Astrometric Observations

Astronomers measure the distance to a star by charting its location on two sightings from Earth at different times, normally 6 months apart. The Earth's orbit changes the perceived (apparent) location of the nearby star, and the parallax angle between the two locations can lead to an estimate of the star's distance. Because stars are so distant, the parallax angle is very small, requiring a precise field of view to calculate the angle. Even with the precision of the FGSs, astronomers cannot...

Image Processing Diagnosing Cancer Earlier

The CCDs used in digital mammography are not Hubble's only exciting news in the fight against breast cancer. Techniques developed for processing images from the Telescope may soon help detect breast cancer in its very early stages. The image processing techniques, used to correct the blurry images sent back to Earth from Hubble before the 1993 servicing mission, have proven effective in finding microcalcifications, whose presence in mammograms indicates breast cancer. The Space Telescope...

Data Management Subsystem

Flight Control Computer Board Subsystem

The DMS receives communications commands from the STOCC and data from the SSM systems, OTA, and science instruments. It processes, stores, and sends the information as requested. Subsystem components are DF-224 computer (will be replaced on SM3A with the Advanced Computer) Four Data Interface Units (DIU) Three engineering science data recorders The components are located in the SSM Equipment Section, except for one DIU stored in the OTA Equipment Section. The DMS receives, processes, and...

Secondary Mirror Assembly

Hubble Space Telescope Primary Mirror

The Secondary Mirror Assembly cantilevers off the front face of the main ring and supports the secondary mirror at exactly the correct position in front of the primary mirror. This position must be accurate within 1 10,000 in. whenever the Telescope is operating. The assembly consists of the mirror subassembly, a light baffle, and an outer graphite-epoxy metering truss support structure (see Fig. 5-23). The Secondary Mirror Assembly contains the mirror, mounted on three pairs of alignment...

EVA Day Mate additional OCEEK connectors for the new FGS Change out SSAT Replace ESTR with SSR Repair MLI

Aearospace Battery

On EVA Day 3, EVA astronauts Smith and Grunsfeld are scheduled to mate additional OCE-EK connectors to allow for the on-orbit alignment optimization of the replacement FGS adjustable, articulated, fold flat 3 mirror. They will replace an S-band single access transmitter (SSAT) that failed in 1998. An identical backup transmitter has functioned perfectly and HST's observing program has not been affected. The astronauts also will install an SSR in place of an E STR. Finally, they will undertake...

Pointing Control Subsystem

Etx Internal Optics

A unique PCS maintains Telescope pointing stability and aligns the spacecraft to point to and remain locked on any target. The PCS is designed for pointing to within 0.01 arcsec and holding the Telescope in that orientation with 0.007-arcsec stability for up to 24 hours while the Telescope continues to orbit the Earth at 17,500 mph. If the Telescope were in Los Angeles, it could hold a beam of light on a dime in San Francisco without the beam straying from the coin's diameter. Nominally, the...

Primary Mirror Assembly and Spherical Aberration

As the Telescope was put through its paces on orbit in 1990, scientists discovered its primary mirror had a spherical aberration. The outer Fig. 5-17 Light path for the main Telescope Fig. 5-17 Light path for the main Telescope incoming image view looking forward v1 axis into page incoming image view looking forward v1 axis into page Fig. 5-18 Instrument sensor field of view edge of the 8-foot 2.4-m primary mirror was ground too flat by a width equal to 1 50 the thickness of a sheet of paper...

Electrical Power Subsystem

Power for the Telescope and science instruments comes from the Electrical Power Subsystem EPS . The major components are two SA wings and their electronics, six batteries, six Charge Current Controllers CCC , one Power Control Unit PCU , and four Power Distribution Units PDU . All except the SAs are located in the bays around the SSM Equipment Section. During the servicing mission, the Shuttle will provide the electrical power. After deployment, the SAs again begin converting solar radiation...