WASHINGTON — The U.S. Air Force should limit any bulk order of Evolved Expendable Launch Vehicle (EELV) rockets from United Launch Alliance (ULA) to three years’ worth of missions to give competing companies a chance to bring alternative vehicles to market, the leaders of the House Intelligence Committee said in a letter to U.S. Defense Secretary Leon Panetta.

“We support the Air Force’s effort to achieve some economies of scale to provide the best value for the taxpayer, but we are concerned that any EELV block buy that goes beyond three years worth of launches will unnecessarily exclude competition,” Reps. Mike Rogers (R-Mich.) and Dutch Ruppersberger (D-Md.) wrote in the Aug. 2 letter. Rogers and Ruppersberger are the chairman and ranking member, respectively, of the House Permanent Select Committee on Intelligence.

The letter, a copy of which was obtained by SpaceNews, urged Panetta to do away with “the infrastructure subsidy we provide to ULA” and quickly develop “clear entrance criteria for new competitors” in the market for launching U.S. national security satellites.

Besides paying Denver-based ULA for the hardware and services associated with specific Atlas 5 and Delta 4 rocket launches, the Defense Department also covers a portion of the company’s overhead under the cost-plus EELV Launch Capability contract.

Rocket maker Space Exploration Technologies Corp. of  Hawthorne, Calif., which is looking to break into the U.S. military launch market, has argued that the Launch Capability contract masks ULA’s true launch costs, giving the Boeing-Lockheed Martin joint venture an unfair advantage.

The lawmakers also said Space Exploration Technologies’ Falcon 9 rocket, which has flown three times to date, and Orbital Sciences Corp.’s Antares rocket, which is expected to make its maiden flight in December, “are opening an important window of opportunity to make room for new EELV competitors and reap significant cost savings without sacrificing launch reliability.”

The Air Force was expected to award ULA a contract this summer for a total of 46 rockets to cover military launch needs from 2013 to 2017.

However, the service recently decided to delay the block buy until at least next year.

In the meantime, the Air Force intends to award ULA a single-year bridge contract no sooner than October, according to a July 26 report from the U.S. Government Accountability Office. The bridge contract does not cover purchases of rocket hardware but rather is for services needed to launch rockets procured in previous years.

Mike Gruss covers military space issues, including the U.S. Air Force and Missile Defense Agency, for SpaceNews. He is a graduate of Miami University in Oxford, Ohio.