Space Test Program
The primary U.S. Department of Defense program for placing space science and technology experiments into orbit.
Last updated August 26, 2026
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Overview
The Space Test Program (STP) is a United States Department of Defense organization that provides access to space for defense-related science and technology experiments. Rather than operating as a conventional aerospace manufacturer or commercial launch company, STP acts as an institutional flight provider and mission-integration authority. It identifies suitable launch opportunities, arranges spacecraft and payload integration, coordinates with launch providers and government partners, and enables experimental systems to reach orbit through dedicated missions, rideshares, secondary-payload adapters, International Space Station logistics, and other forms of hosted access. STP is managed within the Advanced Systems and Development Directorate of the Space and Missile Systems Center, an organization associated with the United States Space Force. Its predecessor was SATAR, and the program had been operating for approximately five decades by 2019. Across that history, it has supported several thousand launches or payload deployments involving military laboratories, universities, civil agencies, and other government research organizations. Its portfolio has covered communications, navigation, space weather, atmospheric science, remote sensing, spacecraft autonomy, propulsion, laser communications, space situational awareness, and components intended for future operational systems. One of STP's historically important contributions was providing flight opportunities for early experiments that helped lead toward the modern Global Positioning System satellite constellation. The program has also helped mature technologies by flying them in realistic orbital environments before possible adoption in larger defense or civil systems. Its role is therefore broader than simply purchasing launch services: it serves as a bridge between laboratory development and operational space capability. STP has used a wide range of launch and deployment arrangements. Missions have flown on Space Shuttle flights, expendable launch vehicles, dedicated military launchers, commercial rockets, International Space Station resupply missions, and commercial rideshare services. The program worked with NASA, the Naval Research Laboratory, the Air Force Research Laboratory, the Defense Advanced Research Projects Agency, the National Nuclear Security Administration, foreign government organizations, and private aerospace contractors. Its payloads have ranged from large experimental spacecraft to CubeSats and small technology demonstrators. Notable missions include Kodiak Star in 2001, the first orbital launch from Kodiak Island, Alaska; STP-1 in 2007, which shared an Atlas V launch among several experimental satellites; STP-S26 in 2010, which tested small-launch and upper-stage technologies; STP-2 in 2019, a major Falcon Heavy mission carrying the Deep Space Atomic Clock, the Green Propellant Infusion Mission, COSMIC-2 satellites, and numerous secondary payloads; and STP-3 in 2021, which carried STPSat-6, the NNSA Space and Atmospheric Burst Reporting System-3 payload, NASA's Laser Communications Relay Demonstration, and additional Air Force experiments. The program continues to support distributed and experimental space architectures. Recent activities include the unsuccessful STP-27VPD mission launched from Spaceport Cornwall in 2023 and the successful STP-CR2301 rideshare mission later that year. Because STP is a government program rather than a consumer-facing company, it has no conventional retail products, public share listing, or independent commercial revenue model. Its significance lies in providing dependable, flexible, and risk-tolerant access to orbit for U.S. defense space research and associated international or interagency missions.
History
The Space Test Program emerged from the U.S. Department of Defense's need for a coordinated way to place experimental spacecraft and scientific instruments into orbit. Its predecessor, SATAR, provided an early institutional basis for flying defense space experiments. Over subsequent decades, STP developed into the principal flight provider for the Department of Defense space science and technology community. The program's operating model has been deliberately flexible. It has used the Space Shuttle and the International Space Station for experiments that required astronaut-supported deployment, external exposure, or retrieval. It has also arranged dedicated launches and shared missions in which multiple spacecraft occupy a common launch vehicle through adapter systems. This approach allows experimental payloads with different sizes, destinations, and maturity levels to obtain access to space without each project requiring a standalone launch campaign. During 2001, STP supported the deployment of the Materials International Space Station Experiment on the Space Shuttle and the retrieval of the MACE II active-control experiment. It also partnered with NASA on Kodiak Star, an Athena I launch that established the first orbital launch operation from Kodiak Island, Alaska. The mission carried several small Department of Defense spacecraft alongside Starshine III. Later that year and in 2002, STP-sponsored SIMPLEX experiments used Shuttle engine burns to study ionospheric disturbances, while the organization also assisted with an extended radio-frequency authorization for the Picosat experiment. In 2003, STP and the Naval Research Laboratory launched the Coriolis satellite on a Titan II. Coriolis supported technology risk reduction connected with the planned National Polar-orbiting Operational Environmental Satellite System and demonstrated capabilities relevant to environmental observation. STP's work during this period also included development of secondary-payload infrastructure with the Air Force Research Laboratory and coordination on geosynchronous imaging and meteorological instrument projects. STP-1 in 2007 illustrated the program's multi-payload model. An Atlas V carried six spacecraft, including DARPA's Orbital Express pair, MidSTAR-1, FalconSat-3, STPSat-1, and CFESat. The use of an EELV Secondary Payload Adapter enabled multiple experimental missions to share one launch. STP also operated the C/NOFS satellite, launched in 2008, which investigated communications and navigation outages associated with ionospheric conditions. The STP-S26 mission launched in November 2010 on a Minotaur IV from the Kodiak Launch Complex. It carried STPSat-2 and other experiments, released payloads into a medium-altitude low Earth orbit, and demonstrated the HAPS upper stage by deploying ballast payloads into a higher orbit. STPSat-2 hosted the Space Phenomenology Experiment and Ocean Data Telemetry MicroSatLink, among other technology demonstrations. STPSat-3 launched in 2013 with the ORS-3 Minotaur I mission and accompanied 28 CubeSats. It carried experiments addressing plasma measurement, component research, wind and temperature observations, calibration, and space situational awareness. The STPSat-5 program was subsequently assigned to Sierra Nevada Corporation's Space Systems, formerly SpaceDev, to develop a next-generation science and technology demonstration satellite. The 2019 STP-2 mission was among the program's most visible launches. A SpaceX Falcon Heavy carried the COSMIC-2 constellation, the Deep Space Atomic Clock, the Green Propellant Infusion Mission, and a broad group of secondary payloads and CubeSats. STP also supported STPSat-4, which launched aboard the Cygnus NG-12 resupply mission in 2019 and was deployed from the International Space Station in early 2020. STPSat-4 hosted multiple experimental instruments, although one modular solar-array experiment only partially deployed; the spacecraft reentered in 2022. STP-3 launched in December 2021 on an Atlas V. Its principal spacecraft, STPSat-6, carried the NNSA's Space and Atmospheric Burst Reporting System-3 and NASA's Laser Communications Relay Demonstration, along with additional Air Force payloads. In 2023, STP supported the STP-27VPD mission from Cornwall, which ended in launch failure, and the successful STP-CR2301 mission on SpaceX's Transporter-8 rideshare. These missions demonstrate STP's continuing role in combining defense, scientific, commercial, and international payloads while testing technologies intended for future space capabilities.
- 2023
STP-CR2301
[1]The mission successfully flew as part of SpaceX's Transporter-8 rideshare service.
- 2021
STP-3
[1]STP-3 launched STPSat-6 and hosted payloads for the NNSA, NASA, and the U.S. Air Force.
- 2019
STP-2
[1]A Falcon Heavy carried a large collection of defense, scientific, and commercial technology payloads.
- 2013
STPSat-3
[1]STPSat-3 launched with the ORS-3 mission and carried several experiments among a large CubeSat rideshare.
- 2010
STP-S26
[1]The Minotaur IV mission launched STPSat-2 and demonstrated the HAPS upper stage.
- 2007
STP-1
[1]Six satellites shared an Atlas V launch through an EELV secondary-payload adapter.
- 2003
Coriolis mission
[1]STP and the Naval Research Laboratory launched Coriolis on a Titan II as a risk-reduction mission for future environmental satellite capabilities.
- 2001
Kodiak Star launches from Alaska
[1]STP and NASA conducted the first orbital launch from Kodiak Island, carrying Starshine III and three Department of Defense technology spacecraft.
Products and positioning
A government-sponsored access-to-space and mission-integration provider for U.S. defense space science and technology.
Experimental satellites · 2007
STPSat spacecraft series
The STPSat series consists of spacecraft used to host and operate multiple defense and scientific technology experiments. STPSat-1 flew on STP-1, STPSat-2 on STP-S26, STPSat-3 on ORS-3, STPSat-4 was deployed from the International Space Station, and STPSat-6 flew on STP-3. Payloads have addressed plasma physics, space environment sensing, communications, calibration, and space situational awareness.
Dedicated launch mission · 2019
STP-2
STP-2 was a Falcon Heavy mission carrying COSMIC-2, the Deep Space Atomic Clock, the Green Propellant Infusion Mission, and several CubeSats and technology demonstrators. It illustrated STP's ability to integrate a complex stack with payloads serving defense, civil, commercial, and scientific objectives.
Dedicated launch mission · 2021
STP-3
STP-3 launched STPSat-6 into an orbit above geostationary altitude. The spacecraft hosted the NNSA's SABRS-3, NASA's Laser Communications Relay Demonstration, and additional Air Force experiments.
Government spaceflight service
Launch and rideshare integration
STP provides mission planning, payload accommodation, integration, and orbital deployment through dedicated rockets, rideshare adapters, secondary-payload opportunities, ISS logistics, and hosted or piggyback arrangements.
Brand decisions
2021
STP-3 launchProduct launchBackground
STP-3 was initially planned for an Atlas V launch in 2020 and was intended to carry multiple strategic and experimental payloads.
Action taken
The mission launched on an Atlas V in December 2021 with STPSat-6, SABRS-3, LCRD, and additional Air Force payloads.
Aftermath
The mission placed the payloads into their planned high-altitude operational environment for technology demonstration and data collection.
2019
STP-2 multi-payload launchProduct launchBackground
STP needed to place a diverse group of defense and scientific experiments into orbit, including COSMIC-2 and several technology demonstrators.
Action taken
The program integrated the payloads for launch on a SpaceX Falcon Heavy, using ESPA-based payload structures and multiple secondary payload accommodations.
Aftermath
The mission delivered a broad set of experimental spacecraft and instruments and demonstrated the value of large shared government launches.
2014
Selection of Sierra Nevada for STPSat-5 developmentStrategyBackground
The program sought a next-generation science and technology demonstration satellite for future Department of Defense experiments.
Action taken
The Department of Defense selected Sierra Nevada Corporation's Space Systems, formerly SpaceDev, to develop and build STPSat-5.
Aftermath
The selection expanded STP's use of commercial aerospace expertise for experimental satellite development.
Recent events
- 2023
STP-27VPD fails during LauncherOne mission from Spaceport Cornwall[1]
Other
The STP-27VPD mission failed in flight, destroying its payloads, which included CIRCE and Prometheus 2 CubeSats for British and American government partners.
- 2023
STP-CR2301 launches successfully on Transporter-8[1]
Product launch
The STP-CR2301 mission flew on a Falcon 9 rideshare and deployed two MISR CubeSats and the XVI spacecraft to demonstrate communications and Link 16 connectivity from space.
- 2021
STP-3 launches STPSat-6 and major hosted payloads[1]
Product launch
STP-3 launched on a United Launch Alliance Atlas V after schedule changes. Its payloads included NNSA's SABRS-3 and NASA's Laser Communications Relay Demonstration.
- 2019
STP-2 launches on SpaceX Falcon Heavy[1]
Product launch
The STP-2 mission carried COSMIC-2, the Deep Space Atomic Clock, GPIM, LightSail 2-related hardware, and several CubeSats and experimental payloads.
- 2010
STP-S26 demonstrates small-launch and propulsion technologies[1]
Product launch · Product generation
A Minotaur IV mission launched STPSat-2 and other payloads from Alaska while also demonstrating the Hydrazine Auxiliary Propulsion System upper stage.
- 2007
STP-1 deploys six satellites on a shared Atlas V launch[1]
Product launch
The STP-1 mission placed six spacecraft into low Earth orbit, using an EELV Secondary Payload Adapter to combine defense, academic, and laboratory payloads on one launch.
- 2001
Kodiak Star becomes the first orbital launch from Kodiak Island[1]
Product launch · Other
STP and NASA launched the Kodiak Star mission on an Athena I rocket. The mission carried NASA's Starshine III and three Department of Defense spacecraft demonstrating new space technologies.
Sources1 sources
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