A research team headed by Jean-Pierre Williams of the University of Califonia at Los Angeles has taken a close look at the Argyre region on Mars and drawn a couple of conclusions that may be of astrobiological importance.
Argyre, a large basin with a diameter of more than 1,200 kilometers and a depth of 4 km, resulted from a large asteroid impact about four billion years ago. There are several such large impact structures on Mars, but the special thing about Argyre is that, according to the new research, volcanism and likely habitable conditions lasted for a long time in this region.
The impact itself would have caused hydrothermal activity—heated water at or near the surface of Mars—at around the same time life originated on Earth. And simulations show that the hydrothermal activity would have persisted after a large impact for hundreds of thousands or even millions of years. Landforms and geological structures on the surface show that habitable conditions likely extended even longer, up to billions of years.
Williams and his colleagues also report that Argyre Mons, a huge 50-kilometer-wide mountain in the basin, is of volcanic origin. The terrain adjacent to the mountain not only shows landforms suggesting volcanic and tectonic activity, but also shows giant polygons that are believed to have formed in a water-rich environment.
The picture of an Iceland-like landscape on Mars emerges. Magma, volcanic activity and hydrothermal heat flows would be interacting with an overlying crust of water ice. This kind of interaction could have provided all the necessary ingredients for life, whether it originated on Mars or arrived in an asteroid during that period, which is characterized by frequent impacts.
Might we still find hydrothermal activity in Argyre Basin today? We don’t know. By the pristine look of some of the landforms, it’s possible. But even if not, Argyre might have been an ancient hot spot for life. And if it was, we might still find traces of it preserved in ice or hydrothermal deposits. That makes Argyre a high-priority target for future astrobiological exploration of Mars.