The Union Recorder

July 31, 2012

Seven Minutes of Terror

Beate Czogalla
The Union-Recorder

MILLEDGEVILLE — In less than a week the Curiosity rover will land on Mars.

If you can stay awake until about 1:30am on Tuesday morning, August 6, you can follow this nail-biter on NASA TV and online. The Mars Odyssey orbiter has been repositioned to be able to relay the landing data back to Earth. Now it’s all or nothing for Curiosity!

I will most certainly be among those who will wish everyone involved with the mission good luck and nerves of steel – they’ll need both! Mind you, there is great confidence in good engineering, but nothing out there is failure-proof, and there are so many things that could go wrong with this landing, which sounds straight out of some fantasy novel.

Curiosity is the biggest rover NASA has ever sent to Mars – about three times the size of Spirit or Opportunity – so the bunch-of-balloons bouncy-ball landing simply won’t work. It’s far bigger and heavier and carries more gear and more science instruments than you can shake a stick at!

In simplest terms, Curiosity is a mobile chemistry lab. Its main focus is to obtain and analyze samples of Martian soil and rocks to determine if the environment of the Red Planet was ever conducive to life. Granted, life occurs on Earth in the most inhospitable of environments – in boiling hot eternally dark waters near deep-sea vents, in hot springs so corrosive they would strip the flesh right off your bones, in solid ice miles below the surface, even in the core of nuclear reactors you can find so-called extremophiles, life forms adapted to the nastiest habitats imaginable. So, lest I forget to mention it: Curiosity isn’t looking for life or fossils – it’s looking for chemical environments.

And while we are well aware of the existence of extremophiles we also know that these tiny life forms have adapted to these extreme living conditions but didn’t develop there.

Here’s where Curiosity comes in with its drills and scoops, sample canisters, analyzers and labs. The intended landing site is Gale Crater, a very large pit on Mars that offers ideal landing conditions and prime science territory. Vast areas of Gale are nice and flat, a great place for our rover to touch down. Those areas are also very low-lying, which is important when you land on Mars: in order for your parachutes to even work you have to have a sufficiently dense atmosphere, so the lower your landing terrain, the thicker the atmosphere, the more your chutes will slow you down. In fact, it’s pretty much impossible to land on one of Mars’ taller mountains, like the extinct volcano Olympus Mons – the atmosphere is simply too thin!

So, we go for the lowest altitude we can find. Gale Crater – like many impact craters – also has a fabulous central mound that resulted from the impact and thus presents a great opportunity for some one-the-spot geology. Moreover, the northwestern slope of the central mound has all kinds of interesting layers of rock, as Mars Global Surveyor and other orbiting spacecraft have discovered, so all that Curiosity needs to do is drive over, take a sample, drive up higher to the next layer, take more samples, and so on. Most of those layers of rock are within a manageable slope that the rover can climb without tipping over, as there are several canyons that provide access.

So, we have a nice thick atmosphere, our chutes can function, but it’s of course not enough for a landing. There is a heat shield to protect the spacecraft from the enormous heat generated during atmospheric entry. This heat shield must be jettisoned at the proper time so the rover can be readied. It will unfurl its wheels and closer to the surface a structure called a “sky crane”, which looks like a big four-legged spider with the rover attached to its belly, will fire rockets to slow down and halt its descent. It will then gently lower the rover to the surface on ropes. The ropes must then be cut and the sky crane will fly off and crash-land somewhere at a safe distance.

If everything goes as planned Curiosity will literally hit the ground running – wheels down and ready to roll!

All of this – from first hitting the Martian atmosphere to the actual landing, will take only about seven minutes, which the Curiosity folks have dubbed “Seven Minutes of Terror”. Worse yet, because the radio signals take a while to travel from Mars to Earth we will actually not even know whether or not everything went as planned until about 14 minutes later! Talk about suspense! Because of this huge time delay there is no help from Earth – the computer has to figure it all out by itself and land the rover safely.

Godspeed, Curiosity! You go, buddy, and hopefully we’ll see you after the touchdown!

Learn more about Curiosity and its curious landing at http://mars.jpl.nasa.gov/msl/