Three satellite instruments slated to fly on NASA’s upcoming Fastsat mission arrived in October at the space agency’s Marshall Space Flight Center in Huntsville, Ala., for testing and intergration, NASA’s aid in an Oct. 26 press release.

The three instruments were built at NASA’s Goddard Space Flight Center in Greenbelt, Md., in collaboration with Marshall and the U.S. Naval Academy, Annapolis, Md. Fastsat, which is short for Fast, Affordable, Science and Technology Satellite, will fly a total of six instruments approved by the U.S. Defense Department’s Science and Experiments Review Board for a multiple-satellite mission dubbed STP-S26. The mission, which is being managed by the U.S. Air Force Space Test Program at the Space Development and Test Wing, Kirtland Air Force Base, N.M., includes Fastsat, three other small satellites and three cubesats due to launch in May atop a single Minotaur 4 rocket out of Alaska.

The three Goddard-built Fastsat instruments include: the Thermosphere Temperature Imager, designed to measure spacecraft drag in orbit; Mini-Me, a low-energy neutral atom imager that will improve global weather prediction; and the Plasma and Impedance Spectrum Analyzer, designed to measure thermal electron populations in the ionosphere and help mitigate radio signal interference for communications and navigation.

Although STP-S26 is planned for launch next spring, Minotaur 4 launches are on hold while the Air Force investigates an unspecified problem relating to the rocket’s third stage. Air Force officials are eyeing several corrective actions, though a final design solution has not been identified, the El Segundo, Calif.-based Air Force Space and Missile Systems Center said in an Oct. 6 statement