Camera Observations Expected To Resume Saturday
NASA is cautiously optimistic the
Hubble Space Telescope is finally on its way back to almost-normal
operations, following a three-week hiatus.
The telescope's Science Instrument Control and Data Handling
system was reactivated on Thursday. This should enable Wide Field
Planetary Camera-2 science observations to resume on Saturday,
October 25. The Advanced Camera for Surveys Solar Blind Channel
science observations should resume sometime next week.
The Independent Review Team, chaired by Wallops Flight Facility
director John Campbell, and the Hubble Program reported their
assessment to Goddard management Wednesday... and they had a lot to
review, following a domino-like series of failures to the aging
telescope.
The team primarily studied the sudden halt of the NASA Standard
Spacecraft Computer-1 -- which occurred on October 16, over two
weeks
after the orbiting observatory suffered a failure of its
command and data-handling system -- along with the
apparent failure during turn-on of the planetary camera’s low
voltage power supply earlier that same day.
The team concluded that a hardware problem did not occur on the
camera. The anomaly was because of a limit-checking algorithm that
triggered before the data that it was checking was valid. A
commanding change on the instrument will eliminate this condition
and both teams expect a nominal low voltage power supply turn-on
when it is commanded on next week.
Regarding the sudden halt of the spacecraft computer, the team
concluded that three separate events occurring with
near-simultaneity were responses to a single triggering event. The
triggering event was most likely caused by a self-clearing
short-circuit, or a transient open-circuit, in the Science
Instrument Control and Data Handling system. One or more such
events would not be highly improbable in hardware inactive since
1990, and will not harm the telescope, although it could cause
another interruption of science operations.
Based on these latest findings, Goddard Center management and
NASA HQ concurred with the Hubble team’s plan to power on the
spacecraft computer and then monitor it for about 24-hours to
assess its operations. Another status report will be issued
following resumption of planetary camera science on Saturday.
Meanwhile, back on Earth plans are underway to add more
repairs to the roster for the STS-125 mission to service
Hubble. That mission, originally scheduled to liftoff earlier this
month, is now planned for February 2009.