Discovery closes in on Hubble, chase will end Tuesday

Monday, December 20th 1999, 12:00 am

By: News On 6

CAPE CANAVERAL, Fla. (AP) -- Space shuttle Discovery and its crew of seven closed in on the Hubble Space Telescope on Monday to make urgently needed repairs to NASA's premier, $3 billion observatory.

The 370-mile-high chase will end Tuesday evening, when the astronauts seize the telescope with the shuttle robot arm and tuck
it into the cargo bay for three days of spacewalking work.

The Hubble has been out of service since Nov. 13.

As of Monday evening, just over a day into the shuttle flight, Discovery had closed the gap to 1,750 miles and was gaining 380 miles on the telescope with each passing orbit.

Shuttle commander Curtis Brown Jr. said he and the crew were looking forward to beginning the repair work on Hubble, after
waiting patiently through a record nine launch delays.

"There's kind of a joke that you always want to have a shuttle mission ahead of you, so you can train and always have something to
look forward to, but in our case, the vehicle was ready to go, the weather was ready to go, we were definitely ready to go, and obviously Hubble is up needing servicing, so we're up here," Brown said from orbit Monday.

It was a relatively quiet day for the astronauts, all but one of them a seasoned space flier. They tested Discovery's 50-foot arm in
preparation for the rendezvous and checked the spacesuits and tools they will use while working on the Hubble. They have about 300
tools at their disposal.

Astronauts last visited the Hubble in February 1997. Since then, four of the Hubble's six gyroscopes have failed because of corroded
wires, leaving the telescope useless until new units can be installed. The gyroscopes are needed to keep the telescope steady.

Replacing all six gyroscopes is the No. 1 priority for Discovery's spacewalkers.

The four spacewalkers also will outfit the Hubble with a new computer, data recorder, radio transmitter, fine guidance sensor,
battery-voltage regulators and thermal shields. Altogether, the new gear cost $69 million.

NASA and astronomers everywhere are anxious to get the 9 1/2-year-old Hubble working as soon as possible. The space agency
spends $25 million to operate the telescope every month, whether it is scanning the universe or not.

Already, the Hubble has missed some 150 astronomical observations. If all goes well, the telescope should be back in action by the second week of January.

After five months without a shuttle flight because of extensive wiring damage, Mission Control was glad to be busy. Discovery's
eight-day mission began Sunday night after an unprecedented nine delays because of equipment trouble and bad weather.

"We're back in business with a beautiful launch and an incredibly smooth Flight Day 1," Mission Control said in a congratulatory note to the crew. "Everyone's prelaunch work paid off."

The shuttle is due back next Monday. NASA wants the shuttle back on Earth before New Year's because it does not want to risk Y2K
computer trouble.