Hubble Space Telescope (HST)

The Hubble Space Telescope is the visible/ultraviolet/near-infrared element of the Great Observatories astronomical program. The spacecraft provides an order of magnitude better resolution than is capable from ground-based telescopes. The objectives of the HST are to: (1) investigate the composition, physical characteristics, and dynamics of celestial bodies; (2) examine the formation, structure, and evolution of stars and galaxies; (3) study the history and evolution of the universe; and (4) provide a long-term space-based research facility for optical astronomy. During inital on-orbit checkout of the Hubble's systems, a flaw in the telescope's main reflective mirror was found that prevented perfect focus of the incoming light. This flaw was caused by the incorrect adjustment of a testing device used in building the mirror. Fortunately, however, Hubble was designed for regular on-orbit maintenance by Shuttle missions. The first servicing mission, STS-61 in December 1993, fully corrected the problem by installing a corrective optics package and upgraded instruments (as well as replacing other satellite components). A second servicing mission, scheduled for March 1997, will install two new instruments in the observatory. Additional servicing missions are planned for 1999, 2002 and 2005. The program includes significant participation by ESA, which provided one of the science instruments, the solar arrays, and some operational support to the program. Responsibility for conducting and coordinating the science operations of the Hubble Space Telescope rests with the Space Telescope Science Institute (STScI) at Johns Hopkins University, who operates it for NASA as a general observer facility available to astronomers from all countries.

Spacecraft
3-Axis stabilized, zero momentum biased control system using reaction wheels with a pointing accuracy of 0.007 arc-sec. Two double-roll-out solar arrays (2.3 m x 12 m) generate 5000 W. Six 60 Ahr batteries. Hydrazine propulsion system. S-band telecom system using deployed articulated HGAs provides uplink at 1 kbps and downlink (via TDRSS) at 256-512 kbps.

Payload
Optics: The telescope is an f/24 Ritchey-Chretien Cassegrainian system with a 2.4 m diameter primary mirror and a 0.3 m Zerodur secondary. The effective focal length is 57.6m. The Corrective Optics Space Telescope Axial Replacement (COSTAR) package is a corrective optics package designed to optically correct the effects of the primary mirror's aberration on the Faint Object Camera (FOC), Faint Object Spectrograph (FOS), and the Goddard High Resolution Spectrograph (GHRS). COSTAR displaced the High Speed Photometer during the first servicing mission to HST. Instruments: The Wide Field Planetary Camera (JPL) consists of four cameras that are used for general astronomical observations from far-UV to near-IR. The Faint Object Camera (ESA) uses cumulative exposures to study faint objects. The Faint Object Spectrograph (FOS) is used to analyze the properties of celestial objects such as chemical composition and abundances, temperature, radial velocity, rotational velocity, and magnetic fields. The FOS is sensitive from 1150 Angstroms (UV) through 8000 Angstroms (near-IR). The Goddard High Resolution Spectrometer (GHRS) separates incoming light into its spectral components so that the composition, temperature, motion, and other chemical and physical properties of objects can be analyzed. The HRS is sensitive between 1050 and 3200 Angstroms.

Country of Origin	United States
Customer/User	NASA, MSFC
Manufacturer(s)	Lockheed
Size	13.3 m long, 4.3 m diameter
Orbit	590 km circular, 28.5 deg inclination
Design Life	15 years (with on-orbit servicing)
Related Sites	Jennifer Green's Hubble Page

Launch Facts

Name	Int'l Desig.	Date	Site	Vehicle	Orbit	Mass(kg)
Notes
Hubble	1990-037B	4/24/90	ESMC	STS 31	LEO	10863
Hubble Space Telescope; deployed from STS-31 4/25/90