— The sun is setting on Delta 2, the medium-lift rocket that has logged 87 consecutive successful launches since 1997 but loses the U.S. Air Force as its prime customer after this year.

Of the 14 remaining Delta 2 rockets,
government and commercial customers have purchased nine. No buyer has yet emerged for the other five.

Without the Air Force to cover infrastructure costs such as launch pad maintenance and postproduction support to supply chain manufacturers, rising launch costs threaten to keep the five unsold Delta 2 rockets from leaving the factory floor.

“It’s an unfortunate situation,” said Ken Heinly, who oversees marketing of Delta 2 to commercial customers as director of launch products and services for Chicago-based Boeing Co. “It gets hard for us to offer competitively once the government is no longer launching. We’ve gotten to the point now where the likely launch period for a new customer would be beyond the period where the government is supporting it.”

NASA will carry the cost of keeping the Delta 2 infrastructure going for the next two years, until its Gravity Recovery and Interior Laboratory mission to measure the Moon’s gravity field lifts off from Cape Canaveral Air Force Station in Florida in 2011, said Bill Wrobel, NASA’s assistant associate administrator for launch services. After that, NASA’s next four science missions will launch aboard the much bigger Atlas 5, which was developed under the Air Force’s Evolved Expendable Launch Vehicle (EELV) program and continues to receive the service’s patronage and financial backing.

“The problem we have is after 2011, it’s not clear [Delta 2] would be a lot less than an Atlas,” Wrobel told Space News April 30.

Denver-based United Launch Alliance (ULA), a partnership between Boeing and Bethesda, Md.-based Lockheed Martin Corp., builds the Delta 2 and markets it to government customers, while Huntington Beach, Calif.-based Boeing Launch Services books the rocket’s commercial missions. Boeing built Delta 2 until forming the ULA partnership with Lockheed to manufacture and launch Atlas 5 and Delta 4 rockets under the Air Force-supported EELV program.

Delta 2 was originally built to launch U.S. GPS satellites, but the rocket counts among its more than 134 launches NASA’s Mars missions, including the
lander in 2007, and a number of Earth observation satellites, including Dulles, Va.-based GeoEye‘s GeoEye-1 remote sensing satellite launched in September.

While the last five Delta 2s are not complete, they are part of a production line in which major parts already have been purchased, Heinly said. If they are not sold soon, ULA will have to decide how long to keep the assembly line open. ULA already has shifted Delta 2 employees to the EELV program to ramp Delta 2 down to one to two launches per year after government support for infrastructure ends.

ULA President Michael Gass said there could be several opportunities in the coming years to assemble and launch the last five Delta 2s as Congress funds new Pentagon and NASA programs requiring a medium-lift launcher.

“We’re aggressively trying to find those customers,” Gass said during an April 27 interview. “Right now there is not any clear additional opportunity in the

The Delta 2 manifest during the next two years includes the last scheduled Air Force launch – a GPS 2R-series satellite scheduled to lift off from Cape Canaveral late this summer – six NASA launches and two commercial launches. The commercial launches are Longmont, Colo.-based DigitalGlobe‘s WorldView-2 and ThalesAlenia Space’s Cosmo SkyMed 4.

said he expects customers with a business case that leaves no room for failure – rather than those launching replacement satellites, for example – still might pay more for Delta
2 in
exchange for the rocket’s high reliability. He acknowledged, however, that emerging rocket manufacturers offering low-cost launches could make it even more difficult to sell off the final Delta 2s.

“There certainly are a number of companies starting up that don’t have the reliability record but have the good price,” he said. “I just don’t know what price is put on reliability.”

declined to discuss Delta 2 launch costs, but said additional infrastructure costs that Delta 2 customers would have to cover after NASA’s support ends in 2011 could drive prices 25 percent higher.

said some estimates put the post-2011 cost of launching a Delta 2 within the range of an Atlas 5. NASA announced in March that it had purchased four Atlas 5 launches at about $150 million apiece for upcoming science missions.

said he is focused on trying to sell the Delta 2 commercially, but acknowledged the production line will probably shut down after the remaining five are sold, if not sooner.

“I think right now, unless there is a big change in direction either by NASA or the Air Force, I would not see Delta 2 continue past this production lot,” Heinly said. “As successful as they’ve been, it would seem there may not be room for Delta