• Satellite Evolution Group

Space Test Program-3 spacecraft encapsulated, mated to Atlas V ahead of Dec. 5 launch

Space Systems Command’s Space Test Program (STP)-3 integrated payload stack, which contains the STP Satellite (STPSat)-6 and the Long Duration Propulsive Evolved Expendable Launch Vehicle (EELV) Secondary Payload Adapter (ESPA), or LDPE-1 space vehicles, has been encapsulated and mated with United Launch Alliance’s Atlas V 551 launch vehicle Nov. 22 at Cape Canaveral Space Force Station.

Space Systems Command’s Space Test Program (STP)-3 integrated payload stack, containing the STP Satellite (STPSat)-6 and the Long Duration Propulsive Evolved Expendable Launch Vehicle (EELV) Secondary Payload Adapter (ESPA), or LDPE-1 space vehicles, were encapsulated Nov. 20 in preparation for mating with United Launch Alliance’s Atlas V 551 launch vehicle Nov. 22 at Cape Canaveral Space Force Station

STPSat-6 and LDPE-1 are co-manifested on the STP-3 mission which is scheduled to launch no earlier than Dec. 5 from Space Launch Complex (SLC)-41 at Cape Canaveral Space Force Station. The two-hour launch window will open at 4:04am Eastern (1:04am Pacific).


With mating completed, the team will perform final electrical and functional testing as an integrated stack and put the vehicles in their final physical flight configuration in preparation for mobile launch platform roll to the launch pad.


STPSat-6 advances warfighting capabilities by delivering operational nuclear detonation detection capabilities and demonstrating new space technologies in the areas of space domain awareness, weather, and laser communications. These updated capabilities proactively combat near peer threats by improving and expediting the intelligence provided to the warfighter.


LDPE-1 is the rideshare spacecraft on STP-3, and is the first mission in the LDPE series to launch. The LDPE program provides modular, flexible features that, when combined with available launch opportunities, create a “freight train to space” for experiments and prototypes in geosynchronous Earth orbit. By rapidly placing multiple, diverse experimental payloads into this valuable orbit, LDPE provides critical data to inform future Space Force programs. More specifically, LDPE-1 hosts payloads that will advance technology concerning communications, space weather sensing, and space domain awareness.


The Space Test Program manages the development of the STPSat-6 satellite and is responsible for the integration of nine payloads. SSC’s Rapid Prototyping Division manages the LDPE program with a matrixed LDPE-1 team composed of Los Angeles Air Force Base and Kirtland Air Force Base personnel. Northrop Grumman is the primary spacecraft contractor for STPSat-6 and LDPE-1.


Space Systems Command, headquartered at Los Angeles Air Force Base in El Segundo, California, is a US Space Force field command responsible for developing and acquiring lethal and resilient space capabilities for warfighters by rapidly identifying, prototyping, fielding and sustaining innovative, space-based solutions to meet the demands of the National Defense Strategy. SSC’s functions include developmental testing, production, launch, on-orbit checkout, and maintenance of USSF space systems, as well as and oversight of USSF science and technology activities.