After 6 or 7 months in inter planetary transit, the Martian crew will be delighted to approach their new home. Upon reaching the surface, the crew will set about establishing their new home, part of which may already be part or fully built by robots or previous deliveries by Starships. However, on arrival there may be some opportunities to have a home comfort, a well needed break in partial gravity. If there are any British astronauts aboard (doubtful) then there could be a call to put the kettle on for a nice cup of tea.
There are limitations on construction of dwellings by robots ahead of time: because there is an essential mass-moving problem to solve here. For 1 m3 of solids that are moved, the robots neee to expend the energy to move it. Even if they move little bits of soil amounting to the total, the same energy, if not more is used. This is because of movement waste of the machines moving from dig site to dump site.
I am talking not about limitations on the bucket size of an excavator, rather the limitation of the power unit for the machine. As we see on Curiosity and Perseverance rovers, the radio- source powered, thermo-electric generator power pack there is good for 110W at the outset before radio decay reduces the power available.
1 m3 of material - Density of sand (fine aggregate) ro = between 1450 – 2082 kg /m3.
[We know that the sands (not really sand because Mars didn't have sea creatures to generate shells to make real sand) is very fine on mars because of the wind erosion over countless millions of years has made the particles very small and round - so we can take a high density, say 1800 kg / m3. lots of mass in a given volume].
volume of material v = 1 m3
The material is lifted into a flatbed machine approx 1 m above grade h = 1m
Assuming the motors are 90% efficient. (n = 0.9)
acceleration due to gravity g = 3.71 kg /m/s2 on Mars (on Earth 9.81 kg/m/s2
mass = 1800 kg / m3 x 1m3
mass = 1800 kg
energy to lift mass 1 m = mgh
energy = 1800 kg / m3 x 3.71 kg / m/s2 x 1 m
energy = 6678 J x (2.77 x 10-7 kWh /J
energy expended = 0.00184 kWh.
Consider that boiling a kettle (raising temperature of 1 L of water in the UK consumes approximately 0.183 kWh. So we use 2 orders of magnitude more energy to achieve that than lifting that much mass.
However, the absolute amount of energy isn't the real issue here - because the Perseverance rover and the ISS has shown that battery storage is key to ensuring that there is enough power available to back up a power source - whether it be solar power or a thermoelectric generator.
The instantaneous lifting power is more important - how much energy is required at the time of doing the work.
In this case, we are looking at roughly 10 W. This is the energy to simply lift the mass.
There is also energy required for mining the surface. More energy will then be used to process the material into a pumpable concrete style material for 3D printing of structures.
In terms of setting up and establishing a routine for the new martians, there will be opportunities to live a life not dissimilar to Earth. Due to a decent amount of gravity on Mars (3.71 m/s2), approximately 1/3 of that on Earth, the crew could have a 'real' shower - depending on water constraints, set up a cup of tea, cook food in a 'real' kitchen set up - at least more real than that of the ISS anyhow. The first bacon sandwich on Mars, vacuum-packed and irradiated bread - would be such a joy after 6 months minimum of space-food.
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Thhanks for sharing
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