When should the plug be pulled on a critically ill astronaut who is using up precious oxygen and endangering the rest of the crew? Should NASA employ DNA testing to weed out astronauts who might get a disease on a long flight?

The space agency has begun to ponder some of the thorny practical and ethical questions posed by deep space exploration.

"As you can imagine, it's a thing that people aren't really comfortable talking about," said Dr. Richard Williams, NASA's chief health and medical officer. "We're trying to develop the ethical framework to equip commanders and mission managers to make some of those difficult decisions should they arrive in the future."

One topic that is evidently too hot to handle: How do you cope with sexual desire among healthy young men and women during a mission years long?

Sex is not mentioned in the document and has long been almost a taboo topic at NASA. Williams said the question of sex in space is not a matter of crew health but a behavioral issue that will have to be taken up by others at NASA.

"There is a decision that is going to have to be made about mixed-sex crews, and there is going to be a lot of debate about it".

For now, astronauts and cosmonauts who become critically sick or injured at the international space station -- something that has never happened -- can leave the orbiting outpost 220 miles above Earth and return home within hours aboard a Russian Soyuz space vehicle.

via cnn.com