The Sky at Night Phần 2 pps

1 Eye on the Universe 3

the telescope really excelled. The images of clusters, nebulae and galaxies are the

best ever taken. Also, pictures sent back of the remotest galaxies within range showed

that we were looking back at the very early history of the universe.

In every way, the Hubble Space Telescope has been an astounding success – and

remember, it has cost less then a nuclear submarine! Originally, it was planned to

operate for 15 years, and this it has now done, but all the time it is sending back

new data, and to lose it would be a scientific disaster. Moreover, no replacement can

be sent up before 2012 at the earliest, and probably not for some years after that.

The planned James Webb Space Telescope will be larger than Hubble, but will

concentrate upon infra-red research. Unlike Hubble it will not orbit the Earth. It

will be sent to one of the “Langrangian points”, a position near the Earth’s orbit

which is stable. It will be well away from any terrestrial interference, but it will be

a million miles away from us, and no servicing missions will be possible so that the

designers must do their best to get everything right first time!

Whatever happens, Hubble will continue to work for several years yet. It was at

first planned to bring it back to Earth without damaging it. When this was deemed

to be too difficult, there was a proposal to boost it into a higher orbit above all the

resting part of the atmosphere, and simply leave it there until we developed techniques

to make it possible to fish down. Now alas, there is a serious proposal to de-orbit it

and allow it to burn away as it comes down. There are dangers here too, because it

is a relatively massive structure, and it could well fall into an inhabited area. I know

that all astronomers – and indeed all non astronomers, too – would be sad to see us

destroying one of our very best achievements. Let us hope this does not happen.

The threat seemed imminent in 2005, when our programme was transmitted, but

receded when NASA changed its mind and authorised a further servicing mission.

So HST is safe for the moment; it cannot remain aloft forever, but it is a vital part

of scientific history, and it will never be forgotten.