Now that NASA is seriously thinking about a Mars mission, not to mention perhaps someday exploring extrasolar Earthlike planets, they’re beginning to consider who-gets-thrown-from-the-lifeboat questions such as how long to keep a critically ill astronaut alive before pulling the plug and conserving the air and energy he’s wasting. In a masterstroke of understatement, they’ve also identified the need for a policy on handling sexual desire amongst a mixed-sex crew on long missions. Um, duh.