``This is a new way of landing a spacecraft on a planet,'' said Brian Muirhead, flight systems manager at NASA's Jet Propulsion Laboratory, in Pasadena, Calif. ``Frankly, we'll be very surprised if everything goes just right.''
If it does, about four hours after landing, Pathfinder will pop up an antenna and radio back the first close-up pictures of Mars since the Viking landings 21 years ago. Live television pictures are expected that evening and daily through the first week of the mission.
In advance of the landing, the Hubble Space Telescope is checking the Martian weather. According to preliminary reports, it will be unusually cold, cloudy and windy.
As its name implies, Pathfinder's purpose is to open a new era of scientific exploration that NASA hopes will lead to a human expedition to Mars early next century. The $250 million Pathfinder mission - inexpensive by NASA standards - is the first of a dozen voyages planned over the next eight years by the United States, Russia, Europe and Japan.
NASA Administrator Dan Goldin says the ultimate goal is to find out if living organisms existed - or still exist - on or under the frosty surface of Mars, the planet in our solar system most like Earth and most likely to support life.
Although the Viking missions found no signs of life in 1976, they sent back thousands of pictures revealing that Mars was once a warm and watery planet - much like Earth when life took hold here.
This visit, NASA officials do not expect to find evidence of Martian life, past or present - although they would be delighted if they did.
