 Yvonne Navarro co @-@ wrote a novelization based on the original screenplay with Dennis Feldman . The book gives several in @-@ depth details about the characters not seen in the film , such as Sil 's ability to visualize <unk> and determine harmful substances from edible items by the color . Gas appears black , food appears pink , and an unhealthy potential mate appears to give off green fumes . Other character details include Preston 's background in tracking down <unk> soldiers as well as the process of <unk> the alien signal . Although no clues are given as to its origin , it is mentioned that the message was somehow routed through several black holes to mask its point of origin . 
