The day-long exercise, which was to involve US and Portuguese military forces and emergency services, will now occur on February 9 on the island of Terceira, a military source told the agency.

Terceira, one of the archipelagos nine islands which is located some 1,500 kilometres (900 miles) off the coast of mainland Portugal, is home to a US air base.

The base is one of only a handful of locations outside the United States where a space shuttle can land in an emergency.

As part of the exercise, hundreds of airmen and civilians were to search for six crew members who had ejected themselves from a troubled US shuttle near the island shortly after it took off from the Kennedy Space Centre in Florida.

Staff at the US airbase were also set to practice how to prepare for the arrival of a 400-strong rapid response team from NASA which would be dispatched to Terceira if the simulated shuttle accident were real.

A year ago Sunday the space shuttle Columbia disintegrated in mid-air, claiming the lives of its seven crew members.

NASA officials said Tuesday the space shuttle fleet, grounded since the Columbia disaster, could fly again by September.

SPACE.WIRE