This story was updated at 12:33 p.m. EDT.
CAPE CANAVERAL, Fla. -- Astronauts aboard NASA's shuttle Endeavour will begin transforming their trusty spacecraft into a 100-ton glider as they gear up for a planned Tuesday landing.
Shuttle commander Scott Kelly and pilot Charlie Hobaugh fired Endeavour's rocket thrusters and tested its flight control surfaces Monday to prime for flight in Earth's atmosphere as concerns over Hurricane Dean's impact on NASA's Mission Control centers eased, mission managers said.
Meanwhile, engineers on Earth completed their analysis of imagery from a late heat shield inspection conducted by Endeavour's STS-118 crew on Sunday, clearing the orbiter for its reentry tomorrow. The now-standard survey allows astronauts to scan their orbiter's nose cap and wing leading edges for signs of damage by micrometeorites or orbital debris.
"They've done just an absolutely super job," Matt Abbott, NASA's lead shuttle flight director, said of Endeavour's crew Sunday, adding that an initial look at some of the inspection imagery yielded no concerns. "We're looking forward to a safe and successful couple of days, and reentry and landing on Tuesday."
Endeavour astronauts scanned their heat shield once before, just after their Aug. 8 launch, to check for damage from fuel tank debris. NASA cleared the shuttle of any launch debris damage concerns, including a gouge in the orbiter's underbelly, and a minor window scuff from micrometeorite debris late last week.
Kelly, Hobaugh and their STS-118 crewmates are slated to land here at NASA's Kennedy Space Center (KSC) at 12:32 p.m. EDT (1632 GMT) Tuesday, with a second opportunity about 90 minutes later. Mission managers are also calling up a backup runway at Edwards Air Force Base in California's Mojave Desert, but hope to land in Florida to avoid additional turnaround time and costs.
Endeavour's astronaut crew, which includes teacher-turned-spaceflyer Barbara Morgan, undocked from the International Space Station (ISS) Sunday morning after nine days of construction work to deliver cargo, spare parts and a new piece of the orbital laboratory's starboard-side framework. Morgan served as NASA's backup to Teacher in Space Christa McAuliffe for the ill-fated 1986 Challenger mission. She later became a full fledged spaceflyer in 1998.
In addition to their flight control systems check, Endeavour's crew is expected to stow items away for landing and speak with students in Canada's La Ronge, Saskatchewan via a space-to-ground video link. Kelly, Morgan and STS-118 mission specialist Dave Williams, a veteran Canadian Space Agency (CSA) astronaut, will participate in the educational event, CSA officials said.
NASA pushed the shuttle's landing to Tuesday, one day earlier than planned, to avoid potential disruptions at its Houston, Texas-based Mission Control at the Johnson Space Center by Hurricane Dean. Current forecasts predict the massive storm will head toward central Mexico, according to the National Hurricane Center.
If the hurricane continues to pose little risk to mission control operations, NASA could target KSC only for any landing opportunities on Tuesday, using the Edwards runway as a backup on Wednesday. But the agency is prepared to relocate to a backup Mission Control at KSC if required, the space agency said.
"That kind of thing, you don't want to make a mistake with," Abbott said of NASA's hurricane considerations.
NASA is broadcasting Endeavour's STS-118 mission live on NASA TV. Click here for mission updates and SPACE.com's NASA TV feed.