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Hubble Facts

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									Hubble Facts
National Aeronautics and
Space Administration
Goddard Space Flight Center
Greenbelt, Maryland 20771

                                                                                      FS-1999-06-015-GSFC


               Hubble Space Telescope Servicing Mission 3A
                             SOLID STATE RECORDER

    To communicate with its operators on the            stores 12 gigabits of data, while the tape recorder
ground, the Hubble Space Telescope uses a group         it replaces can hold only 1.2 gigabits. This ten
of NASA satellites called the Tracking and Data         times greater storage has proven essential in
Relay Satellite System (TDRSS). By way of               allowing Hubble’s new, high-tech scientific instru-
TDRSS, Hubble sends the data from its science           ments to be fully productive.
instruments and spacecraft systems to the Space
Telescope Operations Control Center at NASA’s           Flexibility and Multi-tasking
Goddard Space Flight Center in Greenbelt, Md.               State-of-the-art electronics provide the Solid
When the TDRSS link is not available, Hubble            State Recorder with more capability and flexibili-
stores its science and engineering data in onboard                                           ty than a reel-
recorders for playback at a later time. Hubble                                               t o - r e e l
records all of its science data to prevent any possi-                                        r e c o r d e r.
ble loss of unique information.                                                              This digital
    Prior to the Second Servicing Mission, Hubble                                            recorder is
used three 1970s-style, reel-to-reel tape recorders.                                         designed to
In February 1997, Astronauts replaced one of                                                 perform the
these mechanical recorders with a digital Solid                                              tasks of two
State Recorder. During Servicing Mission 3A                    Solid State Recorder          separate
Astronauts will remove a second mechanical tape                                              mechanical
recorder and install a second Solid State Recorder.     recorders. Unlike a mechanical recorder, the Solid
                                                        State Recorder can record and play back data
More Storage, No Moving Parts                           simultaneously.
    Unlike the reel-to-reel recorder it replaces, the       Another advantage is its ability to record two
Solid State Recorder has no reels, no tape, and no      data streams at the same time, allowing both the
moving parts to wear out and limit lifetime. Data       science and engineering data streams to be cap-
is digitally stored in computer-like memory chips       tured on a single recorder. Unlike the reel-to-reel
until Hubble’s operators command its playback.          recorders, data can be played back without having
Although the Solid State Recorder is about the          to rewind the tape, and information can be instant-
same size and shape as the reel-to-reel recorder, it    ly accessed.
can hold approximately ten times as much data. It
Resilient and Long-lasting                              and the on-orbit performance of the unit already
    Reel-to-reel tape recorders can fall victim to      aboard Hubble, NASA expects this new recorder
single-point failures, such as a break in the tape or   to last the life of the Telescope. The Solid State
a mechanical defect. The Solid State Recorder           Recorder was developed at Goddard.
does not have mechanically moving parts, and its
memory modules have a very low failure rate. This
digital recorder is designed to grow old gracefully,                SSR CHARACTERISTICS
compensating for situations such as a bad chip or
a bad module.                                                Size         12 x 9 x 7 inches
    The recorder automatically detects, corrects
and reports random errors in memory. If the failure          Weight       25 pounds
is too difficult to correct, the affected area can be
isolated and skipped over, leaving the rest of mem-
ory fully functional. The old, mechanical recorders
also had to be sealed in a pressurized enclosure to         FOR ADDITIONAL INFORMATION
protect the tape and the delicately lubricated mov-                       CONTACT
ing parts from the hazards of a space vacuum. This
special packaging is not necessary for the Solid           Nancy Neal
State Recorder.                                            Goddard Space Flight Center
    NASA successfully tested this Solid State              Office of Public Affairs
Recorder during a 10-day Space Shuttle Mission             (301) 286-0039
(STS-95) in October 1998. Based on these results

								
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