Iodine

The Iodine Satellite (iSat) will be the first CubeSat to demonstrate high change in velocity from a primary propulsion system by using Hall thruster technology and iodine as a propellant. The mission will demonstrate CubeSat maneuverability, including plane change, altitude change and change in its closest approach to Earth to ensure atmospheric reentry in less than 90 days. The mission is planned for launch in fall 2017. iSat Preliminary Concept Design

Hall thruster technology is a type of system has been designed to include iodine electric propulsion. Electric propulsion compatible control valves with internal uses electricity, typically from solar panels, heaters and temperature sensors to coincide to accelerate the propellant. Electric with the iodine-compatible thruster. propulsion can accelerate propellant to 10 times higher velocities than traditional A key advantage to using iodine as a chemical propulsion systems, which propellant is that it may be stored in significantly increases fuel efficiency. the tank as an unpressurized solid on the ground and before flight operations. To enable the success of the propulsion During operations, the tank is heated to subsystem, iSat will also demonstrate power vaporize the propellant. Iodine vapor is management and thermal control capabilities then routed through custom flow control well beyond the current state-of-the-art for valves to control mass flow to the thruster spacecraft of its size. This technology is a and cathode assembly. The thruster then viable primary propulsion system that can be ionizes the vapor and accelerates it via used on small ranging from about magnetic and electrostatic fields, resulting 22 pounds (10 kilograms) to more than 1,000 in high specific impulse, characteristic pounds (450 kilograms). iSat’s fuel efficiency of a highly efficient propulsion system. is ten times greater and its propulsion per volume is 100 times greater than current The iSat spacecraft is a 12-unit (12U) cold-gas systems and three times better CubeSat with dimensions of about than the same system operating on xenon. 8 inches x 8 inches x 12 inches (20 centimeters x 20 centimeters x 30 iSat’s iodine propulsion system consists of a centimeters). The spacecraft frame will be 200 watt (W) Hall thruster, a cathode, a tank constructed from aluminum with a finish to store solid iodine, a power processing to prevent iodine-driven corrosion. The unit (PPU) and the feed system to supply the iSat spacecraft includes full three-axis iodine. This propulsion system is based on a control and will leverage heat generated 200 W Hall thruster developed by Co. by spacecraft components and radiators Inc., which was previously flown using xenon for a passive thermal control system. as the propellant. Several improvements have been made to the original system to After the CubeSat has successfully detached include a compact PPU, targeting greater from its launch vehicle, it will deploy its than 80 percent reduction in mass and solar panels, correct for tip-off and maintain volume of conventional PPU designs. The attitude control before ground contact. cathode technology is planned to enable An initial check-out period of two weeks heaterless cathode conditioning, significantly is planned for testing all subsystems. increasing total system efficiency. The feed The spacecraft will charge the power system while in sunlight, using momentum wheels The principal investigator and propulsion lead for the and magnetic torque rods to rotate the vehicle to the iSat mission resides at NASA’s Glenn Research Center required attitude. The thruster will be operated to in Cleveland, Ohio. Busek is providing propulsion perform maneuvers when appropriate. After checkout, system components: thruster, cathode and PPU. the spacecraft will transition to a more automated NASA’s Marshall Space Flight Center in Huntsville, mode, initiating preprogrammed sequences. The Alabama, is tasked with overall project management spacecraft will use propulsion to lower its altitude from and developing the flight systems to support iSat its initial orbit of about 370 miles (600 kilometers) to mission objectives. The propulsion maturation a circular orbit of about 186 miles (300 kilometers). is a partnership between NASA and the U.S. Air Once in its new orbit the CubeSat will perform a plane Force. The project will mature and demonstrate in- change maneuver, complete any final operational flight technology originally funded through NASA’s maneuvers and continue to lower its closest approach Small Business Innovation Research program to Earth until achieving a less than 90-day deorbit. and the Space Technology Mission Directorate’s Propulsion technology is often a critical enabling (STMD) Game Changing Development program. technology for space missions. NASA is investing in technologies to provide high value missions with very The iSat mission is funded through NASA’s Small small and low cost spacecraft, including . Spacecraft Technology Program (SSTP), which is CubeSats, however, currently lack any appreciable chartered to develop and mature technologies to propulsion capability. They are typically deployed enhance and expand the capabilities of small spacecraft and tumble or drift without any ability to transfer to with a particular focus on communications, propulsion, higher or lower orbits, perform orbital maintenance pointing, power, and autonomous operations. or perform de-orbit maneuvers. The iodine thruster SSTP is one of nine programs within STMD. allows iSat to alter its orbital inclination and elevation, For more information about the SSTP, visit: opening up a wider range of mission objectives than http://www.nasa.gov/smallsats previously possible with spacecraft of this size. The iodine Hall technology enables low-cost planetary For more information about iSat, please contact: and human exploration missions. This technology Hani Kamhawi allows CubeSats to easily move between various iSat Propulsion Principal Investigator orbits: e.g., to geostationary NASA Glenn Research Center orbit. Leveraging this capability can reduce launch [email protected] costs by 90 percent and mission studies indicated John Dankanich a reduction in total mission life cycle costs. iSat Project Manager NASA Marshall Space Flight Center [email protected] Roger C. Hunter Small Spacecraft Technology Program Manager Space Technology Mission Directorate NASA Ames Research Center [email protected] Andrew Petro Small Spacecraft Technology Program Executive Space Technology Mission Directorate NASA Headquarters [email protected]

Modified BHT-200 Iodine Thruster

National Aeronautics and Space Administration Ames Research Center Moffett Field, CA 94035

FS #2015-03-22-ARC