Dr. Rick Fleeter, AeroAstro's CEO, said, "AeroAstro's X-Band Transponder offers a small, low-power, and inexpensive communications solution for the space community by taking advantage of the latest in highly integrated GaAs semiconductor components and innovative design practices. Our success in demonstrating its DSN compatibility brings us a significant step closer to a flight-qualified product."

AeroAstro began development of the lightweight, compact X-Band Transponder under funding through the NASA Small Business Innovation Research (SBIR) program, and the technology was baselined for the Nanosatellite Constellation Trailblazer mission when it was selected for ST5 in 2000. AeroAstro recently completed fabrication of a prototype of the transponder, and testing this transponder for operability with the DSN, the ground network to be used for the mission, was the next requirement for this flight on the ST5 mission.

NASA ST5 Program Manager, Dr. Douglas McLennan, said, "We are very excited about the results of the DSN compatibility testing with the X-band transponder and look forward to flight qualification of this technology."

The two major objectives of the testing were to validate the testing AeroAstro performed by independently assessing the prototype transponder's performance and to verify its compatibility with the DSN ground system.

Included in this testing was the first test of a new DSN uplink command module utilizing direct modulation, one of the elements being implemented to simplify the requirements on transponders utilizing DSN.

The major facets of the uplink testing included verification of acquisition and tracking, command detection, and gain control. The receiver portion of the transponder is capable of tracking greater than 8kHz at 5kHz/sec, 80dB of linear automatic gain control, and is able to be directly commanded. On the downlink, the 2-watt transmit power and radiated emissions were verified compliant with all DSN requirements.

With the success of the DSN compatibility testing, AeroAstro is beginning the manufacture of a proto-flight unit with identical form and function to the flight units, which are each expected to weigh only 600 grams in an enclosure approximately 6cm x 6cm x 9cm.

This full duplex coherent transponder can transmit at a date rate of up to 750 kbps and receive at a rate of up to 4kbps, with a power consumption of only 10W for transmit and 4W for receive.

Compatibility testing of the proto-flight unit is scheduled for July 2003, after which flight model fabrication will begin, working towards the ST5 launch planned for 2004.

The NMP ST5 mission consists of three miniaturized satellites that are similar in size to a desktop computer, weighing only about 47 pounds each. These smaller satellites are much easier to manufacture than their larger counterparts, bringing down the total mission cost.

Flying clusters of multiple smaller satellites rather than a single larger satellite reduces the risk of an entire mission failing if one system or instrument fails.

The goal of the ST5 mission is to flight test its miniaturized satellites and the suite of innovative technologies it incorporates, within the Earth's magnetosphere, providing data for future development of spacecraft planned to study this region.

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