The Integrated Solar Array and Reflectarray Antenna (ISARA) mission will demonstrate a Ka-band reflectarray antenna that will increase downlink data rates for small spacraft from the typical existing rates of about 10 kilobits per second (kbps) to over 100 megabits per second (Mbps). The higher data rates that this technology enables will pave the way for high value science and exploration missions using small satellites. The large increase in data flow is accomplished with only a modest increase in mass, volume, and cost.
A data rate of 100 Mbps is comparable to the combined rate of 20 home high-speed internet connections. It The key to this technical advance is the integration of the reflectarray antenna into a deployable solar array would allow you to download an entire music CD in 5 seconds or a high-definition movie in less than six minutes.
The key to this technical advance is using the back of the satellite’s solar panel as a reflecting array to increase the effectiveness of the Ka-band radio transmitter. The satellite being used is a commercially-available Pumpkin 3U cubesat with dimensions of 10 by 10 by 33 centimeters. The cubesat’s deployable solar panel is a standard design but is being modified for this mission to serve as a reflectarray antenna. This antenna is designed to reflect a narrow radio signal from its surface toward the precise location of a specified receiver. The 3U cubesat platform was selected for this demonstration due to the wide range of available commercial off-the-shelf components, low development costs, and opportunities to launch as a secondary payload.
The ISARA project is led by the Jet Propulsion Laboratory of Pasadena, California with funding from NASA’s Small Spacecraft Technology Program. Pumpkin Inc. of San Francisco, California is providing the cubesat bus and solar array. The Naval Research Laboratory is providing flight software support to the project. The two-year project was initiated in October 2012.
ISARA will be validated in space during a 5-month mission to measure the reflectarray antenna output and pattern to include peak gain (correlation of antenna directivity and electrical efficiency); main lobes (direction of maximum signal strength), and side lobes (signal in unwanted directions). Following a successful validation mission, the reflectarray antenna technology will be available for use on space science and other missions that need high bandwidth communications. The ISARA technology will enable cubesats and other small satellites to serve as viable platforms for performing missions that were previously only possible on larger and more costly satellites.
The ISARA mission will launch its 3U cubesat fitted with a solar array that includes the integrated reflectarray antenna, a transmitter, and an avionics subsystem that features a high precision attitude control system needed to accurately point the antenna at a ground station. After deployment, ISARA will deploy its solar panel/reflectarray antenna and ultra-high frequency (UHF) telemetry antenna and then use its attitude determination and control system to stabilize the satellite. The UHF system will be used to establish initial communications between the satellite and the ground and perform on-orbit checkout. In the on-orbit test, the ISARA Ka-band reflectarray antenna will transmit a signal, which will be received by a ground station located at the Jet Propulsion Laboratory (JPL). The received power versus time will be combined with spacecraft location and spacecraft orientation data to reconstruct the antenna signal pattern, which will then be compared against pre-flight ground measurements.
ISARA was selected for a flight opportunity by NASA’s Cubesat Launch Initiative. The ISARA spacecraft will be launched and deployed on a rideshare mission arranged by the Launch Services Program at the NASA Kennedy Space Center. The spacecraft is slated to be ready for launch in late 2014.