A self-portrait of NASA’s Curiosity rover taken on June 15, 2018, during the 2,082nd Martian day, or sol, of Curiosity’s work on Mars. A Martian dust storm has reduced sunlight and visibility at the rover’s location in Gale Crater. Image credit: NASA/JPL-Caltech.
Today, Mars is a planet of extremes — it’s bitterly cold, has high radiation, and is bone-dry.
But billions of years ago, Mars was home to lake systems that could have sustained microbial life. As the planet’s climate changed, one such lake — in Mars’ Gale Crater — slowly dried out.
Scientists have new evidence that super salty water, or brines, seeped deep through the cracks, between grains of soil in the parched lake bottom and altered the clay mineral-rich layers beneath.
The findings published in the July 9 edition of the journal Science and led by the team in charge of the Chemistry and Mineralogy, or CheMin, instrument — aboard NASA’s Mars Science Laboratory Curiosity rover — help add to the understanding of where the rock record preserved or destroyed evidence of Mars’ past and possible signs of ancient life.
“We used to think that once these layers of clay minerals formed at the bottom of the lake in Gale Crater, they stayed that way, preserving the moment in time they formed for billions of years,” said Tom Bristow, CheMin principal investigator and lead author of the paper at NASA’s Ames Research Center in California’s Silicon Valley. “But later brines broke down these clay minerals in some places – essentially re-setting the rock record.”
The network of cracks in this Martian rock slab called “Old Soaker” may have formed from the drying of a mud layer more than three billion years ago. The view spans about three feet (90 centimeters) left-to-right and combines three images taken by the Mars Hand Lens Imager, or MAHLI, camera on the arm of NASA’s Curiosity Mars rover. Credits: NASA/JPL-Caltech/MSSS.
Mars: It goes on your permanent record
Mars has a treasure trove of incredibly ancient rocks and minerals compared with Earth. And with Gale Crater’s undisturbed layers of rocks, scientists knew it would be an excellent site to search for evidence of the planet’s history, and possibly life.
Using CheMin, scientists compared samples taken from two areas about a quarter-mile apart from a layer of mudstone deposited billions of years ago at the bottom of the lake at Gale Crater.
Surprisingly, in one area, about half the clay minerals they expected to find were missing. Instead, they found mudstones rich with iron oxides — minerals that give Mars its characteristic rusty red color.
Scientists knew the mudstones sampled were about the same age and started out the same – loaded with clays — in both areas studied.
So why then, as Curiosity explored the sedimentary clay deposits along Gale Crater did patches of clay minerals — and the evidence they preserve — “disappear”?
This evenly layered rock imaged in 2014 by the Mastcam on NASA’s Curiosity Mars rover shows a pattern typical of a lake-floor sedimentary deposit near where flowing water entered a lake. Shallow and deep parts of an ancient Martian lake left different clues in mudstone formed from lakebed deposits. Credits: NASA/JPL-Caltech/MSSS.
Clays hold clues
Minerals are like a time capsule; they provide a record of what the environment was like at the time they formed. Clay minerals have water in their structure and are evidence that the soils and rocks that contain them came into contact with water at some point.
“Since the minerals we find on Mars also form in some locations on Earth, we can use what we know about how they form on Earth to tell us about how salty or acidic the waters on ancient Mars were,” said Liz Rampe, CheMin deputy principal investigator and co-author at NASA’s Johnson Space Center in Houston.
Previous work revealed that, while Gale Crater’s lakes were present and even after they dried out, groundwater moved below the surface, dissolving and transporting chemicals.
After they were deposited and buried, some mudstone pockets experienced different conditions and processes due to interactions with these waters that changed the mineralogy.
This process, known as “diagenesis,” often complicates or erases the soil’s previous history and writes a new one.
Diagenesis creates an underground environment that can support microbial life. In fact, some very unique habitats on Earth — in which microbes thrive — are known as “deep biospheres.”
“These are excellent places to look for evidence of ancient life and gauge habitability,” said John Grotzinger, CheMin co-investigator and co-author at Caltech in Pasadena, California. “Even though diagenesis may erase the signs of life in the original lake, it creates the chemical gradients necessary to support subsurface life, so we are really excited to have discovered this.”
By comparing the details of minerals from both samples, the team concluded that briny water filtering down through overlying sediment layers was responsible for the changes. Unlike the relatively freshwater lake present when the mudstones formed, the salty water is suspected to have come from later lakes that existed within an overall drier environment.
Scientists believe these results offer further evidence of the impacts of Mars’s climate change billions of years ago. They also provide more detailed information that is then used to guide the Curiosity rover’s investigations into the history of the Red Planet.
This information also will be utilized by NASA’s Mars 2020 Perseverance rover team as they evaluate and select rock samples for eventual return to Earth.
“We’ve learned something very important: there are some parts of the Martian rock record that aren’t so good at preserving evidence of the planet’s past and possible life,” said Ashwin Vasavada, Curiosity project scientist and co-author at NASA’s Jet Propulsion Laboratory in Southern California. “The fortunate thing is we find both close together in Gale Crater, and can use mineralogy to tell which is which.”
Curiosity is in the initial phase of investigating the transition to a “sulfate-bearing unit,” or rocks thought to have formed while Mars’s climate dried out.
The mission is managed by JPL, a division of Caltech, for NASA’s Science Mission Directorate, Washington. Colleagues in NASA’s Astromaterials Research and Exploration Science Division at Johnson and NASA’s Goddard Space Flight Center in Greenbelt, Maryland also are authors on the paper, as well as other institutions working on Curiosity.
This Martian landscape includes the rocky landmark nicknamed “Knockfarril Hill” at center right and the edge of Vera Rubin Ridge, which runs along the top of the scene. The image was made from a mosaic captured by the Mast Camera aboard NASA’s Curiosity Mars rover as it explored the “clay-bearing unit” on Feb. 3, 2019, during the 2,309th Martian day, or sol, of Curiosity’s work on Mars. Credits: NASA/JPL-Caltech/MSSS.
NAIROBI, Kenya (AP) — The body of Ugandan Olympic athlete Rebecca Cheptegei — who died after being set on fire by her partner in Kenya — was received Friday by family and anti-femicide crusaders, ahead of her burial a day later.
Cheptegei’s family met with dozens of activists Friday who had marched to the Moi Teaching and Referral Hospital’s morgue in the western city of Eldoret while chanting anti-femicide slogans.
She is the fourth female athlete to have been killed by her partner in Kenya in yet another case of gender-based violence in recent years.
Viola Cheptoo, the founder of Tirop Angels – an organization that was formed in honor of athlete Agnes Tirop, who was stabbed to death in 2021, said stakeholders need to ensure this is the last death of an athlete due to gender-based violence.
“We are here to say that enough is enough, we are tired of burying our sisters due to GBV,” she said.
It was a somber mood at the morgue as athletes and family members viewed Cheptegei’s body which sustained 80% of burns after she was doused with gasoline by her partner Dickson Ndiema. Ndiema sustained 30% burns on his body and later succumbed.
Ndiema and Cheptegei were said to have quarreled over a piece of land that the athlete bought in Kenya, according to a report filed by the local chief.
Cheptegei competed in the women’s marathon at the Paris Olympics less than a month before the attack. She finished in 44th place.
Cheptegei’s father, Joseph, said that the body will make a brief stop at their home in the Endebess area before proceeding to Bukwo in eastern Uganda for a night vigil and burial on Saturday.
“We are in the final part of giving my daughter the last respect,” a visibly distraught Joseph said.
He told reporters last week that Ndiema was stalking and threatening Cheptegei and the family had informed police.
Four in 10 women or an estimated 41% of dating or married Kenyan women have experienced physical or sexual violence perpetrated by their current or most recent partner, according to the Kenya Demographic and Health Survey 2022.
TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.
Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.
Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.
The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.
The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.
It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.
Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.
Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.
Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.
Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.
Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.
The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”
VICTORIA – The British Columbia government is partnering with a bear welfare group to reduce the number of bears being euthanized in the province.
Nicholas Scapillati, executive director of Grizzly Bear Foundation, said Monday that it comes after months-long discussions with the province on how to protect bears, with the goal to give the animals a “better and second chance at life in the wild.”
Scapillati said what’s exciting about the project is that the government is open to working with outside experts and the public.
“So, they’ll be working through Indigenous knowledge and scientific understanding, bringing in the latest techniques and training expertise from leading experts,” he said in an interview.
B.C. government data show conservation officers destroyed 603 black bears and 23 grizzly bears in 2023, while 154 black bears were killed by officers in the first six months of this year.
Scapillati said the group will publish a report with recommendations by next spring, while an independent oversight committee will be set up to review all bear encounters with conservation officers to provide advice to the government.
Environment Minister George Heyman said in a statement that they are looking for new ways to ensure conservation officers “have the trust of the communities they serve,” and the panel will make recommendations to enhance officer training and improve policies.
Lesley Fox, with the wildlife protection group The Fur-Bearers, said they’ve been calling for such a committee for decades.
“This move demonstrates the government is listening,” said Fox. “I suspect, because of the impending election, their listening skills are potentially a little sharper than they normally are.”
Fox said the partnership came from “a place of long frustration” as provincial conservation officers kill more than 500 black bears every year on average, and the public is “no longer tolerating this kind of approach.”
“I think that the conservation officer service and the B.C. government are aware they need to change, and certainly the public has been asking for it,” said Fox.
Fox said there’s a lot of optimism about the new partnership, but, as with any government, there will likely be a lot of red tape to get through.
“I think speed is going to be important, whether or not the committee has the ability to make change and make change relatively quickly without having to study an issue to death, ” said Fox.
This report by The Canadian Press was first published Sept. 9, 2024.
