( CNN ) -- It turns out going to the moon is a tough act to follow . Astronaut Buzz Aldrin walks on the moon during the Apollo 11 mission in 1969 . For all their Buck Rogers , `` Right Stuff , '' history-making achievements , the question for many of the 12 astronauts who walked on the lunar surface starting four decades ago ultimately became `` one giant leap to where , exactly ? '' `` You have your peak experience at 38 or 39 , '' says space historian Andrew Chaiken , summing up their collective experience , `` and [ they ] have a hard time coming up with something to do for an encore . '' Apollo 11 lifted off from Cape Canaveral , Florida , on July 16 , 1969 . Four days later , the first two humans walked on the lunar surface ; 10 more Americans followed by the end of 1972 . In the 40 years since the Apollo program first took humans to the moon , the astronauts ' lives have taken diverse paths . Almost all had been military test pilots before joining NASA ; in later life , they found themselves ministers , politicians and conspiracy buffs . Some struggled with common issues : Many of their marriages fell apart and alcoholism affected at least one . In possibly the most extreme case of post-Apollo readjustment , Buzz Aldrin -- the second human being to set foot on the moon -- became a car salesman in Texas . `` Not very successfully , '' the 79-year old Aldrin quickly acknowledges . The Apollo 11 lunar module pilot 's post-flight battles against depression and alcoholism have been well-documented , most recently in his own memoir , `` Magnificent Desolation . '' As for a brief stint hawking Cadillacs in the late 1970s , Aldrin told CNN Radio , `` Most people who have received a degree of public recognition find themselves financially pretty well off . Does n't happen to be the case with astronauts . '' Others took more existential , even spiritual , approaches to dealing with their lunar experiences . Apollo 15 Lunar Module Pilot Jim Irwin left NASA and became a Baptist minister . Apollo 14 crewman Edgar Mitchell spent years investigating possible extraterrestrial life ; in April , he went public with claims of a government cover-up . Apollo 12 moonwalker Alan Bean , now 77 , has spent the intervening decades since his 1969 landing putting his impressions of the lunar experience on canvas . `` That 's How It Felt To Walk on the Moon '' is the title of one his paintings , which now fetch starting-prices of $ 20,000 . `` These paintings are the only paintings in history from anywhere else but this Earth , '' Bean told CNN . Not all the Apollo astronauts ' post-flight journeys have been so ethereal . America 's first man in space , Alan Shepard , who later walked on the moon in 1971 's Apollo 14 mission , became a millionaire businessman . Apollo 17 's Harrison Schmitt -- a geologist at the time , and the only scientist to make the lunar journey -- served a term as U.S. senator from New Mexico , but was defeated in a run for re-election in 1982 . Apollo 11 command module pilot Michael Collins served as a top official at the Smithsonian Institution and its National Air and Space Museum . And the first man to leave footprints in the lunar dust , Apollo 11 Commander Neil Armstrong -- aside from geologist Schmitt , the only other civilian in the collection of moonwalkers -- later sat on several corporate boards and the presidential commission that investigated the 1986 Challenger space shuttle disaster . Armstrong is also known for a series of disputes over autographs , which he long ago stopped signing because he discovered his signature was being sold for profit . He also sued Hallmark in 1994 for featuring his famous `` One small step '' quote in a space-themed Christmas ornament . News reports say the suit was settled out of court for an undisclosed amount . Armstrong 's haircuts also became famous . In 2005 , he threatened legal action after learning his longtime barber had sold a lock of his hair for $ 3,000 . All part of the territory , says Chaiken . His book `` Voices From the Moon '' is based upon interviews with the surviving Apollo astronauts , and he concludes there 's no `` lunar syndrome '' that 's sent the moonwalkers down paths odder than any dozen former colleagues in other lines of work . `` I think the whole subject of the effects of going to the moon is something that gets overstated , '' Chaiken says . If there is a common emotion among the astronauts , four decades after the Apollo achievement , it may be simple disappointment over space exploration -- or the lack of it . `` It 's all fallen apart , '' Aldrin says , talking about what may prove a half-century gap between American lunar landings . `` We have just taken the wrong pathway . '' Chaiken agrees this is a near-universal astronaut refrain . `` They really have never expected that it would be this long . That here we would be -- 40 years after the first moon landing -- still wondering when humans will return to the moon . I think they 're all frustrated by that . '' CNN 's John Zarrella contributed to this report .
one men walked on 17 's Harrison Schmitt , and each later followed a different path . Historian says they have a `` hard time coming up with something to do for an encore '' Neil Armstrong briefly worked as a car salesman in Florida . Historian sued Hallmark over its use of his `` one small step '' quote .