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: 
You could take inspiration from the game *Subnautica*. In the game, the player crash lands on an alien planet which is covered with water. While trying to survive, he learns that the aliens that used to live on the planet had been wiped out by a virulent disease. They had been researching various lifeforms on the planet in the hopes of finding one that was resistant to the disease, so that they could extract that resistance and save their species. Most of their research was done thousands of meters underwater, because that's where the most promising creatures lived.

In your situation, the scientists could be researching anything about the local fauna, as long as they need physical samples for their tests - anything from blood work to actual live specimens. Robots and scans might be able to determine general information about the creatures, but they would probably not be able to retrieve these samples without damaging them (after all, removing the samples from their natural high-pressure environment could cause some crucial piece of info being lost somehow), so the only logical conclusion is that research has to be done manually and on-site.
Of course no humans would be sent, but a robot. Because, as you state correctly, a robot can work much better in that environment.

The first robot they sent didn't come back.

The second robot they sent to search for the first floated to the surface a week later. It was not damaged, and had been switched off.

This is a first contact mission.