International Launch Services is renewing its push to capture more satellite-launch business from NASA, a market that Boeing has had largely to itself in recent years with its Delta 2 rocket.

According to industry officials, the Lockheed Martin-affiliated launch services provider sees an opportunity in the impending loss of Boeing’s other main source of Delta 2 business, launching GPS satellites for the U.S. Air Force. The Air Force is shifting GPS missions to its Evolved Expendable Launch Vehicle (EELV) line of rockets, a move that these officials say will drive up the unit cost of the Delta 2 and thus make the larger Atlas 5 more cost competitive.

Lockheed Martin Space Systems of Denver builds the Atlas 5, which along with Boeing’s comparable Delta 4 rocket was developed under the EELV program. International Launch Services of McLean, Va., markets the Atlas 5 along with the Russian-built Proton rocket.

“We believe that as Delta 2 has become the sole NASA launch vehicle for medium-class missions, it’s price has escalated so that the Atlas 5 401 is competitive,” said a Lockheed Martin official, who did not want to be identified .

The Atlas 5 401 , the smallest vehicle in the Atlas family , can loft up to 12,500 kilograms to low Earth orbit and has been offered for NASA missions since June 2000 . But so far, NASA has ordered Atlas 5s for only two missions, the Mars Reconnaissance Orbiter, which launches this summer, and the Solar Dynamic Observatory.

The Delta 2 can launch a little more than 6,000 kilograms to low Earth orbit and for the past decade or so has been NASA’s launch vehicle of choice for most competitively selected science missions.

Boeing Expendable Launch Systems of Huntington Beach, Calif., performed seven Delta 2 launches in both 2003 and 2004: six GPS missions and eight NASA launches. The most recent of those was the January launch of NASA’s Deep Impact probe on its way to a scheduled July 4 meeting with a comet.

The Delta 2 has launched every GPS spacecraft since 1989 and has seven GPS missions remaining on its manifest through 2006. GPS launches aboard Atlas 5 and Delta 4 rockets are slated to begin in 2007.

The Lockheed Martin official said loss of the GPS missions will shift all costs associated with Delta 2 production and launch infrastructure to NASA. “We believe when you add all that up, that the Atlas 5 401 is a very competitive solution,” the official said. “We will be amortizing the cost over government and commercial programs.”

The Lockheed Martin official further noted that the U.S. Space Transportation Policy, released in January, endorses EELV rockets for future U.S. government launch needs .

“The story the government has relayed to the industry is that the programs such as Titan, [older] Atlas and Delta 2, have a great heritage but are very expensive to operate,” the official said.

Boeing spokesman Robert Villanueva said Delta 2 production will be adjusted to ” accommodate shifts in manifest,” but declined to be more specific about the impact of losing the GPS missions .

Villanueva also pointed out that Delta 2 is sold on the commercial market, but the opportunities there are few and far between.

NASA still has 14 Delta 2 launches under contract — although not all have been assigned to specific payloads — that will take the program out through 2008 or 2009, said Karen Poniatowski, NASA’s assistant administrator for launch services said in a January interview.

“For us, Delta 2 or a capability like it continues to be a requirement we have,” Poniatowski said.

Lockheed Martin nonetheless believes there will be some opportunities to capture medium-class NASA launches before the agency’s current Delta 2 order expires.

“We are looking at opportunities between now and 2009 that overlap with NASA’s current position that they will use the Delta 2,” the Lockheed Martin official said. “We are anxious to pursue those missions. We have looked at both approved and potential programs and we’ve identified some programs for which we are a good option.”

The official declined to be more specific.