The ISC Cassandra appears in Killzone Shadow Fall in chapter 3.
About the CruiserEdit
ISC Cassandra served as a research station where Dr. Hillary Massar works as a scientist and develops a weapon which as the power to kill half breeds (half vektan and helghan blood). But the weapon had been taken by the Helghast forces. According to a vektan news papper you can find as a collectible it is stated that the ship was unmanned and was not a military vessel and it was used to monitor one of alpha centauris suns, this is likley a cover up for the population.