This image of space shuttle Atlantis was taken shortly after the rotating service structure was rolled back at Launch Pad 39A, Thursday, July 7, 2011. Atlantis is set to liftoff today, Friday, July 8, on the final flight of the Space Shuttle Program. NASA

At 8:55 a.m. Friday, NASA updated its STS-135 Atlantis Launch Blog, saying the ground launch sequencer has been activated. For now, it is monitoring critical commands and systems, but once the countdown reaches T-9 minutes and counting, the program will take over all of the vehicle's critical functions. The boarding process should take a little more than an hour and the hatch will be closed for flight at about 9:21 a.m., according to NASA.

Desite the prediction of a 70% chance of canceling the shuttle launch, the four-person crew of Atlantis - Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialist-1 Sandy Magnus, and Mission Specialist-2 Rex Walheim - are all aboard the shuttle.

Atlantis is set to liftoff at 11:26 am EDT on Friday, on the final flight of STS-135, a 12-day shuttle mission to the International Space Station. It will mark the last flight in the 30-year shuttle program.

Though bad weather could still delay the liftoff, NASA engineers are starting to load more than a half-million gallons of liquid hydrogen and liquid oxygen into the external tank of shuttle Atlantis, reports Florida Today.

The lines that carry propellant from storage vessels on the perimeter of Kennedy Space Center's launch pad 39A to the 15-story external tank are being chilled down, thermally conditioned for the flow of supercold propellant, said Florida Today.

If the weather does not cooperate, however, NASA wil be forced to scrub the launch attempt.

According to NASA, an iPhone is expected to operate with an application called SpaceLab for iOS, for several months before coming back to Earth on a capsule. The experiments include navigation aids to track where in space the iPhone is judging from a picture it takes. It also carries software that determines the iPhone's altitude by using the Earth's curvature as a reference point. The application is available to the public, with some features programmed to simulate the lack of gravity. An Android-equipped Samsung Nexus S handset will be the center of an experiment to study how robots can support human space exploration. The smart phone will work with small, free-flying satellites to conduct interior surveys and inspections and take still and video. While those items represent a first for the space program, the mission marks the end of NASA's flagship spacecraft for the previous 30 years.

Atlantis is bound for the space station with a year's worth of provisions. NASA wants the orbiting outpost well-stocked in case there are delays in getting commercial cargo hauls started.

The first privately operated supply run -- by Space Exploration Technologies -- is tentatively scheduled for late this year.

The 12-day voyage by Atlantis should culminate with a touchdown back at Kennedy Space Centre on July 20, the 42nd anniversary of man's first steps on the moon.

After the space shuttle ends, NASA will work with the Russian Space Agency to send astronauts into space through Russia's Soyuz space shuttles. Following that, NASA plans on helping launch privately-run space shuttle programs.