Curiosity finds “a surprise” on the Martian surface
- Eve Carruthers
- Jul 19, 2024
- 2 min read
On May 30th, scientists were amazed by a rock that NASA’s Curiosity rover drove over and incidentally cracked open. In doing this, they observed something previously unseen on the Martian surface, pure yellow sulfur crystals.
Since October 2023, Curiosity has been exploring a sulfate rich region of Mars called Mount Sharp. A sulfate is a type of salt that occurs as water is evaporating and scientists believe that billions of years ago, streams and ponds left behind the minerals as the water dried up. Assuming that this idea is correct, these minerals could offer clues as to how – and why – the Red Planet’s climate changed from being more Earth-like to the frozen desert it is today. The minerals were spotted by NASA’s Mars Reconnaissance Orbiter and soon after Curiosity landed and began work in 2012, it has discovered many different types of rocks that have minerals especially salty minerals such as magnesium sulfate (Epsom salt is one kind), calcium sulfate (including gypsum), and sodium chloride (ordinary table salt), that could be indicative of a presence of water.
However what makes this rock different, is how the sulfur found is elemental, or pure sulfur. It is also not clear what relationship, if any, the elemental sulfur has to other sulfur-based minerals in the area. Elemental sodium is also only formed in a small range of situations, such as being formed in volcanic regions as a deposit formed by the emission of hydrogen sulfide, followed by aerial oxidation to the element, therefore when looking at the history of the area in which these crystals were found, it is very strange. Not only is the formation of these crystals a surprise but the sheer amount of them was shocking, as Curiosity has found an entire field of rocks that look similar to the one it crushed.
“Finding a field of stones made of pure sulfur is like finding an oasis in the desert,” said Curiosity’s project scientist, Ashwin Vasavada of NASA’s Jet Propulsion Laboratory in Southern California. “It shouldn’t be there, so now we have to explain it. Discovering strange and unexpected things is what makes planetary exploration so exciting.”
Curiosity has made numerous discoveries while navigating the rugged terrain of the Gediz Vallis channel, a groove that winds down a portion of the 3-mile-tall (5-kilometer-tall) Mount Sharp. The rover has been ascending this mountain since 2014. Each layer of Mount Sharp represents a different period in Martian history. Curiosity’s mission is to investigate where and when the planet's ancient landscape could have provided the necessary nutrients for microbial life, if it ever existed on Mars.
The Gediz Vallis channel is one of the primary reasons that scientists chose to study this region on the planet because they think that the channel was carved out by flows of water and the debris from this left a ridge of boulders and sediment up to 2 miles down the mountainside below the channel. The aim of the research is to develop a better understanding of how this landscape changed billions of years ago.
