WASHINGTON — A group of lawmakers from Alabama and Colorado is urging the U.S. Defense Department not to relax its standards for certifying new rockets to launch national security payloads.

In a Sept. 21 letter to U.S. Defense Secretary Leon Panetta, the lawmakers said prospective new entrants into the lucrative Pentagon launch market have yet to demonstrate their readiness for the job.

“Newly developed space launch systems do not yet meet most government mission needs, have not flown any significant complex payloads, and are still aspiring to launch vehicles at a rate of one or more per year,” the representatives wrote. “These matters of performance, capacity, and a sequence of flights in sufficient number to prove reliability are essential to meeting national security space launch requirements. While new entrants may someday possess such a capability to compete, we must not put the payload and schedule of our national security space assets in jeopardy in a process that also requires the taxpayer to underwrite the development of rockets and engines which have not yet flown.”

Currently the vast majority of U.S. national security payloads are launched by the proven Atlas 5 and Delta 4 rockets developed and operated under the U.S. Air Force’s Evolved Expendable Launch Vehicle (EELV) program. United Launch Alliance (ULA), a Boeing-Lockheed Martin joint venture headquartered in Denver and with manufacturing operations in Alabama, is prime contractor on the program and has a virtual lock on that market.

The Air Force awarded ULA a $1.2 billion contract Sept. 28 for Atlas 5 and Delta 4 launches under the EELV program. The performance period for that contract is scheduled to end Sept. 30, 2013.

Tony Taliancich, director of ULA’s customer program office, said the contract will support 12 launches and that the quoted price represents a maximum that could come down.

The projected cost of the EELV program for the first 150 missions has doubled, to about $70 billion, prompting several prominent lawmakers to press the Air Force to bring competition to the national security launch marketplace. Other companies, most notably Space Exploration Technologies Corp. (SpaceX), a Hawthorne, Calif.-based startup that has notched three successful launches to date of its medium-lift Falcon 9 rocket and at press time was readying a fourth, have expressed interest in competing for Pentagon business.

The Alabama and Colorado representatives said the Air Force and NASA have developed two basic approaches to certifying new entrants into the government launch market: Rockets developed without close government oversight must log 14 consecutive successful launches to be certified to launch operational payloads; those developed with tight government oversight would require only two consecutive successes.

The lawmakers expressed concern about an attempt to circumvent those standards, but were not specific.

The Air Force’s primary strategy for reining in the cost of the EELV program is a block buy under which it would commit to buying up to 10 rocket cores annually during a three- to five-year period. This strategy is intended to stabilize an industrial base that has suffered from the retirement of NASA’s space shuttle and international competition that has effectively priced U.S. rockets out of the commercial satellite launch market.

The Air Force had planned to award a block-buy contract to ULA this summer, but in the face of congressional opposition recently agreed to defer that award until the second quarter of next spring.

In a written response to a Space News query, SpaceX President Gwynne Shotwell said: “SpaceX develops the most reliable rockets in the world. We look forward to completing the rigorous Air Force certification process and providing launch services to the Defense Department using the all-American Falcon rockets, just as we do for our NASA, commercial and international customers today.”