Despite the numerous studies that have shown favorable conditions for microbial life on Mars, there still has not been direct evidence to suggest that the planet ever supported life. In a recent study, planetary geologists at Brown University found mounds of hydrated silica that were left on a volcanic cone in an area of Mars called the Nili Patera three billion years ago.
The hydrated silica’s location on the side of a volcano provides the best context yet in which the mineral can be studied, because the setting is intact and preserved. The area of the mineral’s origin is therefore crucial to what may be one of the more recent habitable environments on Mars.
“You have spectacular context for this deposit,” J.R. Skok, a graduate student at Brown and lead author of the paper in Nature Geoscience said in an interview with ScienceDaily. “It’s right on the flank of a volcano. The setting remains essentially the same as it was when the silica was deposited.”
Both water and heat are present in the silica deposit, which shows that Mars contained a wet and warm environment before it became dry and cold.
“The heat and water required to create this deposit probably made this a habitable zone,” Skok said to ScienceDaily. “If life did exist there, this would be a promising spot where it would have been entombed — a microbial mortuary, so to speak.”
The hydrated silica was found using cameras on NASA’s Mars Reconnaissance Orbiter, a spacecraft that examines Mars from orbit, which exposed patches of a bright deposit on the volcanic cone as well as the surrounding area.
The bright deposits were then identified as hydrated silica by the Hopkins Applied Physics Laboratory’s Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). The CRISM is an instrument that looks for traces of water on Mars’s surface and is one of six instruments that fly on the Mars Reconnaissance Orbiter.
Scott Murchie from the Hopkins Applied Physics Laboratory is now the Principal Investigator of the CRISM, and leads the CRISM team comprised of scientists from various universities.
Silica can dissolve in hot water to form hydrated silica. The CRISM found hydrated silica in uphill locations, which indicates that the deposits on the volcanic cone were caused by hot springs or fumaroles. A fumarole is a hot spring that contains more heat than water, causing the water to boil off through a hole in the earth’s crust in the form of steam. Fumaroles are often found near volcanoes, as is believed to be true in this case.
“The habitable zone would have been within and alongside the conduits carrying the heated water,” Murchie said in a press release.
The volcanic cone stands at 100 yards tall on the Nili Platera, which occupies 30 miles of the Syrtis Major, a volcanic area of Mars. The cone formed when a magma chamber that discharged the lava collapsed. Over time, additional lava flows enlarged the cone.
“We can read a series of chapters in this history book and know that the cone grew from the last gasp of a giant volcanic system,” John Mustard, co-author of the paper. said to ScienceDaily. “The cooling and solidification of most of the magma concentrated its silica and water content.”
The discovery of hydrated silica still intact on the volcanic cone can provide important clues about the time period that potentially supported a microenvironment on Mars.