Mysterious Mars Formation Created When Underlying Ice Lake Melted, Study Suggests

Mars's Aram Chaos, the uneven surface of an ancient impact crater, was formed when an underlying lake of ice melted, a new study suggests.

The Red Planet is home to a number of enigmatic and wholly distinctive features stretching up to hundreds of kilometers, the source of which have long puzzled scientists.

In order to solve the mystery behind this particular one, researches combined observations from satellite photos of the 280 kilometer-wide and four kilometer-deep crater with models of the ice melting process and resulting outflow.

"About 3.5 billion years ago, the pristine Aram impact crater was partly filled with water ice that was buried under a two-kilometre thick layer of sediment," Manuel Roda, a researcher from Utrecht University, explained. "This layer isolated the ice from surface temperatures, but it gradually melted over a period of millions of years due to the heat released by the planet. The sediment overlying fluid water became unstable and collapsed."

According to the study, more than 100,000 cubic kilometers of liquid water, or four times more water than that contained in Earth's largest freshwater lake, escaped when this occurred, carving a valley 10 kilometers wide and 2 kilometers deep in the matter of a month.

Knowing this has significant implications not only for the past, but the present, too, the researchers argue.

"An exciting consequence is that rock-ice units are possibly still present in the subsurface," Roda said. "These never achieved the melting conditions, or melted only a lower thin layer, insufficient to result in a full collapse event."

Moreover, Roda adds, "Buried ice lakes testify of Mars rapidly turning into a cold, frozen planet, but with lakes buried in the subsurface,"

Such lakes, shielded for years from hazardous UV radiation, may yet prove a favorable habitat for life, the researchers conclude.

The study was presented at the European Planetary Science Congress at the University of College London.