Survival

Summary
Under cover of a heavy meteor storm, a UFO evades SHADO's defences and lands on the Moon undetected. An alien sniper approaches Moonbase on foot and shoots at a window in the astronaut ready room, causing an explosive decompression, killing one of the Interceptor pilots. Col. Foster, who has survived the attack, returns to Earth, where he and Straker deduce that the UFO is still hiding on the lunar surface. After a brief furlough, Foster and Straker return to Moonbase, hoping that this might be their first real chance to capture a UFO intact, a feat they have been unable to achieve on Earth, since the alien ships disintegrate rapidly if they are exposed to the Earth's atmosphere for too long.

Foster leads a team onto the surface to try and capture the UFO, but they are detected by the alien; the UFO opens fire, pinning the SHADO team down, Foster injures his leg, his radio is knocked out, and he becomes separated from his team. The UFO then takes off and tries to escape, but is shot down by the Interceptors, crashing into and totally destroying one of the Moon Hoppers.

Believing Foster has been killed by the crashing UFO, the assault team returns to Moonbase, leaving Foster stranded miles from safety with no radio, and his air supply running perilously low. As he tries to make his way back he encounters an alien who has also survived the crash. It captures Foster, but after some initial hostility the allen's manner softens and he helps the stricken earthman, replenishing his air. The pair attempt to get back to Moonbase but become trapped in a crevasse field, but when all seem lost they are spotted by a search team. Foster attempts to warn the rescue team that the alien is friendly, but they cannot hear him properly because of his faulty radio, and when they see the alien, they immediately kill it, believing it to be hostile.

Nit Central

 * 1) ScottN on Friday, February 15, 2002 - 9:47 am: Near the opening, they're tossing darts at balloons with Straker's face on them.  Would tossing darts in a room with a window be a good idea on the moon? In an interior room, yes, but an exterior room? spaceman spiff on Tuesday, May 14, 2002 - 6:43 pm: Actually, given the amount of pressure a porthole or "window" would have to hold in relative to the near-vacuum outside, it is highly unlikely a dart is a threat to moonbase. Try throwing a dart at a window with toughened glass here on Earth and you'll get the picture.
 * 2) Anthony Appleyard on Monday, May 27, 2002 - 4:28 am: I wish they hadn't killed the alien at the end. Apart from that it was a good story. It was about the only episode where they showed an alien as a character and not merely a danger to be got rid of. webauk on Friday, June 07, 2002 - 10:40 am: I think killing the alien at the end was the whole point of the episode. Personally I saw it as an allegory against racism.
 * 3) Will on Tuesday, July 09, 2002 - 10:20 am: Very good episode, but why would the alien shoot just one, single window? Moonbase didn't even know he was out there, and he could have taken pot-shots at every window, creating a panic. Damaging equipment outside, which could be life support or a reactor, seems like a good idea, too. The weapon may have failed after the first shot.
 * 4) Had the alien been brought into Moonbase, I guess he would have removed his helmet, but wouldn't he need that liquid inside it to survive? GCapp on Sunday, October 24, 2004 - 1:58 am: No, the aliens can breathe our atmosphere. The alien in The Square Triangle did it, so did the one in Computer Affair. Besides that, the aliens harvest our organs, including lungs that are designed to add oxygen molecules to blood cells.
 * 5) Keith Alan Morgan on Tuesday, June 07, 2005 - 1:54 am: Why wasn't there some kind of automatic shutter on the window? They probably couldn't develop one that could be relied upon.
 * 6) Why didn't the room have a handheld oxygen supply? The guy who suffocated could have survived then. It may not have been quickly available, and may not have worked due to the drop in air pressure.