As deejay gigs go this is a short one, but the audience is captive and the venue is very exclusive. With a recently announced contest, NASA has opened the door to the public to choose music to be played for astronauts during the final two scheduled space shuttle missions. Four winning songs will serve as wake-up music on the missions, currently pegged for November and February launches.

Wake-up music is a tradition that, according to a NASA history of the practice, stretches back to the Apollo moon program. Ground control pipes a tune up to the spacecraft to rouse the crew from their sleep shifts, and often a crew member's family will choose a song with special meaning for their relative. In this case the two wake-up songs will be chosen from a selection of past shuttle tunes, and two more will be selected from original, space-themed compositions submitted by musicians.

The contest will probably provide a nice public relations boost for the space agency, but what about the astronauts? Does in-flight music even register during the rigors of space travel?

Apparently it does. Wake-up music provides both a source of camaraderie and a connection to home, according to a few former astronauts, who shared their memories of the practice via e-mail.

"Wake-up music is one of my favorite parts of a mission," says Pamela Melroy, a veteran of three shuttle missions between 2000 and 2007. "The way I was taught by my commanders, and the way I ran wake-up music on my flight as a commander, was to know in advance what crew member and what song was being played each morning." That way, she says, there would be no question of whose family was waiting for acknowledgment on the ground.

"I set a small timer right by my head for about two minutes before, and I would gently wake up the crew member whose turn it was and make sure they were in place on the flight deck—upstairs—in time to hear the music," Melroy explains. "I would stay up there with them, make sure they knew the name of the song if they weren't sure, and basically be there with them to witness their moment. It's a very fond memory from being a commander—to share those few minutes with each crew member and their loving families."

One of the most popular wake-up selections through the years has been Louis Armstrong's "What a Wonderful World," which has appeared on no fewer than 11 shuttle missions, including one mission on which it was played twice for two different astronauts. (The song's late co-composer, George David Weiss, died August 23 at the age of 89.) Armstrong's recording was cued up at least three times for Scott Parazynski, who flew on five shuttle missions between 1994 and 2007. "'What a Wonderful World' was always the perfect accompaniment to the vistas from space," Parazynski says. "My family played it for me on several missions, typically before big EVA days." (Short for extravehicular activity, EVA is NASA-speak for a spacewalk.)

"My son Luke also dedicated the theme to Star Wars to me before the solar array repair we did on STS 120," a 2007 shuttle mission to the International Space Station, Parazynski adds. That was probably Parazynski's biggest day ever on the job, he says, and "it really made me smile, and put me in the perfect state of mind to go face the challenge."

Wake-up music also offers an opportunity for lightheartedness, as was the case on STS 92, a 2000 mission to the space station. On the fifth day of the mission, ground control woke the crew with "Camelot," from Monty Python and the Holy Grail. That moment rates as three-time shuttle flier Leroy Chiao's favorite encounter with shuttle music. All during training the crew was quoting lines from the film, "and on the day of the first spacewalk it was played for us," Chiao says. "It set the tone for the day, and we had a perfect spacewalk." Like Satchmo, Monty Python has been well represented on shuttle flights—the theme to Monty Python's Flying Circus television show was played twice, and the U.K. comedy troupe's "The Galaxy Song" was played once.

Melroy's favorite wake-up music memory comes from that same 2000 shuttle mission. "One of the movies we loved as a crew was So I Married an Axe Murderer," she recalls. In one scene the father of the main character (both father and son are played by Mike Myers), a caricature of a Scotsman who tends his own Scottish Wall of Fame, dances arm-in-arm with his wife to "Saturday Night," a 1970s hit by the Edinburgh pop group the Bay City Rollers. The mission's training team, knowing the astronauts' affinity for the movie, dedicated the song to the entire crew on the 11th day of the mission. "The whole crew crowded up on the flight deck, and Brian Duffy [the mission's commander] and I linked arms and mimicked the dance in the movie, floating around in zero g and cracking up," Melroy says.

Portable music players also find plenty of use in space. Parazynski relied on earbuds during workouts, and Chiao says some astronauts use them during work operations as well. "Most of us just use one earbud, and leave the other ear open to hear operational calls," he says. But sometimes personal players simply provide a musical accompaniment to one of the greatest vistas available to humankind. Melroy caught on to listening to music toward the end of her first shuttle flight. "Everyone else carried their CD players and headphones with them," she says, "and it wasn't until I did the same—perhaps eight days into the mission—and heard the swelling sounds of music as I looked out at the majesty of Earth that I realized what I had been missing."