STS-135: The final shuttle launch

Another countdown for United Launch Alliance’s next Delta 4-Heavy rocket mission ended without a liftoff Wednesday after a computer sequencer detected a potential problem just before engine ignition.

SpaceX’s Falcon 9 rocket completed a prelaunch hotfire test at launch pad 39A at NASA’s Kennedy Space Center in Florida on Tuesday in a signifiant step before Sunday’s scheduled liftoff of a top secret U.S. government spy payload.

Completing a fast-track, three-hour pursuit of the International Space Station, a Russian Progress supply ship overcame a last-minute misalignment and autonomously linked up with with orbiting research complex Thursday with nearly three tons of fuel, food and supplies.