What do coal, crude oil, and truffles have in common? Go ahead. We’ll wait.
The answer is thiophenes, a molecule that behaves a lot like benzene. Crude oil, coal, and truffles all contain thiophenes. So do a few other substances. MSL Curiosity found thiophenes on Mars, and though that doesn’t conclusively prove that Mars once hosted life, its discovery is an important milestone for the rover. Especially since truffles are alive, and oil and coal used to be, sort of.
A quote from NASA’s Curiosity website reminds us what the rover’s mission is: “Curiosity was designed to assess whether Mars ever had an environment able to support small life forms called microbes. In other words, its mission is to determine the planet’s ‘habitability.’ ”
A pair of scientists from Berlin’s Technical University thinks that the thiophenes Curiosity found on Mars could be a signature from early Martian life. If they’re right, then Mars was, at one time, inhabited by simple life forms. They’ve presented their findings in a new paper.
The pair are Dirk Schulze-Makuch and Jacob Heinz. Schulze-Makuch is also an astrobiologist at Washington State University. Their paper is titled “Thiophenes on Mars: Biotic or Abiotic Origin?” It’s published in the journal Astrobiology.
MSL Curiosity found the thiophenes in Martian sediments. It’s one of a number of interesting molecules found on Mars that might have a biotic origin. Thiophenes can also have an abiotic origin through diagenesis, which are physical and chemical changes that take place as sediments become sedimentary rock.
Sedimentary rocks on Mars, investigated by NASA’s Curiosity Mars rover. Thiophenes can be produced by biotic processes, or by abiotic processes, like when sediment becomes sedimentary rock. By NASA/JPL-Caltech/MSSS – Catalog page · Full-res (JPEG · TIFF), Public Domain, https://commons.wikimedia.org/w/index.php?curid=30263203
In order to find the thiophenes in the Martian sediments, Curiosity had to first heat the sample above 500 Celsius. Then Curiosity examined it with the SAM (Sample Analysis at Mars) instrument. SAM analyzed the gases coming off the sample using gas chromatography-mass spectrometry. SAM is actually three instruments in one, and together they search for organic chemicals.
“We identified several biological pathways for thiophenes that seem more likely than chemical ones, but we still need proof,” Dirk Schulze-Makuch said in a press release. “If you find thiophenes on Earth, then you would think they are biological, but on Mars, of course, the bar to prove that has to be quite a bit higher.”
Thiophenes have a structure that suggests a possible biotic origin. They have four carbon atoms and a single sulfur atom arranged in a ring, with hydrogen atoms. Hydrocarbons are essential elements in organic chemistry, and hydrocarbon molecules containing atoms of sulfur are an important part of the study of organic chemistry.
The thiophene molecule. Image Credit: By Jynto – Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=11357639
There are non-biological sources of thiophenes. They can be created by meteor impacts, and by a process called thermochemical sulfate reduction, where compounds are heated above 120 Celsius (248 F).
But it’s the biological sources of thiophenes that are the most interesting. In the distant past, perhaps about 3 billion years ago, Mars was a much different place. It likely had a warm and wet environment that could’ve harbored life. Those ancient bacteria could’ve facilitated a sulfate reduction process biologically, which resulted in the thiophenes that Curiosity detected.
Technology moves quickly. Curiosity was much more advanced than its predecessors Spirit and Opportunity. It uses technology that breaks large molecules down into smaller molecules for analysis. But when the next Mars rover, the ESA’s ExoMars mission, arrives on the red planet, it’ll bring even more advanced technology.
ExoMars’ MOMA (Mars Organic Molecule Analyzer) is the premier astrobiology instrument on the ExoMars rover, and also the largest instrument. It’s a little more refined than Curiosity’s instrument, and it doesn’t rely on fragmentation to study molecules. MOMA will allow the collection and study of larger molecules.
The ESA’s ExoMars rover will land on Mars in 2021 and continue the search for evidence of ancient life on Mars. Credit:ESA
MOMA will use the concept of homochirality to identify molecules as either biotic or abiotic, something that MSL Curiosity can’t do. Homochirality is a property of amino acids and sugars. Many of the organic molecules necessary for life, including amino acids and sugars, can come in both left-handed and right-handed types, referred to as their chirality.
In Earth life, 19 of the 20 amino acids are homochiral and left-handed, while sugars, which are part of RNA and DNA, are homochiral and right-handed. Homochirality is essential for an efficient metabolism. But the same chemicals produced in a laboratory will have equal abundances of left-handed and right-handed types. The basic idea is that if we find homochiral building blocks of life, they likely have a biological source.
Life’s molecules need to able to “shake hands” with each other in order to function. People shake hands right-to-right, or maybe left-to-right. It’s not possible to shake right-to-left, or vice versa. Image Credit: ESA
Isotope ratios can also differentiate between the same atoms with either biotic or abiotic origins. Schulze-Makuch and Heinze, the authors of this paper, think that some of the data from the ExoMars rover should be used to also look for isotopes of carbon and sulfur. In particular, the lighter isotopes of both. They think that’s where we’re most likely to find a biological origin.
“Organisms are ‘lazy.’ They would rather use the light isotope variations of the element because it costs them less energy,” Schulze-Makuch said.
Lifeforms tend to alter the balance between light isotopes and heavy isotopes of the elements they produce. That ratio is different than the ratio in the same elements in their building blocks. That’s a “tell-tale sign of life” according to Schulze Makuch.
The discussion over life on Mars has been ongoing for decades. When the Viking landers were on Mars in 1976, they conducted the very first in-situ measurements, looking for organic compounds. What they found is still somewhat controversial today, because no lab experiments have been able to completely recreate those results. However, it’s widely believed in the scientific community that the Viking findings can be explained by abiotic sources.
The late, great Carl Sagan stands next to a model of the Viking lander. Credit: NASA
The ExoMars rover is our next step in understanding ancient Mars’ habitability. Its experimental results may bring us one step closer to knowing definitively if Mars once hosted life. But it might not get us all the way to that conclusion, unfortunately.
“As Carl Sagan said ‘extraordinary claims require extraordinary evidence,’” Schulze-Makuch said. “I think the proof will really require that we actually send people there, and an astronaut looks through a microscope and sees a moving microbe.”
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.
