In both Ridley Scott's and James Cameron's Alien franchise films we see the synthetic Ash drinking a milk-like substance and artificial person Bishop eating some corn bread.

Do they actually process these substances and burn for fuel like humans or are they eating to 'fit in' with everyone else? I know no-one knew at the beginning Ash was a robot so the fitting in part is in regards to Bishop.


According to the Aliens: Colonial Marines Technical Manual, androids (sorry, 'synthetic people') are powered by a "25 kW hydrogen fuel cell". There's no indication that they need to eat for sustenance or gain any energy by doing so.

The modern synthetic is a highly complex machine: stronger, faster and better coordinated than an average human. The basic chassis is a carbon fiber skeleton with latchment points for the artificial musculature. The muscles are vat-grown silicone colloids powered either by pumped microhydraulics or electrical stimulation. Power for the android is supplied by a 25 kW hydrogen fuel cell with a life of approximately 400 days between refueling. As in a human, the skeletal structure is inherently unstable and is effectively suspended by the musculature. No limb locking, joint motorization or gyrostabilization is present as in other anthropomorphic frames such as powerloaders; instead, the muscles must work actively to keep the chassis standing upright while active feedback systems control its stability. Though the muscles can withstand considerable wear and tear, the lack of a self-repair facility means that they eventually lose their strength and become increasingly elastic over time. It is recommended that the muscle system be overhauled on a regular basis and individual elements replaced fully every two years. Muscle layout and operation, as with certain other internal functions, are homologous with those of the human body; indeed, military synthetics are designed to be virtually indistinguishable in appearance from a human.

You might also want to note that the plan diagram of its internal 'organs' is entirely lacking anything that resembles a digestive system aside from a small container that appears to attach to the penis (and presumably the anus) to allow it to store a small amount of food during chow-time and then excrete it convincingly, should the need arises.

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    Running a 25kW cell for 400 days would take, if I'm doing this calculation right, about 6 tonnes of liquid hydrogen (plus about 50 tonnes of oxygen provided by local life-support systems). But I don't think anyone claimed this was hard SF. – Trip Space-Parasite Mar 8 at 22:26
  • @TripSpace-Parasite - You're assuming that their hydrogen fuel cells are the same as ours (except probably a bit more efficient, presumably) whereas this is a society that has mastered tabletop hydrogen cold fusion. – Valorum Mar 8 at 22:40
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    I'd expect them to say "fusion reactor" instead of "fuel cell" instead of that case, because it sounds much cooler. – Trip Space-Parasite Mar 8 at 22:47
  • Meh, I doubt they would actually use even 250 W on average, so why so strong power source? Maybe to be stronger then ox if necessary... – Mithoron Mar 9 at 1:01

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