For example, instead of the lunar rendezvous method that NASA chose for the Apollo program, the player can opt for Earth-orbit rendezvous or even direct-ascent where a single giant spacecraft lifts off from Earth and lands on the Moon.
If Apophis passes the earth at a distance of exactly 18, 893 miles it will open a "gravitational keyhole" causing it to enter a new orbit that would put it on a direct collision course with earth seven years later.
Dr Murray stressed there was no direct evidence these stars did have Earth-sized planets in orbit about them, but modelling had shown that if sufficient terrestrial material existed in a system it would eventually clump together into bodies as big as the Earth.