From: Western University
Posted: Thursday, December 1, 2016
The Mars Camera, officially known as CaSSIS (Colour and Stereo Surface Imaging System), aboard the European Space Agency‘s ExoMars Trace Gas Orbiter (TGO) captured its first high resolution images of the Red Planet last week. The Swiss-led camera worked almost perfectly and has provided spectacular views of the surface.
Developed by a team from the University of Bern led by Nicolas Thomas, CaSSIS was launched with the TGO on March 14, 2016. TGO entered orbit around Mars on October 19, 2016.
As a co-investigator on the CaSSIS imager, Western University’s Livio Tornabene is specifically tasked with simulating how CaSSIS imaging will address its specific science objectives, as well as the overarching objectives of the TGO mission itself.
Today, Tornabene, an Adjunct Research Professor in Western’s Department of Earth Sciences, released a compilation of simulated images, which show some of the possible imaging modes and image-derived products that may be achieved with CaSSIS, and which he and his team will compare to the couple dozen or so real CaSSIS images taken of Mars over the last few weeks.
“I have been keen about raising the scientific community’s awareness of the effectiveness and limitations of a full-colour CaSSIS image, which I have accomplished with my team through the simulation of CaSSIS images over key sites on Mars with currently existing datasets,” explains Tornabene. “These simulated CaSSIS images provide us not only with a visual ‘sneak peek’ of how the Martian surface would be viewed through CaSSIS but more importantly answers questions like: How well will CaSSIS see specific features or active phenomena on the surface of Mars? And which of the four wavelengths (colours) of CaSSIS are required for a given region on Mars?”
CaSSIS can take up to four wavelengths (i.e., colours) that can be combined in different ways to highlight important surface properties. This includes blue-green, red and two infrared colours.
The 26 simulated images Tornabene and his team have created thus far provide the CaSSIS science team, as well as and the greater Martian science community, an idea of what the colour and spatial capabilities of the real CaSSIS images will be, and how to best plan for CaSSIS imaging based on the known context of the properties of the target surface, and the intention of the scientific investigation at that target location.
This compilation of simulated CaSSIS images shows a portion of the Nili Fossae region on Mars, where minerals such as olivine, serpentine, carbonate and clay are found. This mineral diversity is best reflected by the image marked as “BRC”, which combines all four wavelengths of CaSSIS to provide a vibrant and colourful image that informs us about the distribution of these minerals at a spatial resolution that is not possible with the orbiting spectrometers that were used to detect these specific minerals.
The Nili Fossae region is important to the ExoMars 2016 TGO mission as it is thought to be one of the potential source regions for transient methane gas in the Martian atmosphere that the other instruments on the orbiter is hoping to detect, characterize and determine its origins. Olivine and serpentine, both greenish minerals commonly found on Earth, are key towards understanding the origins of methane, as olivine reacts with water and carbon dioxide to form serpentine and methane as a byproduct. These simulated images are approximately 10 km across, which is close to the maximum width of the anticipated CaSSIS images.
In March 2017, the orbiter will begin to make a series of complicated maneuvers to achieve its final mapping orbit, and then begin its science mission in Late 2017/Early 2018. Unitl then, the couple dozen or so test images taken, and the simulated images produced by Tornabene and his team, will help the team plan for the actual science phase of the mission.
Image credits: Livio L. Tornabene (WesternU-CPSX)/NASA/JPL/JHU-APL/MSSS/UofA/ASC-CSA/ESA/Roscosmos/ExoMars/CaSSIS/UNIBE
PAN: Red greyscale “black and white” image; such an image can be taken where there is little to no colour variation in the Martian surface, but where we still wish to capture the diverse landforms and surface features that may be present at a specific location.
IRB1, IRB2: False-colour infrared images that use the two infrared colours interchangeably; these are the best possible image modes for regions on Mars that are known to be colourful and compositionally diverse.
BRC: Band Ratio colour Composite image; this image combines all four wavelengths into a single colour image to show differences in the oxidation (rusting) of iron, which relates to minerals that may have been altered by water (yellows and oranges), and surface materials that remain unaltered (blues). This image product can be generated for the most colourful and compositionally diverse areas of Mars, as long as all four wavelengths are taken by CaSSIS.
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