Evidence is mounting for "a vast reservoir of liquid water" on Mars, according to a new article by Australian National University professor Hrvoje TkalÄiÄ and geophysics associate professor Weijia Sun from the Chinese Academy of Geological Sciences, announcing their recently published paper. "Using seismic data from NASA's InSight mission, we uncovered evidence that the seismic waves slow down in a layer between 5.4 and 8 kilometres below the surface, which could be because of the presence of liquid water at these depths." Mars is covered in traces of ancient bodies of water. But the puzzle of exactly where it all went when the planet turned cold and dry has long intrigued scientists... Billions of years ago, during the Noachian and Hesperian periods (4.1 billion to 3 billion years ago), rivers carved valleys and lakes shimmered. As Mars' magnetic field faded and its atmosphere thinned, most surface water vanished. Some escaped to space, some froze in polar caps, and some was trapped in minerals, where it remains today. But evaporation, freezing and rocks can't quite account for all the water that must have covered Mars in the distant past. Calculations suggest the "missing" water is enough to cover the planet in an ocean at least 700 metres deep, and perhaps up to 900 metres deep. One hypothesis has been that the missing water seeped into the crust. Mars was heavily bombarded by meteorites during the Noachian period, which may have formed fractures that channelled water underground. Deep beneath the surface, warmer temperatures would keep the water in a liquid state — unlike the frozen layers nearer the surface. In 2018, NASA's InSight lander touched down on Mars to listen to the planet's interior with a super-sensitive seismometer. By studying a particular kind of vibration called "shear waves", we found a significant underground anomaly: a layer between 5.4 and 8 kilometres down where these vibrations move more slowly. This "low-velocity layer" is most likely highly porous rock filled with liquid water, like a saturated sponge. Something like Earth's aquifers, where groundwater seeps into rock pores. We calculated the "aquifer layer" on Mars could hold enough water to cover the planet in a global ocean 520-780m deep. InSight's seismometer captured vibrations between the crust of Mars and its lower layers from two meteorite impacts in 2021 and a Marsquake in 2022. "These signatures let us pinpoint boundaries where rock changes, revealing the water-soaked layer 5.4 to 8 kilometres deep." It's an exciting possibility. "Purified, it could provide drinking water, oxygen, or fuel for rockets." And since microbes thrives on earth in deep rocks filled with water, "Could similar life, perhaps relics of ancient Martian ecosystems, persist in these reservoirs?"

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Billions of years ago Mars "had a warm, habitable climate with liquid water in lakes and flowing rivers," writes Ars Technica. But "In order for Mars to be warm enough to host liquid water, there must have been a lot of carbon dioxide in the atmosphere," says Benjamin Tutolo, a researcher at the University of Calgary. "The question we've been asking for at least 30 years was where the record of all this carbon is." Tutolo led a new study of rock samples collected by the Curiosity rover that might have answered this question... Curiosity rover was called Mars Science Laboratory for a reason. It went to the red planet fitted with a suite of instruments, some of which even the newer Perseverance was lacking. These enabled it to analyze the collected Martian rocks on the spot and beam the results back to Earth. "To get the most bang for the buck, NASA decided to send it to the place on Mars called the Gale Crater, because it was the tallest stack of sediments on the planet," Tutolo says. The central peak of Gale Crater was about 5 kilometers tall, created by the ancient meteorite impact... The idea then was to climb up Mount Sharp and collect samples from later and later geological periods at increasing elevations, tracing the history of habitability and the great drying up of Mars. On the way, the carbon missed by the satellites was finally found... It turned out the samples contained roughly between 5 and 10 percent of siderite... The siderite found in the samples was also pure, which Tutolo thinks indicates it has formed through an evaporation process akin to what we see in evaporated lakes on Earth. This, in turn, was the first evidence we've found of the ancient Martian carbon cycle. "Now we have evidence that confirms the models," Tutolo claims. The carbon from the atmosphere was being sequestered in the rocks on Mars just as it is on Earth. The problem was, unlike on Earth, it couldn't get out of these rocks... A large portion of carbon that got trapped in Martian rocks stayed in those rocks forever, thinning out the atmosphere. "While it's likely the red planet had its own carbon cycle, it was an imperfect one that eventually turned it into the lifeless desert it is today," the article points out. But the study still doesn't entirely explain what warmed the atmosphere of Mars — or why Martian habitability "was seemingly intermittent and fluctuating".

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Nuclear fusion — which releases four times the energy of fission — could theoretically happen sooner in space than on earth, reports CNN. "And it could help spacecraft achieve speeds of up to 500,000 miles (805,000 kilometers) per hour — more than the fastest object ever built..." With funding from the UK Space Agency, British startup Pulsar Fusion has unveiled Sunbird, a space rocket concept designed to meet spacecraft in orbit, attach to them, and carry them to their destination at breakneck speed using nuclear fusion... For now, Sunbird is in the very early stages of construction and it has exceptional engineering challenges to overcome, but Pulsar says it hopes to achieve fusion in orbit for the first time in 2027. [Pulsar's founder/CEO says the first functional Sunbird would be ready four to five years later.] If the rocket ever becomes operational, it could one day cut the journey time of a potential mission to Mars in half. CNN says the proposed Sunbird process would use helium-3 — which may be abundant on the Moon — to generate protons which "can be used as a 'nuclear exhaust' to provide propulsion". (And without generating any dangerous radioactive material.) "It's very unnatural to do fusion on Earth," says Richard Dinan, founder and CEO of Pulsar. "Fusion doesn't want to work in an atmosphere. Space is a far more logical, sensible place to do fusion, because that's where it wants to happen anyway...." Sunbirds would operate similarly to city bikes at docking stations, according to Dinan: "We launch them into space, and we would have a charging station where they could sit and then meet your ship," he says. "You turn off your inefficient combustion engines, and use nuclear fusion for the greater part of your journey. Ideally, you'd have a station somewhere near Mars, and you'd have a station on low Earth orbit, and the (Sunbirds) would just go back and forth...." Initially, the Sunbirds will be offered for shuttling satellites in orbit, but their true potential would come into play with interplanetary missions. The company illustrates a few examples of the missions that Sunbird could unlock, such as delivering up to 2,000 kilograms (4,400 pounds) of cargo to Mars in under six months, deploying probes to Jupiter or Saturn in two to four years (NASA's Europa Clipper, launched in 2024 towards one of Jupiter's moons, will arrive after 5.5 years), and an asteroid mining mission that would complete a round trip to a near-Earth asteroid in one to two years instead of three. Other companies are working on nuclear fusion engines for space propulsion, including Pasadena-based Helicity Space, which received investment from aerospace giant Lockheed Martin in 2024. San Diego-based General Atomics and NASA are working on another type of nuclear reactor — based on fission rather than fusion — which they plan to test in space in 2027.

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A new study warns that toxic Martian dust contains fine particles and harmful substances like silica and metals that pose serious health risks to astronauts, making missions to Mars more dangerous than previously thought. The Guardian reports: During Apollo missions to the moon, astronauts suffered from exposure to lunar dust. It clung to spacesuits and seeped into the lunar landers, causing coughing, runny eyes and irritated throats. Studies showed that chronic health effects would result from prolonged exposure. Martian dust isn't as sharp and abrasive as lunar dust, but it does have the same tendency to stick to everything, and the fine particles (about 4% the width of a human hair) can penetrate deep into lungs and enter the bloodstream. Toxic substances in the dust include silica, gypsum and various metals. "A mission to Mars does not have the luxury of rapid return to Earth for treatment," the researchers write in the journal GeoHealth. And the 40-minute communication delay will limit the usefulness of remote medical support from Earth. Instead, the researchers stress that limiting exposure to dust is essential, requiring air filters, self-cleaning space suits and electrostatic repulsion devices, for example.

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NASA's Curiosity rover has detected the largest organic molecules ever found on Mars -- decane, undecane, and dodecane -- suggesting that complex prebiotic chemistry may have occurred in the planet's ancient lakebeds. The findings have been published in the Proceedings of the National Academy of Sciences. From a press release: Scientists probed an existing rock sample inside Curiosity's Sample Analysis at Mars (SAM) mini-lab and found the molecules decane, undecane, and dodecane. These compounds, which are made up of 10, 11, and 12 carbons, respectively, are thought to be the fragments of fatty acids that were preserved in the sample. Fatty acids are among the organic molecules that on Earth are chemical building blocks of life. Living things produce fatty acids to help form cell membranes and perform various other functions. But fatty acids also can be made without life, through chemical reactions triggered by various geological processes, including the interaction of water with minerals in hydrothermal vents. While there's no way to confirm the source of the molecules identified, finding them at all is exciting for Curiosity's science team for a couple of reasons. Curiosity scientists had previously discovered small, simple organic molecules on Mars, but finding these larger compounds provides the first evidence that organic chemistry advanced toward the kind of complexity required for an origin of life on Mars. The new study also increases the chances that large organic molecules that can be made only in the presence of life, known as "biosignatures," could be preserved on Mars, allaying concerns that such compounds get destroyed after tens of millions of years of exposure to intense radiation and oxidation.

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