The future of Mars exploration is, at least in the short term, riding, pardon the pun, quite literally on a two thousand pound car sized rover called Curiosity.
The weight of the two and a half billion dollar mission, called the Mars Science Lab, is not lost on the scientists and engineers at NASA’s Jet Propulsion Laboratory in California who built Curiosity. Mission Chief Engineer Rob Manning doesn’t sugar coat it. “If it does fail is that the end of exploration? Well, it may be the end for awhile. It may require a stop and regroup. Certainly it will.”
Engineer Adam Steltzner is in charge of EDL, that’s the Entry, Descent and Landing phase of the mission. “Full nights of sleep have eluded me for a couple of years now,” says Steltzner.
Why the anxiety? NASA has a good track record landing vehicles on Mars. What is so different this time around? Well, other than the planet, just about everything is different. In fact, the landing method has never been tried before. It is so unique and complicated the Space Agency has dubbed it, “Seven minutes of terror.” From the time Curiosity touches the top of the Martian atmosphere to the time it lands is seven minutes.
In the past, NASA has used either legged landers or has tucked its rovers inside giant airbags that would bounce along the Martian surface. But Curiosity is too big to be stuffed inside an airbag cocoon. And, where it is going requires a far more precision landing than every attempted before. Steltzner says, “We’re going to a place on Mars called Gale Crater and we’re landing quite literally between a rock and a hard place.”
Nestled inside a protective shell, Curiosity will hit the Martian atmosphere at thirteen thousand miles per hour shedding energy as it falls. But unlike in the past Steltzner says, “This time we’re steering as we fly through the upper atmosphere of Mars and using that steering to shrink our landing uncertainty.”
The next step is to deploy a parachute to further slow the spacecraft. But that only reduces the speed down to two hundred miles per hour. So, the spacecraft is equipped with a kind of jetpack.
“At about two kilometers above the surface, a little less,” says Steltzner, “she lets go of her parachute, turns on the rockets and flies until she’s just twenty meters above the surface. Then twenty meters above the surface the rover is lowered below the jetpack and the two together descend their way to the Martian surface.”
The scientists and engineers determined this was the only feasible landing method to get them to the Gale Crater site inside of which sits a mountain. Steltzer says, “At the end of the day we feel that the net result is a very reliable system. This architecture although it looks challenging really in the end results in a higher reliability, safer way of getting a rover of this size onto the surface of Mars.”
It’s a tight fit, says Manning, “To get there safely though we need to be able to land on the one big flat spot that sits right at the foot of that mountain inside the walls of the crater. Now, if we fly outside of those walls and hit the mountain or the walls of the crater, we’re not in good shape.”
Of course, if it all works, the payoff could be historic. Curiosity is designed to detect the building blocks of life. Scientists think water, a primary ingredient, might at one time have flowed inside the Gale crater. If this Sherlock Holmes of rovers finds that life could have existed on Mars or perhaps still does that could spark a new wave of Mars exploration fever.
With limited exploration dollars in the NASA budget, failure, on the other hand, would but a damper on or perhaps end future robotic exploration of Mars.