07:49 UTC Space shuttle Atlantis deployed a small, eight-pound, 5” X 5” X 10” solar cell technology demonstration satellite, called PicoSat, from a canister in the shuttle cargo bay.
Pico-Satellite Solar Cell Experiment (PSSC) is a picosatellite designed to test the space environment by providing a testbed to gather data on new solar cell technologies. This capability will allow for gathering spaceflight performance data before the launch of new satellites with the new solar cell technology as the primary power source. Presently, the two U.S. solar cell manufacturers, Spectrolab and Emcore, are starting production of a new generation of High Efficiency Solar Cells on a two to three year cycle.
The Pico-Satellite Solar Cell (PSSC 2) testbed was scheduled to be deployed after Atlantis undocks from the International Space Station during STS-135/ULF7, becoming the last satellite ever deployed by the Space Shuttle Program. The satellite, also known as “PicoSat,” will perform two DoD experiments during its in-orbit lifetime. First, the Miniature Tracking Vehicle (MTV) experiment goal is to demonstrate the capability of a nano-satellite to serve as an orbiting reference for ground tracking systems while demonstrating 3-axis attitude control, solid rocket propulsion for orbit modification, adaptive communications and active solar cell performance monitoring in a nanosatellite platform. An on-board Global Positioning System (GPS) receiver will provide accurate time and position information to facilitate tracking error analyses. The second experiment, Compact Total Electron Content Sensor (CTECS), will demonstrate a CubeSat form factor space weather sensor with the capability to detect ionospheric density. It uses a modified commercial GPS receiver to detect differences in radio signals generated by occulting GPS satellites.
The PicoSat is 5″ x 5″ x 10″ and weighs 3.7 kg. It is integrated onto Atlantis for the STS-135 mission under the management and direction of the DoD Space Test Program’s Houston office at NASA’s Johnson Space Center. PicoSat will be ejected shortly before shuttle re-entry into a low (less than 360-km altitude) orbit with an expected orbital lifetime of three to nine months, depending on solar activity. Multiple on-board megapixel cameras will image Atlantis as the satellite departs, thus supplying the last in-orbit photos of NASA’s workhorse human space transportation system for the last few decades.
After the satellite’s orbit lowers for approximately one month, four ammonium perchlorate solid rocket motors will provide 40 Ns of impulse each and could extend orbital lifetime by an additional two months or alternatively, actively deorbit the satellite. The PSSC 2 bus, MTV and CTECS experiments will be controlled by a primary ground station at The Aerospace Corporation in El Segundo, Calif., and secondary stations that comprise the Aerospace Corporation Internet-based Picosatellite Ground Station Network.
The satellite has two radios for redundancy, both operating on 914.7 MHz, and both using an omni-directional patch antenna.