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How dry is Mars? – Skywatching – Castanet.net

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With Mars now the most intensively explored planet in the Solar System after ours, it is not surprising that we are continually having to review our ideas and preconceptions.

The Red Planet continues to challenge our imaginations.

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The mainstream idea is that originally Mars had lots of water, but being a smaller world, with weaker gravity, and losing its magnetic field early on, its atmosphere and water got lost to space, leaving a cold, dry desert world.

Now, it looks as though we could be seriously wrong in our assumption that Mars is now a dried-up world.

Current estimates are that around three billion years ago, when life was first getting started in the Earth’s oceans and possibly on Mars too, there was enough water on Mars to submerge the whole planet to a depth of between 100 and 1000 metres.

By comparison, if our Earth were a smooth ball, the existing oceans would cover it to a depth of well over 2000 metres. Mars once had a lot of water; by about a billion years ago, it had disappeared.

There are three places the Martian oceans could have disappeared to.

  • One is, as we know, the loss of water to space.
  • A second is the presence of lots of ice hidden underground, and possibly underground or under-ice briny lakes.
  • A third option is that water got taken up and combined with various minerals. This water is chemically tied up and can remain sequestered for a long time.

At some point in our high-school science career most of us have heated copper sulphate.

As we warmed it, those nice blue crystals turned into white powder and water came off as steam. Before we applied the heat the crystals were perfectly dry.

The water molecules were locked up inside the crystals as part of the chemical. There are many minerals that similarly lock up water.

The first rocks on Mars would have been volcanic. However, Mars, like Earth, was then a wet world, with rain and other weather.

On Earth, rocks are continually attacked and broken down, a process we call weathering. The situation on Mars would have been the same. In the process, minerals in the rock become new minerals that contain water, such as clays.

From observations done from orbit and on the Martian surface, it looks as though there is a lot of water tied up in hydrated minerals.

Apart from our interest in this information in helping us understand the history of the planet in the Solar System most like ours, it also is important regarding our plans to have long-term manned bases, or even colonies on Mars.

The red surface of Mars indicates iron oxides, which contain oxygen. In addition, we can use solar-generated electricity to liberate oxygen from water.

Given that current space technology means Mars is always many months away, the more self-sufficient our bases are for the key needs of energy, water and oxygen, the less dependent they will be upon Earthly support, and the more secure they will be in the long term.

Moreover, the more water there is, the better the long-term prospects of terraforming the planet.

Before messing with the Martian environment, we need to know whether there are living things on the planet. The last thing we would want to do is render their world uninhabitable to them.

The presence of water tied up in minerals rather than just frozen solid offers easier prospects for Martians to make a living, because water is an important component in extracting useful chemicals from their surroundings, maybe, as is the case on Earth, with the help of the Sun.

It is true that the solar ultraviolet radiation level on the surface of Mars is dangerous to us, but that radiation has a lot of energy in it, and there is no reason Martians, if any, will be like us.

  • Mars is high in the southwest after dark.
  • Jupiter and Saturn lie low in the southeast just before dawn.
  • The Moon will be New on the 11th.

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Giant prehistoric salmon had tusk-like teeth for defence, building nests

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The artwork and publicity materials showcasing a giant salmon that lived five million years ago were ready to go to promote a new exhibit, when the discovery of two fossilized skulls immediately changed what researchers knew about the fish.

Initial fossil discoveries of the 2.7-metre-long salmon in Oregon in the 1970s were incomplete and had led researchers to mistakenly suggest the fish had fang-like teeth.

It was dubbed the “sabre-toothed salmon” and became a kind of mascot for the Museum of Natural and Cultural History at the University of Oregon, says researcher Edward Davis.

But then came discovery of two skulls in 2014.

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Davis, a member of the team that found the skulls, says it wasn’t until they got back to the lab that he realized the significance of the discovery that has led to the renaming of the fish in a new, peer-reviewed study.

“There were these two skulls staring at me with sideways teeth,” says Davis, an associate professor in the department of earth sciences at the university.

In that position, the tusk-like teeth could not have been used for biting, he says.

“That was definitely a surprising moment,” says Davis, who serves as director of the Condon Fossil Collection at the university’s Museum of Natural and Cultural History.

“I realized that all of the artwork and all of the publicity materials and bumper stickers and buttons and T-shirts we had just made two months prior, for the new exhibit, were all out of date,” he says with a laugh.

Davis is co-author of the new study in the journal PLOS One, which renames the giant fish the “spike-toothed salmon.”

It says the salmon used the tusk-like spikes for building nests to spawn, and as defence mechanisms against predators and other salmon.

The salmon lived about five million years ago at a time when Earth was transitioning from warmer to relatively cooler conditions, Davis says.

It’s hard to know exactly why the relatives of today’s sockeye went extinct, but Davis says the cooler conditions would have affected the productivity of the Pacific Ocean and the amount of rain feeding rivers that served as their spawning areas.

Another co-author, Brian Sidlauskas, says a fish the size of the spike-toothed salmon must have been targeted by predators such as killer whales or sharks.

“I like to think … it’s almost like a sledgehammer, these salmon swinging their head back and forth in order to fend off things that might want to feast on them,” he says.

Sidlauskas says analysis by the lead author of the paper, Kerin Claeson, found both male and female salmon had the “multi-functional” spike-tooth feature.

“That’s part of our reason for hypothesizing that this tooth is multi-functional … It could easily be for digging out nests,” he says.

“Think about how big the (nest) would have to be for an animal of this size, and then carving it out in what’s probably pretty shallow water; and so having an extra digging tool attached to your head could be really useful.”

Sidlauskas says the giant salmon help researchers understand the boundaries of what’s possible with the evolution of salmon, but they also capture the human imagination and a sense of wonder about what’s possible on Earth.

“I think it helps us value a little more what we do still have, or I hope that it does. That animal is no longer with us, but it is a product of the same biosphere that sustains us.”

This report by The Canadian Press was first published April 24, 2024.

Brenna Owen, The Canadian Press

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Giant prehistoric salmon had tusk-like spikes used for defence, building nests: study

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A new paper says a giant salmon that lived five million years ago in the coastal waters of the Pacific Northwest used tusk-like spikes as defense mechanisms and for building nests to spawn.

The initial fossil discoveries of the 2.7-metre-long salmon in Oregon in the 1970s were incomplete and led researchers to suggest the fish had fang-like teeth.

The now-extinct fish was dubbed the “saber-tooth salmon,” but the study published in the peer-reviewed journal PLOS One today renames it the “spike-toothed salmon” and says both males and females possessed the “multifunctional” feature.

Study co-author Edward Davis says the revelation about the tusk-like teeth came after the discovery of fossilized skulls at a site in Oregon in 2014.

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Davis, an associate professor in the department of earth sciences at the University of Oregon, says he was surprised to see the skulls had “sideways teeth.”

Contrary to the belief since the 1970s, he says the teeth couldn’t have been used for any kind of biting.

“That was definitely a surprising moment,” Davis says of the fossil discovery in 2014. “I realized that all of the artwork and all of the publicity materials … we had just made two months prior, for the new exhibit, were all out of date.”

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SpaceX sends 23 Starlink satellites into low-Earth orbit

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April 23 (UPI) — SpaceX launched 23 Starlink satellites into low-Earth orbit Tuesday evening from Space Launch Complex 40 at Cape Canaveral Space Force Station in Florida.

Liftoff occurred at 6:17 EDT with a SpaceX Falcon 9 rocket sending the payload of 23 Starlink satellites into orbit.

The Falcon 9 rocket’s first-stage booster landed on an autonomous drone ship in the Atlantic Ocean after separating from the rocket’s second stage and its payload.

The entire mission was scheduled to take about an hour and 5 minutes to complete from launch to satellite deployment.

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The mission was the ninth flight for the first-stage booster that previously completed five Starlink satellite-deployment missions and three other missions.

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