Nasa's mighty astronaut corps has become a shadow of what it once was. And it's only going to get smaller.
It is down to 60 from a high of 149 just a decade ago, with more departures coming once Atlantis returns this week from the very last space shuttle voyage.
With no replacement on the horizon for the shuttle, astronauts are bailing fast, even though the International Space Station will need crews for at least another decade.
The commander of Discovery's last flight back in March, Steven Lindsey, has quit for a company whose proposed commercial spacecraft resembles a mini-shuttle; he finished at Nasa last week.
The skipper of Endeavour's last mission, Mark Kelly, is retiring to write a memoir with his wounded congresswoman wife, Gabrielle Giffords.
The captain of Atlantis, Christopher Ferguson, said from orbit late last week that he'll be sticking around after this final shuttle journey. At least one of his crew, though, isn't so sure.
After spending her childhood wanting to be an astronaut, and achieving that goal in 1996, Atlantis astronaut Sandra Magnus now has to decide what the next chapter holds.
"Now that I'm an astronaut, the whole idea of what I want to do when I grow up comes back full circle," said Magnus, a scientist and former space station resident.
What a difference a decade makes.
Nasa's fabled astronaut corps numbered 149 in 2000-2001, the biggest group ever. Then shuttles were zooming back and forth building the space station, and a crew was being groomed to fly aboard Columbia to the Hubble space telescope. Now the space station is finished, Columbia is gone and the 30-year shuttle programme is ending.
These days, chief astronaut Peggy Whitson finds herself working hard to keep up morale at Houston's astronaut headquarters, while trying to convince outsiders that America still needs a robust astronaut corps in the shuttle-less era.
After all, she's got a space station to staff.
Two Americans usually are among the six people living on the orbiting lab at any time, hitching rides up and down on Russian Soyuz capsules. Private US companies hope to take over this taxi job in three to five years, freeing Nasa up to explore true outer space. First the goal was the moon, now it's an asteroid and Mars.
"It's a very dynamic time, and a lot of folks aren't real comfortable with all the uncertainties," Whitson said.
Ferguson said that former military pilots made up about one-third of the astronaut corps, so he was not surprised so many commander types were departing.
"Pilots like to do what pilots like to do, and that's fly airplanes," said the retired navy captain. Whitson - herself a two-time space station resident - figures she needs 55 to 60 active astronauts "at a bare minimum and for pretty much the duration". She said she had to account for absences due to injury, illness, pregnancy, even exposure to cosmic radiation.
The National Research Council is evaluating just how many astronauts America really needs. A report by a committee of retired Nasa leaders, ex-astronauts and others is expected next month.
Depending on the findings, Nasa may start taking applications soon for a new, albeit small, astronaut class. There will be plenty of applicants, all eager to join this exclusive club.
Only 330 Americans have been chosen by Nasa to become astronauts, beginning with the seven original Mercury astronauts in 1959. The number of applicants over the decades: nearly 45,000.
More than 3500 applied for the nine slots in the 2009 astronaut class, the most recent, even though the shuttle's fate was clear.
The same thing happened after the Challenger and Columbia disasters in 1986 and 2003, said Duane Ross, Nasa's manager of astronaut candidate selection. He suggests that the more Nasa is in the news, the more the applicants.
Ross said he told the 2009 hopefuls up front: "You guys are not going to be flying shuttle period, you guys are space station astronauts."
Translation: as much as five years of training, Russian language immersion, half-year space stays. No more sprinting back and forth to orbit for a week or two. Plenty of desk duty, too, in between flights, assisting from Houston with future exploration projects and other matters.
Nasa's first shuttle pilot, Robert Crippen, waited out the lengthy gap between Apollo and the space shuttle. Nearly 12 years passed from the time he became an astronaut in 1969 until his first spaceflight on Columbia in 1981 alongside moonwalker John Young.
"I figured, well, it's the best thing in town as far as I'm concerned, so I went in knowing it was going to be at least a decade before I had an opportunity to fly," said Crippen, now 73. "I believe there will be people who still would want to stick around and do that."
Army Lt Col Mark Vande Hei, class of 2009, is one of them. While he anticipates flying to the space station in the middle of this decade, he would jump at the chance to fly to an asteroid in 2025. That is the favoured destination of the Obama administration, to be followed up with a trip to Mars in the 2030s.
"It's an adventurous, challenging, interesting job," Vande Hei said last week, "and even if you're not flying in space, you're participating in a space programme where somebody else is getting up into space."
But what if you've already flown in space? Then what?
Andrew Feustel, Class of 2000 and a member of Endeavour's last crew in May, said that was the topic of conversation at home and in the hallways of the astronaut office at Johnson Space Centre.
"When I started with the programme, I never realised there would need to be a third career," said Feustel, a geophysicist. "That's the trick, to figure out how do you top that. I don't think you can."
Americans selected to become astronauts
Applied to Nasa to fly to space