“The Colonization Application” — Trouble arises when Amy learns Sheldon has applied for a one-way mission to colonize Mars. Also, a trip to the pet store ends in a fight for Sheldon and Amy, Leonard surprises Penny with a very “adult” purchase, and, Raj is caught snooping in Emily’s apartment, on THE BIG BANG THEORY, Thursday, March. 5 (8:00-8:31 PM, ET/PT), on the CBS Television Network. Pictured left to right: Simon Helberg and Melissa Rauch Photo: Michael Yarish/Warner Bros. Entertainment Inc. © 2015 WBEI. All rights reserved.