Tuesday, 18 September 2012

Detailed Mars Landing Pt.II

The landing came about in stages, even though they might sound simple in theory. Practical applications is a different story. The massive interplanetary payload is very sensitive to electrical and magnetic radiation, a la the Sun (Which emits enormous amounts of photons) Can damage any devices that aren’t properly EMP shielded. Since outer space does not have an atmosphere, anything that travels in it will not be protected by the thick atmosphere that we have gracing us on Earth. (The Aurora Borealis is a shining visual example of the magnetosphere protecting us from solar flares)

The first stages of the landing procedures for the Curiosity rover will begin after 8 and a half months of traveling through space between Earth and Mars. Reaching Mars outer atmosphere. Entering Martian atmosphere at about 13,000 mp/h. After this point the space payload will lose communication between NASA command center and Curiosity for approximately  7 minutes. This will be one of the most challenging moments in the endeavor. Since nothing can be deterred from this and no solid conclusion as to where it reaches its destination in one piece or completely destroyed across the landscape. Leaving no clue or evidence as to what went wrong. As the payload enters the atmosphere, the friction of the atmosphere heats the shield on the front of the lander to 1,600c thus slowing it down to 1,000 mp/h. Much slower than the 13,000 mp/h before. Still traveling at super sonic speeds. The next stage of the landing process is the sub sonic parachute that is deployed from the top of the rover.

 Fig.1 The rover pod in descending stage, about to enter Mars atmosphere
Credit: NASA/JPL-Caltech
The heat shield is decoupled from the main unit after its job is done. Falling to the surface at high speeds. Leaving the main unit falling much slowly. The most amazing aspect about this parachute is the fact that it is the biggest super sonic parachute ever built. Weighing only a measly 100 pounds and have 65,000 pounds of stopping power. Utilising some of the most advanced materials available.

The next stage is interesting, the fuel decent. Attached to the frame of the parachute chassis is the main rover unit. Which is decoupled from the parachute chassis and retro-rockets are ignited to aid in the rest of the landing procedure. This is an interesting part as not only does it decouple from the main chassis, but has to move at an angle away from the other unit as not to crash into the bottom of it, causing destruction to the rover. The retro-rockets are angled away from the ground and makes the unit move to the side to allow the other unit to fall past the rover and fall to the surface. The rockets are then slowly powered gently to the surface. But there is one more stage, the final stage. The sky crane manoeuvre! This is where the rocket chassis, lowers the Curiosity rover to the ground over a 21ft crane. You are probably asking why this is needed? You need to remember that Mars surface is very dusty and the particles are dry and very light. Especially with the lower gravity, particles will travel much higher then they would on Earth. This could destroy any electrical/analytical instrumentation that is on board permanently, rendering the experiment useless. The Rover is lowered by a large crane so the rocket boosters do not kick up the dust from the ground. Once complete, the cable cranes will decouple and the rocket pod will blast of and crash way of into the distance. At this stage assuming everything went according to plan. The rover will send a signal to Earth informing that the touchdown was a success.

 Fig.2 The first picture of the Mars surface taken by the Rover.
Credit: NASA/JPL-Caltech

Thankfully it did touch down and scientific exploration and analysis can begin on the surface of Mars.



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