. While many astronomers concluded that the radar reflection was the result of a 1.4 km thick formation of relatively pure water ice, there has been an ongoing debate ever since as to whether the SPLD is water ice or something else entirely. For the sake of their study, Lalich and his colleagues ran computer simulations on the MARSIS data to investigate what could have generated the strong radar reflections.
As they explained in their paper, radar reflections of this kind are the result of liquid water on Earth, as indicated by buried lakes like Lake Vostok, located under the East Antarctic Ice Sheet. But on Mars, the prevailing opinion was that conditions are too cold for similar lakes to form. To investigate this, Lalich and his colleagues used a one-dimensional modeling procedure commonly used to interpret MARSIS observations.
This describes the interaction between a material and how electromagnetic radiation passes through it instead of being reflected by it. In the end, they found that simulations using three layers produced reflections as bright as the MARSIS observations. This effectively showed that geological layers could account for the SPLD readings without the presence of water or other rare materials.
Given its importance to future missions and to understanding the evolution of Mars, it is vitally important that scientists determine where water is on Mars . The presence of liquid water beneath the polar cap could also have important implications for its age, the internal heating of Mars, and how the planet’s climate evolved in recent geological periods. Much the same is true of the many otherdetected in recent years.
“If there is liquid water, maybe there’s life, or maybe we could use it for future human missions to Mars. None of the work we’ve done disproves the possible existence of liquid water down there. We just think the interference hypothesis is more consistent with other observations. I’m not sure anything short of a drill could prove either side of this debate definitively right or wrong.”