SPHERES are basketball sized mini-satellites, designed and programmed to dock and fly in formation within the weightless environment of the ISS. The units consist of an aluminum structure covered with a Lexan shell. A carbon-dioxide propulsion system maneuvers the units. They are battery powered and programmed by an upload from the ground that can be tweaked by engineers as the experiments progress. Hardware on the shell of the units serve as beacons, emitting ultrasound signals to determine directional information.

RFM is pleased to be working with the Massachusetts Institute of Technology (MIT) Space Systems Laboratory and Payload Systems, Inc. supplying multiple DR2000 and DR2001 short-range radio modules for communications between SPHERES and a laptop aboard the ISS. The radio modules use RFM's patented transceivers, which are part of its Virtual Wire low-power product line.

Bob Nelson, Field Application Engineer for RFM, stated "Developing the RF protocol for the SPHERES Project and working with the MIT Space Systems Laboratory has been a thrilling experience. SPHERES is an ideal application for RFM's low-power transceivers in a battery-powered environment where long battery life and a small foot print and profile are essential."

The MIT Space Systems Laboratory is developing the SPHERES formation flight test bed to provide a wide range of government and industry scientists with a long term, replenishable, and upgradeable test bed for the validation of high-risk metrology, control, and autonomy technologies. These technologies are critical to the operation of distributed satellite and docking missions that will launch this decade.

In addition, NASA has recently awarded a grant, through the Small Business Innovation Research (SBIR) program, to Payload Systems, Inc. for the development of a space shuttle payload in the Mars Sample Return project in which two spacecraft are to be launched to Mars. One of the spacecraft will land, collect samples, and then launch by rocket toward the other orbiting craft that captures it using SPHERES technology.

Virtual Wire products are fully functional radio frequency transmitters, or receivers and transceivers based on proprietary amplifier-sequenced hybrid (ASH) radio architecture. This architecture integrates RF Ics with surface acoustic wave filtering and frequency control devices in a single hybrid package, which greatly simplifies and accelerates RF design tasks.

No external RF filters, intermediate frequency filters, resonators or crystals are required. All critical interconnections between the IC and the filtering and frequency control devices are implemented in the self-shielding hybrid package. ASH radios are optimized for a given application by selecting non-critical base-band and antenna tuning components.

RFM's Virtual Wire product line has been developed to support products manufactured each year that utilize low-power wireless technology for data links, telemetry, control and security. New applications for low-power wireless connectivity are emerging continuously and the potential applications are limited only by the customers' imagination.

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