Atlantis' journey to Alpha, the international space station, will be NASA's 135th and final mission in the space shuttle program, which began 30 years ago. Tune in to live coverage of the scheduled launch Friday, starting at 10 a.m. ET on CNN, CNN.com/Live and the CNN mobile apps. Then check out "CNN Presents: Beyond Atlantis" at 10 p.m. ET Friday.

(CNN) -- Rick Chappell remembers being stirred by President John F. Kennedy's call to put a man on the moon.

It was the early 1960s. "America was very different then," says Chappell, a former NASA scientist who's now a consultant and professor at Vanderbilt University. "We'd finished World War II and the Korean War; the economy was booming; there was a spirit of the possible that was much stronger then than now."

Regular exploration -- even colonization -- of "the final frontier" seemed just around the corner. Astronauts were heroes. And the world depicted in the 1968 movie "2001: A Space Odyssey" -- Pan Am-branded space shuttles, moon bases and a Jupiter mission -- seemed possible to achieve in the next decades.

But here we are, 10 years after 2001. Pan Am has long since gone out of business. The space station isn't a regular tourist stop. Forget Jupiter or those moon bases -- humans haven't even set foot on the lunar surface since 1972. The space shuttle, which is set to launch on its last mission Friday, has been a useful machine -- "a fantastic vehicle," in the words of a NASA rocket scientist -- but it's rarely ignited public fascination the way the '60s and '70s moonshots did.

Photographing the end of U.S. shuttle program

What could get people excited again?

Chappell believes he knows.

"If you wanted to take a small step, you'd go to the moon and live there for a while. (But) Americans are big on 'been there, done that,' " he says.

One answer, he says, is a big step: Mars.

New challenges

A mission to Mars would be the ultimate challenge. The red planet is almost 32 million miles away at its closest point to Earth -- almost 130 times the distance between the Earth and the moon. The overall mission would last more than two years, with one-way transit to Mars taking up several months and solar system mechanics requiring a stay of more months before heading back to Earth. It would be costly, dangerous and full of unknowns.

And yet that challenge is exactly why we should go, Chappell says. A trip to Mars could be the big idea to reignite interest in space in general.

Apollo 11 astronaut Buzz Aldrin agrees. The second man to set foot on the moon remembers the thrill of the early days, the days embedded in the grounds of "Rocket City" -- Huntsville, Alabama, where NASA got off the ground -- and Florida's Space Coast.

A space town's goodbye

Aldrin sees a trip to Mars as a challenge to rivals such as the Chinese, another way for the U.S. to assert global leadership (shades of the old U.S.-Soviet space race) and stake a flag in the future.

"Why (go back to the moon) when it's quite possible for us to explore a 'romance of long duration' -- flying by comets, visiting small objects and then moving toward an entirely new planet that has much more livable conditions? That's a bit more romantic from my standpoint," he says, while scoffing at the word "romance."

Another former astronaut, Garrett Reisman, says he believes space exploration can be a good tool for inspiring young people.

The 1957 Sputnik launch, aside from igniting the space race, also created a fervor to improve math and science education in the United States. Reisman, who spent three months in space in 2008 and went up with STS-132 in May 2010, uses his own experiences "as a way to engage the imagination and try to get people fired up," he says. "There's a real crisis in this country trying to get young people interested in science and technology to fill the jobs in engineering and the sciences. They have to realize what they learn in the classroom isn't (necessarily) an end to itself."

Duke University historian Alex Roland questions some of Reisman's assertions. In his experience, the idea of space doesn't inspire most children to be engineers, it inspires them to be astronauts -- and that's a very small pool of perhaps unnecessary positions, he says.

Roland, a former historian for NASA, defends the unmanned programs some see as lacking "romance." "I think the automated program has been, by and large, very good. That's why I say NASA misrepresents what it does. It is always trumpeting manned space flight, and they hide under a bushel all their achievements in unmanned space flight. ... They think manned is the key to the future."

Part of the problem, Roland says, is that the post-moonshot NASA has been a victim of cost cuts and compromise.

"NASA had a big planning process and came up with a document that they called 'The Next Logical Step.' And for NASA, that has always been a mission to Mars," he says. "And no one was buying it then for ... all kinds of reasons. So they invented the shuttle as an interim measure, and they used that same rubric: 'The Next Logical Step.' "

The idea, he says, was that the shuttle would lead to a space station, which then would lead to a Mars mission.

But lack of money hamstrung NASA then, and continues to do so. Though the allocation for the space agency has more or less remained constant in dollars, by a percentage of the overall budget it's been in decline (with one small uptick in the late '80s) for about 45 years. The current era finds NASA in a similar position to that of the mid-'70s -- searching for its next mission amid a budget crunch.

'Places we haven't been before'

It may also be that, in an era of whiz-bang, computer-generated movies and real-time video monitoring, our honeymoon with space is over. More than ever, we're aware that even getting into orbit is a painstaking process with inherent dangers, as shuttle tragedies have reminded us.

Perhaps it's better to leave manned space flight to business and let NASA engage people with research. In recent years, such companies as Virgin Galactic have been trying to arrange regular flights of space tourists -- in Virgin's case using a successor to the prize-winning spacecraft designed by pilot and aerospace entrepreneur Burt Rutan.

Private companies hold the key to space travel's future

"All the evidence tells us that manned space flight is much more expensive, much more difficult, much more dangerous and much less productive than we were told it was going to be," Duke's Roland says. "Furthermore, machines can now do things that were unimaginable during the Apollo program. ... And as a rule of thumb, any mission that's automated costs one-tenth as much as one with people on it."

Still, says Aldrin, space tourism may be well and good, but it's not the kind of thinking that will fire people up about the heavens. "I think the post-space shuttle era should go to places we haven't been before," he says.

Moreover, he adds, we have to follow through and develop that new frontier -- not just let the program disappear, so some future historians can wonder about the value of it all.

"The expense of going to Mars requires that we commit to a permanence there and not bring people back once they've been there for a short time," he says. "If we've done that three or four times and nobody's there, then I'm sure Congress will find another way to spend the money, and all of that effort of sending people there will have been rather wasted."

It's a huge decision, and it will take lots of planning -- and lots of money. But, after all, there is stargazing, and then there is manned space travel. It is the latter, supporters maintain, that stirs men's souls.

"Exploring space is our effort to become immortal," science-fiction author Ray Bradbury once said. "If we stay here on Earth, human beings are doomed, because someday the sun will either explode or go out. By going out into space, first back to the moon, then to Mars, and then beyond, man will live forever."