Hubble Space Telescope

(HST) Archive System

NASA Langley Research Center
Hampton, Virginia

First Servicing Mission

The Hubble Space Telescope (HST) was deployed at an altitude of 331.6 nautical miles and at an inclination of 28.5 degrees on April 25, 1990. This orbit is similar to that of the Long Duration Exposure Facility (LDEF) which was returned to the Earth in January, 1990 after 5.7 years in low-Earth orbit (LEO). During HST's 3.6 years in LEO, HST was exposed to an atomic oxygen fluence estimated to be 7.59 x 10²⁰ atoms/cm² in the velocity or ram direction.

The first HST servicing mission, STS-61, lifted off Pad 39B at 4:27 AM EST on December 2, 1993. After the Shuttle Endeavour followed the observatory for several orbits, HST was captured at 316.8 nautical miles by the Endeavour crew on December 4, 1993, where the observatory was grappled and berthed in the shuttle's cargo bay. The crew, together with the controllers at JSC and GSFC, completed all eleven servicing tasks during five EVAs. During the six day servicing mission, all of the planned goals were achieved, making this Shuttle mission arguably the most successful in Shuttle history.

The primary objective of the servicing mission was to replace the High-Speed Photometer with the Corrective Optics Space Telescope Axial Replacement (COSTAR). The installation of COSTAR allowed the HST to overcome its inherent spherical aberration flaw. COSTAR routes properly focused light to three of Hubble's five instruments. The optically-corrected Wide Field Planetary Camera (WF/PC-II) was substituted for the WF/PC-I. The WF/PC-II was designed so that the light reaching each of the instrument's four cameras was corrected by relay mirrors polished to a prescription compensating for the incorrect figure produced by Hubble's primary mirror. Eight fuse modules were replaced along with two rate sensors units (2 gyroscopes in each) and two electronic control units. New solar arrays replaced the original solar arrays, of which one solar array was returned to Earth for study and the second array was jettisoned. A new coprocessor to the DF-224 was added to the HST. Also, the new Goddard High Resolution Repair Kit and two magnetometers were installed. The old magnetometer multi-layer insulation (MLI) and side plate were returned to Earth. HST was redeployed on December 10, 1993 at 321.1 nautical miles via the Shuttle Remote Manipulator System (RMS) at 5:26 AM EST.

The next HST servicing mission is expected to occur around February, 1997. It is expected that HST will have declined to an altitude of 319 nautical miles by that time. During the second servicing mission, astronauts will install two new instruments: the Space Telescope Imaging Spectrograph, and the Near-Infrared Camera and Multi-Object Spectrograph (NICMOS). The third servicing mission is scheduled for November, 1999, during which the Hubble Advanced Camera for Exploration, which will greatly enchance the HST's imaging capabilities, will be installed.

Crew Observations

The STS-61 crew made the following general observations of HST's physical condition during the servicing mission.

Meteoroid & Debris Damage of Surfaces
Some impact-pitting was observed on HST, however, the inside of the telescope was pristine. One penetration, approximately 1/4 inch in diameter, was seen on the V3 high-gain antenna.

Painted Surfaces & Particulate Contamination
The white zinc orthotitanate (ZOT) paint on the WF/PC-I radiator appeared clean with no evidence of degradation. The yellow paint on the Orbiter handrails was observed to come off as particulate matter when force was applied to the rails. The yellow paint also appeared on the crew's gloves.

Multi-Layer Insulation (MLI)
The multi-layer installation balnkets appeared to be stretched tight. During RSU changeout, a three (3) inch square of MLI was seen floating over the starboard wing.

Photo Documentation
Over 6,000 photos were taken on-orbit for use in studying the condition of the HST.

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