Space is hard – and getting to Mars is really hard. Over 50% of all Earth missions that have been sent to Mars have ended in failure. The huge obstacle in exploring Mars is actually landing on the planet.
The surface area of Mars is comparable to Earth’s land mass. Imagine having to choose just one spot to land on and call home. Selecting the right place could mean the difference between achieving your scientific goals and failure.
Fortunately, planetary scientists have got stacks and stacks of data and images of the Mars surface to help them pick the best spot. They want to be somewhere with a mix of rocks and also for places where there are signs of water.
Robots are carried from earth to where they are going within special space modules. As these modules enter Mars’s atmosphere, they will be travelling ballistically – that’s around 21,000 kilometres per hour. At that speed, it’s going to get seriously hot, and so needs to hide behind a heat shield.
Travelling through the atmosphere will slow it down to a degree, and once it’s slowed to what we call its terminal velocity, the module will deploy a small parachute. It needs to be small because a big parachute would be ripped to shreds at those speeds.
Now once the module has slowed down further, a second and larger parachute will be deployed to help slow the module down further – to a more gentle free fall.
The module now lose its heat shield and fires retro rockets to bring it into a low hover a few metres above the surface of Mars. At this point the rockets are switched off as otherwise dust could be kicked up which could get into the equipment. The module though does have shock absorbers to stop it getting damaged but there are all sorts of things that could go wrong.
Once on the surface, the robot can emerge from the module and get on with its work.
You can hear Deep Space High: Destination Mars on Fun Kids Radio or listen to the series below!