The first space shuttle landings rattled the Mojave Desert around Edwards Air Force Base (search) with the thunder of sonic booms — and might do so again Tuesday.

NASA (search) was looking closely at the base and a second backup site in New Mexico for the homecoming of Discovery as poor weather Monday forced officials to scratch two Florida landing opportunities.

Edwards Air Force Base, home to NASA's Dryden Flight Research Center (search), is less prone to finicky weather than the shuttle fleet's Florida home. And even as Kennedy Space Center has taken over as both launch and landing site, the space agency has kept up Edwards as its No. 1 backup.

Of the 111 shuttles that have landed since 1981, 49 came in at Edwards, 61 touched down in Florida, and one landed at New Mexico's White Sands Missile Range.

NASA prefers to land at Kennedy to avoid the $1 million cost and potential for damage involved in flying the shuttle back to Florida atop a modified Boeing 747.

The last shuttle to land at Edwards was Endeavor, which was diverted from Florida in 2002 because of bad weather.

The lone shuttle landing in New Mexico came in 1982, when runways in Florida and California were both flooded. The abrasive gypsum sand runway contaminated Columbia's engines and the damage required extensive repairs.

NASA has invested about $10 million in shuttle-related upgrades at Edwards, despite its backup status. It has new equipment to cool the shuttle after a landing, and work has been done on the vertical steel structure used to mate the shuttle to the 747 for its ride home, getting rid of lead-based paint and asbestos.