Scientists spot buried remnants of polar ice sheets on Mars – Astronomy Now

May 22, 2019 - Comment

On this view of Mars’ north polar ice cap, the vertical scale has been exaggerated to focus on elevation adjustments. New analysis signifies sufficient water is locked up in buried remnants of polar ice sheets to cowl the crimson planet to a depth of 1.5 meters (5 ft). Picture: SA/DLR/FU Berlin; NASA MGS MOLA Science



On this view of Mars’ north polar ice cap, the vertical scale has been exaggerated to focus on elevation adjustments. New analysis signifies sufficient water is locked up in buried remnants of polar ice sheets to cowl the crimson planet to a depth of 1.5 meters (5 ft). Picture: SA/DLR/FU Berlin; NASA MGS MOLA Science Group

Scientists have found remnants of historical ice sheets buried in sand a mile beneath Mars’s north pole, they report in a brand new examine. The findings present conclusive proof of the waxing and waning of polar ice on the crimson planet as a result of adjustments in its orbit and tilt, in accordance with the examine’s authors.

Researchers on the College of Texas at Austin and the College of Arizona made the invention utilizing measurements gathered by the Shallow Radar (SHARAD) instrument on NASA’s Mars Reconnaissance Orbiter. SHARAD emits radar waves that may penetrate as much as a mile and a half beneath Mars’s floor.

The brand new findings, revealed in the present day in AGU’s journal Geophysical Analysis Letters, are necessary as a result of the layers of ice are a file of previous local weather on Mars in a lot the identical method that tree rings are a file of previous local weather on Earth, in accordance with the researchers. Learning the geometry and composition of those layers might inform scientists whether or not local weather circumstances have been beforehand beneficial for all times.

The staff discovered layers of sand and ice that have been as a lot as 90 p.c water in some locations. If melted, the newly found ice can be equal to a world layer of water round Mars a minimum of 1.5 meters (5 ft) deep, which may very well be one of many largest water reservoirs on the planet, in accordance with the researchers.

“We didn’t anticipate finding this a lot water ice right here,” stated Stefano Nerozzi, a graduate analysis assistant on the College of Texas Institute for Geophysics (UTIG) and lead writer of the brand new examine. “That seemingly makes it the third largest water reservoir on Mars after the polar ice caps.”

A composite picture of alternating layers of ice and sand captured by the HiRISE digicam aboard NASA’s Mars Reconnaissance Orbiter. The picture was processed to indicate water ice as light-coloured layers with sandy layers a darker blue. Skinny patches of frost present up as white. Picture: NASA/JPL/College of Arizona

The findings have been corroborated by an unbiased examine utilizing gravity knowledge as an alternative of radar, led by researchers at Johns Hopkins College and likewise revealed in the present day in Geophysical Analysis Letters, of which Nerozzi is a co-author.

The authors suspect the layers fashioned when ice accrued on the poles throughout previous ice ages on Mars. Every time the planet warmed, a remnant of the ice caps turned coated by sand, which protected the ice from photo voltaic radiation and prevented it from dissipating into the ambiance.

Scientists have lengthy recognized about glacial occasions on Mars, that are pushed by variations within the planet’s orbit and tilt. Over intervals of about 50,000 years, Mars leans towards the solar earlier than regularly returning to an upright place, like a wobbling spinning high. When the planet spins upright, the equator faces the solar, permitting the polar ice caps to develop. Because the planet tilts, the ice caps retreat, maybe vanishing completely.

Till now, scientists thought the traditional ice caps have been misplaced. The brand new findings present that actually vital ice sheet remnants have survived beneath the planet’s floor, trapped in alternating bands of ice and sand, like layers on a cake.



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