REAL EARTH, VIRTUAL MARS: USING DIGITAL TECHNOLOGY TO EXPLORE MARS VIA EARTH ANALOGS

Recent advances in technology have made imaging techniques developed for spacecraft accessible at reasonable costs. Smartphone-mounted thermal cameras collect thermal infrared light that is interpreted to produce temperature images. Gigapixel panoramic images ('GigaPans') are easily acquired via digital cameras and specialized camera mounts. Both are an opportunity to use hands-on classroom and field activities to relate "real" geology on Earth with "virtual" geology on Mars.

Interpretation of thermal images of planetary surfaces often involves examining the temperature of the surface, which is controlled by solar heating and the thermal inertia of the surface. Variations in thermal inertia, or the resistance of the material to a change in temperature, are often interpreted as changes in particle size, although thermal inertia is also related to albedo, composition, density, and packing state. Dusty or sandy surfaces (small particle sizes) undergo relatively fast changes in temperature over the course of a day, while rockier surfaces take longer to heat up/cool down.

A simple lab setup using a plastic container of sediment heated with a plant lamp illustrates how different materials react to daily changes in solar energy. The thermal imager is used to record the relative temperatures of the surface and sides of the container as they warm when exposed to light, and then as they cool when the light is turned off. The relationship of particle size and albedo with temperature are visible in the surface view, while images of the sides of the container give a view into how the subsurface responds to diurnal heating/cooling.

The hands-on experiments can be related to temperature images from thermal infrared satellite data. Complete temperature mosaics of the Martian surface are available online: these mosaics of the daytime and nighttime temperature were compiled from images taken by the Thermal Imaging System (THEMIS) instrument on Mars Odyssey. The results from the experiments above can be related to the interpretation of temperature variations observed on Mars. These small scale thermal experiments can then be related to larger outcrop scales via panoramic images, which can be directly compared to panoramic images collected on Mars by rovers on the surface (e.g. examples presentted by Johnson and Piatek, NE-GSA 2015).