Uncrewed, remotely operated rovers have explored other celestial bodies since 17 November 1970, when the Soviet Lunokhod 1 landed on the Moon. Since then, nine rovers in total have operated on the lunar surface - including three crewed Lunar Roving Vehicles of the Apollo programme.

Yet none used continuous tracks: tracks have considerably greater mass than wheels, drastically increasing mission cost. In parallel, a strong miniaturisation trend produced palm-sized and CubeSat-scale robots that cut launch mass. The #COSMOBOSS micro-rover follows this trend - but departs from convention by adopting a tracked chassis.

Reduced gravity and the absence of an atmosphere make it hard to drill deeper than 1-2 m on the Moon. The force pressing the bit into the formation - the weight-on-bit (WOB) - is fundamentally limited by the low weight of any equipment.

• Moon gravity ≈ 1/6 of Earth
• 1 kg on Earth → only ~167 g of weight on the Moon
• Solution: deliberately add mass through tracks

Regolith is the loose, weathered layer of dust and crushed rock covering celestial-body surfaces; on the Moon it forms a thick layer, in places several metres deep.

Its grains are extremely fine and unusually sharp - with no atmosphere, there is no wind to polish them. The resulting abrasive dust damaged equipment as early as Apollo 11. These properties make trafficability and the avoidance of sinkage central design problems - and motivate the experimental study of the track-regolith interaction reported here.

The prototype used rubber tracks of width 2 cm and length 16 cm; each track carries 68 grousers that increase effective contact area and total traction.

Grousers improve grip on loose soil and prevent loss of adhesion - vital for such a small vehicle, which on a flat surface under low gravity can easily slip. The prototype has a small mass of only 400 g; later versions, using heavier and more durable materials and more accurate instruments, will weigh several times more.

Rubber tracks will be replaced by purpose-designed, 3-D-printed segmented tracks; each segment carries a grouser, a guide tooth, and a hinge connecting successive segments.

Six road wheels were adopted as the optimum number: per Hou et al. (2021), this limits the sinking of tracks into regolith by about 35% - highly important given the small ground clearance of low-slung micro-rovers.

Segmented-track configuration on Earth: m = 0.4 kg, n = 6 road wheels of d = 3 cm, pitch p_t = 2 cm, width b = 5 cm → single-road-wheel ground pressure ≈ 58.8 Pa.

A 60 × 100 cm field holds a ~10 cm layer of the lunar regolith analogue AGK-2010, with bauxite blocks as obstacles; a camera recording at 60 fps is mounted on a tripod spanning the whole stand.

AGK-2010 is a Polish analogue of the CHENOBI simulant, with comparable grain-size fraction and internal friction angle, and a bulk density of 1.295 kg/l (about 1.45% below CHENOBI). A characterised analogue is essential: grain-size distribution, density, cohesion and internal friction angle govern traction and sinkage.

In the control run the tracks are lifted clear of any surface and motors run to maximum speed in air (no friction load). No-load speed: V₀ = L / t, with L = 0.4 m total track length.

Mean revolution time t = 0.45 s → no-load maximum speed V₀ ≈ 0.89 m/s. In the research test the rover crosses the regolith field, and the dimensionless speed-loss index is evaluated as a trafficability proxy - not a Coulomb friction or traction coefficient.

The mean speed-loss index μ̄ ≈ 0.063 (runs 0.040-0.069) means the rover reaches roughly 50-65% of its no-load top speed on the analogue - loose soil resists motion only weakly, favourable for trafficability.

This index is a motion-resistance proxy, not a friction or traction coefficient. The internal friction angle of regolith simulants is φ ≈ 31-50°, and the drawbar-pull coefficient of grousered tracks on soft soil is typically 0.4-0.7 - an order of magnitude larger and of different physical origin.

The paper presented the concept and prototype of the tracked #COSMOBOSS micro-rover - a palm-class platform departing from the wheeled convention of planetary rovers in order to carry a drill.

The central rationale - turning the historical drawback of tracks (their mass) into the principal advantage for a drilling micro-rover - is supported by a reproducible mobility-testing methodology and seven runs giving a low mean speed-loss index of about 0.063, confirming good trafficability on AGK-2010.