Mars Mobile — An Electric Vehicle Concept for Space Exploration
Mars Mobile is a concept vehicle we work on as a showcase platform for our electric motor applications in space exploration.
A very thin atmosphere, a wide and very low temperature range, and very low atmospheric pressure on Mars make it extremely difficult to work with pneumatic and hydraulic systems — especially when the system is produced and tested on Earth before being sent to Mars. This is great news for Turncircles, and a strong proving ground for our electric motor capabilities.
Through this concept, we investigate:
- Regenerative design applicability
- In-wheel application adaptation
This work will later be integrated into our AF24PM-S ultra light custom axial flux DC electric motor. In-wheel motors are also used in electric vehicle drivetrains on Earth — see our article on a four quadrant transducer system for hybrid electric vehicles for more on traction motor and regenerative braking design.
Development Notes
Mars Mobile is conceived as an interplanetary vehicle that can be operated both on Earth and on Mars, meaning the parameters used in its development are driven by both Martian and Terran conditions. For example, the vehicle must be strong enough to safely carry its load under Earth's 9.80 m/s² gravity while still providing good grip and traction under Mars' 3.71 m/s² gravity to operate safely on Mars. As with gravity, many other parameters at the two operating locations need to be taken into consideration.
NASA presents a very detailed Earth vs. Mars comparison on their website: "All About Mars". ESA also provides in-depth knowledge on Mars: Mars Express. Below are the key environmental parameters we refer to from NASA and ESA:
| Parameter | Earth | Mars | Developer notes |
|---|---|---|---|
| Average distance from Sun | 93 million miles | 142 million miles | The amount of sunlight — and therefore photons — will be much less than on Earth. |
| Tilt of axis | 23.5 degrees | 25 degrees | Seasonal changes will also occur on Mars. |
| Length of year | 365.25 days | 687 Earth days | Seasons will take roughly twice as long as on Earth. |
| Length of day | 23 hours 56 minutes | 24 hours 37 minutes | Similar day and night duration will probably produce a similar temperature change at scale. |
| Gravity | 9.80 m/s² | 3.71 m/s² | The total weight of the Mars Mobile is limited by launch capabilities on Earth. |
| Temperature | −88°C to +58°C, average 14°C | −140°C to +30°C, average −63°C | A cold environment is very good for the conductors and magnets of electric motors, keeping efficiency consistently high. |
| Atmosphere | 78% nitrogen, 21% oxygen, 1% others | 96% carbon dioxide, 2% argon, 2% nitrogen, trace others | The atmospheric composition on Mars provides a good anti-corrosion effect for metal parts. No oxidant gases are available, so no combustion is possible. |
| Average surface pressure | 101,325 Pa (14.696 psi) | 610 Pa (0.088 psi) | A very thin atmosphere — the "air" plays a very important role in cooling electric motors. |
Regenerative Design
Regenerative design is one great way to put machine algorithms to work exploring lighter design solutions and saving weight. In addition to saved weight, it also allows working with conventional materials and production methods that are inexpensively available.
In the Mars Mobile case, one design note is to close the electric motor housing to protect the stator, and the electric motor as a whole, from sandstorms. However, closing the housing requires more material — and more material means more weight. Here we can take advantage of regenerative design to close the housing without increasing the weight, or, where that's unavoidable, to ensure a very small impact on weight.
Mars Mobile is a work in progress. As the concept advances, we will share news here on this page. Stay tuned! If you have any questions, feel free to contact us.
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