Mars is a dry, desert world devoid of any life (that we know of). But once upon a time, that wasn’t the case. Data collected by the robotic emissaries we’ve sent to explore the planet on our behalf indicate that the red planet was once a lush and wet world.
However, scientists are still trying to piece together Martian history to understand what happened to the planet’s water. While we know much of it was lost when the planet’s atmosphere was stripped away, what we don’t know is where the water originated from. Researchers uncovered a crucial clue in Martian meteorites found here on Earth.
“A lot of people have been trying to figure out Mars’ water history,” Jessica Barnes, an assistant professor of planetary sciences in the University of Arizona Lunar and Planetary Laboratory, said in a statement. “Like, where did water come from? How long was it in the crust (surface) of Mars? Where did Mars’ interior water come from? What can water tell us about how Mars formed and evolved?”
Like the Earth, Mars is made of different layers: a crust, mantle, and a core. Meteorites, like the ones that fell to Earth, are made of the Martian crust, which can tell us a lot about the planet’s composition when the pieces are analyzed. According to a study published this week in Nature Geoscience, there could be at least two distinct reservoirs of ancient water lurking below the Martian surface. Each with its own (different) chemical signature.
This means that Mars probably never had a global ocean of magma beneath its surface like we do on Earth.
For this study, Barnes and her team looked for clues as to the Mars’ water history by analyzing the ratio of two types (isotopes) of hydrogen. They’re not the first to do so, but previous results have been very inconsistent.
To better understand how the planet formed and where its water came from, the researchers examined two different meteorites: a coin-sized sample known as Black Beauty (or NWA 7034), which formed when a huge impact cemented together various pieces of the Martian crust, and Allan Hills 84001 (ALH84001), a sample once thought to contain Martian microbes. The data shows that water comes from two different sources.
The team was searching for different isotopes of hydrogen — light hydrogen and heavy hydrogen — which can help trace the origin of water in rocks. (Isotopes are variations of chemical elements, with different numbers of neutrons.)
“Light hydrogen” contains one proton (and no neutrons) in its nucleus, whereas “heavy hydrogen,” also known as deuterium, contains one proton and one neutron in its core. The ratio of these two isotopes act like a fossil record of water, telling a planetary scientist its origin.
Here on Earth, protium (or light hydrogen) is the most abundant isotope. It’s found in the atmosphere, in rocks, and the ocean. On Mars, however, deuterium (heavy hydrogen) is the most abundant in the atmosphere, while Martian rocks contain a range of ratios from Earth-like to Mars-like.
To better understand the vast variation, Barnes and her team decided to focus on samples they knew came from the Martian crust — Black Beauty and Alan Hills. The team found that both samples interacted with water at different point in Mars’ history, but had similar isotope ratios, that was very similar to younger rocks analyzed by the Curiosity rover.
This data suggested a surprising result: that the chemical composition of that water hasn’t changed for nearly 4 billion years.
“Martian meteorites basically plot all over the place, and so trying to figure out what these samples are telling us about water in the mantle of Mars has historically been a challenge,” Barnes said.”The fact that our data for the crust was so different prompted us to go back through the scientific literature and scrutinize the data.”
So the team compared their results to previous isotope studies, where the meteorites originated in the Martian mantle. They discovered that the isotope ratios were consistent with two types of volcanic rock, known as shergottite, that’s found in the Martian mantle.
This means that the water within the meteorite samples came from two different sources. It also indicates that Mars lacked a global magma ocean, which would have made the mantle more consistent in its composition.
“These two different sources of water in Mars’ interior might be telling us something about the kinds of objects that were available to coalesce into the inner, rocky planets,” Barnes said.
Meaning two distinct planetary precursors with vastly different water contents could have collided, but never thoroughly mixed. And understanding how Mars formed is essential for understanding its past habitability and potential for life.
Tesla has reached a notable benchmark in its autonomous driving program after its Robotaxi fleet surpassed one million miles of unsupervised operation. The company made the announcement during its Cybercab event in Austin on September 3.
Tesla Vice President of AI Ashok Elluswamy told attendees he was happy to report the fleet had achieved one million miles of unsupervised Robotaxi operation as a testament to safety.
The new total marked a sharp increase from the 380,000 unsupervised miles Tesla disclosed during its second-quarter 2026 earnings update in late July.
In roughly six weeks, the company added about 620,000 miles. That acceleration followed Tesla’s decision to remove in-vehicle safety monitors from most of its operations outside the San Francisco Bay Area.
Credit: Tesla
Tesla first launched Robotaxi service in Austin in June 2025 with safety drivers present. It later began fully unsupervised rides and expanded into Dallas, Houston, Miami, Orlando, and Tampa. The San Francisco Bay Area remains the exception, where a safety monitor still rides in the vehicle under California permitting rules.
The company has not released a city-by-city breakdown of the one million unsupervised miles.
The milestone arrived as Tesla began offering public Cybercab rides in Austin. The purpose-built vehicle has no steering wheel or pedals and is designed only for autonomous ride-hailing. Production versions joined the existing fleet of modified Tesla vehicles already operating in the service.
Tesla’s unsupervised mileage is growing at a double-digit weekly rate according to earlier company comments, yet its fleet size remains modest compared with established competitors. Waymo has accumulated more than 200 million fully autonomous rider-only miles. Tesla has described its own unsupervised operations as having recorded zero notable incidents in the period leading up to the July update.
The one-million-mile figure reflects Tesla’s shift from supervised testing to broader driverless service in multiple states. It also highlights the company’s strategy of using both existing Model Y vehicles and the new Cybercab to scale its network.
Credit: Tesla
Whether the rapid recent growth continues will depend on further city expansions, regulatory approvals, and the performance of the purpose-built Cybercab in everyday paid rides. Tesla has not specified how many of the latest miles involved the new vehicle versus the rest of the fleet.
The announcement underscores Tesla’s progress toward a larger robotaxi network while illustrating the remaining gap in total autonomous experience relative to longer-operating rivals.
Tesla AI lead Ashok Elluswamy said this week that 24-hour Robotaxi service is close. Replying on X to a rider who wanted Cybercab trips all night, he wrote that the capability would arrive “next month or so” once “the next tech to merge on the v15 plan” is ready.
The comment landed on September 4, one day after Tesla opened public Cybercab rides in Austin. It is the clearest near-term timeline yet for overnight unsupervised operation. Tesla’s paid Robotaxi network currently runs from 6 a.m. to 10 p.m. seven days a week across Austin, Dallas, Houston, Miami, Orlando, and Tampa.
next month or so. the next tech to merge on the v15 plan will enable it.
— Ashok Elluswamy (@aelluswamy) September 4, 2026
That 16-hour window is shorter than the 6 a.m. to 2 a.m. schedule the company used for much of the prior year.
Elluswamy did not name the specific feature or say whether the change would apply first to purpose-built Cybercabs, the existing Model Y fleet, or both. He also offered no city-by-city rollout list. The link to Full Self-Driving v15 is nevertheless significant.
Tesla has described v15 as a step-change architecture with seven parallel improvement tracks and roughly ten times more parameters than earlier builds. Early versions of that software already operate on the Robotaxi fleet and contain about 40 percent of the planned gains.
By July 2026, the unsupervised fleet had logged more than 380,000 miles across six cities in two states with what the company called an impeccable safety record and no notable incidents caused by the vehicles themselves. Tesla has repeatedly argued that camera-based end-to-end neural networks, rather than extra sensors, are the core of the solution.
Overnight service would test that claim in lower-light conditions and would also raise vehicle utilization, a key variable for Robotaxi unit economics. The company has already begun using public Superchargers at night and is building dedicated Robotaxi charging sites.
Riders have asked why software must change if the cars already drive in the dark. The practical answer appears to be reliability and scale: Tesla has held back mass expansion until more of the v15 stack is merged, citing the need for higher confidence before putting thousands of unoccupied vehicles on streets around the clock.
If the next module arrives on the timetable Elluswamy sketched, 24-hour service could begin in October 2026 in at least some markets.
That would mark a shift from a daytime-bounded pilot to a service that can run whenever demand exists, including the late-night hours that have so far remained out of reach.
Tesla is beginning to roll out Full Self-Driving Supervised v14.3.9 with a new active safety layer that can take control even when the driver is operating the car manually.
Tesla AI said the software can activate FSD on the driver’s behalf when an imminent collision is detected and Automatic Emergency Braking may not be enough. It may also engage if the system detects heavy distraction or an accidental FSD disengagement.
FSD Supervised v14.3.9 starting to roll out shortly
This release includes a new active safety feature set: FSD Supervised can now activate on your behalf when an imminent collision is detected and Automatic Emergency Braking (AEB) may not be enough.
It may also engage if we…
— Tesla AI (@Tesla_AI) September 4, 2026
The capability is essentially Automatic Collision Evasion. However, unlike conventional AEB, which mainly applies the brakes in a straight line, this feature can use steering, braking, and acceleration together if the car calculates that stopping alone will not prevent impact and a safer path exists. The system may change lanes or move toward a shoulder when conditions allow, then continue driving after the immediate threat is handled rather than simply coming to a stop.
The intervention is meant as a last-resort safety net, not a replacement for attentive driving.
Tesla Full Self-Driving v14.3.7 early review: FSD saved me from an accident
Tesla’s own description still frames FSD as supervised assistance. Secondary reports on internal release notes say the feature can fire while the car is being driven manually if cabin-camera monitoring suggests the driver is not sufficiently attentive, such as reaching toward the back seat, or if FSD appears to have been turned off unintentionally.
After the emergency maneuver, the car is expected to alert the driver and request a return to manual control.
The safety case is straightforward. Many collisions happen in the last second because a driver is looking away, fumbles a control, or faces an obstacle that braking cannot fully solve. A system that can both recognize that AEB is insufficient and execute a coordinated evasive path can reduce those remaining high-severity events.
Re-engaging after accidental disengagement also addresses a practical failure mode: a small steering nudge that drops FSD at the worst moment. The advantage is a background safety net that uses the same vision stack already running in v14, instead of leaving the car solely to emergency braking once the driver is no longer in command.
The feature still depends on FSD being enabled and, according to reports, an active FSD purchase or subscription. It does not make the vehicle unsupervised. Drivers remain responsible, and Tesla has not published how often the system is expected to intervene or how it will handle false positives.
If the rollout is conservative and the false-alarm rate stays low, the update is a meaningful step: FSD is no longer only a feature the driver turns on. In the rare moments when disaster is already forming, it can step in.
Tesla crosses major Unsupervised Self-Driving milestone
Tesla Robotaxi will be a 24/7 service: here’s when
