doi:10.1038/nindia.2012.123 Published online 22 August 2012
Researchers have designed a new prototype sensor that could measure ambient light on a planetary surface. Such sensors could be fitted to rovers headed for the Moon or Mars. A wireless network of such sensors could also record spatio-temporal measurements of various planetary surface parameters and beam the data back to Earth.
Information about ambient light on a planetary surface is useful for scientific analysis, navigation, path-planning and electrical operations of solar-powered rovers. Although various spacecraft have tried to measure ambient light, no long-term direct measurements of ambient light have been achieved.
To measure ambient light on a planetary surface, the researchers designed a prototype light-sensing module. This module contained two digital sensors (1 & 2) fitted with a radiofrequency part and a universal serial bus port allowing compatibility with computers. To avoid sensor saturation, sensor 2 was covered with a neutral glass filter.
To clarify the potential of this module, the researchers carried out experiments in the presence of artificial light sources and sunlight at varying intensities from sunrise to sunset and made comparisons with readings from a standard light meter.
The module registered slight variations in intensities of outdoor and indoor light. To assess this ability to detect variations less than 1 lux, the researchers measured the luminosity of the full moon. The module detected moonlight variations of about 0.01 lux.
"The light-sensing module could be used in a wireless sensor network to probe a large area of a planetary surface on a rover-based platform, with the coordinator node sitting on the rover and the other sensor nodes scattered around," says lead researcher S. V. S. Murty from the Physical Research Laboratory, Ahmedabad.