The Friday shuttle launch has been pushed back to at least Monday. Click here for update.

Is watching a shuttle launch on your bucket list? There are only two shuttle launches left to go.

The youngest of NASA's space shuttles is about to retire.

Space Shuttle Endeavour is scheduled for launch at 1:47 pm Mountain Time on Friday, April 29. This will be the shuttle's 25th journey in 19 years.

Crowds are estimated to surge to more than 700,000 by Friday afternoon at Cape Canaveral, Florida. Shuttle Commander Mark Kelly's wife, Rep. Gabrielle Giffords (D-AZ), is expected to be watching as well as the Obama's: this will be the first-ever visit by an entire presidential family.

Endeavour's 14-day mission will include four spacewalks, the last by any shuttle crew member. The shuttle is carrying spare parts for the International Space Station and is delivering a two billion dollar particle physics experiment.

The big pumpkin-colored fuel tank propelling the shuttle into orbit has some impressive scars. The 10-year-old tank was in a building in New Orleans when Hurricane Katrina hit in 2005. The building's roof partially collapsed and caused more than 100 nicks in the tank's foam and dented a piece of metal. The fuel tank now has 103 patches and also a plaque showing Endeavour flying in the eye of a hurricane.

After Endeavour's final mission is over the shuttle will be retired to the California Science Center in Los Angeles.