Landing on Mars

An artist concept of the NASA's Mars Science Laboratory Curiosity rover examining a rock on Mars with a set of tools on the rover's arm,   which can extend about 7 feet.

After five decades of sending  robotic explorers to the surface of Mars, the journey is still fraught with  dangers for every rover, probe and lander that humans launch. About two-thirds  of all Mars missions have failed; many of them very publicly, bringing equal  embarrassment to Russian, European and American space agencies.

So, when the Mars Science Laboratory launches from Cape Canaveral late this fall, the stakes will larger  than ever. The project contains the next generation rover, Curiosity. NASA has  invested years of work and over $2 billion into the project so far and been  dogged by cost-overruns and missed deadlines.

Nonetheless, the agency that brought us Apollo and  the Space Shuttle has had a string of recent successes on Mars. In the last  decade, NASA has seen huge results from not only its two long lived rovers, but  also the Mars Reconnaissance Orbiter and the Phoenix Lander.

That doesn't leave astronomers any less concerned for  the fate of MSL. In 1999, the Mars Climate Orbiter was ripped to shreds as it  hurtled  through the planet’s atmosphere after  engineers failed to convert their units from feet into meters. The Mars Polar  Lander, which followed several months later, was also never heard from after  its attempted landing.

MSL raises the stakes because it’s  more complex than anything ever attempted on the surface of the red planet.

Looking to build on the success of the Mars  Exploration Rovers Spirit and Opportunity, NASA  decided to go big with Curiosity – the rover is five times larger than its  predecessor rovers and will carry ten times the mass of scientific instruments–  but that super-sizing means NASA had to reimagine how they would land the  craft.

This image of the Mars rover family shows how the craft have increased in size since the Mars Pathfinder.

The task requires new landing technologies that will  slow the craft from more than 13,000 MPH, allow it to survive the extreme heat  of entering the atmosphere and then gently place it wheels-up on the planet’s  surface.

Spirit and Opportunity,  each about the size of riding lawn mower, used a system of parachutes and  retrorockets to slow down from orbit and massive airbags inflated around the  rover and it bounced its way across the surface at freeway speeds until it came  to a complete stop.

Caption:  Engineers prepare the heat shield for MSL at Lockheed Martin Space Systems in Denver  this spring. The shield has a diameter of nearly 15 feet and is the largest ever built for a planetary mission.

When Curiosity reaches Mars, it will be folded up  inside the largest heat shield ever used in space to protect it from the  extreme friction of passing through the atmosphere. The heat shield will slow  the craft down from its interplanetary travel speed to twice the speed of sound  so that a supersonic parachute can be deployed

The heat shield then falls away  and the 165 foot by 50 foot parachute unfurls while travelling at over 1,000  MPH. When the craft reaches a mile in above the surface, eight rockets begin to  fire, slowing the fall even further. Meanwhile, the rover moves from its stowed  position and its wheels deploy for landing.

In perhaps the most frightening of  the landing stages, the rover is then lowered to the surface by the hovering  platform via a system of cables that must be severed by small explosives for a  “soft-landing.” The hovering craft must fly far enough away afterwards that its  crash landing doesn’t impact the rover.

If any one of these carefully  calculated and tested systems fail, the rover might suffer the same fate as many  of its predecessors.

Descent

But if the mission succeeds,  Curiousity is better equipped than any other Mars mission to unravel the  planet’s secrets. Recent missions have shown that water was once abundant on  the surface and water ice still might lie just beneath where our instruments  can penetrate.

Curiousity will give further  insights into those things, but also help unravel the largest mystery in the  solar system: Alien life.

The rover will spend two Earth  years trying to determine if Mars could have ever supported microbial life and  if it still can.