More than 100 electric motors from maxon have been used on the Red Planet, and have withstood cosmic radiation, dust storms and temperature fluctuations. With the Perseverance rover, precision drives once again flew to Mars. The key to success is the same as before: standard industrial products.
Mars missions without maxon drive systems? Unthinkable! In the last three decades, these DC motors have been used in virtually all successful robot missions. More than 100 of them are already on the Red Planet, and the number went up again with the landing of NASA’s Perseverance rover in 2021. Space missions make up only a small part of maxon’s projects, however. Most of the DC and BLDC motors, controllers, gearheads, and encoders made by the Swiss company end up in medical applications, industrial automation or robotics.
So why is maxon such an important supplier for space projects? The short answer is because of the high quality of its standard products. All the drives that have been used on Mars are based on products from the company’s catalogue, and are used on Earth in all kinds of different applications. Naturally, modifications need to be made to them so the products can withstand the harsh conditions. Nevertheless, the basic designs are the same.
Into the unknown with 11 DC motors
In 1997, for the first time in history, a vehicle roamed around on the surface of Mars, taking photos and investigating the soil. NASA’s Sojourner Rover, with six wheels and weighing just 11 kilograms, was intended at the time to be a relatively low-cost experiment.
Sojourner, the first rover on Mars, landed in 1997. maxon supplied 11 DC motors with a diameter of 16 mm for the drives, the steering and the scientific instruments.
The choice was made to use as many standard industrial products as possible – such as the 11 DC motors used for propulsion, steering and the operation of scientific instruments. The maxon drives, with their typical ironless rotor and rhombic winding, were more powerful and more dynamic than conventional DC motors. maxon’s engineers also modified the brushes and the lubricant. At the time, they were unsure if the modifications would be enough for a successful Mars mission. They had no previous experience and the challenges were daunting. The drives had to survive strong vibrations during the rocket launch, vacuum and cosmic radiation during the journey, a hard landing on Mars, dust storms and temperature fluctuations from -120 to 25°C. However, the mission was a success and maxon became world renowned.
The urge to undertake further exploratory missions to the Red Planet grew among space agencies. They were after answers to big questions such as: Is there water or ice on Mars? Does life exist there or could life at least have existed there earlier? And why did the planetary neighbours Earth and Mars develop in such different ways?
A duo exceeds all expectations
After the success of Sojourner, NASA decided to send two more scientific research robots into space at the same time: the twin rovers Opportunity and Spirit. They were in a whole different class from Sojourner, each weighing 185 kg and equipped with instruments that could brush the ground and drill into Martian rock. In 2004, the vehicles landed on the planet separately from one another and started their mission, which was intended to last at least three months. Spirit ultimately worked for six years before it got stuck in the sand. Its twin, Opportunity made it to 15 years, during which it travelled more than 45 km. For the scientists involved, this mission was a dream come true. With the help of the rovers, they were able to demonstrate that liquid water must have once existed on the Red Planet – a prerequisite for life.
maxon made an important contribution. Each of the vehicles housed 35 brushed DC motors with diameters of 20 or 25 mm.They were responsible for propulsion, control and the robotic arm. Another eight electric drives were used in the rovers’ landing unit.
Similar motors were used again in 2008 when NASA sent its next mission to the Red Planet with the stationary Phoenix probe. It searched for frozen water and finally found it in a soil sample that was heated for analysis. maxon supplied nine RE 25 brushed DC motors with specially designed ball bearings, for the alignment of the solar panels and for moving the robotic arm.
A motor hammers through the Martian soil
Many technical developments have occurred since then. Today, there are two more robots on Mars. One is the Curiosity Rover which, in terms of its size and measuring instruments, dwarfs all previous missions. The vehicle has been in use since 2012, weighs almost a ton, and is equipped with ten instruments. It is powered by a radioisotope thermoelectric generator. maxon equipped it with precise encoders that were fitted on the drive axes for control of the motors.
At the end of 2018, the next stationary probe, InSight, landed on Mars. To extend its solar panels, the NASA engineers used the proven RE 25 motors that were previously installed in Spirit and Opportunity. Meanwhile, a new brushed DCX drive was deployed for the first time in order to hammer a temperature probe called a ‘mole’ several metres into the Martian soil.
Searching for ancient signs of life
In 2021, NASA’s Perseverance rover landed on the Red Planet. On board were ten brushless maxon DC motors in combination with a GP 22 UP planetary gearhead. It is helping to discover traces of former life. Its most important job is to take multiple soil samples, seal them in containers, and deposit them on the surface of Mars so that a future mission can return them to Earth. Several maxon BLDC motors are being used to handle the samples inside the rover. Some are installed in the robotic arm, which will move the samples from station to station. maxon motors will also be used when sealing and depositing the sample containers.
These drives are based on standard products from maxon’s catalogue – nine EC 32 flat motors and one EC 20 flat, in combination with a GP 22 UP planetary gearhead. maxon’s engineers have modified and thoroughly tested the drives over many years, working together with the specialists from the Jet Propulsion Laboratory (JPL), which handles all unmanned missions for NASA.
Flying high
Perseverance was not alone. It carried with it the helicopter drone, Ingenuity. Weighing 1,8 kilograms, it was solar powered, and designed to take aerial photographs during short flights. In an achievement on a par with the Wright brothers’ first flight, Ingenuity tested the limits. It achieved the first powered, controlled flight by an aircraft on another planet. It kept going for three years and flew a total of 72 missions and 17 kilometres, giving NASA’s scientists undreamed of access to landscapes previously unseen. It’s no surprise to find that maxon was involved in this device too. Six brushed DCX motors, with a diameter of 10 mm, controlled the tilt of the rotor blades, which determine the direction of flight. Sadly the little helicopter’s mission is at an end after it lost a rotor blade during a hard landing.
A small contribution to a space revolution
Today maxon can rightly claim to be an important supplier for space projects. The Swiss company’s drive systems are found in satellites, are used to regulate rocket engines, and are installed on the International Space Station. This success is no accident. maxon’s engineers have learned a great deal over the years – particularly from their close collaboration with customers, especially the JPL, which handles all unmanned missions for NASA. As a result, quality standards have been progressively raised and new test procedures and processes have been developed.
maxon now has a specialised team handling all space projects. However, their fundamental approach to tackling all kinds of different applications is the same as ever. The standard catalogue product is modified and tested until it completely satisfies all requirements. This approach is playing an important part in the current revolution in space missions. High-priced specialty products are increasingly being replaced by modified industrial products. This results in lower project costs, which, in turn, opens up access to space for a broader range of participants. maxon will be able to develop many more exciting applications for this new space market in the years to come.
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