The crew of shuttle Columbia. Israeli astronaut Ilan Ramonn is at far right. Image: NASA/JSC.

NASA's awkward efforts to keep shuttle launch times secret were dealt a blow last week when one of its contractors posted on the internet a target launch window for the space agency's most sensitive upcoming mission.

Spacehab Inc., which provides NASA with shuttle cargo bay modules, disclosed the launch time for the July flight of Columbia carrying Ilan Ramon, who will become the first Israeli to fly in space. The launch time was available for at least four days on the company's website before it was deleted around noon EST Monday morning.

A Spacehab official said the information had appeared inadvertently and was removed from the web site as soon as the company was alerted to the problem.

NASA officials are attempting to implement new security measures that include keeping shuttle launch times and countdown events secret and not disclosing the astronauts' schedules in the last days before lift-off. The measures, they say, are to deter terrorist attacks.

Michael Braukus, a spokesman at the space agency's Washington, D.C., headquarters said it was the responsibility of NASA's field centers to inform the various contractors who work for the space agency about the plan for secrecy.

"A policy directive went out to all the NASA centers and all the points of contact with regard to NASA," he said "The information was to filter down to all the contractors as well."

The flight of an Israeli astronaut is considered a high profile target for terrorists and much of the increased security is rumored to have been put in place in readiness for this particular mission. Unlike the launch times for space station missions, which can be roughly calculated by computer software or simple subtraction, the launch window for Columbia's July mission should be easier for the space agency to keep secret.