Map of the Pacific Ocean region with the Vandenberg launch site and French Polynesia noted. Photo: CIA

The U.S. Air Force is keeping alive hopes to launch an Orbital Sciences Taurus rocket on Saturday if last-minute diplomacy resolves a safety concern with an island in the South Pacific.

The rocket and its experimental military satellite cargo have been grounded since last Friday at Vandenberg Air Force Base, Calif., after the Tahitian government revoked a safety clearance issued for the launch.

Tahitian authorities reversed an earlier launch approval after determining about 200 people now live on a tiny island located in the predicated area where the rocket's spent third stage could land.

When the rocket's trajectory to space was originally created, launch planners used Air Force maps and a United Nations database that incorrectly listed the French Polynesian island of Maria as uninhabited.

The island sits inside a 100-mile long and 30-mile wide stretch of the Pacific where the rocket's stage should impact after being jettisoned from the rest of Taurus about 307 miles above Earth, the Air Force says. The solid-propellant stage is an Alliant TechSystems Orion 50 motor.

View of the tiny island of Maria. See full map of French Polynesia. Photo: CIA

Maria, located at 21.88 degrees South latitude and 136.33 degrees West longitude, is just one of 118 islands and atolls that make up French Polynesia, a territory of France. Maria is home to tropical coconut plantations and lies in the Gambier Islands, the southeasternmost extension of French Polynesia.

After the launch was blocked on Friday, Air Force officials turned the matter over the U.S. State Department.

"The State Department is still working the issue through their channels," Lt. Colleen Lehne, spokeswoman for the Air Force's Space and Missile Systems Center, said on Tuesday.

The main options available to resolve the matter include evacuating the island, tweaking the rocket's launch timeline or changing the trajectory to avoid Maria altogether.

Officials said it would take at least one month to disassemble the Taurus rocket atop the launch pad and reprogram its flight computer with a new trajectory.

Taurus rocket on pad at Vandenberg Air Force Base, California. Photo: Orbital

Launch managers were expected to meet on Wednesday to discuss what progress has been made in the diplomatic arena. If the dilemma can be put to rest, a formal decision to proceed with a Saturday morning liftoff would be made on Thursday at the traditional Launch Readiness Review.

"We have about 48 hours of pre-launch work to do," Lehne said. "We won't want to start that on Thursday morning if we are not going to launch on Saturday."

The launch window on Saturday would extend from 0923 to 0950 GMT (4:23-4:50 a.m. EST).

Once launched, the fifth Taurus rocket will deliver the Multispectral Thermal Imager satellite into space for the U.S. Dept. of Energy's Office of Nonproliferation and National Security.

MTI is a research and development satellite to test multispectral and thermal imaging. The technologies might one day be used on spy satellites to detect facilities on Earth suspected of making nuclear or chemical weapons of mass destruction.