The hits simply carry on coming from the Mars Perseverance rover. It’s exploring Jezero Crater on the Pink Planet, searching for proof of microbial life within the planet’s historic (and even current) previous. Just lately it noticed a really strange-looking rock with black and white stripes. Its look and site sparked numerous questions. Perseverance group members have named it “Freya Citadel.”
From the picture, this chunk seems to be remarkably much like metamorphic rocks on Earth. Essentially the most acquainted are gneiss, marble, and schist (to call a number of). In keeping with Jeffrey Kargel of the Planetary Science Institute, who speculated on what Freya Citadel may very well be, it resembles a really high-grade kind of rock much like what we discover right here at house. “It seems to be like and plausibly is, a metamorphic rock containing feldspar or different white-ish minerals organized in one thing known as boudinage,” he stated. “That phrase stems from French, referring to a chain-link sausage-like construction. Within the case of rocks, it kinds when you will have layered materials, normally sedimentary rocks, the place the layers are compressed from above underneath situations of excessive warmth and strain. A lot of the rock responds plastically squishing down and spreading out.”
Kargel, who will not be related to the Perseverance mission, identified that the situations underneath which Freya Citadel fashioned on Mars could be much like Earth’s. “These situations have been frequent on Earth, and erosion then finally exposes the rocks on the floor. If that is an indigenous Mars rock, it probably would have undergone metamorphism within the decrease crust, after which an impression blasted it out, and the rock landed the place the rover may study it,” he stated. Different transport prospects embrace a deposit by fluid supply, which is sensible since water has flooded the crater previously.
What Form of Rock Is It?
So, what’s the story with this rock? Based mostly on the picture, it seems to be fairly out of context with a lot of the mud and sedimentary materials within the crater. That makes it value reviewing the area in a bit extra element. An impression some 3.8 billion years in the past carved out Jezero Crater. It lies on the western edge of a giant impression basin known as Isidis Planitia. A big impression created that basin throughout an impression about 3.9 billion years in the past. In some unspecified time in the future within the distant previous, water stuffed Jezero not less than twice. There’s a river delta in addition to move channels exiting the crater.
The place there’s water, there’s sediment, which hardens into sedimentary rock. ( The principle sorts of rock are igneous (volcanic or intrusive in origin), sedimentary (deposited by wind or water), and metamorphic.) Not surprisingly, the Perseverance rover continues to search out sedimentary deposits and layers at Jezero. The delta is clay-rich, and the crater accommodates different supplies identified to keep in touch with water. Nevertheless, a number of the rocks in Jezero are additionally igneous. Meaning they have been created by volcanic exercise and in some way dropped at the crater.
That brings us again to Freya Citadel, which seems to be metamorphic at first look. Such rocks have skilled some sort of warmth, strain, or different kinds of geologic stress. That course of modified them from one kind to a different. It additionally altered the feel of the unique rock and the mineral composition.
Making a Metamorphic Rock
On Earth, metamorphics are a big a part of our planet’s crust. They’ll kind deep underneath the floor the place temperatures and pressures are excessive. Tectonic exercise additionally forces metamorphism. So do impression occasions. Each warmth and compress the encircling rock. An impression additionally “excavates” rocks out from deep beneath the floor and tosses them throughout the floor. Volcanism may very well be one other offender, sending sizzling magma into cracks and openings of current rocks and “morphing” them. Metamorphism can be the product of the motion of sizzling, mineral-rich fluid injected into different rocks by hydrothermal exercise. If that occurred, the fluids may have discovered their approach into the layers. The outcome could be deposits of “intrusive” minerals, leading to a layered look.
On Mars, all these processes additionally occurred all through historical past. An excellent evaluation of the rock’s minerals may give extra particulars concerning the mineral make-up of Freya Citadel. That will settle the query of what sort of rock it’s. Such research may additionally give some perception into situations on Mars on the time it fashioned.
One factor to remember is that Perseverance checked out Freya Citadel with its Left MASTCam-Z digital camera. A more in-depth examine of the rock’s mineralogy and chemistry utilizing its onboard spectrometer may reveal much more details about Freya Citadel’s origins. Planetary scientists raised questions on whether or not the Perseverance group may ship the rover again to do a mineralogical examine. For now, nevertheless, the MASTcam imagery has prompted a lot hypothesis.
“If the rock seems to be metamorphic and from the decrease crust of Mars, it is likely to be a really uncommon alternative to look at a rock from an especially historic interval–maybe a former sedimentary rock that fashioned when Mars was extraordinarily younger, fashioned because the Martian crust was simply growing,” stated Kargel. “It would probably bear proof of the oldest hydrosphere identified on Mars, or wherever within the Photo voltaic System.”
How Did It Get There?
No matter its make-up, planetary scientists now want to find out how this uncommon rock acquired to Jezero Crater within the first place. For the reason that area has been inundated not less than twice in Mars’s lengthy historical past, the most definitely interpretation is that it fashioned elsewhere and was probably blasted out from beneath the floor throughout an impression. Then, it acquired carried alongside by water. There’s proof within the Perseverance picture of slight rounding of the protruding edges to help the thought of fluid transport. Supplies in a flood can get eroded as they tumbled and bounced alongside within the water. One scientist at PSI urged that the rounding reveals the rock acquired carried throughout not less than a number of kilometers.
At the least one “outlier” suggestion is that possibly the rock has an Earth origin. An historic impression on our planet may have despatched Freya Citadel out to Mars, the place it landed as an Earth meteorite. That’s not a possible origin, nevertheless, for the reason that dynamics of getting Earth meteorites out from Earth to Mars are advanced.
Freya Citadel’s existence at Jezero Crater factors out the historic forces that formed the planet. Specifically, it’s a clue towards understanding the advanced sequence of occasions that introduced this rock to its present resting place in Jezero Crater. It takes time to investigate these occasions and the rock itself, which is probably going what the Perseverance group is doing because the mission itself continues its trek throughout the Martian panorama.
Observe: Particular due to researchers on the Planetary Science Institute for discussing particular facets of metamorphic rock formation with the creator.
