Mars Rover 'Curiosity' set for hair raising descent to the surface tomorrow night
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.
A minute and a half later with the craft now about a mile (1.6 km) high and falling at nearly 200 mph (322 kph), the back shell of the capsule and the parachute are jettisoned, leaving the rover attached only to the belly of a jet pack called a sky crane.
Eight jet thrusters on the crane immediately fire, jerking the craft out from under the parachute and slowing Curiosity's descent to about 1.5 mph (2.4 kph) as it nears the surface.
The sky crane then lowers the rover to the ground on nylon tethers that unspool from beneath the hovering jet pack. The cords are severed once Curiosity's wheels are on the surface, and the sky crane flies off to crash a safe distance away.
So hopeful are they of the sky crane's success that NASA officials see it as a model for the next generation of landers.
"I think what we have is a workhorse for the future," said Doug McCuistion, NASA's mars exploration program director.
Still, the engineers at mission control are leaving nothing to chance - not even superstition. In keeping with a decades-long tradition, the NASA flight team plan to break out a can of peanuts about an hour before touchdown, said David Oh, a flight director.
"Landing day will take all the good engineering and all the luck we have," he said.
Curiosity will be the most sophisticated, scientifically advanced rover ever to explore Mars. It is stuffed with high tech science gear "that will allow it to answer questions about Mars' wet history, current atmosphere and climate, and the possibility of ancient or contemporary life.":
Possibly the coolest Curiosity instrument is the ChemCam, which uses a laser beam to shoot rocks (and maybe a Martian or two) in order to vaporize a small sample. A spectrograph will then analyze the vapor, determining the composition and chemistry of the rocks. Situated on Curiosity's head, ChemCam can shoot up to 23 feet and should provide unprecedented detail about minerals on the Martian surface.
The Chemistry and Mineralogy (CheMin) instrument will look at various minerals on the Martian surface. Specific minerals form in the presence or in the absence of water, revealing the history of an area and helping scientists to understand whether or not liquid existed there. Curiosity will drill into rocks to obtain samples for CheMin, pulverizing the material and transporting it into the instrument's chamber. CheMin will then bombard the sample with X-rays to determine its composition.
The Rover Environmental Monitoring Station (REMS) will be Curiosity's weatherman, providing data about daily atmospheric pressure, wind speed, humidity, ultraviolet radiation, and air temperature. REMS will sit on Curiosity's neck and also help assess long-term seasonal variation in Mars' climate.
The landing is set for 1:31 AM Eastern time on Monday morning.