaces
    • 07:40 EDT: T+13:21:01 Discovery begins to feel the effects of the Earth's atmosphere.
    • 08:08 EDT: T+13:21:29 Commander Eileen Collins takes control of Discovery for final approach to Runway 22.
    • 08:11 EDT: T+13:21:32 Discovery touches down at Edwards Air Force Base. NASA commentator: "and Discovery is home."
    • 08:12 EDT: T+13:21:33 Eileen Collins reports "Wheel stop."
    • 10:13 EDT: Crew leaves shuttle.

    Wake-up calls

    As has become traditional for NASA spaceflights since the days of Apollo the crew of STS-114 were awoken daily by the Capcom with the following musical tracks.

    In-flight repair

    On the third EVA of the mission, two areas on the underside of the shuttle where photographic surveying identified protruding gap fillers were dealt with. According to NASA, the gap fillers, which each serve different purposes, are not required for reentry. One filler prevents "chattering" of tiles during ascent, which would occur due to the sonic booms from the noses of the solid rocket boosters and the external fuel tank. The other, in a different location where there is a wider gap between tiles, simply functions to reduce the gap size between tiles, which in turn reduces heat transfer to the shuttle. Even without this filler NASA did not expect the increased heat to cause a problem during reentry (it is present to avoid a level of heating which would only be problematic if experienced many times over a vehicle's design life). Since the gap fillers are not necessary for re-entry, it was acceptable to simply pull them out. An overview of the situation, including procedures for dealing with the protrusions were sent electronically to the crew and printed aboard the shuttle. The crew were also able to watch uploaded videos of NASA personnel on the ground demonstrating the repair techniques. Both the videos and 12 page procedure document * were also made available publicly via NASA's website.

    During the third EVA both the fillers were successfully removed with less than a pound of force without the need to use any tools. Stephen K. Robinson gave a running commentary of his work: "I'm grasping it and I'm pulling it and it's coming out very easily" ... "It looks like this big patient is cured".

    If it were not possible to pull the fillers out then the protruding sections could have been simply cut off. The gap fillers are made of a cloth impregnated with ceramic - they are stiff and can be easily cut with a tool similar to a hacksaw blade. Protruding gap fillers are a problem because they disrupt the normally laminar air flow under the orbiter during reentry, which causes turbulence at lower speeds. A turbulent air flow results in a mixing of hot and cold air which can have a major effect on the shuttle temperature.

    The decision to make the repair balanced the risks of the EVA with the risks of leaving the protruding gap fillers as they were. It is thought that gap filler protrusions of a similar magnitude were present on previous missions, but they were not observed in-orbit. Consideration was also given to the risks of elements of the procedure which would involve the ISS arm being used to carry Stephen K. Robinson below the shuttle, possibly the use of a sharp tool which has potential to damage the EVA suit or shuttle tiles. The possibility of making things worse by attempting a repair was given serious consideration. Cameras on the shuttle arm and on Robinson's helmet were used to monitor the activities under the shuttle.

    Protruding gap fillers had been identified as an issue on previous flights, notably STS-28. A post-flight analysis * identified that gap filler was the likely cause of the high temperatures observed during this re-entry. Protruding gap fillers were also seen on STS-73.

    A further in-flight repair was considered to remove or clip a damaged thermal blanket located beneath the commander's window on the port side of the orbiter. Wind tunnel testing by NASA determined that the thermal blanket was safe for re-entry, and plans for a fourth spacewalk were cancelled.

    Contingency planning

    Since the loss of Columbia in STS-107, it had been suggested that on future shuttle missions there would be a planned rescue capability involving having a second shuttle ready to fly at short notice. Even prior to the sensor problem causing the delay in the launch, a rescue option (called STS-300 by NASA) had been planned, which involved the crew of STS-114 remaining docked at the International Space Station until Atlantis could be launched with a four-person crew to retrieve the astronauts. Discovery would then be ditched by remote control over the Pacific Ocean, with Atlantis bringing back both its own crew, as well as that of Discovery.

    A further option for rescue would be to use Russian Soyuz spacecraft. Nikolay Sevastyanov, director of the Russian Space Corporation Energia, was reported by Pravda as saying: "If necessary, we will be able to bring home nine astronauts on board three Soyuz spacecraft in January and February of the next year". *

    Launch sequence anomalies

    Around 2.5 seconds after lift-off, a large bird struck near the top of the external fuel tank, and appeared in subsequent video frames to slide down the tank. NASA did not expect this to hurt the mission because it did not hit the orbiter, and because the vehicle was traveling relatively slowly at the time.

    A small fragment of thermal tile, estimated to be around 1.5 inches (38 mm) in size, was ejected from an edge tile of the front landing gear door at some point before SRB separation. A small white area appeared on the tile as the piece detached, and the loose shard could be seen in a single frame of the video. It is unknown what object (if any) struck the tile to cause the damage. The damaged tile was inspected further when the images from the umbilical camera were downloaded on day three. Engineers requested that this area be inspected by the OBSS, and flight managers scheduled the operation for July 29. This represented the only known possible damage to Discovery that could have posed a risk during re-entry.

    Some seconds after SRB separation, a large piece of debris separated from the Protuberance Air Load (PAL) ramp, which is part of the external tank (see animation, above right). The debris was thought to have measured 24 to 33 inches (610 to 838 mm) long, 10 to 14 inches (250 to 356 mm) wide, and a few inches thick – and to weigh about half as much as the piece of foam blamed for the loss of Columbia. Fortunately, it did not strike any part of the Discovery orbiter. Images of the external tank taken after separation from the orbiter show multiple areas where foam insulation was missing.

    Around 20 seconds later, a smaller piece of foam separated from the ET and apparently struck the orbiter's right wing. Based on the mass of the foam, and the velocity at which it would have struck the wing, NASA estimated it only exerted one-tenth the energy required to cause potential damage. Laser scanning and imaging of the wing by the OBSS did not reveal any damage.

    On July 27, NASA announced that it was postponing all Shuttle flights until the foam loss problem can be resolved.

    On August 5, USA Today reported that* NASA was looking into extensive handling as a possible explanation for the loss of foam on the external tank. NASA Administrator Michael Griffin stated that the earliest the next shuttle could launch is 22 September, but that's only "if next week, the guys have a eureka moment on the foam and spot why this big chunk came off." Later in August, it became clear that a September launch date would not be possible, and that the earliest date for the next launch would be in March 2006. With the destruction suffered by Lockheed's Michoud Assembly Facility and NASA's Stennis Space Center in Mississippi due to Hurricane Katrina and the subsequent flooding, the launch of the next shuttle mission (STS-121) was further delayed. That mission was ultimately launched on July 4, 2006.

    Gallery

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    See also

    Media

    External links and sources

    Space Shuttle missions | 2005

    STS-114 | STS-114 | STS-114 | STS-114 | STS-114 | STS-114 | STS-114 | STS-114 | STS-114

 

This article is licensed under the GNU Free Documentation License. It uses material from the "STS-114".

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