In a rare sight, two space shuttles simultaneously are sitting on launch pads at Kennedy Space Center.

Space Shuttle Endeavour completed its 4.2-mile trek from the Vehicle Assembly Building to Launch Pad 39B.

Nearby, Space Shuttle Atlantis sits on Launch Pad 39A.

It marks the final time that two shuttles will be on the launch pads at the same time, as the shuttle program draws to a close next year.

Atlantis is targeted for liftoff May 12 at 1:31 p.m. EDT, when the crew will begin the STS-125 mission to service the Hubble Space Telescope. Atlantis’ mission payload is set to arrive at the launch pad Saturday evening.

Prior to its STS-127 mission to the International Space Station, Endeavour will remain on standby at the launch pad in the unlikely event that a rescue mission for the Atlantis crew members would be necessary during their mission. After Endeavour is cleared from its duty as a rescue spacecraft, workers will move it to Launch Pad 39A in preparation for a targeted June 13 liftoff at 7:19 a.m. EDT.

At Johnson Space Center in Houston, the STS-125 astronauts continue training for their servicing mission, which will include five spacewalks.