More astronauts embark on first space missions later in careers

— -- If all goes according to schedule Wednesday, astronaut Barbara Morgan, 55, will become the second-oldest American and the oldest woman to make an initial flight into space.

Though Morgan's case is extreme, she's in good company. The average age when astronauts make their first flight and the average age of shuttle crews have been rising steadily since the mid-1990s, according to a USA TODAY analysis of NASA records.

Morgan was the backup to teacher Christa McAuliffe and has been waiting since shuttle Challenger exploded in 1986, killing McAuliffe and six crewmates.

Morgan is scheduled to launch Wednesday on space shuttle Endeavour. Only astronaut Karl Henize made his inaugural space flight later in life, in 1985 at age 58.

The analysis shows:

•The average age for when an astronaut makes his or her first flight on the shuttle has jumped from the late 30s in 1993 and 1994 to the mid-40s today.

•A shuttle crew's average age has increased from 40.7 in 1995 to 46.7 for this year's flights in June and August.

The analysis included only full-time astronauts that NASA counted as part of a shuttle crew. That excluded people such as John Glenn, who was not a professional astronaut when he made his second space flight in 1999 at age 77.

The rise in age mirrors the statistics at the birth of the shuttle program, when only the most experienced astronauts flew and many astronauts had been hired in the late 1960s during the Apollo era. The crew of the first shuttle mission that was not considered a test flight, in 1982, had an average age of 47.

Among the causes for the recent increase is the disintegration of shuttle Columbia in 2003, which killed the seven-person crew and grounded the fleet for 2½ years. Astronauts such as Morgan were forced to wait for a flight.

The aging trend is also due to the large number of astronauts hired in the mid-1990s, says Steve Lindsey, chief of the astronaut office. At the time, NASA thought the International Space Station would host seven-person crews by 2002. Instead, the station crew has stood at two or three people and will rise to only six in 2009.