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It's just over a year since Nasa spectacularly landed its Curiosity rover on Mars. In that time its grabbed headlines for firing its laser and analysing soil. The rover is now about to start its climb up Mount Sharp, a 6km Martian hill, to find out more about how Mars' environment has evolved over time.
Despite being a media star for the last year, Curiosity is not the only robot to escape the Earth's atmosphere and successfully aided mankind's reach for the stars. It's part of a group of rovers being built all over the world which are planned to explore both the Moon and Mars during the next decade. Then, further ahead, there are several innovative designs in development for the next generation of space rovers.
Below is our list of the world's foremost space rovers.
For an in depth look at the next rover to arrive at Mars, the European Space Agency's Exomars, click here.
Rovers now...
Curiosity
This car-sized rover weighs 900kg and is by far the biggest and heaviest interplanetary rover ever made. Packed with 80kg of instrumentation, Curiosity carries on NASA’s goals of establishing if Mars could ever have supported life, determining the role of water on the planet and studying the climate and geology of Mars.
The rover is 2.9m long by 2.7m wide by 2.2m in height and is powered by a plutonium fuelled radioisotope thermoelectric generator, which can generate 9 MJ (2.5 kilowatt hours) per day and also provides heat to the rover’s systems to prevent them from freezing. The nuclear generator has a designed life span of 14 years and the rover has two rechargeable lithium-ion batteries.
Curiosity uses the same rocker-bogie design for its hollow titanium “legs” as previous NASA Mars rovers, which enable it to keep all of its six wheels on the ground. Each wheel has its own motor. Curiosity has a top speed of 4cm per second, an average speed of 2cm per second and a range of 12 miles during its prime mission.
The rover is equipped with a wide array of equipment, including a drill, a laser, a robotic arm, a microscope, spectrometers and sensors for analysing the chemical composition and structure of rock and soil samples. The rover also has an “Environmental Monitoring Station” to analyse the climate on Mars. It has several different cameras and uses its main 1600 x 1200 pixel colour mast cam for exploration. Communications with Earth is provided by a number of redundant systems, via NASA’s three Mars satellites. The robot has two on board computers and a high level of autonomy.
This website has a good diagram of Curiosity.
Opportunity
Nasa's predecessor to Curiosity landed on Mars in 2004 with the Spirit rover. Today, Opportunity continues to collect and analyse soil and rocks looking for clues of past water presence on Mars, despite being having exceeded its designed lifespan by almost nine years. The rover has six wheels on a rocker-bogie system, is 1.5m high, 2.3m wide and 1.6m long and weighs 180kg. Each wheel has its own motor, the vehicle is steered at the front and the rear and it is designed to operate safely at tilts of up to 30 degrees. The rover’s maximum speed is 0.5 cm/s although average speed is about a fifth of this.
Opportunity is powered by a solar array which generates about 2.1 MJ (0.6 kilowatt hours) per day and has lithium-ion batteries for storage. It’s instrumentation includes two black and white cameas, a panoramic camera, and spectrometers and microscopic imagers for analysis of samples.
Exomars
The next rover to land on Mars’ surface is planned for 2018 by the European Space Agency and Russian space agency Roscom. The rover is being developed by European firms EADS Astrium and Thales Alenia and although smaller than Curiosity packs in a lot of scientific equipment and innovation.
Chang’e 3
This rover is planned to be landed on the moon by the China National Space Administration “later” this year. China’s first lunar rover has been developed by the Shanghai Aerospace Engineering Institute.
The six wheeled robot is 1.5m high and weighs 120kg. According to Chinese news reports, the rover will have a payload capacity of 20kg, will be able to transmit video in real time and dig and perform soil sample analysis.
Energy will be provided by a solar panel, allowing the rover to operate through lunar days. The rover is designed to explore an area of 3 square kilometres during its 3-month mission, with a maximum travelling distance of 10 km (6.2 mi). It is equipped with a radar on its underside, to enable the first direct measurement of the structure and depth of lunar soil down to a depth of 30m and to investigate the lunar crust structure down to several hundred meters' depth. It will also carry an alpha particle X-ray spectrometer and an infrared spectrometer.
Chandrayaan 2
This rover is being made by the Indian Space Research Organisation after being designed in Russia. The Chandrayaan-2 rover is designed to pick up samples of soil or rocks, perform chemical analysis and send the data back to Earth via the Chandrayaan orbiter.
The rover will have six wheels, each driven by an independent electrical motor. Four of the wheels will also be capable of independent steering. A total of 10 electrical motors will be used for traction and steering. Indian science academy IIT Kanpur is developing the mobility systems, which includes a stereophonic 3D camera to visualise the terrain. The rover will weigh 30-100 kg and be solar powered.
...and the next generation?
Athlete
The All-Terrain Hex-legged Extra-Terrestrial Explorer, is a six-legged robotic lunar rover prototype being developed by the Jet Propulsion Laboratory (JPL). Athlete is a testbed for future robotic systems and is designed for use on the Moon. The system is in development at Nasa's Johnson and Ames Centres, Stanford University and with Boeing. Athlete is designed, for maximum efficiency and to be able to both roll and walk over a wide range of terrains.
Scarab
This rover is designed to explore the lunar South Pole. The Scarab is capable of autonomously traversing dark polar craters. It uses laser mapping to navigate and carries a science payload. The science payload is capable of taking a 1m core sample and analysing it for water and gasses. Scarab can also be used to test varying mobility techniques and the next generation of lunar wheels. It is being developed by the Robotics Institute of Carnegie Mellon University, supported by NASA.
Hedgehogs
By far the most “sci-fi” of the next generation rovers, the Hedgehog is being designed in the US, and could form the exploratory half of a visit to the Martian moon of Phobos. The rovers would run alongside a mother spacecraft that stays in orbit to handle positioning and communications.
The Hedgehogs are spiked spheres about half a metre wide and would hop, tumble and bounce across the surface of the Phobos. Instead of wheels the Hedgehogs would have three internal flywheels, each pointing in a different direction. In Phobos’ weak gravity, the spinning discs would allow the hedgehogs to move “nimbly and precisely”.
The Hedgehog is being designed by researchers from Stanford University and Nasa’s Jet Propulsion Laboratory MIT. Two prototypes have already been produced and the next step is for tests in a low gravity environment. Marco Pavone, an assistant professor at Stanford University’s Departmnet of Aeronautics and Astronautics, says: “It’s a piece of technology that is needed before any more expensive type of exploration is considered. We need to deploy rovers in order to acquire information about the surface.”
The Phobos Surveyor mission could occur within the next 10-20 years.