NASA’s Launch Services Program Office at the Kennedy Space Center, Fla., will divvy up a potential $15 billion worth of launch services contracts over 10 years among four U.S. aerospace firms to deliver various types of robotic explorers and scientific probes to orbit, the agency announced Sept. 16.

Under the terms of the indefinite-delivery, indefinite-quantity agreements, NASA will have the option to order up to 70 launch services missions over the life of the contracts. The selected firms are: United Launch Alliance of Littleton, Colo., for the Atlas 5 rocket; Lockheed Martin Space Systems of Denver, which along with Minneapolis-based Alliant Techsystems is offering the Athena family of rockets; Dulles, Va.-based Orbital Sciences Corp., provider of the Pegasus and Taurus rockets; and Hawthorne, Calif.-based Space Exploration Technologies Corp., which operates the Falcon 1e and Falcon 9 vehicles.

The minimum requirement for inclusion in the contract is the ability to launch satellites weighing 250 kilograms into a 200-kilometer orbit at an inclination of 28.5 degrees. NASA will entertain launch services proposals from other companies that meet minimum contract requirements on an annual basis, the agency said.