STS-52

STS -52 (English Space Transportation System) is name for a flight of the U.S. Space Shuttle Columbia ( OV -102) as part of the Space Shuttle program of NASA. The launch took place in Florida on 22 October 1992 from the Kennedy Space Center.

The main task of the ten -day mission was exposing the American- Italian geodesy satellites LAGEOS 2 and the operation of the U.S. Microgravity Payload -1, one mounted in the cargo bay of space shuttle discovery platform. After the end of the classified successfully flight landed Columbia on 1 November 1992, with its six -man crew back at the Kennedy Space Center. It was the 51th Space Shuttle mission and the 13th flight of the Space Shuttle Columbia.

• 2.1 Start
• 2.2 Exposure of LAGEOS 2
• 2.3 Operation of USMP -1

• 5.1 Literature
• 5.2 Notes and references

Team

The crew of mission STS -52 was given on August 23, 1992 announced by NASA:

• James Wetherbee ( second space flight), Commander
• Michael Baker ( second space flight), Pilot
• Charles Veach ( second space flight), Mission Specialist
• William Shepherd ( third space flight), Mission Specialist
• Tamara Jernigan ( second space flight ), Mission Specialist
• Steven MacLean ( first space flight), Payload Specialist (CSA / Canada)

Backup crew

• Bjarni Tryggvason for MacLean

Mission highlights

The main task of the mission STS -52 was the exposure of Geodesy Satellite LAGEOS 2, by the Italian Space Agency ASI had made ​​in collaboration with NASA. The comparatively small satellite served as a complement to LAGEOS 1, which was launched in 1977 with a Delta rocket. Both LAGEOS satellites were used for the accurate measurement of the earth's surface and thus helped, among others, to monitor faults in earthquake zones.

In the payload bay of the space shuttle was located beyond a research platform for material science experiments. The payload with the name United States Microgravity Payload -1 ( USMP -1 ) completed its first flight during the mission and consisted of three ground- controlled experiments, which were mounted on a novel carrier platform.

Steven MacLean, the third Canadian astronauts aboard the Space Shuttle, worked during the flight on its own test program, the Canadian experiment -2 ( CANEX -2). They included a total of ten experiments and based on a series of research mission STS -41 -G from the year 1984. Moreover, the crew for the operation of a number of other payloads in the middeck of the crew cabin and payload bay was responsible.

Start

The preparations for the mission STS -52 began on 10 July 1992, after Columbia had returned from their previous space flight STS -50. After the completion of the compulsory Nachinspektionen and maintenance work, the Space Shuttle on 20 September in the shuttle assembly building at the Kennedy Space Center, the Vehicle Assembly Building, connected to the external fuel tank and two solid rocket was. Then, the space shuttle was driven to the launch pad 39B where the spacecraft completed a countdown demonstration. The originally planned for mid-October launch was delayed, however, there had to be replaced on the launch pad one of the three main engines of the space shuttle. The replacement of the propellant plant became necessary after there had been indications of cracks in a refrigerant distributor nozzle.

The countdown for STS- 52 was added at the Kennedy Space Center, bringing the launch preparations entered its final phase on 19 October by 16 clock ostamerikanischer Time ( EDT). The external fuel tank was filled up on the morning of October 22 with liquid hydrogen and liquid oxygen. The crew boarded the Columbia at 9 clock EDT. The two and a half hours long launch window opened at 11:16 EDT clock ( clock 16:16 Central European Time ). Due to bad weather at an overseas emergency landing in Banjul ( Gambia) and strong side winds at the launch site, the planned start date delayed by about two hours. NASA finally decided nevertheless to a start, although the cross winds exceeded the termination criteria on the runway at the Kennedy Space Center. To clock 13:09:39 EDT ( 18:09 Central European Time Clock ) raised from the Space Shuttle from the launch pad, bringing the mission STS -52 officially began. The total launch mass was 2046 tons.

After 2:03 minutes of flight time, the two solid rocket boosters of the shuttle were separated after they had burned their fuel. The three main engines reached their burnout 8:30 minutes after the start; the external tank was severed at 8:50 minutes of flight time. An analysis after the flight arrived later to the conclusion that several parts of the foam insulation of the tanks had dissolved during ascent. The Space Shuttle was not hit by the debris, however. 37 minutes after take-off stabilized a 2:17 minutes long firing of the orbital maneuvering system ( OMS), the orbit of the Columbia. The Space Shuttle was then in an orbit whose erdfernster point ( apogee ) was located at an altitude of 302 kilometers. The erdnächste point ( perigee ) was at an altitude of 296 kilometers; the orbital inclination (inclination ) was 28.5 degrees. An orbit of the earth lasted around 90 minutes.

Exposure of LAGEOS 2

The geodetic satellite LAGEOS 2 (Laser Geodynamics Satellite ) was successfully exposed on the second flight day. Under the supervision of Mission Specialist Tamara Jernigan of the spin- stabilized satellite time left Houston at 8:56 clock ( clock 14:56 Central European Time ), the payload bay of Columbia. Subsequently, the Italian-made solid upper stage IRIS (Italian Research Interim Stage) LAGEOS 2 brought an engine ignition from the parking orbit of the space shuttle into an elliptical orbit with an altitude of 5,900 kilometers and an inclination of 52 degrees. Ignition of the satellite 's apogee led LAGEOS 2 a few hours later in its final orbit, where he began his scientific operation after a 30 day long testing program.

LAGEOS 2 is a fully passive earth satellite, which is used exclusively for the laser distance measurement ( Satellite Laser Ranging). In this case, laser beams are transmitted from the earth to the satellite and the time elapsed from transmission to return of the beam are recorded. With this method, the distance between the ground station on Earth and satellites in space with high accuracy can be determined. The method allows a precise monitoring of the movements of the earth's crust, which contributes to the observation of regional faults in seismic regions such as California or the Mediterranean in particular. In addition, can be characterized using the laser distance measurement size and shape of the earth and determine the length of a day in more detail. Also, information about changes in the Earth's axis are obtained with this technique.

LAGEOS 2 is made of two aluminum half-spheres, which are mounted around a central brass core. The spherical satellite has a diameter of 60 cm, and weighs 405 kg. This compact design is necessary to ensure maximum system stability. Inside of LAGEOS 2, there are 426 equally spaced prisms. They have a diameter of 3.8 centimeters, and have been made ​​predominantly from fused silica. The prisms reflect the light back in the direction of the origin. LAGEOS 2 is currently still in operation, and will re-enter the Earth's atmosphere until 8 million years.

After the satellite LAGEOS had 2 leave the cargo bay of Columbia, Commander James Wetherbee fired the maneuvering of the space shuttle twice to lower the orbit of the Columbia at an altitude of 287 kilometers. The low orbit wore the needs of USMP experiments invoice and increased beyond the number of landing opportunities at the end of the mission. Also on the second day of flying tested the Mission Specialist Charles Veach the robot arm of the shuttle (RMS) with a two-part procedure to check its functionality.

Operation of USMP -1

The second main payload of the mission STS -52 was the research platform USMP -1 ( United States Microgravity Payload), which was used on this flight for the first time. It included three materials science experimental arrangements, which were mounted on a novel support structure in the payload bay of Columbia. All experiments were performed essentially by the Payload Operations of the Marshall Space Flight Center remote control, which a participation of the occupation on the operation of the platform was rarely necessary. USMP -1 was thus conceived as a test run for similar remote-controlled operations on board space stations and other earth satellites.

For its first flight, the USMP payload consisted of three experiments, which served mainly to basic research in microgravity:

• The lambda point experiment (LPE) examined the behavior of helium, as it changes from a liquid to a superfluid state. Helium is in the superfluid phase, it loses all internal friction and also has an unusually high thermal conductivity. The transition from the normal helium liquid ( fluid ) to the superfluid state takes place at the so-called lambda point which is at a temperature of 2.17 Kelvin. In space, can this change be better explored, because the gravity on the earth pressure differences caused in a helium sample. When lambda point experiment, a helium - material sample was in the superfluid state in a cryostat. During a two hour run, the temperature was then raised in each case for a short time via the lambda point, whereby the thermal conductivity of the liquid was recorded during the different phases.
• The MEPHISTO experiment arose from a collaboration between NASA, the French space agency CNES and the French Atomic Energy Commission CEA. Its purpose was to investigate the behavior of metals and semiconductors, as they solidify. Characterized the influence of gravity on the surface between the solid and liquid phases should especially ( the so-called interface ) can be determined. MEPHISTO had a cylindrical shape, and containing three rod-shaped samples of tin -bismuth alloys which could be heated by means of two kilns. During the mission, the samples were melted several times over the course of several runs of the test and re-solidified. The temperature changes at the interface were constantly measured by a low voltage.
• The Space Acceleration Measurement System ( SAMS ) came only one of the experiments of USML -1 with previous shuttle missions today. The system was designed to record low accelerations during operation of the platform, which could distort the results of the experiments. During the mission, STS- 52, two SAMS units on the carrier deck of USMP -1 were installed. They both had two sensor heads to register accelerations that exceeded the allowable limits. The collected SAMS data could be transmitted during the flight to the Payload Operations, whereby the operation of USMP experiments could be adjusted if necessary.