NASA, who knows a thing or two about space PR, is calling the latest Mars probe’s descent to the surface “7 Minutes of Terror.” And why not? It’s never been tried before, and given the track record for Mars landers, it is more than possible that it won’t work and $2.5 billion of US taxpayer money will end up as a smudge on the surface of the Red Planet.
But, in a way, it is heartening. NASA is taking a risk with the reward being advancing our knowledge and understanding of Mars further and faster than any other probe ever sent. Curiosity is the size of a small car, the largest planetary lander in history. Thus, the unusual re-entry system where several complex maneuvers will guide the craft down to the surface.
Over twice as large and five times heavier than either of the twin rovers Spirit and Opportunity that landed on Mars in 2004, Curiosity weighs too much to bounce to the surface in airbags or fly itself to the ground with rocket thrusters, systems successfully used by six previous NASA landers.
Instead, rocket power will be used in combination with several other components during Curiosity’s descent and landing.
Plunging through the top of Mars’ atmosphere at an angle producing slight aerodynamic lift, the capsule’s “guided entry” system uses jet thrusters that actually steer the craft as it falls, making small course corrections on the way down.
At an altitude of seven miles (11 km) and a velocity of 900 mph (1,448 kph), a giant parachute will open, and in less than half a minute, the heat shield will fall away, exposing the underside of the rover.