The drill bores through dry regolith at a rate proportional to available drill power until it reaches the ice table at the chosen site depth. Available power itself is capped by a solar array whose output is attenuated by the dust-storm slider: P_solar = P_max·(1 − 0.85·dust), split between the drill and the resistive heater.
Once the ice is exposed, heater power raises its local temperature toward a steady state set by Newtonian heat loss to the −63°C (210 K) Martian regolith. Vapor pressure of the ice follows the Clausius–Clapeyron relation:
P_sat(T) = P_triple · exp[ −L_sub/R_v · (1/T − 1/T_triple) ]
with the water triple point (T_triple = 273.16 K, P_triple = 611.66 Pa), sublimation latent heat L_sub ≈ 2.834×10&sup6; J/kg and the specific gas constant of water vapour R_v = 461.5 J/(kg·K). The sublimation mass flux then follows the Hertz–Knudsen equation:
J = P_sat(T) · sqrt( 1 / (2π·R_v·T) )
integrated over the borehole cross-section and accumulated over time into the collected-water readout. Hotter ice has an exponentially higher vapour pressure, so the heater slider has an outsized effect on yield — exactly the trade-off real Mars ISRU (in-situ resource utilisation) concepts have to balance against limited solar power during dust storms.
- Brown band — dry regolith the drill must pass through.
- Blue band — the ice table, exposed once the drill reaches it.
- Rising dots — water vapour escaping the borehole, rate scaled to the sublimation flux.
- Canister — fills as collected water accumulates.