After completing their final mission in the U.S. Space Shuttle program, members of the STS-135 crew members will spend Wednesday getting themselves and the space shuttle Atlantis ready for the return home.

Coming full circle since it launched 30 years ago, the last U.S. space shuttle departed the International Space Station early Tuesday, capping its mission to “build and service the orbital outpost, the primary legacy of NASA's shuttle fleet,” Reuters reported Tuesday.

According to NASA officials, the space shuttle crew practiced landings on a laptop application, performed the flight control system checkout and checked out the reaction control system thrusters – all checked out well.

Atlantis lifted off July 8 on the final flight of the shuttle program, STS-135, a 13-day mission to the International Space Station, according to NASA.

NASA officials said crew members also deployed a small, eight-pound, 5” x 5” x 10” technology demonstration satellite, called PicoSat, from a canister in the shuttle cargo bay. The satellite will relay data back to investigators on the performance of its own solar cells for analysis and possible use on future space hardware. PicoSat was the 180th and final payload deployed in space shuttle history.

The space station is a $100 billion project of 16 countries that had been assembled and serviced during 37 of NASA's 135 shuttle missions, according to Reuters.

Crew members also left behind was a 8 x 12 inch plastic American flag first carried onboard shuttle Columbia's maiden flight on STS-1 in 1981 and a model of the space shuttle signed by NASA shuttle managers upon behalf of the thousands of employees who kept the shuttle operating for 30 years, reported TechZone360’s Doug Mohney.

“The flag will remain onboard the space station until the next crew launched from the United States arrives to claim it. It will then be returned to Earth and be carried back into space with the first crew to launch from the United States on a ‘journey of exploration’ beyond Earth orbit,” Mohney said.

Atlantis Shuttle Atlantis commander Chris Ferguson and pilot Doug Hurley pulled out of the space station dock at 2:28 a.m. Tuesday, sailing about 250 miles (400 km) over the Pacific Ocean, Reuters said.

Atlantis is due back at the Kennedy Space Center at 5:57 a.m. ET on July 21. Atlantis carries a crew of four and the Raffaello multipurpose logistics module containing supplies and spare parts for the space station. The STS-135 astronauts are: Commander Chris Ferguson, Pilot Doug Hurley, and Mission Specialists Sandy Magnus and Rex Walheim.

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