doi:10.1038/nindia.2013.87 Published online 28 June 2013
Researchers have invented a new kind of wireless sensing device that could be used for locating ice on the Moon in future space missions .
The lunar surface is covered by a layer of debris (called regolith). The debris is expected to harbour water ice in the permanently dark regions of the Moon. However, a lunar rover may be unable to reach these rugged terrains. A wireless sensor could overcome this problem.
To this end, the researchers designed a wireless impedance sensor node (WISN). It consists of an impedance-measuring circuit, a signal processing unit, a memory and a 2.4-GHz transceiver. Data from the sensor is transmitted by an antenna at 2.4 GHz.
The researchers tested its effectiveness at detecting pure ice by inserting the electrodes of the WISN into ice formed from deionized water. The collected data was then transmitted wirelessly to another WISN, which acted as a data aggregator, receiving the data and then sending it to a computer. The study found that WISN was able to differentiate between regolith and ice.
The researchers say that the sensor hardware needs to be as compact as possible and that it should be protected from extreme temperature changes and cosmic radiation. The sensors could be deployed from an orbiter by using a free-falling packet that lands on the lunar surface. Ejected like a lander from the orbiter the packet would open and scatter the sensors to cover the zone of interest.
In sunlit regions, the sensors can use solar cells to harness sunlight. "In permanently shadowed regions, microwave transmission from the orbiter can power the sensors," says J. P. Pabari, a co-author of the study. He notes that such sensors could be used to detect lunar ice in the polar region in the future.