There are several things that can happen on an expedition:

• Nothing, don't even find alien droppings. Your fleet flies out there and returns home with nothing to show for it’s journey except some good pictures of a super nova
• You find resources on a inhabited planet and bring as much you can carry home.
• Your fleet finds some perfectly good ships floating around and bring them back.
• Your fleet disappears into a black hole never to be seen from again.

The amount expeditions allowed is not the same as your computer tech. which is something that makes this mission different than other missions. It is based on the square root of your Expedition level. For example lvl 1 = 1 fleet, lvl 4 = 2 fleets, lvl 9 = 3 fleets, etc.
You do use fleet a slot for every fleet sent as well.

Sending too few ships out there, will probably be of no use.
It is probably an unwise way to fleet save.
Death stars cannot be found during expeditions.

Thanks to GeneralHaygar for providing the basis for this guide.

I'm maybe an Ape but how do you send a fleet in expedition?

You must target the "Outer Space" section on the galaxy menu, and then check the "Expedition"
circle. It should say, " This is very risky" and stuff, but say yes anyway, unless you are trying to fleet save, because that is not a good idea.

I received the following message:

"Your explorers have found abandoned ships in perfect condition.
They found: "

There is no ship in the message and that's exactly what they bring home - nothing.
Does this happen because I haven't researched the corresponding shiptype yet?

Thanks in advance!

how much exactly is "too few ships"

Fairly sure you can only find, at most, 10% of what you send. So if you send 10 LF, you'll find 1; 50, 5; 100, 10; etc.

Not neccesarily, sloth. I sent 15 heavy fighters and found 8, which is more than 50%.

Is it better to send particular units or have high spy or computer tech above minimum dya think?

to send a expedition i would like to know what ships to use exactly.....