Seven Minutes

By Mike Deliman

Mike Deliman Photo

This week, NASA hosted the Jet Propulsion Laboratory (JPL) scientists in charge of the Mars Science Laboratory rover, Curiosity, for a pre-landing press conference.  The landing sequences, called “ED&L” – Entry, Descent, and Landing – are the most action packed and critical operations other than the initial launch.  Pete Theisinger has described the EDL sequence as “7 minutes of terror.”

This stage of exploration is similar to that of other landers NASA has sent – Mars Pathfinder, Mars Exploration Rovers, and Mars Polar Lander all survived their landings on the red planet after their 7 minutes of EDL terror.  It was these experiences that led Pete to this description.

The NASA/JPL press conference was about an hour long, and packed full of information.  The long and short of it is that we have made giant strides in advancing the technology of placing payloads on the surface of Mars, and the science returned so far has drastically changed our understanding of the red planet, and of planetary evolution in general.

When choosing a place to land on Mars we have to take into account just how accurately we can place a lander and how much space it requires to come to a stop.  With the rovers we’ve sent previously, using the parachute and airbag method (“drop, bounce, roll”), we needed a significant area just to arrest the horizontal momentum of the craft.  By using a retro-rocket method, that area is reduced greatly.  Combining a heat-shell and parachute with the retro-rockets, we can reduce that area and reduce the weight of the rockets required to land a vehicle.

Using retro-rockets has its own problems – mostly, the rockets need to be under the lander, and may contaminate the area landed on.  A rover can get away from the contamination, but if there are exhaust nozzles under the rover, they can hang up on objects and prevent the rover from…well, roving.  Enter the idea of the sky crane. The sky crane will provide the final slowing of descent and horizontal momentum, and place the rover on the best spot it can sense using radar.  This provides the ability to place the rover with precision, upright, without the danger of hanging-up on thrust nozzles after landing.  The crane will fly off to gently crash elsewhere.

Curiosity will be using a host of science instruments to explore Mars looking for evidence that fulfills the mission objectives.  The basic objective is to confirm whether or not Mars could have – at any time in history – been able to support life as we know it.  This means looking for more evidence of liquid water on the surface.  It will also be looking for evidence of biologically related organic chemicals.  There are some organic molecules that can result from purely physical processes, and others that can only result from biological activity.  Curiosity will rove to a mountain in the center of the crater it is landing in – taller than any mountain in the 48 contiguous states – in search of this evidence.

A confirmation of life on Mars would be the discovery of the century for sure.  But considering the technologies we’re testing and improving just getting to Mars, a successful landing is a marvel of technology itself.  A precision landing instrument like the Sky Crane could enable us to send provisions for manned exploration, delivering them spot-on to sites easily accessible to a crew temporarily living on Mars – not to mention it is technology we could use to make precision deliveries to our own Moon and other planets and moons, as well!

The part Wind River’s VxWorks real-time operating system plays is similar to the role it plays in devices you use every day without knowing we are there.  It is the “smarts” that provides the coordination necessary to carry out precision actions in response to the operating environment, with extreme accuracy.  It helps provide the ability to manage the terror in the 7 minutes of ED&L, making such incredible feats possible.

Wind River is proud of NASA / JPL for these achievements over the past two decades of exploring our solar system.  I am extremely fortunate to have worked with such excellent and passionate engineering teams, and I am looking forward to watching the EDL coverage on the evening of August 5th!


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