Remote Sensing: A Tool for Earth and Space Exploration

Remote sensing is the discipline of acquiring and interpreting aerial images of the earth or other planets using sensor-based technology. Those images, covering subjects like the earth’s surface, the atmosphere, oceans, objects and phenomenon, are then analysed to provide precise data that would not be possible to obtain easily by other means.

While the term "remote sensing" was coined in the 1960s, the first aerial photographs were taken in the 1850s, following the invention of the camera. Using a hot air balloon French photographer Gaspard-Félix Tournachon, also known as Nadar, took the first successful aerial photograph of a French village in 1858.

Today, remote sensing is a specialist field, done using state-of-the-art sensors and cameras attached to planes, space craft and robotic vehicles that detect and monitor the physical characteristics of an area by measuring its reflected and emitted radiation.

The data interpreted from those images is used in numerous fields by, amongst others, mining companies searching for minerals, environmentalists looking for micro-plastics and space agencies scanning the Moon, Mars and other planets.

Dr Joseph Michalski, Associate Professor, Department of Earth Sciences at the University of Hong Kong, is a geologist and planetary scientist who uses remote sensing to study the mineralogy and geology of planets at HKU’s Planetary Mineralogy and Spectroscopy Laboratory.

“Remote sensing is an incredibly powerful tool that allows us to understand, big, complex systems on this planet, Dr Michalski said. “Looking toward the future, remote sensing will only become a bigger part of how we see our own planet, and how we map distant worlds.”

Part of Dr Michalski’s research is focussed on how the geology of the early Earth led to the origin of life on this planet, and whether life might have formed elsewhere in the Solar System.

 “When NASA sends rovers to Mars, they use instrumentation to look at the detail mineralogy of samples at very high resolution,” he said. “We're doing that in our laboratory to prepare for China's mission to Mars, and for future missions to the moon and other planets.”

Using the latest FTIR spectrometer equipped with multiple detectors and beam splitters, Dr Michalski and his team are able to analyse geological and biological materials of all parts of the spectrum from wavelengths of 350 nanometers to 35 micrometers. They plan to use infrared measurements of hydrothermal minerals as a basis to interpret the detection of important minerals on Mars.