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NASA To Launch Dual Mars Probes
GoBamaRollTide points to this MSNBC article, writing: "
OK, so NASA wants to launch two identical probes, with different targets, about a week apart. Theoretically, this will allow a mission to continue, even if one has a "Major Malfunction." So, what do you think? Good Idea, or just crashing probes twice as fast? Two craters for the price of one!" Besides some interesting information about the benefits of a 2003 launch date, the article says: "Each spacecraft would be launched on a Delta 2 rocket for a 7½-month cruise to Mars. Upon entering the Martian atmosphere, a parachute would deploy to slow the spacecraft down, and then airbags would inflate to cushion the 50-mph landing."
For all of its technical wisdom, and fascination with space exploration and science fiction, I am very surprised how clueless most Slashdot folks (including the poster) are on this one.
First, NASA has sent redundant probes before. Many times. Consider : Viking 1 and 2 to Mars, Pioneer 10 and 11 and Voyager 1 and 2 to the outer solar system... the list goes on and on.
Second, the cost of the second mission is far less than the first. The bulk of the expense of a space mission is sunk into the research and development of the probe, and subsequent mission support over its lifetime... not in the material manufacture or in the launch (though these are substantial in and of themselves).
In sum, two missions can be done for less than twice the cost of one mission, and you gain enormously by redundancy. Random catastrophes are unlikely to strike both probes simultaneously, and system difficulties with the first mission can be detected and solved in the intervening time before the second probe arrives.
This makes "faster, cheaper, better" missions more feasible. These missions are being launched on mere dimes where dollars were spent before. The problem is that they have suffered from reliability issues. Two missions for the price of 1.5 missions gives one _both_ reliability and low cost.
Science, like Nature, must also be tamed, with a view turned towards its preservation.
I should probably chime in here.. We had a guy give a speech here at the U (University of Arizona, Tucson..big place for space research and all) back in 98 once all the data from the lander and the rover had been collected. This guy's job was to design and implement the cameras on both the lander (not the rover.) and clued us into the sorts of stuff they were doing with it.
Part of his speech included materials he'd brought with him from other portions of the design team. One of those things were some films of actual test-drops of the airbag system done out in the desert. Its certainly not as elegant as a parachute+retro burn landing, but it works, and works more often in tests. Simply cushioning the hell out of the unit and letting it bounce to a stop is statistically the best method to use. He pointed out an example in one of the tests where one entire side of the airbag was left intentionally uninflated -- The unit successfully bounced off the earth, settled, and deployed just fine -- It was just by luck that during the bounces, the side without the airbag was never face-down. Thats opposed to having 3 rocket burns, where 1 rocket fails.. The damn thing will cartwheel out of control and crash.
I guess it all sort of depends on how you think a landing should be done. Having it fall out of the sky on a parachute, and bounce for over half an hour (and a mile's distance!) before coming to rest can be thought of repeatedly exposing the lander to undue trauma. But it works.
PS..Seeing an ultra-high resolution slide of the surface of Mars in color-seperated 3D with a pair of 3D glasses was unbelievably cool..Handed out little cardboard glasses to everybody, and sat back for half an hour picking out things in the landscape..hehe...was unbelievably cool.
Bowie J. Poag
Bowie J. Poag
I'm starting to get my own theory's here...
Rich