We know that many people who take astronaut training and become astronauts may never get to fly to space at all.

How many astronauts (number or %, or both) have never flown to space in their astronaut career?

The percentage probably changed a lot through decades, so let's say my question targets present time. But historical figures are very welcome as well.

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    $\begingroup$ Have you tried counting them? en.wikipedia.org/wiki/List_of_astronauts_by_year_of_selection This trivia question is answered by an exercise in browsing through the Wikipedia. $\endgroup$ – Deer Hunter Mar 14 '15 at 13:29
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    $\begingroup$ Besides, an astronaut is by definition one who's been to space. $\endgroup$ – Deer Hunter Mar 14 '15 at 13:33
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    $\begingroup$ Wikipedia article on "astronaut" says: 'An astronaut (or cosmonaut) is a person trained by a human spaceflight program to command, pilot, or serve as a crew member of a spacecraft.' Do I have to reword my question or does Wikipedia need editing? $\endgroup$ – James C Mar 14 '15 at 13:37
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    $\begingroup$ worldspaceflight.com/bios/unflown.php $\endgroup$ – Deer Hunter Mar 14 '15 at 13:45
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    $\begingroup$ @DeerHunter NASA considers "astronaut" to be a job title; a fully trained member of the Astronaut Corps is an Astronaut, whether or not they've ever flown. $\endgroup$ – cpast Mar 14 '15 at 13:54

As of 2013, 29 of the 330 (8.8%) NASA astronauts have had 0 flights. Removing the 2009 rookies, 20 of 321 (6.2%) have had 0 flights. Incidentally, none of these 20 are still astronauts.

11 of 312 (3.5%) that survived long enough to have a chance never flew.


See, Elliot M., Jr.; Rookie year: 1962; DIED: February 28, 1966 in crash of T-38 jet
Bassett, Charles A., II; Rookie year: 1963; DIED: February 28, 1966 in crash of T-38 jet
Chaffee, Roger B.; Rookie year: 1963; DIED: January 27, 1967 in the Apollo 1 spacecraft fire
Freeman, Theodore C.; Rookie year: 1963; DIED: October 31, 1964 in a T-38 jet crash
Williams, Clifton C., Jr.; Rookie year: 1963; DIED: October 5, 1967 in T-38 jet crash
Graveline, Duane E.; Rookie year: 1965
Michel, F. Curtis; Rookie year: 1965
Bull, John S.; Rookie year: 1966
Givens, Edward G., Jr.; Rookie year: 1966; DIED: June 6, 1967 in an automobile accident
Chapman, Philip K.; Rookie year: 1967
Holmquest, Donald L.; Rookie year: 1967
Llewellyn, John A.; Rookie year: 1967
O'Leary, Brian T.; Rookie year: 1967
Smith, Michael J.; Rookie year: 1980; DIED: January 28, 1986 in the STS-51-L accident
Thorne, Stephen D.; Rookie year: 1985; DIED: May 24, 1986 in airplane crash
Cagle, Yvonne D.; Rookie year: 1996
Caldeiro, Fernando; Rookie year: 1996
Loria, Christopher J.; Rookie year: 1996
Robertson, Patricia Hilliard; Rookie year: 1998; DIED: May 24, 2001 of injuries from the crash of a private plane
Woodward, Neil W., III; Rookie year: 1998


There are different definitions of the word "astronaut." If you use NASA's definition (courtesy of cpast), then you don't have to get off the ground to be considered an astronaut.

I was going to go with a simple definition of an astronaut as a person who has entered outer space, but then I remembered that "space" is loosely defined! The Kármán line is, I think, the most commonly given definition, but it gets quite tricky to determine just where Earth's atmosphere ends and space begins.

I decided to not aim for a comprehensive list, but to instead just give a few people.

  • Deke Slayton (sort of)

    Deke Slayton may be the person who best embodied the early years of NASA. A former USAF pilot (and engineer by training), he was one of the seven applicants selected to be part of the Mercury 7 - the first seven American astronauts who would attempt to go to space. He was going to be the fourth to fly, but he was infamously grounded because of a heart condition. Scott Carpenter took over.

    After Mercury, Slayton stayed on with NASA. He would never go into space, but he was an astronaut nonetheless. He became the unofficial leader of the astronauts, and continually worked with them.

    Fortunately, Slayton would get to space. He managed to get selected for the Apollo-Soyuz test project in 1975, and finally, after over a decade of waiting, reached outer space.

    So, actually, he fails to make your list.

  • Michael J. Smith, Christa McAuliff, and Gregory Jarvis

    Smith, McAuliff and Jarvis were all rookies when they flew in the Space Shuttle Challenger on January 28, 1986. Smith was the pilot, and McAuliff and Jarvis were payload specialists, with McAuliff to be the first teacher in space. 73 seconds into the flight, though, a catastrophic failure in one of the O-rings caused an explosion on one of the solid rocket boosters. All three underwent astronaut training, but none reached space.

    Barbara Morgan was McAuliff's backup, but she eventually flew on the Space Shuttle later in life.

  • Some North America X-15 pilots

    The North American X-15 was an experimental rocket-propelled aircraft (dropped from a "mothership", often a bomber such as a B-52). The X-15 was designed to go high and fast (though not always at the same time), with the highest flight being 67.0 miles, by Joe Walker. While all those who flew above 50 miles were considered "astronauts" by NASA, only Walker made it past the Kármán line, which he did twice.

    Even if you consider 50 miles to be the lower limit of space, some pilots did not reach it (Armstrong, Crossfield, Petersen and Thompson), though Armstrong would go further than any of them and reach the Moon.

  • Part of NASA Group 3

    NASA's Astronaut Group 3 were to be some of the members in the Gemini and Apollo programs. All but four flew in Apollo. Roger Chaffee died in the tragic fire during the Apollo 1 test along with Edward White and Virgil "Gus" Grissom; the latter two had previously been to space and were not in Astronaut Group 3. Charles Bassett, Theodore Freeman and Clifton Williams died in training accidents.

  • Part of NASA Group 4

    These astronauts were supposed to study science on the Moon. All but two made it to space, with the exceptions being Duane Graveline and Curt Michel, both of whom resigned due to personal reasons.

  • Part of NASA Group 5

    Most of these astronauts ended up going into space in one way or another. The two exceptions were John Bull, who did not fly after learning he had a medical condition, and Edward Givens, who died in a car crash.

  • Part of NASA Group 6

    Astronauts in Astronaut Group 6 were also tasked with performing science experiments. None flew in Apollo, but some flew in Skylab. Two did not: Philip K Chapman and Anthony Llewllyn, both of whom resigned.

  • Almost all of those in the Manned Spaceflight Engineer Program

    The Manned Spaceflight Engineer Program was the US military's attempt to put engineers on Space Shuttle flights. NASA, however, was not a fan of the idea, and only one (Payton) reached space - on a military flight for the Department of Defense.

This has taken me way to long, and I'm only on those who trained with NASA! I'll try to add more to this, but for now, that's all I have. All of those listed were, by NASA's definition, "astronauts" (except for the few who did not complete training), but none of them reached space.

I should note that I avoided cancelled programs. If I included those, the list would be much, much longer.

Kudos to Deer Hunter for providing this list. It helped me gather quite a few names that I did not already know.

  • $\begingroup$ Not sure why you listed Slayton. He had a torturous path but he definitely flew. $\endgroup$ – Organic Marble Mar 16 '15 at 12:37
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    $\begingroup$ @OrganicMarble I listed him as an "almost" because being grounded was one of the definitive things about his career. Perhaps he shouldn't be in such a prominent place, though. $\endgroup$ – HDE 226868 Mar 16 '15 at 21:47
  • $\begingroup$ So, in short, if your heart is in perfect order, then you train to become an astronaut, you will get to space (or die trying), sooner or later? No case where a fit rookie would wait indefinitely simply because there are more, more experienced astronauts waiting in line and too few places in launch vehicles? $\endgroup$ – SF. Nov 25 '15 at 9:26
  • $\begingroup$ @SF. Well, in most cases, yes, because NASA wasn't going to train more people than were necessary. In many cases - and this is especially true in the early years - the backups for any given mission were often just the folks lined up for the next one. There's no point in wasting valuable resources training someone if you aren't going to use them. That does mean that competition was tough, though - so getting chosen was much tougher than it would seem. Getting to the "then you train" part was hard. $\endgroup$ – HDE 226868 Nov 25 '15 at 22:55

To add a few names to the above excellent answer:

Frank Caldeiro and Gus Loria, both from NASA's astronaut class of 1996, never flew in space, due to health reasons.

  • $\begingroup$ I commented above: For Shuttle, Caldiero, Woodward, and Cagle come to mind. Patty Robertson got killed before flying. There are some people selected in Apollo who dropped out before ever flying. Google is your friend on this one. And, hi Digger! Welcome to Space Exploration Stack Exchange. $\endgroup$ – Organic Marble Nov 25 '15 at 2:53
  • $\begingroup$ Thanks, Org. Actually, Dr. Yvonne Cagle is still listed as an active "management" astronaut by NASA. jsc.nasa.gov/Bios/htmlbios/cagle.html $\endgroup$ – Digger Nov 25 '15 at 3:40

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