WASHINGTON — The U.S. Air Force in June plans to issue a request for proposals to deliver two fully integrated cubesats for monitoring environmental conditions in space, according to a May 10 posting on the Federal Business Opportunities website.

The Air Force Space and Missile Systems Center, Los Angeles, will be seeking a contractor to design, build, test and deliver two experimental satellites with Space Environmental Monitoring payloads, the posting said. Cubesats are standardized satellite platforms that measure 10 centimeters on a side and weigh about a kilogram. The term is sometimes used to describe the so-called 3U variant that is the size of three 10-centimeter cubes connected end to end.

The service plans to issue a draft request for proposals May 25, the posting said. In a November request for information, the Air Force said the satellites would be required to fly at an altitude of 400 kilometers for a one-year mission and deorbit within five years.