STPSat 4

STPSat 4 [NASA]

STPSat 4 is an experimental spacecraft for the Department of Defense's Space Test Program (STP).

STPSat-4 carries several experiment packages into low earth orbit. One of these is the MSA (Modular solar array).

• iMESA-R (Integrated Miniaturized Electrostatic Analyzer Reflight) a U.S. Air Force Academy mission designed to measure plasma densities and energies, which assembles a long-term database with multiple data points for space weather environmental data.
• MATRS (Modular Solar Array) requires exposure to synergistic space environment at a high integration level (solar cells, interconnections, harnesses), and collects this on-orbit synergistic data for solar array model correlation and validation.
• RF Modular Tiles requires experimentation to prove enabling phased array technology performance and address fundamental issues in the combined-effects environment of LEO.
• NISTEx (Navy Interferometric Star Tracker Experiment) observes how well its star tracker detects and tracks stars and how well an interferometric star tracker determines the orientation of a spacecraft.
• NTE (Nanosatellite Tracking Experiment) - Passive Retroreflector.

STPSat-4 is a free flying spacecraft to be ejected from the international space station (ISS) via the SSIKLOPS (Space Station Integrated Kinetic Launcher for Orbital Payload Systems) deployment system. Launch took place in late 2019 and the satellite was deployed from the ISS in January 2020. One of the arrays failed to deploy.