WASHINGTON — NASA has claimed three of the five remaining rockets from the discontinued Delta 2 program and will use those vehicles, along with a relatively new rocket design, the Falcon 9, to launch four Earth observation satellites from the West Coast between 2014 and 2016, NASA announced July 16.

Denver-based United Launch Alliance got a $412 million contract to launch three of the missions aboard the venerable Delta 2 from Space Launch Complex 2 at Vandenberg Air Force Base, Calif. ULA will launch NASA’s Soil Moisture Active Passive spacecraft in October 2014, the Orbiting Carbon Observatory-2 in July 2014, and the Joint Polar Satellite System-1 in November 2016. NASA in March said that ULA was likely to get a contract for these missions.

Hawthorne, Calif.-based Space Exploration Technologies (SpaceX) Corp., meanwhile, will get $82 million to launch Jason-3, a French-U.S. satellite that will measure the height of global sea surfaces. The mission will ride to space aboard a Falcon 9 in December 2014 from Vandenberg’s Space Launch Complex 4, NASA said. SpaceX also bid on the trio of Earth science launches that went to ULA.

Jason-3 stands to be SpaceX’s first launch of a NASA science satellite. If all goes according to the company’s public launch manifest, the mission would be SpaceX’s fourth West Coast launch. SpaceX, which has yet to launch from Vandenberg, is scheduled to loft commercial payloads from the Air Force-controlled range for Canada’s MDA Corp. and Taiwan’s Thaicom in 2012 and 2013, respectively.

These missions will all fly from Space Launch Complex 4’s eastern pad, which SpaceX is refurbishing to host both the Falcon 9 and the planned 27-engine Falcon Heavy rocket, company spokeswoman Kirstin Grantham said July 18.

Elsewhere at Vandenberg, NASA’s Delta 2 order will help keep the lights on at the range’s Space Launch Complex 2 through 2016.

ULA’s Delta 2 was once the go-to medium-lift vehicle for NASA and the Air Force, launching more than 150 missions between its debut in 1989 and last fall. But when the Air Force, which long covered most of the rocket’s support costs, began shifting the bulk of its launch traffic to ULA’s more powerful Atlas 5 and Delta 4 rockets, NASA found itself looking at steep future price hikes for Delta 2.

NASA concluded in 2007 that it could not afford to be the sole user of Delta 2 and announced that, like the Air Force, it would phase out its use of the rocket in favor of Atlas 5 and Delta 4.

Adding Delta 2 back to its launch manifest — at an average cost of $137 million per mission — will require NASA to pick up support costs previously borne by the Air Force.

The $412 million the agency is paying to ULA “includes the costs to maintain the launch facility throughout the period of performance,” ULA spokeswoman Jessica Rye wrote in a July 18 email.

For West Coast launches, Delta 2 flies from the western pad at Vandenberg’s Space Launch Complex 2. The last launch from that facility was in October, when a Delta 2 launched NASA’s Suomi NPP weather and climate satellite. Prior to NASA’s decision to buy three more Delta 2s, the NPP launch was thought to be the last for the workhorse rocket and Complex 2. Now, with the bills for pad upkeep paid through the Joint Polar Satellite System-1 launch in 2016, ULA is free to shop its remaining Delta 2 rockets to other customers, including other NASA programs in the hunt for a reliable medium-lift rocket.

“We are actively marketing these vehicles to prospective customers,” Rye said.

Not counting the three now committed to mid-decade NASA Earth science launches, ULA has parts for two more Delta 2 rockets left in inventory.

NASA Earth science officials have said that they are willing to pay a premium for launch reliability to avoid losing any more payloads. Back-to-back failures of Orbital Sciences Corp.’s Taurus XL rocket in 2009 and 2011 doomed two Earth science satellites — the Orbiting Carbon Observatory and Glory, respectively — at a cost of about $1 billion to the agency, NASA Earth Science Director Michael Freilich said July 10. NASA subsequently scrapped plans for launching the Orbiting Carbon Observatory-2 aboard Taurus XL.

Dan Leone is a SpaceNews staff writer, covering NASA, NOAA and a growing number of entrepreneurial space companies. He earned a bachelor’s degree in public communications from the American University in Washington.