Last Friday, Feb. 3, just before 6 p.m. EST, the crew aboard the International Space Station (ISS) deployed an unusual satellite into the space. During a planned spacewalk, the two station crew members, space station commander Bill McArthur and flight engineer Valery Tokarev, released an unoccupied Russian Orlan spacesuit fitted with radio transmitter, a controller, sensors to measure temperature and battery power, and three 28 V batteries. Called SuitSat-1, this new satellite transmits recorded greetings of students from Paint Branch High School and Eastern Middle School in Silver Spring, Md. The greetings are in English, French, Japanese, Russian, German, and Spanish.

"All you need is an antenna (the bigger the better) and a radio receiver that you can tune to 145.990 MHz FM," noted Frank Bauer of NASA's Goddard Space Flight Center. "A police scanner or a hand-held ham radio will work just fine," he said.

Awards will be given to students who correctly identify the coded messages.

"In fact, SuitSat is a Russian brainstorm," said Bauer. "Some of our Russian partners in the ISS program had an idea. Maybe we can turn old spacesuits into useful satellites."

SuitSat is the first test of that idea. It is designed to help scientists determine the durability of spacesuits, the life of the batteries that power the suit, and if a tumbling suit affects the clarity of radio transmissions. It will lay the groundwork for SuitSats of the future. It transmits one of three types of messages for 30 seconds, pause for 30 seconds, and then repeat. It is sponsored by an international working group called Amateur Radio on the International Space Station (ARISS), which consists of volunteers from national amateur radio societies and the internationally based Radio Amateur Satellite Corporation (AMSAT), along with the Russian space agency and NASA.

Microchip Technology engineers, under the supervision of Principal Applications Engineer Steve Bible, played a key role in designing and developing the controller board, which uses a PIC18F8722 microcontroller, an MCP9800 temperature sensor and MCP6022 op amps. Voices and telemetry messages are stored in a single 8-Mbit flash EPROM. Likewise, the switchbox was also designed and assembled at Microchip. However, the transmitter was built around a Kenwood handheld amateur radio (model TH-K2) by an ARISS team led by retired NASA engineer Lou McFidan. The battery pack was removed and the radio was mounted on a block of aluminum that acts as a heatsink (see top photo). The radio is powered from the controller box (12 V regulated from 28 V).

The frequency of the radio was set to 145.99 MHz, power output was set to 500 mW, and the front panel was locked to prevent inadvertent changing of the settings. The radio is only used as a transmitter, no receive capability was built into SuitSat-1. The ARISS team also designed and developed the antenna, which is supposed to be a standard quarterwave groundplane antenna design used by ISS. While all the electronics is made to fit inside the suit, the quarterwave antenna and switch box are fitted onto the helmet with special techniques.

According to Microchip, two complete flight units were sent to NASA, which were further shipped to Russia for final certification testing and integration.

As you can see, all the components and ICs used in this project are commercial off-the-shelf parts. No rad hard devices were used in this project. However, they have been carefully selected, tested and repackaged to withstand the rigors of space. Last checked, the Suitsat was still alive and sending signals. For more on Suitsat audio recordings from around the world, visit www.aj3u.com/blog. For more on Suitsat, go to www.suitsat.org.

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