2001: a Hubble odyssey

四月 14, 1995

THES reporters unravel the tangle of pension options facing staff three years after the reorganisation of higher education and examine the barriers to a unified system.

Ancient tape-recorders that record the Hubble space telescope's signals in space are playing up and could break down at any time, the director of the Space Telescope Science Institute said in Wales last week. The 20-year-old technology is used on Nasa satellites that relay Hubble information to Earth. Similar technology has failed catastrophically after five years of use on other satellites - as long a period as the recorders have been operating for Hubble.

Despite this prospect, Europe is discussing extending its involvement with the Hubble space telescope beyond 2001, which would mean sending up a new instrument to the telescope on a servicing mission planned for 2002. The European Space Agency met Nasa last week to discuss extending its memorandum of understanding on Hubble. The Hubble space telescope was launched in 1990 with a planned lifetime of 15 years. Servicing missions are planned for 1997, 1999 and 2002.

Robert Williams, director of the STSI, told the National Astronomy Meeting held by the Royal Astronomical Society in Cardiff last week that, although the telescope was functioning well, he was "very worried" about the tape recorders, which contain moving parts and, he said, are less advanced than the technology that can be bought in a telephone answering machine at a local electronics shop. So far, one is slipping, causing small amounts of data to be lost, and the other does not keep its correct speed.

If the recorders were to fail, he said, scientists would be forced to take the data immediately it was produced, rather than being able to store it: "We would lose a lot of data," he said.

One solution would be to send up new equipment on the next servicing mission in 1997, but this would cost an extra $10 million (Pounds 6.25 million) on top of the $450 million (Pounds 281 million) cost of the mission, he said.

But the telescope proper is functioning beautifully, he said, with viewing time oversubscribed by five to one. "We in the United States would really like to have your involvement, we benefit from your science," he told the meeting.

Europe provided the solar panels that power the Hubble telescope, and one of Hubble's four main instruments, the Faint Object Camera. Fifteen ESA staff work at the institute, at Johns Hopkins University in Baltimore, and ESA provides a coordinating facility in Munich. In return it is promised a minimum of 15 per cent of viewing time - higher if European proposals merit it.

Dr Williams said that while the telescope is functioning so well, he intends to rush through a programme that will study the evolution of galaxies. "We understand the evolution of stars but galaxies are not forming at the moment," he said. "For some reason almost all of them formed long ago. We do not understand how they came into being. It is one of the great scientific problems this century."

Hubble images have turned out to be so good that it can detect events throughout 80 per cent of the time that the universe has existed. "We have arrived recently at the point where we can see galaxies forming," he said. "I never thought we would live to see the day where we could see far enough out to see this. We did not really appreciate how good the images of distant galaxies would be."

However, to study evolution of galaxies properly, the telescope's range of vision will have to be extended to the infra-red region, which was not planned when it was built. Galaxies emit most of their light in the visible region but the expansion of the universe has the effect of shifting the signal into the infra-red region.

In 1997, therefore, it is planned to send up NICMOS (near infra-red camera multiple object spectrograph), which will extend Hubble's coverage.



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