A rock on Mars has yielded a surprising yellow treasure after Curiosity accidentally broke open its unremarkable exterior.
When the rover rolled its 899-pound body over the rock, it shattered and revealed yellow crystals of elemental sulfur. Although sulfates are fairly common on Mars, this is the first time sulfur has been found on the Red Planet in its pure elemental form.
What's even more exciting is that the Gediz Vallis channel, where Quriosity found the rock, is strewn with rocks that look suspiciously like the sulfur rock before it was happily crushed. This suggests that somehow, in some places, there may be an abundance of elemental sulfur there.
"Finding a field of rocks made of pure sulfur is like finding an oasis in the desert," says scientist Ashwin Vasavada of NASA's Jet Propulsion Laboratory.
"It's not supposed to be there, so now we have to explain it. Discovering strange and unexpected things is what makes planetary exploration so exciting."
Sulfates are salts that form when sulfur, usually in the form of a compound, mixes with other minerals in water. When the water evaporates, the minerals mix and dry out, leaving the sulfates behind.
These sulfate minerals can tell us a lot about Mars. For example, about the history of its water and how it has weathered over time.
Pure sulfur, on the other hand, is formed only under a very narrow set of conditions that are not known to have occurred in the region of Mars where the probe made its discovery.
Frankly, there's a lot we don't know about the geologic history of Mars, but the discovery of quantities of pure sulfur just hanging out on the Martian surface suggests there's something pretty big we don't know about.
It's important to understand that sulfur is an essential element for all life. It is normally taken up in the form of sulphates and is used to produce two of the essential amino acids that living organisms need to make proteins.
Since sulfate has been known about on Mars for some time, the discovery tells us nothing new in this area. Either way, we haven't found any signs of life on Mars yet. However, we continue to encounter remnants of particles that living organisms would find useful, including chemicals, water, and past habitable conditions.
Stuck here on Earth, we are quite limited in the ways we can access Mars.
Quriosity's instruments were able to analyze and identify sulfide rocks in the Gediz Vallis channel. However, if it hadn't taken a route that capsized and cracked one of them, it might have been a while before we found it.
The next step will be to find out exactly how, based on what we know about Mars, this sulphur could have ended up there. This will take a bit more work, probably involving detailed modelling of the geological evolution of Mars.
In the meantime, Quriosity will continue to collect data on the same. The Gediz Vallis Channel is an area rich in Martian history, an ancient waterway whose rocks now bear the imprint of the ancient river that once flowed through them, billions of years ago.
The probe drilled a hole in one of the rocks, taking a powder sample from its interior for chemical analysis, and is now making its way deeper down the channel to see what other surprises might be waiting behind the next rock. | BGNES
