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Mars’ longtime polar mystery may have finally been solved
From the surface, Mars may seem like a dry, desert-like world lacking water, but a closer look at the planet’s poles will some striking structures: massive polar ice caps.
At the north pole, the ruddy terrain peeks through the ice, like zebra stripes. In the south pole lurks a mystery, a massive deposit of frozen carbon dioxide and water ice. Scientists have spent decades trying to understand how it formed and how it’s linked to the amount of carbon dioxide (CO2) in the Martian atmosphere.
A pair of scientists in the 1960s came up with a plausible theory, and now, decades later, a new study published in Nature Astronomy may have confirmed their findings.
The massive deposit — measuring 3,280 feet (1 kilometer) thick — contains sheets of water ice and carbon dioxide arranged in alternating layers, like a cake. It’s topped off with a thin frosting of carbon dioxide ice, and scientists noticed something interesting: the massive ice deposit contains as much carbon dioxide as the entire Martian atmosphere.
Peter Buhler, a planetary scientist at NASA’s Jet Propulsion Laboratory led the new study. The team used computer simulations to map out the ice, and they were surprised at how closely their models matched with what Robert B. Leighton and Bruce Murray predicted decades ago.
“Usually, when you run a model, you don’t expect the results to match so closely to what you observe,” he said in a statement. “But the thickness of the layers, as determined by the model, matches beautifully with radar measurements from orbiting satellites.”
The ice cap puzzled researchers because according to science, it shouldn’t exist. That’s because water ice is more thermally stable and darker than carbon dioxide ice, which means that it should destabilize when layered between water ice.
However, the new model explains this behavior. Buhler and his team say there are three reasons why the frozen carbon dioxide exists. First, Mars wobbles as it orbits the sun, and when it does, the slight changing of the tilt alters the amount of sunlight that hits the ice. Second, each type of ice reflects the sun a bit differently. And lastly, because of the exposure to sunlight, the carbon dioxide sublimates–meaning it goes directly from a solid to a gas–which alters the atmospheric pressure.
As Mars wobbles, the amount of sunlight reaching the ice varies, causing the ice to form and then later sublimate. When the carbon dioxide ice was forming, water ice would’ve been trapped with it. But when that ice sublimated, the more stable water ice would have remained behind, forming the layers we now see at the south pole.
https://www.youtube.com/watch?v=8Gj8dr6AsYg
Mars’ climate, just like Earth’s, has changed over millions of years. To that end, not all of the carbon dioxide ice was lost; some were left behind to build up the varying layers we see—a process that has altered the red planet’s atmospheric pressure.
This is what Leighton and Murray hypothesized back decades ago, and this is what Buhler’s new model shows.
“Our determination of the history of Mars’s large pressure swings is fundamental to understanding the evolution of Mars’s climate, including the history of liquid water stability and habitability near Mars’s surface,” Buhler said in a statement.
By understanding what processes formed the south polar ice cap, scientists can better understand more of what happened in Mars’ history.
Elon Musk
Elon Musk and Tesla AI Director share insights after empty driver seat Robotaxi rides
The executives’ unoccupied tests hint at the rapid progress of Tesla’s unsupervised Robotaxi efforts.
Tesla CEO Elon Musk and AI Director Ashok Elluswamy celebrated Christmas Eve by sharing personal experiences with Robotaxi vehicles that had no safety monitor or occupant in the driver’s seat. Musk described the system’s “perfect driving” around Austin, while Elluswamy posted video from the back seat, calling it “an amazing experience.”
The executives’ unoccupied tests hint at the rapid progress of Tesla’s unsupervised Robotaxi efforts.
Elon and Ashok’s firsthand Robotaxi insights
Prior to Musk and the Tesla AI Director’s posts, sightings of unmanned Teslas navigating public roads were widely shared on social media. One such vehicle was spotted in Austin, Texas, which Elon Musk acknowleged by stating that “Testing is underway with no occupants in the car.”
Based on his Christmas Eve post, Musk seemed to have tested an unmanned Tesla himself. “A Tesla with no safety monitor in the car and me sitting in the passenger seat took me all around Austin on Sunday with perfect driving,” Musk wrote in his post.
Elluswamy responded with a 2-minute video showing himself in the rear of an unmanned Tesla. The video featured the vehicle’s empty front seats, as well as its smooth handling through real-world traffic. He captioned his video with the words, “It’s an amazing experience!”
Towards Unsupervised operations
During an xAI Hackathon earlier this month, Elon Musk mentioned that Tesla owed be removing Safety Monitors from its Robotaxis in Austin in just three weeks. “Unsupervised is pretty much solved at this point. So there will be Tesla Robotaxis operating in Austin with no one in them. Not even anyone in the passenger seat in about three weeks,” he said. Musk echoed similar estimates at the 2025 Annual Shareholder Meeting and the Q3 2025 earnings call.
Considering the insights that were posted Musk and Elluswamy, it does appear that Tesla is working hard towards operating its Robotaxis with no safety monitors. This is quite impressive considering that the service was launched just earlier this year.
Elon Musk
Starlink passes 9 million active customers just weeks after hitting 8 million
The milestone highlights the accelerating growth of Starlink, which has now been adding over 20,000 new users per day.
SpaceX’s Starlink satellite internet service has continued its rapid global expansion, surpassing 9 million active customers just weeks after crossing the 8 million mark.
The milestone highlights the accelerating growth of Starlink, which has now been adding over 20,000 new users per day.
9 million customers
In a post on X, SpaceX stated that Starlink now serves over 9 million active users across 155 countries, territories, and markets. The company reached 8 million customers in early November, meaning it added roughly 1 million subscribers in under seven weeks, or about 21,275 new users on average per day.
“Starlink is connecting more than 9M active customers with high-speed internet across 155 countries, territories, and many other markets,” Starlink wrote in a post on its official X account. SpaceX President Gwynne Shotwell also celebrated the milestone on X. “A huge thank you to all of our customers and congrats to the Starlink team for such an incredible product,” she wrote.
That growth rate reflects both rising demand for broadband in underserved regions and Starlink’s expanding satellite constellation, which now includes more than 9,000 low-Earth-orbit satellites designed to deliver high-speed, low-latency internet worldwide.
Starlink’s momentum
Starlink’s momentum has been building up. SpaceX reported 4.6 million Starlink customers in December 2024, followed by 7 million by August 2025, and 8 million customers in November. Independent data also suggests Starlink usage is rising sharply, with Cloudflare reporting that global web traffic from Starlink users more than doubled in 2025, as noted in an Insider report.
Starlink’s momentum is increasingly tied to SpaceX’s broader financial outlook. Elon Musk has said the satellite network is “by far” the company’s largest revenue driver, and reports suggest SpaceX may be positioning itself for an initial public offering as soon as next year, with valuations estimated as high as $1.5 trillion. Musk has also suggested in the past that Starlink could have its own IPO in the future.
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NVIDIA Director of Robotics: Tesla FSD v14 is the first AI to pass the “Physical Turing Test”
After testing FSD v14, Fan stated that his experience with FSD felt magical at first, but it soon started to feel like a routine.
NVIDIA Director of Robotics Jim Fan has praised Tesla’s Full Self-Driving (Supervised) v14 as the first AI to pass what he described as a “Physical Turing Test.”
After testing FSD v14, Fan stated that his experience with FSD felt magical at first, but it soon started to feel like a routine. And just like smartphones today, removing it now would “actively hurt.”
Jim Fan’s hands-on FSD v14 impressions
Fan, a leading researcher in embodied AI who is currently solving Physical AI at NVIDIA and spearheading the company’s Project GR00T initiative, noted that he actually was late to the Tesla game. He was, however, one of the first to try out FSD v14.
“I was very late to own a Tesla but among the earliest to try out FSD v14. It’s perhaps the first time I experience an AI that passes the Physical Turing Test: after a long day at work, you press a button, lay back, and couldn’t tell if a neural net or a human drove you home,” Fan wrote in a post on X.
Fan added: “Despite knowing exactly how robot learning works, I still find it magical watching the steering wheel turn by itself. First it feels surreal, next it becomes routine. Then, like the smartphone, taking it away actively hurts. This is how humanity gets rewired and glued to god-like technologies.”
The Physical Turing Test
The original Turing Test was conceived by Alan Turing in 1950, and it was aimed at determining if a machine could exhibit behavior that is equivalent to or indistinguishable from a human. By focusing on text-based conversations, the original Turing Test set a high bar for natural language processing and machine learning.
This test has been passed by today’s large language models. However, the capability to converse in a humanlike manner is a completely different challenge from performing real-world problem-solving or physical interactions. Thus, Fan introduced the Physical Turing Test, which challenges AI systems to demonstrate intelligence through physical actions.
Based on Fan’s comments, Tesla has demonstrated these intelligent physical actions with FSD v14. Elon Musk agreed with the NVIDIA executive, stating in a post on X that with FSD v14, “you can sense the sentience maturing.” Musk also praised Tesla AI, calling it the best “real-world AI” today.
Elon Musk and Tesla AI Director share insights after empty driver seat Robotaxi rides
Starlink passes 9 million active customers just weeks after hitting 8 million
