This image shows a flattened (Mercator) projection of the Huygens probe’s view of Saturn’s moon Titan from 10 kilometers altitude. The images that make up this view were taken on Jan. 14, 2005, with the descent imager/spectral radiometer onboard the European Space Agency’s Huygens probe. The Huygens probe was delivered to Titan by the Cassini spacecraft, managed by NASA’s Jet Propulsion Laboratory, Pasadena, Calif. Credit: ESA/NASA/JPL/University of Arizona photo
A study led by Western astrobiologist Catherine Neish shows the subsurface ocean of Titan—the largest moon of Saturn—is most likely a non-habitable environment, meaning any hope of finding life in the icy world is dead in the water.
This discovery means it is far less likely that space scientists and astronauts will ever find life in the outer solar system, home to the four ‘giant’ planets: Jupiter, Saturn, Uranus and Neptune.
“Unfortunately, we will now need to be a little less optimistic when searching for extraterrestrial lifeforms within our own solar system,” said Neish, an Earth sciences professor. “The scientific community has been very excited about finding life in the icy worlds of the outer solar system, and this finding suggests that it may be less likely than we previously assumed.”
The identification of life in the outer solar system is a significant area of interest for planetary scientists, astronomers and government space agencies like NASA, largely because many icy moons of the giant planets are thought to have large subsurface oceans of liquid water. Titan, for example, is thought to have an ocean beneath its icy surface that is more than 12 times the volume of Earth’s oceans.
“Life as we know it here on Earth needs water as a solvent, so planets and moons with lots of water are of interest when looking for extraterrestrial life,” said Neish, a member of Western’s Institute for Earth and Space Exploration.
In the study, published in the journal Astrobiology, Neish and her collaborators attempted to quantify the amount of organic molecules that could be transferred from Titan’s organic-rich surface to its subsurface ocean, using data from impact cratering.
Comets impacting Titan throughout its history have melted the surface of the icy moon, creating pools of liquid water that have mixed with the surface organics. The resulting melt is denser than its icy crust, so the heavier water sinks through the ice, possibly all the way to Titan’s subsurface ocean.
Using the assumed rates of impacts on Titan’s surface, Neish and her collaborators determined how many comets of different sizes would strike Titan each year over its history. This allowed the researchers to predict the flow rate of water carrying organics that travel from Titan’s surface to its interior.
Neish and the team found the weight of organics transferred in this way is quite small, no more than 7,500 kg/year of glycine—the simplest amino acid, which makes up proteins in life. This is approximately the same mass as a male African elephant. (All biomolecules, like glycine, use carbon—an element—as the backbone of their molecular structure.)
“One elephant per year of glycine into an ocean 12 times the volume of Earth’s oceans is not sufficient to sustain life,” said Neish. “In the past, people often assumed that water equals life, but they neglected the fact that life needs other elements, in particular carbon.”
Other icy worlds (like Jupiter’s moons Europa and Ganymede and Saturn’s moon Enceladus) have almost no carbon on their surfaces, and it is unclear how much could be sourced from their interiors. Titan is the most organic-rich icy moon in the solar system, so if its subsurface ocean is not habitable, it does not bode well for the habitability of other known icy worlds.
“This work shows that it is very hard to transfer the carbon on Titan’s surface to its subsurface ocean—basically, it’s hard to have both the water and carbon needed for life in the same place,” said Neish.
An artist’s rendering shows a Dragonfly quadcopter landing on the surface of Saturn’s moon Titan, unfolding its rotors and lifting off again to survey the landscape and atmosphere. Credit: Steve Gribben/Johns Hopkins
Flight of the Dragonfly
Despite the discovery, there is still much more to learn about Titan, and for Neish, the big question is, what is it made of?
Neish is a co-investigator on the NASA Dragonfly project, a planned 2028 spacecraft mission to send a robotic rotorcraft (drone) to the surface of Titan to study its prebiotic chemistry, or how organic compounds formed and self-organized for the origin of life on Earth and beyond.
“It is nearly impossible to determine the composition of Titan’s organic-rich surface by viewing it with a telescope through its organic-rich atmosphere,” said Neish. “We need to land there and sample the surface to determine its composition.”
To date, only the Cassini–Huygens international space mission in 2005 has successfully landed a robotic probe on Titan to analyze samples. It remains the first spacecraft to land on Titan and the farthest landing from Earth a spacecraft has ever made.
“Even if the subsurface ocean isn’t habitable, we can learn a lot about prebiotic chemistry on Titan, and Earth, by studying the reactions on Titan’s surface,” said Neish. “We’d really like to know if interesting reactions are occurring there, especially where the organic molecules mix with liquid water generated in impacts.”
[embedded content]Credit: JPL
When Neish started her latest study, she was worried it would negatively impact the Dragonfly mission, but it has actually led to even more questions.
“If all the melt produced by impacts sinks into the ice crust, we wouldn’t have samples near the surface where water and organics have mixed. These are regions where Dragonfly could search for the products of those prebiotic reactions, teaching us about how life may arise on different planets,” said Neish.
“The results from this study are even more pessimistic than I realized with regards to the habitability of Titan’s surface ocean, but it also means that more interesting prebiotic environments exist near Titan’s surface, where we can sample them with the instruments on Dragonfly.”
More information:
Catherine Neish et al, Organic Input to Titan’s Subsurface Ocean Through Impact Cratering, Astrobiology (2024). DOI: 10.1089/ast.2023.0055
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Saturn’s largest moon most likely uninhabitable (2024, February 14)
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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.
