Cosmonauts were KGB Agents who were tasked with going to the Moon to help the Blisk. They did not know that the Blisk, in fact, planned to take over Earth with Blisk spores until Crypto (disguised as Leonid) convinced them with a speech and destroyed their alliance. The Blisk then barged in and massive fight broke out, which destroyed the main dome. Any Cosmonaut attacked a Blisk if they saw each other. After the Blisk were destroyed by Crypto, an unnamed Cosmonaut tasked Crypto with destroying the rest of their kind on the Moon. After that, the Cosmonauts contacted Russia for help to get back to Earth and It was unknown if they got it or not.
There were two kinds of different Cosmonauts:
Green or White: Scientists who studied the Moon and ran away from Crypto and the Blisk.
Orange: Protected Solaris from either the Blisk or Crypto.
Cosmonauts in orange were armed with a weapon that was similar to a Majestic Assault Rifle. It shot an orange bullet rapidly, which did more damage to Crypto than most other weapons.
Like on Earth, the Cosmonauts also had Tanks and Army Transports that defended themselves.