ESA’s Mars Express has aboard some pioneering radar experiment currently investigating the Red Planet and searching for any evidence of sub-surface reservoirs of water and ice. This technology holds great promise for subsurface oceans under the icy crusts of Europa and Titan as well. In our experience to date, liquid water = Life!
However the technology used by Mars express cannot be used directly here on earth, as the frequency of 5 Mhz used for Mars would quickly interfere with radio communications. Experiments are currently underway to adapt the technology for use at 435 Mhz where the radar will not cause disruption to earth based communications.
So what are these experiments all about? In a boost for earth science research, funded by ESA’s General Studies Program, a new study, which has been dubbed the Advanced Concept for RAdar Sounder (ACRAS) is underway. This technique has been proposed once before by ESA in the late 90′s, however at that time the technology was not available to filter out false signals. These false signals come firstly from the earths Ionosphere and then secondly from terrain outside the radar’s target area.
ACRAS appears to have found a way around this problem by the use of multiple radar beams, in this case 3 beams, each with slightly different properties, using the principles of the Doppler effect. The Doppler effect is best demonstrated by the changing pitch of siren on a fast moving vehicle, as it first moves towards you then away from you.
This new study is meeting with success and opens the doors for even more precise instruments that could work around Earth. A satellite fitted with this type of radar could accurately estimate the ice sheet thickness of the Antarctic and other ice covered regions. The data coming back would reveal the three-dimensional internal structure of the ice sheets, the contours of the underlying terrain and give information right down to the bedrock. Watching how this changes over time will give climate scientists invaluable data. Currently, expensive and difficult drilling programs largely do work such as this.
As we all hear in the news day after day, melting ice from the Polar Regions are set to have a huge impact on climate change. The most recent example of this is the evidence of a potential large scale break up of the Ross Ice Shelf in Antarctica. Not only could this work make a real difference to our understanding of the effects of climate change here on the lovely blue green planet we call home, it could unlock the doors to the search for life in our own solar system.
The ACRAS study is set to conclude in October this year and although a fully-fledged earth based satellite mission is a long way off yet. Florence Heliere, the ESA study officer says, “We hope to conduct an airborne test of the technique.” Source: ESA.
So as you go out to gaze up at the night sky, looking at the prominent planets Mars and Saturn in the early evening and Jupiter late in the evening. Spare a thought for the hardworking scientists who have made it possible for this pioneering work to be done.
By: Ian Maclean
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