WASHINGTON (Reuters) - Tuesday’s collision of two satellites in space may not be the last unless big changes are made in the way government and commercial satellite operators share data, an expert on satellite orbits warned on Friday.

“Just because it took 50 years for it to happen doesn’t mean it’s going to be 50 years before the next one,” said retired U.S. Air Force Colonel T.S. Kelso, who was the first director of the Air Force Space Command Space Analysis Centre and is advising Iridium Satellite LLC, whose communications satellite was destroyed in the crash.

Kelso runs a website dedicated to tracking satellites and debris for the private Centre for Space Standards & Innovation and has developed a sophisticated computer program that provides regular information when satellites are going to be passing close by each other or space debris.

The model projected 151 other objects had been more likely to collide on Tuesday than the defunct Russian military satellite and the Iridium satellite, Kelso said. The closest approach was expected to be about 74 metres (243 feet) between another Russian satellite and debris from a second Russian satellite.

Iridium 33, the satellite that crashed, was due to pass within 527 metres (1,729 feet) of another object, even closer than the projected pass by the Russian satellite, Kelso said.

“The process is only as good as the data. If we don’t all share the best data we have, we’re going to have more collisions,” said Kelso, who added he had been urging the Air Force for years to adopt use of the computer-based system and disclose fully all its orbital data.

He said U.S. officials needed to work more closely with commercial and civilian satellite operators and share data to avert future collisions. “There’s absolutely no reason for anybody to be withholding data that could have been used to avoid collisions like the one on Tuesday.”

The U.S. Defence Department has said it did not predict the collision and Iridium has said it had no warning before the collision, which created two big clouds of debris, containing at least 500 to 600 identifiable pieces.

Some space experts question if the Air Force had better classified data in its possession than it makes public, as officials have sometimes suggested. If so, it may have simply not focussed on the Iridium satellite.

“There’s plenty of blame to go around,” said one expert who asked not to be identified. “I don’t know if you can talk about incompetence, but it’s pretty borderline.”

Bryan Whitman, a Pentagon spokesman, said on Thursday it was not possible for the U.S. military to track and predict the movements of all 18,000 objects in space all the time.

The Air Force and Defence Department historically have resisted disclosing what they consider classified data to satellite operators, but experts and several nongovernmental organizations have warned for years that failure to share data could eventually result in a collision.

Space has become increasingly crowded due to more nations launching satellites and growing numbers of dead satellites still in orbit but no longer controllable, including a new U.S. missile-warning satellite that failed in September.

Marine Corps General James Cartwright, vice chairman of the Joint Chiefs of Staff and former head of the command that runs U.S. military space operations, said on Thursday he would like to see more information-sharing on debris avoidance with Russia, China, France and other countries using space.