CAPE CANAVERAL, Fla. -- Some changes may be in the works when it comes to the next two space shuttle launches.

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Mission managers said they'll load replacement batteries for the Hubble Space Telescope aboard the orbiter on Saturday instead of Friday. That would put the crew behind schedule, but workers are still hoping they will make Atlantis' October launch date.

During the Atlantis mission, astronauts will not be near the International Space Station if their shuttle is damaged, so the second shuttle will stand by to launch to the rescue if necessary. This is the first time a shuttle rescue mission has been planned in advance to this degree.

Space shuttle Endeavour was rolled into the Vehicle Assembly Building last week, and is on its transporter in the upright position, and ready to go to Launch Pad 39B. It was ready on Wednesday night, but lightning but the rollout on hold for a day. Weather permitting, crews plan to roll it out Thursday night.

Atlantis remains on 39A, waiting for its launch. Some trouble with its cargo has put launch preparations slightly behind schedule.

Two shuttles have not been on the launch pads at the same time since 2001. It will likely be the last time there will be a shuttle on both pads because the program is slated to end in 2010.

Atlantis is scheduled for launch on Oct. 10. Endeavour has a planned liftoff set for Nov. 12.