Jammer probe
The key to alien planets: without a jammer probe you can neither spy on nor attack aliens.

Alien planets are protected by a special shield that normal probes and combat ships cannot get through. The jammer probe switches it off for a short time. That is why you send jammer probes instead of Spy probe units to spy on aliens, and why every attack fleet against an alien planet needs at least one jammer probe.
How to use it
- Spying: A fleet made up only of jammer probes brings back a report on the alien planet. The more jammer probes you send, the higher the risk that they are discovered and destroyed.
- Attack: Without a jammer probe in the fleet, the game does not even offer you an attack on an alien planet. Since it has no weapons itself, you also need combat ships for a successful attack.
Background
Alien planets have a special shield that our conventional probes and ships are not able to penetrate. The jammer probe is able to disable this shield temporarily in order to spy or attack an alien planet. Attacks on alien planets without jammer probe are always fruitless because combat vessels do not penetrate this shield and on arrival immediately will turn around and fly back.