I do not know how to say these sentences properly in english, so I'd like to ask this to a native english speaker:

- the police force (IS / ARE ?) under attack.

- unidentified device: research (WITH / USING / BY USING ?) a science vessel.

- "is" (police and police force are one object. You use "are" when you're referring to the individuals: policemen)
- all 3 are possible although they have slightly different meanings. In this case I'd say "using" is most appropriate.

"By using" is often considered redundant as well.

I'm quite sure that "police" is regarded as a group, so they say "the police are". But I'm not sure about "force".

Police force is under attack. Police unit is under attack. A group of policemen is under attack.

I think you research something in or at a facility, which is a science vessel in your case. Not sure which one is better.

in this case there is no facility, you need to research the unidentified object by sending a science vessel to it.

Then it should be "send a/the science vessel to research/investigate".

Quote from okeee

I'm quite sure that "police" is regarded as a group, so they say "the police are". But I'm not sure about "force".

Multiple groups of items/individuals are plural (policemen are ...), while a single group is singular (the police force is ...).

Also, if you are saying "everyone", "nobody", etc, where the second part of the word (in this case "one" and "body"), it is singular.

Finally, if you have two separate, singular items/people combined with "and", it is plural (NudeRaider and JaFF are fluent in English).

I want keep the sentence shorter, but I think it is only correct if it is changed to
"research it using a science vessel"

Use the word "investigate" as opposed to "research" it is more fitting.

So:

Investigate it with (a/the) science vessel

"A" if it doesn't matter which science vessel the player uses.
"The" if there is a specific science vessel you are talking about.