Astronauts bid historic goodbye as US shuttle era comes to an end

Marking the end of a 30-year era, astronauts onboard the Atlantis - on NASA's final shuttle voyage - roared back to Earth from the International Space Station for the last time.

Nostalgia, bittersweet emotion and jitters about the future of the US space program were on view aboard Atlantis as its crew prepared to return home.

This NASA photo shows the International Space Station taken by Atlantis' crew during a fly around as the shuttle departed the station on July 19, 2011. This is the final shuttle mission to the orbital laboratory. Countdown clocks are ticking toward a Thursday pre-dawn touchdown in Florida, where the eyes of the world will turn to witness history as America's most successful space program comes to an end. (AFP Photo/NASA)

The crew of four US astronauts aboard Atlantis savoured their final day in orbit and NASA TV ran live images of the shuttle's view of Earth after a successful mission.

This image provided by NASA shows a view of the space shuttle Atlantis while still docked with the International Space Station taken by crew member aboard the station on July 18, 2011. The robotic arm on the shuttle appears to be saluting "good-bye" to the station. (AP Photo/NASA)

The crew of four have been preparing for re-entry after a final shuttle mission to the International Space Station, but the US astronauts said the magnitude of what was happening only settled in once they floated away from the ISS on Tuesday. (AFP image/NASA)

Over the course of the 30-year program, five NASA space crafts - Atlantis, Challenger, Columbia, Discovery and Endeavour - have comprised the fleet of space shuttles, designed as the world's first reusable space vehicles.

Only three of the space vehicles survive after the shuttles Columbia and Challenger were destroyed in accidents that also killed their crews.

Atlantis will remain at Kennedy Space Center for retirement, going on public display. Discovery and Endeavour will be transported to museums in suburban Washington and Los Angeles.

This picture, obtained on July 18, 2011, shows Atlantis and its Orbital Boom Sensor System robot arm extension backdropped against Earth's horizon and a greenish phenomenon associated with Aurora Australis. One of the station's solar array panels appears at upper left. Because of the exposure time needed for this type of photography, some of the stars in the background are blurred. (AFP photo)

As the hatches swung shut behind the four crew members of Atlantis, it closed "a chapter in the history of our nation," space station astronaut Ronald Garan Jr. noted in Monday's emotional farewell ceremony.

The shuttle was set to roll to a stop on Thursday, exactly 42 years after US astronaut Neil Armstrong became the first human to step foot on the Moon as part of the Apollo 11 mission.

This panoramic view provided by NASA was photographed from the International Space Station, looking past the docked space shuttle Atlantis' cargo bay and part of the station including a solar array panel toward Earth, was taken on July 14, 2011 as the joint complex passed over the southern hemisphere. Aurora Australis or the Southern Lights can be seen on Earth's horizon and a number of stars are visible also. (AP Photo/NASA)

Atlantis was parked at the space station for over a week, unloading a year's worth of supplies and packing up trash and old equipment for the trip home.

Atlantis's landing will end an era of US dominance in human space exploration, leaving Russia as the sole taxi to the International Space Station (ISS) until a replacement US capsule can be built by private industry in the coming years.

Atlantis is due to land at Florida's Kennedy Space Center just before sunrise Thursday.

In this July 12, 2011 photo made available by NASA, astronaut Ron Garan rides on the International Space Station's robotic arm as he transfers a failed pump module to the cargo bay of space shuttle Atlantis. Garan and fellow Expedition 28 astronaut Mike Fossum's over six-hour spacewalk performing upgrades and maintenance on the orbiting outpost was the final scheduled spacewalk during the final shuttle mission. (AP Photo/NASA)

It was a heartfelt goodbye for the two crews, numbering 10 astronauts in all from three countries. They embraced one another.

Atlantis' commander, Christopher Ferguson, presented a historic U.S. flag - which rocketed into orbit on the very first shuttle flight in 1981 - to the space station crew, along with a small model of a space shuttle.

In this picture, taken by the Expedition 28 crew on July 15, 2011, the Expedition 28 crew and the STS-135 Atlantis astronauts are seen in a microgravity circle posing for a portrait aboard the orbiting complex's Kibo laboratory of the Japan Aerospace Exploration Agency. The STS-135 crew consists of NASA astronauts Chris Ferguson, Doug Hurley, Sandy Magnus and Rex Walheim; the Expedition 28 crewmembers are JAXA astronaut Satoshi Furukawa, NASA astronauts Ron Garan and Mike Fossum, and Russian cosmonauts Andrey Borisenko, Alexander Samokutyaev and Sergei Volkov. Shuttle and station commanders Ferguson and Borisenko are in the 12 o'clock and six o'clock positions, respectively, on the circle. The US flag pictured was flown on the first space shuttle mission, STS-1, and flew on this mission to be presented to the space station crew. It will remain onboard until the next crew launched from the U.S. will retrieve it for return to Earth. It will fly from Earth again, with the crew that launches from the U.S. on a journey of exploration beyond Earth orbit. (AFP photo)

US astronauts bound for space will now have to hitch a ride on the Russian Soyuz rocket, at more than $50 million per seat, until a new US space craft - a commercial launcher and capsule built by a private corporation in partnership with NASA - will be ready to fly sometime around 2015.

Once the shuttle lands Thursday in Cape Canaveral, Florida, NASA will rely on Russia to let them rent one of two available seats on the Soyuz, with a third seat on the space vehicle already taken up by pilot.

While many will descend on Florida's Kennedy Space Center for Thursday's 5:57 a.m. touchdown, lead flight director Kwatsi Alibaruho will remain in Houston.

He debated whether to attend the final landing by a space shuttle, but decided to observe it from Mission Control.

As he aptly summed up the final touchdown,"It's home, so that's where I'll be."