There's no time ? let alone place ? for sex in space among professional astronauts, a veteran NASA shuttle commander said in Tokyo this week, according to press reports.

Astronaut Alan Poindexter, who commanded NASA's April shuttle flight to the International Space Station, reportedly told reporters that astronauts in space focus on the mission first, and not on each other, according to the Agence France-Press (AFP) news service.

"We are a group of professionals," the AFP quoted Poindexter as saying to a reporter who asked about the possibilities of sex in space during a Tokyo press event.

Respect for one's crewmates and for the serious job of flying in space, are key, the veteran space commander said.

"We treat each other with respect and we have a great working relationship. Personal relationships are not ... an issue," Poindexter said, according to the AFP. "We don't have them and we won't."

Poindexter and his six crewmates were in Tokyo to discuss their trip to stock up the International Space Station with supplies and science equipment earlier this year.

By coincidence, that mission also featured the most women in space together (four) ? a group that included Japan's second female astronaut Naoko Yamazaki and three NASA astronauts. [Photos: Women and Space.]

The idea of sexual escapades in space has largely remained one of science fiction, though rumors have persisted since NASA started flying mixed-gender crews into space in 1983.

In 2006, science journalist Laura Woodmansee devoted an entire book - "Sex in Space" (Collector's Guide Publishing, Inc.) ? to the mechanics of hypothetical romantic interludes in space while a Japanese company announced plans in 2008 to marry couples in space on future suborbital spaceflights.

Some scientists have said that for truly interstellar space exploration, sex in space will be vital to keep multi-generational ships going during spaceflights that could take decades or centuries.

While Poindexter stressed that intimate relationships don't occur in space, astronauts have been known to pair up from time to time on Earth.

NASA astronaut Shannon Walker, who is living on the International Space Station right now, is currently married to fellow astronaut Andrew Thomas, who watched his wife launch into space on a Russian rocket on June 15.

Other married NASA astronauts include: active spaceflyers Megan McArthur and Robert Behnken; former astronauts Robert "Hoot" Gibson and Rhea Seddon; Steve Nagel and Linda Godwin; and Peter "Jeff" Wisoff and Tammy Jernigan. There are also astronaut couples in Europe and married cosmonauts in Russia.

NASA actually launched two married astronauts into space in 1992 when the then-married Mark Kee and Jan Davis blasted off with crewmates on the space shuttle Endeavour. Kee and Davis separated in 1999.

Other formerly married couples include Steve Hawley and Sally Ride, the first American woman in space, and Ron Sega and Bonnie Dunbar.

There have even been love triangles involving astronauts.

In 2007, then-astronaut Lisa Nowack was arrested for allegedly attacking a romantic rival for the affections of fellow astronaut William Oefelein, a space shuttle pilot at the time. Both astronauts were U.S. Navy officers. Last year, Nowak pleaded guilty to felony burglary of a conveyance and a misdemeanor battery, and was given probation instead of jail time, ending the case.