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RFID Sensors Help NASA to Monitor Conditions in Antarctica

The NASA Johnson Space Center and the National Science Foundation are testing an inflatable habitat that uses RFID tags combined with sensors to transmit temperature and air-pressure data to the United States.
By Claire Swedberg
The researchers set up two RFID systems. In one case, they employed battery-powered tags using the RuBee wireless protocol to send and receive data via long-wave (LW) magnetic signals. The RuBee tags transmit at a frequency of 131 kHz. Hong and Hafermalz installed a loop antenna around the inside of the structure to receive transmissions from the 40 RuBee tags connected to sensors monitoring the interior temperature.

The tags capture that temperature, and to save battery life, they transmit it to the interrogator's antenna only once every 15 minutes. The interrogator is cabled to the laptop, which then sends the information back to the United States via communication satellite—first to NASA's Denver office, where the Internet-based data is then sent to Johnson Space Center. The system utilizes Visible Assets' hardware, including tags, antenna and RFID reader, as well as software to translate data from that interrogator.


A RuBee transceiver, to the right of the laptop, receives data from sensors that measure the habitat’s interior temperature.

In a separate system, approximately eight passive Honeywell RFID tags transmit at 434 MHz using a proprietary air-interface protocol. The tags are embedded in the walls and wired to sensors measuring temperature and air pressure within the wall. A dedicated interrogator antenna for each tag transmits to a multiplexer, which sends the data at a rate of about five times per minute to a single interrogator, also cabled to the laptop computer.

By using the multiplexer, researchers are able to avoid backscatter from multiple tags received by one interrogator that would be unable to properly interpret those multiple transmissions. Honeywell provided the software that identifies the antenna and tag number, and translates sensor data. As with the Visible Assets solution, Hong explains, the Honeywell system data is transmitted via satellite. With both systems, Hafermalz says, researchers have been able to bring up and examine data in real time, with a delay of a few seconds.

So far, Hafermalz says of the inflatable structure, "It's holding up pretty well—there is a lot of snow drift on top, but it hasn't affected the internal structure thus far." When it came to the RFID system, Hong says, "One of our concerns was the availability of power. They had some shutdowns of power, which corrupted some of our files." By having a camera system to view the computer and sensors, however, Hong and Hafermalz were able to conduct troubleshooting. Occasionally, the McMurdo staff has had to manually press the generator's reset button. Since then, Hong says, the team has added an uninterruptible power supply (UPS) system.

The researchers are not yet ready to declare either the RFID systems or the structure itself a success. "We are still in the early phases of data analysis," Hafermalz says. "Time will tell whether the structure holds up over a year. We have a high degree of confidence that, ultimately, the habitat and the sensor systems used to monitor the structure will prove successful." In December 2008, the structure and sensors may be further tested at that location, or the structure may be removed.

USER COMMENTS

Pietro Battistoni 2008-06-12 07:44:22 PM
Battery I wonder which temperature the active TAG effectively has to work. Frozen battery are still a challenge for us, in active TAG.

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