This is n. p. r.'s morning edition i'm bob edwards the space shuttle discovery is scheduled for launch tonight on a ten day mission to repair the hubble space telescope parts of the telescope have been failing gradually over the past few years astronomers have not been able to use it at all for the past months n. p. r.'s nasa officials hope to fix it and for spacewalks in the coming weeks and p. r.'s richard harris reports

The hubble space telescope has been one of nasa's most successful scientific instruments producing dazzling pictures of the cosmos and answering fundamental questions about our universe the telescope also has had its share of problems first and foremost its main mirror was built in the wrong shape

Two previous missions to hobble outfitted the telescope with corrective lenses and repaired and upgraded other components the telescope is now showing more signs of age it has been in space for ten years some critical components had failed so earlier this year nasa decided to add an unscheduled mission to the space telescope with a crew of experienced astronauts you can get ready in a hurry this is not a regime servicing mission it's not an emergency mission and somewhere in between

Nasa scientist ed weiler says the biggest problem is the telescope's gyroscopes a spin like miniature bicycle wheels to hold the telescope steady the telescope has sex but four have failed leaving the telescope safe but unable to hold still enough to do any astronomy hubble can still point its solar panels at the sun to keep its batteries charged and the space shuttle could still rendezvous with the telescope in its unsteady conditions and grab it with the shuttle's robot arm

But project scientist david the ground says

Nasa is planning to make it a bit easier for the crew a few hours before the hour

Let's approach the end of the telescope and the shuttle we're going to put hubbell into a different state until quite a deep state of statement and the verge of doing that is that there are some credible fashion mechanical gyros unworkable federal reserve to be used just what is in this keep the sake of conditions it's called overstatement and those gyros will serve to stabilize couple very nicely and that will make it easier for the crew to grapple over with

We know so far once they grabbed the space telescope they will encourage of the shuttle

And astronauts will proceed with a series of spacewalks to replace faulty equipment astronaut steve smith says his first assignment working with john rumsfeld is to replace all six gyros a more humble pie considered a very difficult task and that the clearances are very small and both john and i will be doing this i have not only will actually be inside of the hubble space telescope workers are small

Course is always a concern when you open up the doors on the backhoe that you'll contaminate something we thought that through them we think of all the contamination controls in place

Astronauts will also replace the piano sized device called the fine guidance sensor they will upgrade the telescope's computer by adding a computer based on the chip that earthlings considered hopelessly outdated and intel four eighty six processor this particular computer has the advantage however of being resistant to radiation which is important in the harsh environment of space in fact that's basin varmus has taken its toll on the telescope

Radiation micro meteorites and corrosive oxygen atoms have been eating away at the hubble's protective coating to later in the nation european space agency astronaut claude nicollier a will install some new protective blanket on the outside of the telescope

It's going to be pretty much like putting more than a hundred one shown that he is a former professional thank you tom rhodes

So i going to have to the attention

That's the top of the telescope and we were hundred of them are willing and eager audience you can put them on on on the surface that have focused at the table when it was now this mission has been delayed several times as a result of mechanical problems with the space shuttle discovery and nasa officials have decided that if they can get off the ground by saturday they'll put it on hold against of a part in orbit come midnight december thirty first hubble scientist david frum says the concern then is the y. two k. computer glitch

Nasa's invested a tremendous amount to make sure it's like you can't compatible but we have lingering researcher about international power grid for example that there should be power outages are the things that sort of your local one of every utilities on this lingering that conservatives and that we want to make potato chips is whatsoever with our our very precious resources here

Look on says they will be prepared to try again in early january if need be richard harris n. p. r. news washington