The unmanned space probe, silent since Saturday, continued to fail to respond to electronic messages from engineers at the Jet Propulsion Laboratory in Pasadena, southern California. Contemplating the possibility that the craft is lost, Arden Albee, the project's chief scientist, said simply: 'It's terrible, terrible, terrible.'
The craft, which is on a dollars 1bn mission to study Martian terrain and climatic conditions, was supposed to radio Earth on Tuesday before firing its thrusters and beginning to orbit Mars. But it remained silent - so scientists have no idea what happened. It could have started circling Mars, or have shot past the planet into the Universe beyond. It could also have been destroyed.
Nasa had been pinning final hopes on the possibility that the craft would reset itself and resume transmitting data. But an automatic reset cycle that was due to turn the transmitter back on last night, failed.
If the craft has missed Mars, Nasa may be able to instruct it to go into a wider, less scientifically valuable, orbit around the planet - but this depends on re-establishing contact. If it is already in orbit, Nasa believes it will only be facing a transmitter problem, which it hopes eventually to solve.
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