If looking at this Mars vista conjures up childhood memories of the song, "One of these things is not like the others," NASA scientists are right there with you.
Perseverance, a car-size lab on six wheels, traveled into the Red Planet's Neretva Vallis last week. Though this region may look like a barren desert, it was once an ancient river channel that fed into the Jezero crater billions of years ago.
As Perseverance traversed the inlet, the rover came upon a hill covered in boulders, with one in particular attracting the science team's attention: a light speckled rock amid a sea of dark lumps.
"Every once in a while, you'll just see some strange thing in the Martian landscape, and the team is like, 'Oh, let's go over there,'" Katie Stack Morgan, deputy project scientist of NASA's Mars 2020 mission, told Mashable. "This was like the textbook definition of (chasing) the bright, shiny thing because it was so bright and white."
The boulder is so exceptional, scientists have said it's in a league of its own. Closer analysis with the rover's instruments shows it is likely an anorthosite, a rock type never seen before while exploring Mars, Stack Morgan said, though there have been signs such rocks should exist. Not even the Curiosity rover, which has observed more variety in Gale Crater, has seen one quite like this.
Though such anorthosite rocks are on the moon and in mountain ranges on Earth, they're generally considered rare in the solar system. True Martian examples have eluded researchers, including within our planet's inventory of Red Planet meteorites that traveled through space to get here.
This discovery could bolster the idea that Mars' early crust was way more complex than once thought — and perhaps similar to Earth's original crust. Understanding the ancient Martian crust also could help unlock secrets about the evolution of Earth and how life emerged here.
"This was like the textbook definition of (chasing) the bright, shiny thing."
The rover team named the special boulder, about 18 inches wide and 14 inches tall, "Atoco Point" after a landmark in the Grand Canyon.
"Seeing a rock like Atoco Point is one of these hints that, yes, we do have anorthosites on Mars, and this might be a sampling of that lower crust material," Stack Morgan said. "If we see it later on in the context of other rocks, it can give us a sense for how the earliest crust of Mars kind of came to be."
Anorthosites are predominantly made of feldspar, a mineral linked to lava flows. Feldspars are more rich in silica than basalts and some of the last stuff to crystallize out of magma. On the other hand, basalts, dark volcanic rocks rich in iron and magnesium, are ubiquitous on Mars' surface.
Many of Perseverance's scientists think magma below the surface made the minerals in Atoko Point, and that a giant impact on Mars may have excavated the rock to the surface, a chunk later falling from the crater rim to its present site. Others think the boulder was made somewhere else far away and a gushing ancient river carried it there.
Whether scientists will ever get their hands on this rock or one like it remains to be seen. Perseverance has been collecting samples from Jezero crater since 2021. The region, an ancient dried delta, is one where scientists think microscopic organisms might have existed long ago. But the plan to fly rocks and dust grains to Earth, a complex mission called Mars Sample Return, is in jeopardy. Its rising costs have led to layoffs and warnings of cancellation from Congress. The agency is now making a desperate plea for ideas to save the mission.
Perhaps surprisingly, the rover team chose to drive away from Atoco Point without even taking a sample, despite its significance. That's because the team hopes to discover many more like it in a couple of months when the rover reaches the crater rim. Finding examples from its original location could provide the scientists with a lot more context.
"We said, 'OK, let's keep this rock in mind,'" Stack Morgan said. "'Maybe we'll come back here if we don't find this elsewhere in the crater rim.'"
Topics NASA
