The shuttle took off today from Edwards Air Force Base in California bolted on top of a modified 747. Rob Navias at the Johnson Space Center says the length of the trip is dependent on the weather.
"We are very careful about the weather conditions along the way to make sure we're not flying through any potential rain or clouds with electrical potential that could pose a problem for the thermal protection tiles on the shuttle."
The piggyback trip stops once to refuel and it does not fly at night for security reasons and to better monitor the weather.
Navias says it costs just under two-million dollars to fly the shuttle back to Florida.
"We assume that on every shuttle flight they we will land out west not in Florida. When we do land at the Kennedy Space Center it's a luxury, not our baseline plan in terms of budget. So, it cost about 1.8-million dollars but that's already factored into NASA's annual budget."
While NASA likes the trip back to take a day, this time, because of the weather, it may be tomorrow or Friday before Endeavour is back at its home port.
Photo credit: NASA