Archive: December 2022

The six wheels have a design inspired by Perseverance wheels: before discussing the choices made for Mimas, it is worthy to briefly analyse the design made by JPL for their rovers. Machined out of a block of flight-grade aluminium and equipped with titanium spokes, each one of the Perseverance's six wheels is slightly larger in diameter and narrower than Curiosity's, with skins that are almost a millimetre thicker. They also feature new treads or grousers: In place of Curiosity's 24 chevron-pattern treads are 48 gently curved ones. For Mimas, steel was used to make a strong and flexible structure with inner suspensions made of bendy but strong steel strips. To obtain the 48 treads, the plan is to use a strong rubber (PU PX60) that will act as a tyre. In reality, rubber and plastic materials are not allowed for travels to Mars, since at very low temperatures, rubber acts as glass, becoming very brittle. Thanks to Lynn Chalmers, the technician for the polymers laboratory at Merchiston Campus, the manufacturing of the six wheels for Mimas can proceed smoothly!

• [Hours of work: 3h]
• [People involved: Giorgio, Lynn]

Even though a Mars rover's aesthetics aren't precisely a top concern, success also depends on how the vehicle is painted. White paint may provide a vital reflecting surface for any space-bound item in addition to giving it a simple, clean appearance. And, as John Campanella (the lead painter of Perseverance) said: "any good paint job is preceded by a great tape job". Mars 2020 employed primer and paint that were far from typical of a hardware shop. They have undergone extensive testing to show that they can adhere to aluminium, withstand shocks, vibrations, UV rays, and other annoyances of a trip to Mars, as well as be tough enough to survive the Martian cold, all while not outgassing organic compounds and other materials that could affect the mission's science experiments. On Mimas, the painting used is an enamel paint, a type of paint that air-dries to a hard, giving a glossy finish. It is ideal for coating surfaces that are outdoors or otherwise subject to hard wear or variations in temperature: these characteristics look ideal for the purpose of the project. The photo shown below is the first layer of painting made on the Mast Tower.

• [Hours of work: 6h]
• [People involved: Giorgio]

All sensors, motors and other electrical components located outside the Rover's belly, will be connected to the Raspberry Pi4 through cluster cable connectors attached to the WEB. The 3D component shown below can host up to 12 cables: 6 for the wheels on each side of the rover (each DC motor has 2 wires), and 6 for the servo motors located on top of the steering wheels (each servo motor has 3 wires).

• [Hours of work: 1h]
• [People involved: Giorgio]

The Emulated "Mars Environmental Dynamics Analyzer" also known as E-MEDA makes weather measurements including pressure, temperature and humidity, emulating the sensors used on Perseverance. The temperature sensors are housed in two small Booms structures mounted orthogonal to the Mast Tower of the Rover. For Mimas, two types of sensors were selected: the component shown in the picture above is attached to the Mast through an M3 bolt inserted in the 3D-printed part by melting the plastic. A precise description of the E-MEDA system will be provided in a future update.

• [Hours of work: 2h]
• [People involved: Giorgio]