Two out of three missions to the red planet have failed. One reason there have been so many losses is that there have been so many attempts. "Mars is a favorite target," says Dr. Firouz Naderi, manager of the Mars Program Office at the Jet Propulsion Laboratory. "We -- the United States and former USSR -- have been going to Mars for 40 years. The first time we flew by a planet, it was Mars. The first time we orbited a planet, it was Mars. The first time we landed on a planet it was Mars, and the first time we roved around the surface of a planet, it was Mars. We go there often." Another reason is that getting to Mars is hard.To get there, Spirit and Opportunity, the two Mars Exploration Rovers launched this past June and July, will have to fly through about 483 million kilometers (300 million miles) of deep space and target a very precise spot to land. Adjustments to their flight paths can be made along the way, but a small trajectory error can result in a big detour and or even missing the planet completely.

The space environment isn't friendly. Hazards range from what engineers call "single event upsets," as when a stray particle of energy passes through a chip in the spacecraft's computer causing a glitch and possibly corrupting data, to massive solar flares, such as the ones that occurred this fall, that can damage or even destroy spacecraft electronics.

View: Full Article | Source: Nasa.gov