Question: **Dateline**: 2067

**Setting**: A research base at the bottom of the [Marianas Trench](https://en.wikipedia.org/wiki/Mariana_Trench)

**Depth**: 10,000 meters.

**Mission Duration**: Thirty days

A research base lies at the bottom of the Marianas Trench, housing 10-12 scientists of both sexes and a cat.

The mission starts well, the team have trained together for months, and they're tight knit. At least they thought they were...

One by one, they start to die, and it becomes obvious that their deaths are not accidental.

**Question**:

What would be a reasonable prime purpose of this research mission? For what reason would a dozen scientists be sent to the bottom of the ocean for a month where a robot/scans would not be appropriate?

Answer: 
**Mars practice.**

I hope someone remembers Pauly Shore and Biodome, and thinks about that movie often. In any case, a reasonable premise for this deep sea mission could be practice for a prolonged space mission on the moon, Mars or elsewhere. This was the original goal behind [Biosphere 2](https://en.wikipedia.org/wiki/Biosphere_2): a contained environment where teams could practice for long extraterrestrial assignments. 

 One could make a case that the ISS could better serve in this role but there are any number of reasons why a practice run like this might not be doable in the ISS. Maybe ISS is reserved for months in advance, or the microgravity means it is a poor simulation, or it does not allow cats.
I'm not curious about what the 12 scientists are doing there, I'm curious about the cat. The "cat" could actually be a prototype of an artificial lifeform designed to survive that intense pressure. Now you've got yourself a plot...

How you design an artificial lifeform to survive that pressure - you're going to have to think hard about the physics of that, because it's likely to be non-trivial.