'Mars a graveyard for shuttles'

The first of two NASA rovers is safely on way to Mars, but the most risky part of its journey lies ahead, as some humiliating failures have shown all too well, say experts.

The first of two NASA rovers is safely on its way to Mars, but the most risky part of its seven-month journey to the Red Planet lies ahead, as some humiliating failures have shown all too well.

'Mars tends to eat spacecraft. It's a graveyard,' Edward Weiler, NASA associate administrator for space science, said on Wednesday.

Embarrassed by the back-to-back losses of two Mars spacecraft in 1999, NASA has added more backup systems to its new rovers, along with more testing and reviews.

'We have done all we can to correct the errors on the two missions that failed,' Weiler said.

NASA launched the robotic explorer Spirit on Tuesday from Cape Canaveral, Florida.

The spacecraft still must cross 500 million kilometres of space and safely land on the planet - an endeavour that ended in failure for six of the nine Mars landing missions mounted by the United States and the Russians over the past three decades.

The cruise to Mars is expected to be relatively straightforward. The real risks come upon arrival.

The spacecraft carrying the first new rover is expected to enter the Martian atmosphere on January 4 at 12,000 mph (19,310 kph), using atmospheric friction, a parachute, rockets and an airbag to slow down and cushion its landing.

'This is among the most unforgiving endeavors you can take up, because you can do 10,000 things right and just one wrong and that's enough. So I'm never going to say there's no risk,' rover flight systems manager Richard Cook said recently.

Software errors doomed the last lander NASA sent to Mars, 1999's Polar Lander; it smashed into the planet. And a mix-up between English and metric units caused the destruction in 1999 of another Mars spacecraft, the Climate Orbiter. It burned up in the Martian atmosphere.

After those two failures, the space agency took a closer look at itself, and found mismanagement, unrealistic expectations and anemic funding underlying the failures. Then-NASA Administrator Dan Goldin, whose mantra was 'faster, better, cheaper,' took responsibility, saying he had 'stretched the system too thin' and may have made some failure inevitable.

This time, the space agency extensively tested both rovers before launch to catch any problems that could jeopardize the missions; several were found, slightly delaying launch. And during the trip to Mars, an independent team will review all navigation-related data. The two rovers, worth a combined $800 million, will drill into the Martian rocks and soil for indirect evidence that the planet was once hospitable to life. Each rover is targeted to land on opposite sides of the planet, in locations that may once have been rich in water.

On the Net: http://mars.jpl.nasa.gov/mer