Wednesday, July 4, 2012

Landing on Mars in just one month!

Well, okay, it's a month and a day.  But today is Independence Day here in the U.S., and while contemplating achievements that are so far uniquely American, landing on Mars and successfully doing science there stands out in my mind.
Viking 2 image from the surface of Mars.

The first successful landings were by Vikings 1 and 2 in 1976, our bicentennial year.  In fact, Viking 1 was originally scheduled to land on the 4th of July, until late June of that year when its orbiting mother ship snapped the first detailed photo of its intended landing site and found it was way too rough to ensure a safe landing.  A safer site was found in time to land 16 days later on an equally historic date, July 20th ("One small step...").  Over two decades later, Mars Pathfinder touched down safely on the 4th of July, 1997.

NASA has had the good fortune (along with brilliant, meticulous engineering) to succeed at 6 of 7 attempts to land on Mars.  The odd one out was Mars Polar Lander, which in 1999 apparently descended safely to a tantalizing 40 meters (130 feet) above the Martian surface before its retrorockets turned off prematurely and it free-fell to a crash landing.  Ironically, NASA has failed more frequently at Mars missions that didn't even attempt to land, including the Mariner 3 flyby mission and the planned orbiters Mariner 8, Mars Observer, and Mars Climate Orbiter.  We've enjoyed a 100% success rate in the past decade, but getting to Mars safely is still a challenge.

The Challenges of Getting to Mars: Curiosity's Seven Minutes of Terror.  Credit: NASA/JPL-Caltech

Late at night on August 5th (technically 1:30 AM EDT on August 6th), the Mars Science Laboratory mission will attempt to land the massive and highly capable Curiosity rover.  Because of Curiosity's unprecedented mass, a new landing system must be used for the first time.  The above video describes the awesome complexity of this system, which includes the planned detonation of 76 pyrotechnic charges ("fireworks").  For the rover, it will be quite a ride.  If you're here in Atlanta, you can watch the action live in the Centergy Building in Tech Square: come join our Mars Landing Party!
Gale crater, with Curiosity's landing ellipse in black and superposed approximate landing ellipse previously considered for Spirit (blue).

Where will Curiosity land?  In Gale crater, a massive impact scar 150 kilometers (95 miles) across that holds a mountain of sedimentary rocks—Mount Sharp—over 5 km (3 miles) high.  The plan is to land on the flat northern crater floor and then to climb Mt. Sharp, examining each sedimentary layer as we cross it – analogous to reading a Martian history book, one page at a time.  Gale's sedimentary record is thicker than that exposed in western America's Grand Canyon, and it has been a high-priority Martian landing site for years now.  It was briefly considered as a destination for the Mars Exploration Rover Spirit, but Spirit's landing system was much less precise, and would have risked landing on the rugged crater walls or the steep slopes of Mt. Sharp.  Curiosity can instead target a small area known to be relatively safe from extensive orbital imaging, this time acquired well in advance of the planned landing date.

Happy 4th of July, and keep crossing your fingers for Curiosity.  Pending a safe landing, she will change our perceptions of Mars for years to come.


  1. What an interesting post! Thank you for sharing. I will definitely be keeping my fingers crossed for Curiosity and hoping that this complicated landing system works successfully!

  2. What an exciting landing, a huge congratulations to all those involved with MSL! Go Curiosity!


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