SPACE CENTER, Houston (AP) _ A robot probe was flying right on target to Venus and Atlantis' astronauts landed here after a successful four-day space shuttle mission that put U.S. planetary exploration back on track.

At Edwards Air Force Base, Calif., initial inspections of the shuttle showed little damage to the thermal tiles, the National Aeronautics and Space Administration said.

''The vehicle looks as clean as any one that I've ever seen,'' said Navy Rear Adm. Richard Truly, NASA's acting associate administrator for space flight.

Commander David Walker, pilot Ronald Grabe, and mission specialists Mary Cleave, Mark Lee and Norman Thagard were greeted at Ellington Field late Monday by 200 relatives, friends, co-workers and even a few of the family dogs.

''It's really nice to have the mission finished and we couldn't have done it without you,'' said Ms. Cleave, who helped deploy the Magellan probe.

She said the astronauts had a great time and it was good to be back knowing that there's a spacecraft en route to Venus and ''we were all a part of it.''

After returning to work today, the crew planned to view photographs taken during their 1.68-million-mile journey, Johnson Space Center officials said.

On Wednesday, the astronauts will begin briefing officials.

The 97-ton Atlantis glided to a smooth landing as scheduled at 3:43 p.m. EDT Monday afternoon.

Twelve minutes before touchdown, the crew was ordered to land on a concrete runway rather than a hard-packed clay runway because crosswinds on the runway were too high.

''Obviously this mission was an outstanding success,'' NASA science chief Lennard Fisk told reporters at Edwards Air Force Base.

''Magellan is on its way to Venus. The deployment was very successful. The trajectory is about as accurate as you can get. The spacecraft is working without any difficulties whatsoever.''

Truly praised the performances of the crew, the shuttle and the Magellan.

''With all these things coming together, it's really hard not to have a big grin on your face and be proud of what we're doing,'' Truly said.

About 27,500 spectators, the smallest crowd ever to attend a shuttle landing, withstood the 90-degree heat to watch. The smallest previous crowd was 35,000, in 1985. An estimated 460,000 were here for Discovery's landing March 18.

Thursday's deployment of Magellan was the mission's primary goal.

The $550-million Magellan mission is the first U.S. planetary probe launched in 11 years and the first ever from a shuttle. In October, another Atlantis crew is to start the Galileo on its way to Jupiter.

Early today, Magellan was more than 676,000 miles from Earth and was zipping along at a rate of nearly 6,000 mph. It will travel 806 million miles and loop 1 1/2 times around the sun before reaching Venus in August 1990.

Once in orbit above the cloud-shrouded planet, the probe will use its high resolution radar to map up to 90 percent of the Venusian surface.

The radar images to be collected by Magellan are expected to show features as small as a football field and be 10 times clearer than pictures obtained by earlier spacecraft. The pictures should provide an avalanche of data that could help scientists discover how Venus evolved so differently from Earth.

The weight of the probe and its rocket booster - 45,000 pounds - restricted the number of experiments the shuttle could carry.

The crew did work on an experiment involving crystallizing a metal sample in a furnace and photographed lightning and pollution on Earth.

The only glitch reported occurred Sunday when one of the shuttle's four main computers failed and the crew replaced it with the on-board spare.

The problem posed no threat to the flight, but ground controllers decided to take no chances and had the spare installed. NASA said the shuttle could land with only one computer.