STS -120 (English Space Transportation System) is the mission name for the 34th flight of the American Space Shuttle Discovery. It was the 120th space shuttle mission. The launch took place on 23 October 2007.

  • 4.1 Start
  • 4.2 Inspection and coupling
  • 4.3 Working on the ISS
  • 4.4 return


  • Pamela Melroy ( third space flight), Commander
  • George Zamka ( first space flight), Pilot
  • Scott Parazynski ( fifth space flight), Mission Specialist
  • Stephanie Wilson ( second space flight ), Mission Specialist
  • Douglas Wheelock ( first space flight), Mission Specialist
  • Paolo Nespoli ( first space flight), Mission Specialist (ESA / Italy)

ISS crew Departure

ISS Expedition 16

  • Daniel Tani ( second space flight), flight engineer

ISS Crew Return

ISS Expedition 16 15/ISS-Expedition

  • Clayton Anderson ( first space flight), flight engineer

Mission overview

Main payload of STS -120 was the Harmony connecting node, which was brought to the International Space Station. During the first spacewalk Harmony was provisionally fixed at the Unity module. After the flight, the module of the space station crew on its final location on the Destiny laboratory was moved. This was necessary because the space shuttle was docked during the mission itself on the Destiny module. In addition, the P6 solar module was moved to its position on the starboard end of the lattice structure.

The mission was one of the most complicated and counts with 15 days of the date the longest shuttle history. Of the original five field operations of a was canceled because a solar wing on the ISS was torn and had to be sewn. The exit, in which Scott Parazynski repaired the crack was risky, but could be carried out successfully.


After the end of the last mission of Discovery (STS -116 ) on 22 December 2006, the space shuttle has been moved to the Orbiter Processing Facility. There was the routine follow-up and repair the damage that was caused during the flight. The new SSPTS energy transfer system (Station -to- Shuttle Power Transfer System) was installed at the Discovery After some changes were made that had previously received the sister ferry Endeavour. With this, the orbiter applies during the coupling power from the space station and can prolong his stay. In addition, the outdated TACAN navigation system was replaced by GPS.

On May 2, the freight train had an accident, which should deliver the booster segments for this and the next mission at the Kennedy Space Center (KSC ), the collapse of a low bridge. In this case, six people were injured, one seriously. The train was on its way from the manufacturer ATK in Utah to KSC in Florida when he was derailed in the state of Alabama.

On July 18 began in the Vehicle Assembly Building ( VAB), the construction of two boosters, each consisting of four segments. The assembly was completed after four weeks.

The external tank this mission was loaded on 24 July on a barge and transported from the Michoud Assembly Facility from Louisiana to Florida. After five days, the tank reached the KSC and was taken to the VAB on July 30.

After (STS -118 ) were dissolved in early August 2007 pieces of foam from the external tank during the previous flight of the orbiter Endeavour, scheduled for August 20, mounting of the tank between the two booster was postponed. Instead, the areas of the fuel line on which flaked off the insulation were x-rayed. This fine cracks were discovered. On August 24, told Wayne Hale, the head of the shuttle program, with that you 'll be the Isolierschaumabdeckungen covering the clamps of the outboard fuel line for the liquid oxygen modify. After one and a half weeks this work was completed, so that the tank on September 5, could be connected with the solid rocket boosters.

On September 17, NASA, the transfer of the Discovery of the maintenance hangar to the VAB decided to move because a few days earlier a leak at one of the trucks had been discovered. The right main landing gear of the orbiter lost hydraulic fluid and the corresponding parts had to be replaced. Two days after announcing the repairs in the OPF were performed. The shock absorber has received four new seals after this, the majority of the chassis had to be expanded.

Due to the additional work, the transfer of the orbiter delayed in the assembly hall by four days - the discovery could be driven to the VAB until September 23. There was two days after the assembly of the Space Shuttle with the external tank and two solid rocket boosters.

The Discovery arrived at the launch pad on September 30. The five and a half kilometers long transport had to be deferred for ten hours due to bad weather. A little later loaded them technicians Harmony in the cargo bay of the Space Shuttle.

At the start of a two-day conference in preparation for the Special Air loss - at the same time graduated from the team at KSC the countdown dress rehearsal - was born on 9 October that there were safety concerns about the airworthiness of three RCC panels (Reinforced Carbon Carbon ) on the wing leading edges. In these, the upper protective layer had been peeled off, resulting in a burn-through during re-entry could have led and would have caused a similar accident as with STS -107.

During the Flight Readiness Reviews, the flight readiness acceptance, on 16 October, the provisional start date - October 23 - confirmed. Shuttle program manager Wayne Hale said then that it was not necessary, the three question RCC panels ( one on the left, two on the right wing ) to replace. In the worst case could be solved during reentry only the coating.

Mission History


A day after the crew from Houston arrived in Florida on October 19, the countdown began for the mission. The weather forecast for the day to start first went from a probability of 60 percent for good weather. An expected low cloud cover and occasional rain areas could drop to 40 percent of the forecast for a launch on October 23.

At the suggestion of director Mike Leinbach start the countdown this mission had been changed somewhat in advance. Should order an ice formation on the external tank to counteract the time is filled with the cryogenic fuel tank on the ramp can be shortened. For this purpose, the holding time at T -3 hours, which began immediately after refueling, three was reduced to two and a half hours in the countdown. In addition, half an hour was started later with the refueling process. Thus, a lesson was saved.

On October 23, had during fueling of the external tank of the sky over the KSC cleared up and the probability for a start had risen to 80 percent. The emergency landing Moron and Istrès reported good weather.

After the crew had gone into the Discovery, ice formation was detected on the external tank, which would have made or may be a rejected take-offs necessary. However, NASA decided to start because the ice had receded. The discovery raised the first launch attempt on 23 October 2007 at 15:38:19 UTC.

Inspection and coupling

As usual since STS -114 on the second flight day (October 24 ) were examined the most sensitive parts of the heat shield with the OBSS - Inspektionsarm ( Orbiter Boom Sensor System) for damage. Successively, the wings and the Orbiternase sampled. Initial analyzes revealed no damage.

On October 25, the third Mission Day, occurred at 12:40 UTC, the coupling with the International Space Station. One hour before the discovery led compulsory rotated by 360 ° on the pitch axis. This allowed the ISS crew to make around 300 high resolution photos from the heat shield. As at 14:39 UTC, the bulkheads were opened, greeted each other with ISS Commander Peggy Whitson and shuttle commander Pamela Melroy first time two women who ran a space mission at the same time. On the same day sparked Mission Specialist Daniel Tani from ISS Flight Engineer Clayton Anderson, by the Soyuz seats have been replaced. The new SSPTS power transmission system has been activated, with the discovery of the related current ISS.

Work on the ISS

On the fourth flight day (October 26 ) began at 10:02 UTC, the first spacewalk of the mission. This Parazynski and Wheelock first built from an S- band antenna, which was stowed in the cargo bay of Discovery and brought back to Earth. Then they brought the Harmony module to an anchor point for the ISS robotic arm, so that Harmony could lift out of the loading bay. While Harmony was fixed at 15:38 UTC on its preliminary position on Unity, the two astronauts went to the P6 lattice structure to separate some connections to the Z1 element. The EVA ended at 16:16 UTC.

On October 27, the fifth day of flying, Harmony was activated for the first time. In addition, a more detailed inspection of the heat shield was rejected by the flight line. The evaluation of the photos that had made the ISS crew during the approach of the Discovery, showed no evidence of damage.

The second exit of Parazynski and Tani began on October 28 at 9:32 UTC (sixth day of flying ). First P6 was released from the Z1 element. Subsequently, the duo parted. Parazynski prepared Harmony before any further work, while Tani himself went to the S3/S4-Modul to check the Solar Alpha Rotary Joint there ( SARJ ), the Ausrichtmechanik the solar array. With this strong frictions and vibrations were observed in the last few weeks. This Tani discovered metal shavings, of which he took a sample for examination on the ground. After P6 was "parked" in free space. The EVA lasted a total of 6 hours and 33 minutes.

On October 29, the seventh mission day, P6 was passed as in a relay race from arm to arm. From the park position the solar panel was initially passed by the ISS arm to the robot arm of the Discovery, so that the Stationsarm could drive to the external port end of the lattice structure. There P6 was again taken over by the Canadarm2 and placed in its final position. In addition, the S1- radiators were deployed.

Throughout the day has been equipped by the remaining crew Harmony. In addition, the flight line decided to extend the mission by one day to inspect the problems on the SARJ during the fourth EVA detail.

During the third spacewalk of the mission, which began on October 30 at 8:45 UTC, Parazynski and Wheelock P6 installed permanently at the port end of the ISS - lattice structure. Controlled by Stephanie Wilson and Daniel Tani, the robot arm of the station P6 had maneuvered directly to P5, so that Wheelock and Parazynski could combine the two elements together. Then Parazynski examined the SARJ - port rotary joint. NASA engineers wanted to obtain comparative values ​​to get the problem of other SARJ on the track. The astronaut reported that it look flawless and he could not detect any impurities. The EVA ended after seven hours and eight minutes.

After completion of the exit set mission specialist Wheelock a small hole in the top layer of his glove firmly. On the right thumb he found a two by three millimeters large crack. The flight line instructed Wheelock to use a spare glove for the next outdoor use.

After getting the solar panels of P6 were extended again. While there were no problems with the 2B- wing, the crew discovered the 4B wing damage. The extension was then stopped at a length of 80 percent and various photographs made ​​from the wing at different angles. It was also informed that the P6- collector gave 95 percent of its normal power output.

On October 31 ( the ninth day of flying ) met the team preparations for the fourth exit. Wheelock and Parazynski were taught how to familiarize with the new procedures, because the tasks were changed. The demonstration of repair techniques on heat protection tiles were canceled. Instead, only the problem with the SARJ - starboard joint should be tackled the next day.

At the beginning of the tenth mission day (November 1 ) informed the flight line, the space driver that the exit has been postponed to November 3. This will give the engineers plenty of time to work out the repair techniques. The exact evaluation of the recordings that had made the occupation of the defective panel 4B, revealed two cracks, the larger was almost a meter long. The concern of NASA was not an energy reduction, but the loss of stability.

Interrupted by a short interview with the former U.S. president George Bush, who attended with his wife, the Johnson Space Center, the astronauts prepared on 1 and 2 November, the necessary tools for the upcoming exit. Of 20 meters of wire, and strips of aluminum screw stabilizers were made in order to relieve the damaged portion of the blade and to prevent further tearing.

According to Michael Suffredini, head of the ISS program, probably one of the three lead ropes have hooked in a loop, causing the crack. With the withdrawal should be attempted to untie the rope and release the tension from the structure. Should the repair attempt fails, you could do another the following day. As a precaution we have decided to waive the originally planned fifth outdoor use and to let this carry on the ISS crew after the separation of Discovery.

The astronauts Parazynski and Wheelock left on 3 November (12th flight day ) at 10:03 UTC, the Quest airlock to begin the repair. Previously, the robot arm of the ISS had been connected to the OBSS - Inspektionsarm to reach the inaccessible location can. Parazynski fastened by means of a foot rest at the end of the OBSS. With five self-made wire snares he clinched the solar wings to close the two cracks and to prevent this increase. He also solved the tangled tension wires. To avoid that touches the Parazynski under high voltage panel, he used with electrical tape taped tools - a spacer, which resembled a hockey stick, and a pair of pliers. Wheelock assisted from the base of the P6- carrier, by which operated the robot arm Stephanie Wilson, gave instructions and was careful that Parazynski kept enough distance to the wing. Upon successful repair, the 4B- panel was completely unfolded and the two " craftsman " returned to the airlock. The withdrawal ended after 7 hours and 19 minutes.

On November 4, the last of the space shuttle goods were brought to the station and passed the crew of STS- 120. At 20:03 UTC, closed the hatches between Discovery and ISS.


Scheduled put on 5 November (14th flight day ) at 10:32 UTC, the Discovery after 10 days and 22 hours from the space station from. After a half hour circumnavigation took off the Orbiter from the ISS. The rest of the day once again examined the team with the OBSS the heat shield of the orbiter for damage.

November 6th was dedicated to testing the time needed for landing systems and the stowage of equipment. To Anderson to facilitate the re-entry phase, a special reclining seat for him was erected in the middle deck. In addition, Melroy and Zamka trained with the PILOT Laptop (Pilot Inflight Landing Operations Trainer) landing.

After the wake-up call on 7 November ( 16 Flugtag ) the crew began preparations for landing. The first option was for the KSC at 18:02 UTC. Before the flight line of the team was 16:49 UTC green light, the cargo bay doors were two and a half hours earlier closed and programmed the main computer. At 16:59 UTC began with the brake ignition, the landing maneuver. An hour later, at 18:01:18 UTC, put the Discovery safely on runway 33 of the Shuttle Landing Facility.

The return flight departed from the earlier Shuttle landings: the first time since the Columbia crash in 2003 was the route over large parts of the U.S.. Reason was the wish of Commander Melroy to be allowed to land in daylight. Originally, the Discovery was supposed to return at night. Here, the approach over the South Pacific, Central America and the Gulf of Mexico had taken place. By airplane extension passed on 16 Mission Day only two landing opportunities in Florida ( 18:02 UTC and 19:36 UTC ), each, the northwestern United States led across the North Pacific to Florida.

An hour after landing, the crew left the Discovery and took the obligatory tour of the ferry. Clay Anderson was due to its muscle weakness after about five months in space not participate in it. Paolo Nespoli also was not present at the " walkaround " because he was still being investigated medically.

After the backup works, the Discovery was towed to the Orbiter Processing Facility, where it is prepared for its next mission (STS- 124).