Space shuttle managers decided yesterday to extend Challenger's mission by a day, until Tuesday, to give the astronauts more time to add to their scientific harvest now that the ship's $60 million telescope pointer and most other instruments are working.

The new landing time was set for 3:47 p.m. EDT Tuesday at Edwards Air Force Base in California.

The extension was requested by ground scientists, who have expressed delight over data being gathered on the sun, stars, galaxies and the Earth's atmosphere.

National Aeronautics and Space Administration officials made the decision after determining that Challenger had enough fuel for the extra day, plus enough for two contingency days beyond Tuesday. Forecasters said weather should be good Tuesday at Edwards.

Challenger was slightly low on liquid hydrogen and liquid oxygen, which are used to generate electricity, but the seven astronauts have been conserving in case the flight was extended, said flight director Al Pennington.

The astronauts spent much of yesterday doing scientific experiments. Their conversation was confined to technical exchanges with scientists on the ground.

Mission scientists said they would like the extra day primarily to gather data from three telescopes mounted on a $60 million Instrument Pointing System (IPS) that was inoperative from Monday's launch until Friday, when the astronauts repaired it with a new computer program worked out on the ground.

The spacemen, operating round the clock in two shifts, began an almost nonstop survey of the sun, studying flares, sunspots and other phenomena that might help scientists better understand how the sun influences our solar system, including its effect on communications and weather on Earth.