Saturday 23 July 2011

NASA sets its sights on Gale Crater, Mars.

On the 22nd of July this year NASA announced that it's next Mars rover, the Mars Science Laboratory, or Curiosity, will target Gale Crater, just south of the Martian equator on the fringes of Elysium Planitia. The Mars Science Laboratory is a car-sized rover intended for launch in November or December this year; it will cary the most advanced set of tools for the analysis of geological samples yet sent to Mars.
An artist's impression of the Mars Science Laboratory in action.

Gale Crater was chosen from a list of thirty potential landing sights due to it's extremely low elevation; water runs downhill so, logically, if Mars once had any liquid water, then the last places it endured would have been the lowest points, and anything being carried in the water would have a good chance of being carried to the lowest points on the planet. Evaporites (minerals formed when salt-laden water evaporates) have already been found on Mars; what the Mars Science Laboratory will be looking for in particular will be any organic compounds that could indicate that life once existed on the Red Planet.

Like many craters on bodies with little or no atmosphere Gale Crater (named after the Australian amateur astronomer Walter Frederick Gale) has a central peak. These are caused by material compressed during the original impact rebounding. In Gale Crater this is surrounded by an enormous mound of unidentified debris; in the southern part of the crater this is thought to be 4.5 k think, and overtops the rim of the crater. It is this unidentified debris that is of interest to scientists. It appears to be layered in structure, and may have been laid down over a period of 2 billion years (the crater itself is between 3.5 and 3.8 billion years old). Some scientists believe it is the eroded remains of an ancient sea- or lake-bed that once competely covered the crater.

3D Animation of the Gale Crater Landing Site.

The Mars Science Laboratory will be launched from Cape Canaveral Air Force Station in Florida between the 25 November and the 18 December 2011, using an Atlas V 541 Launch Vehicle, with four solid propellent rocket motors.

The Cruise Stage, weighing about 400 kg, will separate from the launch vehicle and carry the lander to Mars. It will have a propulsion system made up of eight thrusters fueled by hydrozene rocket fuel from two titanium tanks, and derive power from a large solar array. As well as carrying the probe to Mars the cruise stage will have to carefully monitor and regulate its temperature during the journey. To this end it has a system of coolant pipes, radiators and insulation blankets, monitored by a system of thermostats which can activate the cooling and heating systems as needed.

When the vehicle reaches Mars the Lander Stage will separate from the Cruise Stage and descend into the atmosphere, using a parachute to slow itself. As it nears the surface it will activate a set of four rocket motors, then detach itself from the parachute, decelerating as it descends the remaining distance. When it gets close enough to the surface it will hover on the rocket motors and lower the lander stage to the surface on a cable. The descent stage will then disconnect from the lander and accelerate away.

The lander itself is a car sized robot exploration vehicle with six independently controlled wheels on extended legs, designed to be able to get over obstacles 50 cm high. It will be fueled by a small nuclear power system with a plutonium power source. It has an array of cameras for navigation, hazard avoidance and scientific imaging, as well as an extendable arm, with a variety of scientific instruments.

Animation of the Mars Science Laboratory mission.

See also Pluto gains a forth moon, Visiting Vesta and Mars on Sciency Thoughts YouTube.