Could There Be Life In Them Thar Pits?

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Recent images from ESA’s Mars Express spacecraft reveal long rows of crater-like depressions lining the flanks of ancient Martian volcanoes located in the planet’s vast Tharsis region. Rather than being the result of impact events, these “pit chains” were likely caused by underground lava flows — and could be a prime location for look for life.

Like similar features found on Earth, lava tubes on Mars are the result of rivers of magma that carved channels beneath the surface. When these channels empty out, a hollow tube is left. If the roof of a particularly large tube is near the surface the roof can eventually collapse, creating a surface depression… or, in some cases, opening up to the surface entirely.

Even though volcanism on Mars isn’t currently active — the last eruptions probably took place at least over a million years ago — the features left by volcanic activity are still very much present today and likely well-preserved beneath the Martian surface.

Shielded from harsh solar and cosmic radiation, the interior of such lava tubes could provide a safe haven for microbial life — especially if groundwater had found its way inside at some point.

Even though the surface of Mars can receive 250 times the radiation levels found on Earth, the layers of soil and rock surrounding the tubes can provide adequate protection for life, whether it be ancient Martian microbes or future explorers from Earth.

A wider image of the Tractus Catena region showing the large shield volcano Ascraeus Mons. Credits: ESA/DLR/FU Berlin (G. Neukum)

Of course, water and protection from radiation aren’t the only factors necessary for life. There also needs to be some source of heat. Fortunately, the pit chains imaged by Mars Express happen to be within one of the most volcano-laden areas of the Red Planet, a region called the Arcadia quadrangle. Within this area exist some of the largest volcanoes on Mars — and the Tractus Catena pits are located right in the middle of them.

If a heat source were ever to have been beneath the surface of Mars, there would be a good chance it would have been here.

And if our own planet is any measure of such things, where there’s heat and water there is often some form of life — however extreme the conditions may be.

“I’d like to see us land ON a volcano,” Dr. Tracy Gregg, a volcanologist with the University of Buffalo, had once told Universe Today back in 2004. “Right on the flanks. Often the best place to look for evidence of life on any planet is near volcanoes.”

“That may sound counterintuitive, but think about Yellowstone National Park , which really is nothing but a huge volcano,” Gregg elaborated. “Even when the weather in Wyoming is 20 below zero, all the geysers, which are fed by volcanic heat, are swarming with bacteria and all kinds of happy little things cruising around in the water. So, since we think that the necessary ingredients for life on Earth were water and heat, we are looking for the same things on Mars.”

As far as any remaining geothermal activity still happening beneath the Martian surface?

“I strongly suspect there are still molten (or at least mushy) magma bodies beneath the huge Tharsis volcanoes,” Gregg had said. (Read the full article here.)

On Earth, lava tubes, caves and underground spaces of all kinds harbor life, often specialized forms that are found no place else. Could this be (or have once been) the case on Mars as well? Only future exploration will tell. Until then, places like Tractus Catena will remain on scientists’ short list of places to look.

Read more on the ESA website here.

How Hot is Lava

How Hot is Lava

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We all know that the lava is molten rock that is spewed from a volcano. However how hot is lava? The temperature of lava can range anywhere from 700° C to 1200° C. Lava is not really lava until it meets the earth’s crust before that it is known as magma. Magma is the ocean of molten rock that lies beneath the earth’s crust. When it escapes through cracks the earth’s crust it creates volcanoes. The magma that comes out of volcanoes is what we call lava. Lava can be as much 100,000 times as viscous as water.

The different types of lava vary depending on composition and temperature. The three main types of lava are felsic, intermediate, and mafic. There are two types of felsic lava. They are rhyolite and dacite. These types of lava are composed of aluminum, silica, potassium, sodium, calcium, and liquid quartz and feldspar. Felsic lava normally erupts between 650° C to 750° C.

Intermediate lava is the next type of lava. Intermediate lava is also known as andesitic lava. Andesitic lava has lower levels of aluminium and silica. However this kind of lava is richer in magnesium and iron than felsic lava. This kind of lava occurs on steep composite volcanoes like those found in the Andes mountain range. Since andesitic lava has a lower level of aluminum and silica in its composition it is normally hotter with a range of 750-950° C.

The last type of lava is mafic lava or basaltic lava. This is one of the hottest types of lava coming out at temperatures exceed 950 degrees Celsius. This type of lava is rich in iron bearing minerals. This is what accounts for as high temperature. There are also the kinds of mafic lava that are even a hotter than normal basaltic lava. One type is all ultra-mafic lava.

Lava temperature tells us a lot about the different types of lava. Each brings important minerals and nutrients to the surface. So getting a better understanding of lava flows gives a better of the Earth’s composition and how certain minerals came to the surface of the Earth’s crust.

We have written many articles about lava for Universe Today. Here’s an article about the types of lava, and here’s an article about the viscosity of lava.

If you’d like more info on lava and volcanoes, take a look at the USGS’ Volcanoes Hazard Program, and here’s a link to Volcano World from Oregon State University.

We’ve also recorded an episode of Astronomy Cast all about volcanoes. Listen here, Episode 141: Volcanoes, Hot and Cold.

References:
NASA Earth Observatory
USGS

Basalt

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Basalt is a hard, black volcanic rock with less than 52% silica. Because of this low silica content, basalt has a low viscosity (thickness), and so it can flow for long distances after erupting from a volcano. During an eruption, a basalt lava flow can easily move more than 20 km away from a vent. Basalt is the most common rock type in the Earth’s crust. In fact, most of the ocean floor is made up of basalt.

Basalt is made up of dark colored materials like pyroxene and olivine, but it also contains lighter minerals like feldspar and quartz. These crystals form because the lava cools slowly after erupting out of a volcano. Although a lava flow might look cool shortly after an eruption, it might take months or even years to cool all the way through. The crystals are bigger in the middle of a cooled lava flow because that part had longer to cool. If a lava flow cools quickly, like when it falls into a lake or ocean, it becomes a glass-like rock called obsidian. This is because the crystals in the rock don’t have time to form.

Shield volcanoes are made up entirely of basalt lava eruptions. A good example of this are the volcanoes Mauna Loa and Mauna Kea on the Big Island of Hawaii. Over hundreds of thousands of years, they have built up tall volcanoes that are extremely wide because of the fast flowing basalt lava.

Geologists have found large outpourings of lava covering hundreds of kilometers of land called flood basalt. The largest of these is known as the Siberian Traps in northern Russia. This is a region of 1.5 million square kilometers covered by basalt.

We have written many articles about volcanoes for Universe Today. Here’s an article about obsidian, and here’s an article about different types of lava.

Want more resources on the Earth? Here’s a link to NASA’s Human Spaceflight page, and here’s NASA’s Visible Earth.

We have also recorded an episode of Astronomy Cast about Earth, as part of our tour through the Solar System – Episode 51: Earth.

A’a Lava

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There are several different kinds of lava, depending on the chemical composition and temperature of the molten rock that erupts from a volcano. The smooth variety is called pahoehoe, and the rougher variety is known as a’a (pronounced ah-ah). A’a is a Hawaiian word meaning “stony with rough lava”.

If you’ve ever been to the Big Island of Hawaii and gone for a hike, you’ve seen a’a lava. It’s incredibly rough and jagged black rock that takes forever to walk across; and tears your shoes apart as you go.

During an eruption, a’a lava comes out of the volcano as a very thick (viscous) lava that travels very slowly. The inside of an a’a lava flow is thick and dense. Surrounding this thick dense core is a sharp spiny surface of cooling rock. These fragments of rock are carried on the top of the a’a lava flow and make a crunching grinding sound as the lava flows downhill.

Once the lava flow stops, it can take weeks or even years for the lava to harden completely. The interior dense core hardens in place with the jagged fragments surrounding it. This is why old a’a flows are so sharp and jagged.

A’a flows move slowly – you could easily outrun one – but they move fast enough to tear down buildings, cover roads, and destroy vegetation.

The smoother pahoehoe lava can turn into a’a lava as it gets further downhill. This happens because of the delicate balance of gas content in the lava, the changes in lava viscosity, and the rate of deformation as the lava flows and cools. Once this balance changes, the pahoehoe can change into a’a. Of course, a’a lava never changes back into pahoehoe.

We have written many articles about volcanoes for Universe Today. Here’s an article about lava tubes on Pavonis Mons… on Mars. And here’s an article about the dark lava floor of crater Billy.

Want more resources on the Earth? Here’s a link to NASA’s Human Spaceflight page, and here’s NASA’s Visible Earth.

We have also recorded an episode of Astronomy Cast about Earth, as part of our tour through the Solar System – Episode 51: Earth.