The Air Force will release the final Request for Proposals (RFP) for its Orbital/Suborbital small and medium lift program (OPS-3) by the end of April, according to an Air Force Space Command spokesman.

The goal of OSP-3 is two-fold: lifting satellites weighing 400 lbm (pound mass) to 4,000 lbm and 4,000 lbm to 20,000+ lbm into Low Earth Orbit (or equivalent), including suborbital capabilities, according to a notice posted on Federal Business Opportunities.

The primary objective of OSP-3 is to provide an enhanced capability and flexibility in the development of small and medium launch vehicles and services while providing an on-ramp for emerging capability, according to the notice.

The Defense Department announced Monday it wants to launch an Integrated Payload Stack (IPS) into space as part of OSP-3, according to a Mission Requirements Document (MRD) posted on Federal Business Opportunities.

The DoD Space Test Program (STP) is sponsoring the launch, known as Sample Mission 2.4 (SM-2.4). The primary goal of SM-2.4 is to launch an IPS, which consists of two co-prime space vehicles (SV), up to six auxiliary payloads (APLs) with a minimum of two and up to eight separate Poly-PicoSatellite Orbital Deployers (P-PODs), according to the MRD.

The two co-prime SVs are Constellation Observing System for Meteorology, Ionosphere and Climate-2 (COSMIC-2) and the Demonstration and Science Experiments (DSX), according to the MRD. COSMIC-2 is a set of six identical satellites with a deployment structure, according to the MRD. DSX uses an Evolved Expendable Launch Vehicle (EELV) Secondary Payload Adapter (ESPA) for its primary structure, which hosts an avionics and payload module on opposing ports, according to the MRD.

The baseline launch location for this mission will be from the Eastern Range, Fla., while the Initial Launch Capability (ILC) is scheduled for August 2015, according to the MRD.

The entire OSP-3 FBO notice can be viewed here: http://bit.ly/Id1eRJ