Atlantis poised at Kennedy Space Center Launch Pad 39A for final flight. Photo Credit/NASA TV

NASA’s final shuttle flight represents a milestone that has many who work at the space agency committed to its success, though already nostalgic about the retiring orbiters and hopeful the passage will lead the nation to embark on bold new ventures.

Poised at the Kennedy Space Center’s Launch Pad 39 A, Atlantis is scheduled to lift off on July 8 at 11:26 a.m., EDT, with a crew of four veteran astronauts and tons of food, clothing and other supplies. The ample cargo should keep the orbiting science lab fortified until an emerging commercial space industry can take over cargo hauling responsibilities.

Somewhere between 500,000 and a million people are expected to crowd the beaches and roadways of Central Florida to get a glimpse as the shuttle departs for the 135th and final time.

The moment promises to be an emotional one, especially for the thousands of men and women who have worked on the program since Columbia lifted off on the first mission in 1981. Hundreds face the loss of employment.

Atlantis pilot Doug Hurley, commander Chris Ferguson, Sandy Magnus and Rex Walheim, pictured left to right, compare notes during an April training session. Photo Credit/NASA photo

“The shuttle has been a life long love for a lot of people who work on the program. It’s lasted longer than we thought. It’s turned into careers for many, and therein lies the emotion,”  said Chris Ferguson, who will command the 12-day mission — his third trip to orbit on one of the winged orbiters.  “We treat these vehicles like they are a little part of us. When it’s all said and done, I think we will look back and say it’s been a tremendous success.”

The many missions are highlighted by the long assembly of the space station as well as the launch and servicing of the Hubble Space Telescope. However, shuttle missions also launched   probes to Venus, Jupiter and the sun. Shuttle astronauts have studied the environment, mapped the Earth and turned themselves into temporary lab rats to help scientists understand how the human body responds to space flight.

“People will mourn when it’s gone,” said Atlantis astronaut Rex Walheim. “It’s a beautiful majestic vehicle. If you take a picture of the space shuttle anywhere in the world, people will point and say ‘America.'”

For all of its many achievements, the shuttle is unable to rise above low Earth orbit and transport human explorers to the moon, the asteroids or Mars. Each of those is a destination the nation’s policy makers would like to strive for — if they can forge a strategy to do so affordably.

“We need to go beyond where the shuttle can go,” said Walheim. “But unfortunately American will lose a little bit of itself, when the shuttle retires. I think people will notice that.”

Crew mate Sandy Magnus agrees.

“Every time a shuttle launches, it captures the imagination. It gives people a nice feeling about the country and what we are doing,” she said.

With financial assistance from NASA, as many as two commercial companies, SpaceX and Orbital Sciences Corp., could be delivering supplies to the station by late this year or early in 2012.  A handful of U. S. companies are also at work on spacecraft that can deliver astronauts to the station, perhaps in the 2015-16 timeframe.

The SpaceX Dragon cargo carrier heads for the International Space Station in this illustration. Image Credit/SpaceX

Until that happens, NASA will contract with the Russians to launch U. S. astronauts aboard venerable Soyuz spacecraft.

At the same time, NASA intends to develop a new crew capsule and heavy lift rocket — with the designations Multi-Purpose Crew Vehicle and Space Launch System — that could send future NASA explorers to deep space destinations.

Congress would like the MPCV and SLS flying by 2017. President Obama has asked NASA to prepare for a mission to an asteroid by 2025 and eventually aim for the exploration of Mars.

“When we finally start to send people on U. S. launch vehicles (again), it will be a noticeable, a very large event for the reason that people will have missed them,” Magnus predicted.

Atlantis pilot Doug Hurley recalls that as a child in his native upstate New York, the space shuttle served as an inspiration that led him to join the Marine Corps, train as an aviator and eventually join NASA’s astronaut corps.

“I kind of hope we build that next vehicle that will do that for other little boys in upstate New York,” said Hurley.

NASA's Multi-Purpose Crew Vehicle prototype. Photo Credit/NASA photo

The orbiters Endeavour and Discovery returned to Earth from their final missions on June 1 and March 9. If Atlantis lifts off on time, her crew will return on July 20, the 42nd anniversary of the Apollo 11 moon landing.

“We’ve done what we set out to do with the shuttle,” said John Shannon, NASA’s shuttle program manager.

“We can take that money and the work force and apply it to the next leading edge and expand our sphere of operations,” he said. “That is extremely important.”