Question: When they start exploring the catacombs under the prison, where did they get a flashlight?
Smokyoak
29th Apr 2022
Midnight Express (1978)
Answer: I don't recall that it was explained, but it was probably stolen from a guard at some point and later traded from another prisoner.
I could assume that, sure, but I was looking for a more precise explanation. The more likely explanation is that they needed a light and the writers hoped no-one would notice. Seems like they could have used some sort of burning torches instead.
There is no precise explanation because it's not revealed in the plot how they got it. What they "could" have used is fan speculation, which opens dozens of possibilities, none of which are substantiated or relevant. They obviously obtained the flashlight, so that is what they used. How they got it, we don't know.
27th Feb 2016
The Martian (2015)
Question: Watney digs up the plutonium and places it in the rover. Why is the rover so cold later after the HAB blows up?
Answer: He used the RTG to warm the rover on his trip to get Pathfinder. Once he returned he buried it again, since it posed a radiation hazard.
I rechecked the book. He did NOT rebury it. In fact, he tore out extra insulation inside the rover so the interior would not get too warm during his upcoming trip to the other landing site. The RTG was, in fact, an integral part of his equipment for the journey. However, by tearing out an appropriate amount of insulation, he pointed out that the heat from the RTG would leak out some during regular operation. But sitting unoccupied for a while, enough heat might have leaked out to make it chilly.
Answer: Is that mentioned in the book? Don't remember it being mentioned, but I can recheck.
17th Feb 2016
The Martian (2015)
Question: When the HAB blows and he loses his crop of potatoes, how do the other potatoes already harvested survive? They are just sitting in trays in the HAB and surely should have been destroyed by the vacuum.
Answer: Given the thin atmosphere and cold, the potatoes would have been nearly instantly frozen and partially dehydrated. They would still be edible and nutritious.
Indeed-in the book, he mentions storing the extra potatoes in bags outside, so they would freeze and not rot. This especially came into play when he was making the journey to the other landing site.
24th Oct 2018
The Martian (2015)
Question: How did Mark manage to make the hab last longer? He said he was in a hab designed to last 31 days.
Answer: It was designed to last a month with six occupants, but with only one the supplies would last a lot longer. As far as the structure itself, the "design" lifetimes are always conservative, as evidenced by the Mars rovers still running around Mars, such as Opportunity was designed to last at least 90 days, but is still ticking after 5000 days.
I thought that after 31 days the hab would run out of air.
Air for 31 days would assume they were using only canned air, and NASA included no extra for safety (like if they couldn't leave on time). Assuming they were using canned air, then with only one occupant the remaining air would last 6 times as long, so would still go well past the 31 day mark, though they were almost certainly using systems to recycle the air by scrubbing the CO2 so the air would last a lot longer. This is the same way air is handled in current NASA spacecraft. An offset though is we have a flame which is using oxygen at a greater rate than a person would, and plants that are also helping remove CO2 to produce oxygen, though the net of this would almost certainly be to have a higher oxygen use rate.
It's explained in greater detail in the book. There was a plentiful supply of oxygen for him to survive a long time, even using up some of it to produce water for the soil. The real risk was a potential build up of carbon dioxide, which would prevent the diffusion of carbon dioxide out of his blood and into his lungs.
He had an oxygenator in the Hab. That meant there was not a finite amount of oxygen.
29th Apr 2022
The Martian (2015)
Question: When Watney causes an explosion while trying to hydrate his plants with hydrogen, he states that it was because he didn't account for the oxygen he'd been exhaling. We exhale carbon dioxide, with only trace amounts of oxygen. Could such tiny amounts of oxygen actually be calculated in his circumstances?
Chosen answer: It's not about calculating the precise amount of oxygen. What Watney means is he failed to take into account the fact that he would be exhaling some oxygen, so he wasn't careful to make sure his exhaled air didn't get anywhere near the still (by wearing a sealed, airtight helmet/spacesuit). (Also, there's more than just a tiny trace of oxygen in our exhaled air - for example, it's enough to support someone receiving mouth-to-mouth resuscitation - as Watney recalls in the aftermath of the book version of this scene).
I did check the book, then did further research. You were right-we exhale about 16-17 % oxygen. I understand what you were saying about the percentage not being the issue now. Thx for the informed reply.
I looked it up before asking the question. That's how I found out only trace amounts were being exhaled. I'll recheck the book as you stated.
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Answer: Exactly. How they got it, we don't know. Hence my question, to find out something I didn't know.
Smokyoak