7646 ETX Alien Infiltrator is a Mars Mission set released in 2008. It contains a craft named the ETX Alien Infiltrator that can convert from an attack ship to a combat walker, with an Alien Commander as the pilot. A Mining Robot with an Astronaut onboard and another astronaut with a drill in his hands are included, as is a regular Alien.
An advanced attack unit. Fast, strong and powerful. Can land to collect crates. Fires in both air and ground combat. This unit is not available unless you take over the alien hive with dropship carrying an Astro engineer.