Category: 7. Science

New models from recent Martian probe data suggest the fourth planet from the Sun once hosted a fluctuating desert environment with intermittent oases of water.

Researchers led by the University of Chicago’s Edwin Kite found evidence for carbon dioxide cycling on the Red Planet in data from Curiosity rover. The discovery of hidden carbonates in Gale Crater potentially unlock the reason why the once warm, water-rich planet saw a thinning out of its atmosphere and a loss of liquid water on its surface.

To summarize, the researchers modelled a situation where:

1. Increased solar luminosity melts water on Mars, leading to more liquid water
2. The liquid water interacts with carbon dioxide in the atmosphere, which then reacts to minerals in the rocks, trapping the carbon in the rocks themselves and thus reducing the greenhouse effect, making Mars colder and dryer
3. Lower volcanic activity on Mars (compared to Earth) means that this trapped carbon dioxide is not returned to the atmosphere, leading to a fluctuation desert/oases steady state, which is also driven by changes in orbit
4. Over billions of years, leaking atmosphere lowers the planet’s atmospheric pressure, causing more evaporation of water (the pressure on the surface then drops below the triple point of water, when all three phases – solid, liquid, and gas can exist)
5. Liquid water is no longer stable on the surface, and we get the cold, dry Mars we see today

Scientists had already digested evidence of wet and dry periods on Mars, but puzzled over what was driving the cycles and how all the liquid water ended up disappearing.

Secret was locked away in the rocks

As on Earth, atmospheric carbon dioxide on Mars can be stored in rocks as carbonates. So Kite’s team built a climate model based on the assumption that the carbonates from the Gale Crater reflect cycles on the Red Planet and let it run over 3.5 billion years.

“Past climates with surface and shallow-subsurface liquid water are recorded by Mars’s sedimentary rocks, including strata in the approximately 4-kilometer-thick [circa 2.5 miles thick] record at Gale Crater,” the paper published in Nature this week said.

“Those waters were intermittent, spatially patchy and discontinuous, and continued remarkably late in Mars’s history,” they hypothesize.

The researchers propose that carbonate formation on Mars actually helped drive changes in the planet’s climate. In their model, increasing solar luminosity makes water more available, leading to carbonate formation, which in turn, sucks carbon dioxide from the atmosphere, curtailing the greenhouse effect and leading to a colder and drier planet.

“Chaotic orbital forcing modulated wet–dry cycles. The negative feedback restricted liquid water to oases and Mars self-regulated as a desert planet. We model snowmelt as the water source, but the feedback can also work with groundwater as the water source. Model output suggests that Gale faithfully records the expected primary episodes of liquid water stability in the surface and near-surface environment,” the researchers said.

In the end, the loss of Mars’ atmosphere means it approaches water’s triple point, resulting in a reduction of liquid water and making the surface environment less habitable.

The researchers said their model can explain why oases on Mars were patchy and intermittent, but more surface missions would be required to test its assumptions.

“We assume that the carbonate content found at Gale is representative, and as a result, we present a testable idea rather than definitive evidence,” the paper said. ®

In July 1975, millions of people watched on television as a U.S. Apollo spacecraft docked with a Soviet Soyuz capsule in a crewed mission in orbit that symbolized collaboration between the two superpowers at the height of Cold War enmity.

That remarkable moment 50 years ago is being commemorated on a Soyuz rocket carrying a Russian cargo spacecraft that launched from the Baikonur Cosmodrome in Kazakhstan – early on Friday, Baikonur time – and is scheduled to reach the International Space Station after a two-day trip. The spacecraft is loaded with more than 2.5 tons of fuel, drinking water, food, medicine, science equipment, and other supplies for the crew on the station.

The Soyuz rocket currently heading to the ISS is painted white and blue and has an emblem marking the anniversary of the Soyuz-Apollo docking, which was the first international space mission. It had begun on July 15, 1975, when two Soviet cosmonauts launched from Baikonur and, hours later, three American astronauts blasted off from Cape Canaveral, Florida. The Russians and the Americans connected in space two days later, shaking hands, exchanging gifts, and sharing a meal.

The show of comity in space contrasted with the intense competition between the two global rivals that was known as the “space race,” which included the Soviet launch of the Sputnik satellite into orbit in 1957 and the Apollo 11 landing of American astronauts on the moon in 1969.

“I really believe that we were sort of an example … to the countries. We were a little of a spark or a foot in the door that started better communications,” Apollo astronaut Vance Brand had said, according to a NASA account of the Apollo-Soyuz mission.

Tensions between Russia and the United States escalated after Moscow launched a large-scale invasion of Ukraine in 2022, though relations improved after U.S. President Donald Trump took office for a second term in January. The U.S. and Russian space agencies have continued to collaborate over the course of the protracted war.

Roscosmos, the Russian space agency, refers to the cargo spacecraft currently in orbit as Progress MS-31, while the U.S. agency NASA uses the term Progress 92 because it’s the 92nd Russian resupply craft to launch in support of the International Space Station since its construction began in 1998. The Apollo-Soyuz mission has been described as a precursor of the ISS project.

Professor Jane Williamson from the School of Natural Sciences at Macquarie University, senior author on the study, said the findings underscored the urgent need for action on climate change.

The research team used high-resolution drone imagery to map coral bleaching in March 2024, returning in June to assess survival and mortality rates across the same reef areas.

“Using drone-derived imagery, we followed the amount of bleached and living coral during and after the bleaching event,” said Professor Williamson. “Use of this technology lets us upscale the effects of the bleaching event over larger areas but still in high precision.”

The team recorded the highest coral bleaching mortality on the Great Barrier Reef, with over 92% of corals experiencing mortality. 

“Our results are concerning for coral resilience, considering the increasing frequency and intensity of extreme heat events predicted for the near future, with potentially irreversible consequences for reef ecosystems such as those studied in our Great Barrier Reef,” Williamson added.

More alarming still is that coral mortality actually exceeded 99% in some areas measured. 

Coral reefs at Lizard Island have experienced repeated disturbances over the past decade, including severe bleaching in 2016 and 2017, cyclones, and Crown-of-Thorns outbreaks. These events have only compounded the ecosystem’s vulnerability, despite some signs of recovery in recent years.

The team behind the assessment are now running additional surveys at Lizard Island to track the recovery, if any, of corals into 2026 as part of an Australian Museum Lizard Island Critical Grant.

Click here for more from the Oceanographic Newsroom.

A rock on Mars spilled a surprising yellow treasure after Curiosity accidentally cracked through its unremarkable exterior.

When the rover rolled its 899-kilogram (1,982-pound) body over the fragile lump of mineral in May last year the deposit broke open, revealing yellow crystals of elemental sulfur: brimstone.

Although sulfates are fairly common on Mars, this represents the first time sulfur has been found on the red planet in its pure elemental form.

Related: Largest Mars Rock on Earth Could Sell For US$4 Million

What’s even more exciting is that the Gediz Vallis Channel, where Curiosity found the rock, is littered with objects that look suspiciously similar to the sulfur rock before it got fortuitously crushed – suggesting that, somehow, elemental sulfur may be abundant there in some places.

“Finding a field of stones made of pure sulfur is like finding an oasis in the desert,” said Curiosity project scientist Ashwin Vasavada of NASA’s Jet Propulsion Laboratory in July 2024.

“It shouldn’t be there, so now we have to explain it. Discovering strange and unexpected things is what makes planetary exploration so exciting.”

Sulfates are salts that form when sulfur, usually in compound form, mixes with other minerals in water.

When the water evaporates, the minerals mix and dry out, leaving the sulfates behind.

These sulfate minerals can tell us a lot about Mars, such as its water history, and how it has weathered over time.

Pure sulfur, on the other hand, only forms under a very narrow set of conditions, which are not known to have occurred in the region of Mars where Curiosity made its discovery.

There are, to be fair, a lot of things we don’t know about the geological history of Mars, but the discovery of scads of pure sulfur just hanging about on the Martian surface suggests that there’s something pretty big that we’re not aware of.

Sulfur, it’s important to understand, is an essential element for all life. It’s usually taken up in the form of sulfates, and used to make two of the essential amino acids living organisms need to make proteins.

Since we’ve known about sulfates on Mars for some time, the discovery doesn’t tell us anything new in that area. We’re yet to find any signs of life on Mars, anyway.

But we do keep stumbling across the remains of bits and pieces that living organisms would find useful, including chemistry, water, and past habitable conditions.

Stuck here on Earth, we’re fairly limited in how we can access Mars. Curiosity’s instruments were able to analyze and identify the sulfurous rocks in the Gediz Vallis Channel, but if it hadn’t taken a route that rolled over and cracked one open, it could have been sometime until we found the sulfur.

The next step will be to figure out exactly how, based on what we know about Mars, that sulfur may have come to be there.

That’s going to take a bit more work, possibly involving some detailed modeling of Mars’s geological evolution.

Meanwhile, Curiosity will continue to collect data on the same.

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The Gediz Vallis channel is an area rich in Martian history, an ancient waterway whose rocks now bear the imprint of the ancient river that once flowed over them, billions of years ago.

Curiosity drilled a hole in one of the rocks, taking a powdered sample of its interior for chemical analysis, and is still trundling its way deeper along the channel, to see what other surprises might be waiting just around the next rock.

An earlier version of this article was published in July 2024.

Since 1998, when the International Space Station (ISS) launched, there has been a place for astronauts around the world to run experiments in space, from growing food to learning how low-Earth orbit affects the human body.

More recently, the Chinese Tiangong Space Station was fully completed, with its third and final module, the Mengtian, added on Oct. 31, 2022. Tiangong sits at the same height as the ISS.

What is it?

NASA’s James Webb Space Telescope (JWST) has produced a new image of the Bullet Cluster, which is a titanic collision between two individual galaxy clusters.

The image, produced in conjunction with NASA’s Chandra X-ray Observatory, reveals not only the location and mass of dark matter present, but also points the way toward one day figuring out what dark matter is actually made of.

A gigantic array of radio dishes proposed for the Utah desert could advance our understanding of physics and help us decode cosmic radio signals. Now, scientists have outlined how it would work.

Beginning in the 1950s, radio astronomy has opened up a powerful view into the inner workings of the universe, revealing everything from how stars form to incredible images of our galaxy’s gigantic black hole. Now, astronomers are building a gigantic array of radio dishes, called the Deep Synoptic Array 2000 (DSA-2000). The array consists of 2,000 radio dishes, each 16 feet (5 meters) across, laid out in a radio-quiet part of the Utah desert.

While the shortest day of the year typically falls in winter, summer will have its fair share of abnormally short days this year. According to TimeandDate, Earth will spin unusually fast in July and August, resulting in shorter days.

From the point of view of the sun, it takes Earth roughly 86,400 seconds (24 hours) to complete one full rotation. This changes slightly from day to day, and these small variations are measured with atomic clocks. The number of milliseconds above or below 86,400 seconds is referred to as length of day.

Until 2020, the shortest length of day ever recorded was -1.05 milliseconds, meaning it took the Earth 1.05 milliseconds less than 86,400 seconds to complete one rotation. Since then, Earth has beaten this record every year, with the shortest day of all being -1.66 milliseconds.

This month,TimeandDate reports that Earth will get close to its previous record. On July 9, the length of date is expected to be -1.30 milliseconds, followed by -1.38 milliseconds on July 22 and -1.51 milliseconds on August 5.

“Nobody expected this,” Leonid Zotov, a leading authority on Earth rotation at Moscow State University, told the outlet. “The cause of this acceleration is not explained.” Zotov added that most scientists believe it is something inside the Earth. “Ocean and atmospheric models don’t explain this huge acceleration,” he said.

Despite this acceleration, Zotov predicts that Earth will slow down soon. “I think we have reached the minimum,” he told TimeandDate. “Sooner or later, Earth will decelerate.” In the meantime, scientists will continue to study the reason behind Earth’s length of day variations.