November 17, 1999. Copyright, 1999, Graphic News. All rights reserved

HUBBLE HIBERNATES
By Elisabeth Ribbans

LONDON, November 17, Graphic News:  IF YOUÕVE ever lost your holiday snaps, youÕll still only have some idea of how the astronomers who depend on the pictures produced by the Hubble Space Telescope feel.

The Hubble shut down in mid-November after the fourth of its six gyroscopes - its steadying devices - failed. The observatory needs at least three to function, so must remain dormant in Òzero-gyro safe modeÓ until astronauts aboard the space shuttle Discovery arrive on a servicing mission scheduled for take-off on December 6.
The HST, created and operated jointly by Nasa and the European Space Agency (ESA), was launched by the Discovery in April 1990.

Designed to probe the outer universe, the telescope is positioned 380 miles (610km) above the Earth, well clear of our murky atmosphere. It circles the planet at 18,000mph (28,800kmph), completing one orbit in just 97 minutes.

The images it has returned have revolutionized astronomy. It has brought evidence of massive black holes and brown dwarfs (mysterious objects between the size of a planet and a star), spied previously unknown galaxies, witnessed the birth of stars and helped scientists calculate the age of the universe.

The gyroscopes are essential to its task. The Space Telescope Science Institute in Maryland, which conducts HubbleÕs scientific operations, says the precision required for the gyroscopes to lock onto distant stars, planets and galaxies is Òthe same as pointing and holding a laser on a dime 400 miles awayÓ.

The U.S.$2bn telescope has been serviced twice before: in December 1993, when a major fault with its vision was corrected by the installation of the COSTAR system; and again in February 1997. DecemberÕs 10-day mission had already been forwarded from next year in a bid to pre-empt gyroscope failure. Hopes of going up even earlier were thwarted by technical hitches with the shuttle last month. The launch date remains dependent on weather conditions.

ÒTo the individual astronomer, three weeks of pictures is a lot to lose from their research. I know some are very upset,Ó says Lars Christensen, a spokesman for ESA. ÒBut compared to nearly 10 years of successful observation it is very small. We are fortunate it happened so close to the service mission.Ó The Hubble is expected to continue working beyond the original 15-year plan and should return to Earth aboard the space shuttle in 2010. To date, estimates for the total cost of the project range between $3.5 and $5bn.

Sources: NASA; ESA; STSI; UKHST; Penguin Dictionary of Astronomy
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