Let’s talk a bit about failures. It’s on everyone’s mind. It’s damn tough to land on Mars.
But it appears as if a lot of the scientists and engineers are trying to keep hopes low. Here’s an example of NASA lowering expectations. “The global success rate in getting to the surface of Mars is less than 50%,” said Doug McCuistion, Mars Exploration Program chief, at a press conference yesterday.
And that’s true. Of the 11 spacecraft that got to the edge of Mars’ atmosphere, only five reached the surface and survived for more than a few seconds. But all five of those successful missions were NASA run. The failures were all either Soviet or British (let’s not speak of poor Beagle 2, pictured here in what it might have looked like after crashing).
For NASA attempts at landing on Mars, the success rate is five out of six. That’s a much more respectable 83% success rate.
But the reason why everyone is worried is because the Phoenix lander is based on designs for the one NASA Mars landing that did fail, the Mars Polar Lander, which was lost above Mars in 1999. NASA had another lander, called Mars Surveyor lander, all set to go, based on the failed Polar lander architecture. Surveyor was canceled after the polar lander failure, and the parts were put into storage.
Phoenix IS that same spacecraft, albeit one that has been combed over for glitches, and spiffed up. It was rescued from the warehouse, and will, supposedly, rise from the ashes of the earlier failed and canceled missions. Thus the name. And thus the anxiety.
Even if the Phoenix team has ironed out all the software glitches, there is still much that can go wrong. Within the seven-minute atmospheric descent alone, 26 separate pyrotechnic events – little firecrackers that serve to separate, open or release spacecraft components – have to happen in succession, said Barry Goldstein, Phoenix project manager at JPL. Even if each popper has a 99% reliability, the risk of overall failure begins to stack up if each pyrotechnic is integral to the mission. (Think of the old Christmas tree lights, wired in series. When one goes, they all go.)
Once Phoenix touches down, its resilience will improve. Components can fail without the whole mission following suit. But until then, Goldstein will be nervous. “It doesn’t matter how many times we land successfully or unsuccessfully on Mars, this is a jittery time,” says Goldstein.
For those who are counting, continue reading to see all of the Mars landing attempts, with their outcomes:
Image: Beagle 2
Mars 2, 1971, USSR. Crash landed.
Mars 3, 1971, USSR. Landed softly, but died within seconds.
Mars 6, 1974, USSR. Did not survive descent.
Mars 7, 1974, USSR. Lander separated early.
Viking 1, 1976, USA. Success.
Viking 2, 1976, USA. Success.
Mars Pathfinder, 1997, USA. Success.
Mars Polar Lander, 1999, USA. Lost contact upon descent.
Beagle 2, 2004, UK. Crash landed.
Spirit rover, 2004, USA. Success.
Opportunity rover, 2004, USA. Success.