Hundreds of thousands people had logged on to the Internet to witness the landing and receive data firsthand on their home computers. But instead of receiving graphic pictures, weather data, and, for the first time, actual sounds of mars, they were treated instead to blank screens.
NASA said the problem could be as simple as a mispointed antenna or as serious as a catastrophic failure during the descent that was intended to complete the 11-month mission to reach Mars' south pole.
One possibility is that the probe activated its safe mode immediately after landing, in which case it would delay sending its first signal. Another scenario could be that the probe did not correctly predict where to point its antenna. As it descended through the atmosphere, the lander had to keep track of every twist and turn to keep its bearing.
Last night, mission controllers were sending up commands directing it to transmit as it sweeps the sky.
The glitch in the latest Mars mission is acutely embarrassing for NASA. Only 10 weeks ago, the lander's sibling spacecraft, the pounds 80m Mars Climate Orbiter, burned up in the planet's atmosphere because of a failure to convert navigation data into metric units.
The Polar Lander was designed to slice through Mars' thin atmosphere at precisely the correct angle, separate from its heat shield, deploy a parachute and fire a dozen thrusters before setting down - all without radio contact with Earth. Thousands of lines of computer code were to have mapped out every final move, with the probe slowing from 15,400mph to 5 mph just before touchdown.
Scientists had hoped to learn about Mars' complex climate by studying layers of dust and possibly ice during the next 90 days and instruments were to measure vapour in the atmosphere.
"Entry, descent and landing are very complex, and a lot of things have to go correctly," a NASA spokesman said. "That's just part of the risk associated with the mission."
Engineers still have several opportunities over the weekend as the lander adjusts its antenna 157 million miles away.
Meanwhile, two tiny microprobes that rode along with the lander were due to slam into the planet at 400mph as the main spacecraft descends, their fall unbroken by parachutes or thrusters.
If the mission succeeds, the Polar Lander and the microprobes would join Mars Pathfinder and the two Viking spacecraft as the only craft to have explored the surface of the `Red Planet'. In 1993, the Mars Observer, a pounds 600m NASA spacecraft, disappeared just before going into orbit around the `Red Planet'. It is believed to have exploded as its fuel lines were being pressurised.
LOG ON TO CYBERSPACE
t Jet Propulsion Lab (JPL) main Mars site: www.marslander.jpl.nasa. gov or www.mars.jpl.nasa. gov/msp98
t JPL's home page: www. jpl.nasa.gov
t JPL's Mars Educational site: www.marsnt3.jpl. nasa.gov/education/index.
t The UCLA Volatiles and Climate Surveyor: www.mars.ucla.edu
t The Planetary Society: www.planetary.org
t The Mars Society: www.marssociety.orgReuse content