There are several possibilities for replicating existing rover designs that are already on the surface of planets or that plan to go there.
Google Lunar XPrize
The teams competing in this competition to get a lunar rover to the moon and to send back a broadcast to Earth have employed many different designs for their proposed rovers.
This design is like a buggy or car in that it uses four wheels. It seems quite compact and could house the
necessary electronics and equipment within the conical body.
This design has wheels in a loose sense of the word, but instead of tires there are flexible feet on spokes that are designed to cope with rough or uneven terrain. The chassis is flatter and provides a large area for solar power cells.
This rover design is comprised of two large wheels that encompass the body to give it a decent ground clearance. It has two smaller wheels for stability support at the back, but several teams seem to have gone for a design where there are two large wheels with the main body between them. It doesn’t leave room for many scientific instruments, but it is perhaps an effective way of traversing large distances across the surface.
Nasa’s Mars Rovers
Nasa’s Opportunity Rover (and its twin Spirit which is no longer contactable) was launched in 2003 and landed on Mars in January 2004. It has six wheels on long stabilising legs, which ensures that it has as many wheels on firm ground at one time as possible. It has a long, movable ‘neck’ on which its main camera is situated, and many scientific instruments including scoops and collectors for analysing surface samples. It has large photovoltaic cells to harness as much solar energy as possible due to the planet’s further distance from the Sun. It’s primary function is to travel and explore as much of the surface as possible while performing experiments along the way.
Nasa’s Curiosity Rover (also known as the Mars Science Laboratory) is a much larger rover, approximately the size of a car. Although is looks quite similar to Opportinity, there are many more scientific instruments on it. A major difference is the lack of solar cells. Curiosity has a radioisotope thermoelectric generator power source that means that it does not require sunlight to function. The earlier static Mars landers Viking 1 and 2 used this method.
A much smaller rover was launched aboard the pathfinder mission to Mars in 1997. Sojourner is only a micro rover, but it still has the same six-wheeled design. There are less scientific experiments done using this rover, and it had to remain close to its base lander unit.
This image (right) shows the comparative size of the wheels of these three Nasa Mars Rovers. When designing my rover, I need to think about the size and whether I want to scale a larger design of rover down, or make it on a 1:1 scale.
I also need to decide whether I choose to base it on an existing rover, or look to the future of rovers and what they might look like, or create a design that I think might represent the future of rovers. This image (left) is the proposed design for Nasa’s 2020 mission to Mars. It is very similar to Curiosity, but has more and better instruments designed to inform us of the possibility of human travel to the planet.