The northern lowlands and sedimentary regions of Mars are dotted with curious formations. Tens of thousands of conical hills, many topped with small craters, and surrounded by deep channels scoured from the surface by flowing liquid.
That sounds a lot like volcanoes found here on Earth – but on a planet like Mars, where we can’t easily go and look, and where conditions can be so very different from Earth’s, you have to be wary of making assumptions.
The features on Mars may resemble Earth’s lava flows, but there’s also a type of volcano on Earth that spews up something completely different – sludgy, oozy mud.
And scientists have just found that, under the very low atmospheric pressure and temperature conditions found on Mars, mud can flow very differently from Earth’s mud volcanoes. In fact, it can look a heck of a lot like lava.
“This is of interest because we see many flow-like features on Mars in spacecraft images, but they have not yet been visited by any of the roving vehicles on the surface and there is some ambiguity about whether they are flows of lava or mud.”
(NASA/JPL-Caltech/University of Arizona)
Scientists have long thought that large amounts of water once flowed freely on the Martian surface, released for a very short period of time and eroding the landscape before drying up, or being covered by volcanic activity and sediments deposited by the wind.
But soggy sediments trapped under the surface could have later been pushed up and out by underground pressure, creating mud volcanoes. This is what the researchers wanted to figure out.
Their experimental set-up consisted of a low-pressure cylindrical chamber 90 centimetres in diameter and 180 centimetres in length (35 to 70 inches). This was carefully pressurised at 7 millibars to simulate Mars atmospheric pressure for 15 experiments, and 1,000 millibars to simulate Earth atmospheric pressure at sea level for 6 experiments.
In both sets, mud was poured over sand cooled to a temperature consistent with the surface temperature of Mars, -20 degrees Celsius. The researchers then studied and characterised the way the mud flowed across that surface.
In terrestrial conditions, the mud flows didn’t expand, form an icy crust, or create lava-like flows. But the mud flows under Martian conditions did – because of the lower atmospheric pressure.
When atmospheric pressure lowers, so too does the boiling point of water. That’s why water boils at a lower temperature at higher altitudes; if you were to find yourself floating in space without protective gear, saliva would boil right off your tongue (among other, more fatal things).
The effect on mud flows in simulated Martian conditions is fascinating. The water in the mud begins to boil and evaporate, and that process absorbs the latent heat from the vapour. This cools the mud, and a crust freezes on its surface.
“However, the impact of this familiar effect on mud has never been investigated in an experiment before. Once again, it turns out that different physical conditions must always be taken into account when looking at apparently simple surface features on other planets. We now know that we need to consider both mud and lava when analysing certain flow phenomena.”
What happens after the crust freezes is where it gets really good. The mud flow behaves like the pahoehoe lava flows seen in Hawaii and Iceland. The mud still pushing up from underneath erupts through the icy crust, oozing out and refreezing into a new flow lobe. But, while the process is similar, the shape of the mud flows is different, the researchers found.
While there are limitations to the study – Martian gravity couldn’t be replicated, for instance – the research does show that mud volcanism wouldn’t be impossible on the Red Planet after all. And the research has important implications for other kinds of volcanism in the Solar System, such as the ice volcanoes thought to exist on far objects such as Titan and Pluto.
It shows that, even though we may think we understand what’s going on, there could be environmental conditions that change the processes in fundamental ways.
More than a month after testing positive for COVID-19, a Winnipeg toddler is fighting another illness – a possible rare inflammatory syndrome that could be part of the body’s reaction to new viruses.
The girl’s mother told CBC News doctors are trying to find out whether the one-year-old has developed Kawasaki disease, or multi-system inflammatory syndrome in children, now that she is negative for COVID-19 but is still seriously ill.
To read more of this story first reported by CBC News, click here.
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June’s full moon, which is the last full moon of spring or the first of summer, is traditionally called the Strawberry Moon.
This full moon brings with it a penumbral eclipse, which occurs when the moon crosses through the faint outer edge of Earth’s shadow (the penumbra), making part of the moon appear slightly darker than usual. Unlike a full lunar or solar eclipse, the visual effect of a penumbral eclipse is usually so minimal that it can be difficult to see.
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This eclipse was only visible from parts of Australia, Asia, Africa, Europe, and South America, but notfrom North America.
The tradition of naming moons is rich in history. According to the Old Farmer’s Almanac, the name, Strawberry moon, originated with Algonquin tribes in eastern North America who knew it as a signal to gather the ripening fruit of wild strawberries.
Other names for this moon include the Honey Moon and the Mead Moon. It has also been called the Rose Moon, as many roses begin blooming in June.
Historically, full moon names were used to track the seasons and, for this reason, often relate closely to nature. The moon names used today come from Native American and Colonial-era sources. Traditionally, each full moon name was applied to the entire lunar month in which it occurred, rather than just the full moon itself.
Greeks witnessed a rare phenomenon watching the first full moon of the summer on Friday night, as the sky was illuminated and then went dark for a few minutes.
The first full moon of the summer – the strawberry moon – was accompanied by an eclipse, as the moon was “entangled” in the net of the earth’s shadow for a few minutes, before taking its place high in the sky.
The penumbra eclipse is a phenomenon in which the moon passes through the half-shadow of the Earth, i.e. the outer part of the shadow of our planet.
People in Attica watched in awe the special phenomenon from several vantage points such as Sounio, Syntagma Square, and the Filopapou and Lycabettus hills.
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