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Skywatching

Life on Mars

One day, we will be living on Mars, either as visitor explorers and scientists, or as colonists.

It might take a while, but if the will is there, our technology will get us to where it becomes economically and logistically feasible.
 
Mars presents a challenge. Its atmosphere is so thin we will need a space suit to move around outdoors. What atmosphere there is consists mostly of nitrogen. It is not toxic, but it is of no use to us.

There are some other problems. The thin atmosphere means there is little greenhouse effect to trap heat, so daily temperatures vary enormously.

During the summer, it can get above freezing during the day and then go down to 100 Celsius or more below at night.

Even though Mars is further from the sun than Earth is, the lack of any significant atmosphere means more solar ultraviolet radiation reaches the surface. In addition, Mars has no global magnetic field.

This, together with the lack of atmosphere, means other high-energy radiation can reach the surface of the planet.

It could be that living things might have appeared a billion or more years ago, when Mars was warm and wet, but now, with the planet being an almost air less, frozen desert, if anything survives, it must be hiding underground.
 
For a long time, our visions of colonies on Mars and similar worlds have been of life under inflated, clear plastic bubbles. Inside, you get the sunlight and, if the bubbles are made of the right material, the greenhouse effect will provide some solar heating.

However, the thin plastic will have little insulation value against low temperatures outside, and warm rising air would be cooled off.

It also offers little protection against radiation. A more realistic approach would be to build habitations underground, where a few metres of soil would provide insulation against temperature variations and screening against radiation.

However, an interesting dimension here is that there is a lot of ice under the Martian surface.

On one side it means we will have locally available water. We can drink it, and using locally available solar energy, unless there is a dust storm, we can break down that water to get oxygen to breathe.

On the other side, building a warm habitation in or on the Martian surface could cause the same problems as we get in the Arctic if we do something that melts the permafrost.

We will have to locate our habitations very carefully, otherwise they could end up collapsing in pools of meltwater.

Stays of weeks or months in Earth orbit or on the Moon are very different from the long journey times involved in getting to Mars, and the long stays on Mars made necessary by waiting until Mars and Earth are in the right position for the return trip.

Our environmental needs become larger. In addition to the need to meet nutritional and sanitary requirements, there is the problem that we constantly shed flakes of skin, oily sweat, hair, and so on.

On Earth we are surrounded by living things, such as bacteria and dust mites, which deal with and recycle them, stabilizing our ecosystem.

Otherwise, they will accumulate behind panels and in nooks and crannies, becoming food for bacteria and fungi, making us sick. The longer we are away from home, the more of our ecosystem we will have to take with us.

These days we talk or dream about terraforming worlds, changing their atmosphere and other conditions so that we can set up an entire ecosystem to suit us, and can live with little or no technical assistance.

These are at the moment just ideas. Of course, whether we end up terraforming Mars depends on one other issue.

If there are still any surviving Martians, we should leave things alone. They might not want us to do it.

  • Jupiter is lost in the sunset glow.
  • Saturn lies low in the south-southwest after dark
  • Mars is still bright in the south-southeast. 
  • The moon will reach First Quarter on the 16th and be full on the 24th.


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Sand dunes have a story

All of us, either in desert movies like David Lean's Lawrence of Arabia, or in real life have seen sand dunes. They look like huge waves or crescents, up to 300 metres high and 200 kilometres long.

For them to form, we require two ingredients:

  • lots of dry material with loose grains more or less the same size
  • a steady, dry wind.

Heat is useful because it ensures the ingredients are dry, but it is not essential. For example, there are dune fields in Saskatchewan and British Columbia.

An absolutely steady wind blowing close to or in contact with the Earth's surface will be unstable, breaking into waves.

Sand starts to accumulate under the peak of a wave. This makes the wave bigger. The wind or current blows material up the longer, upwind side of the accumulation.

Eventually, the ridge of sand is high enough for the flow to detach, and an eddy forms on the downstream side, which is much steeper than the upstream side. What we see is sand climbing the upstream slope and tumbling down the steep downstream side.

A bit further downstream the wind reconnects with the ground and the process starts over. The result can be wave after wave of sand, forming dune fields over thousands of kilometres.

Since we know the recipe for making dunes, and the circumstances under which they form, their presence tells us a lot. This is especially useful when we see them on other worlds.
 
We have discovered dune fields not only on Earth, but also on Mars, Titan and Pluto. Since Mars is so similar to Earth, their presence is not really surprising. Mars is mostly a cold desert. The atmosphere is very thin.

At the surface, the air pressure is around 0.4 kilopascals, compared with the Earth's surface pressure of about 100 kilopascals. However, the winds are strong enough to blow sand around, forming dune fields and even dust devils — mini-tornadoes of dust and sand.
 
The presence of dune fields on Titan, the largest moon of Saturn, the sixth planet out from the sun, is more intriguing. However, in some ways it resembles the Earth more than Mars does. It has rivers, lakes and a thick atmosphere.

The pressure at ground level is around 148 kilopascals, about one and a half times that here on Earth. However, the average temperature on Titan is about -180 Celsius.

On that world, water is a permanently frozen rock mineral, and those lakes and rivers are liquid hydrocarbons, such as methane, and the atmosphere is mostly nitrogen gas.

The particles making up the dunes could be ice or frozen hydrocarbons, and rock dust. The main requirement is that they are all sufficiently deeply frozen so as not to stick together. We know that Titan has weather as we would understand it, clouds, dust storms in the dry places, and hydrocarbon rain.

The dune fields show us dry areas with steady winds, which tell us a lot about how the weather works on that cold world.

Pluto is a stranger issue. It is so cold that nitrogen, methane and the other gases driving Titan's weather are all frozen solid.

The planet's surface is mostly frozen nitrogen, carbon monoxide and methane. In the sun's heat, a tiny bit evaporates, making a very thin atmosphere of nitrogen and carbon monoxide.

Particles of frozen nitrogen and methane would be good raw materials for dunes. However, there are two big questions:

  • how did the frozen material get divided into lots of loose particles
  • what is blowing them around.

Pluto's atmosphere is around a million times thinner than Earth's. However, it appears that if the particles are small enough, on a world with weaker gravity than Earth, even with a very thin atmosphere the wind could be strong enough.

  • Jupiter is vanishing in the sunset glow.
  • Saturn lies low in the south-southwest after dark
  • Mars is still conspicuous in the south-southeast.
  • The moon will reach First Quarter on the 16th.


Black hole of Huge Data

We now live in an age of Big Data.

Once we developed the technologies for handling and storing huge amounts of information, we went on to collect more and more of it. In the same way, astronomy is now in the age of Huge Data.

Not very long ago making astronomical observations consisted of setting up the telescope and instruments attached to it, pointing it at the object of interest and then manually recording the data. When computers first moved into astronomy, they were used to automate the operation of the telescope and to record data.

We took the results away and used computers to analyze it. Then, as computers got smaller, faster and cheaper the game changed.

With computer help, our telescopes could record more data about more things, faster. We can now carry out and process large-scale surveys of the sky, and keep an eye open for transient events.

We can make networks of many radio telescopes distributed over thousands of kilometres, processing their outputs digitally to emulate one huge radio telescope. Multitudes of small, high-speed computers now form parts of our instruments, no longer just controlling them.

The result is a tsunami of data we have to store, make accessible, and somehow, analyze.

One other issue we needed to address is the enormous amount of astronomical information that has accumulated from past observations. Some came from large-scale surveys made at some observatories, and stored there. 

In addition, sitting in astronomers' offices around the world was data from observations they had made in the past. This led to two serious problems.

First, astronomers would propose new observations not knowing that someone else had already made those observations.

Second, with the rapid evolution of data storage technology, stored data might have become unreadable because nobody has the devices to read it.

For example, who these days has the means to read a floppy disc? The solution is to put all the data in special-purpose data centres, where it is archived, backed up and provided in a form that astronomers and other researchers can access as and when they need it.

Our national system is called the Canadian Astronomy Data Centre — the CADC.

We have all heard of something out there in our digital world called "the cloud."

This rather mystical name refers to a number of huge "server farms" — data storage places that hold, archive and generally look after your data and software, and provide additional tools you might need for accessing and working with it.

The CADC and other astronomical data centres form a "cloud" for the scientific community.The huge amounts of data coming out of the latest astronomical instruments and our desire to make that data as broadly accessible as possible forces us in that direction. 

However, having all this data available poses another serious problem. How can we search an enormous number of files and databases for the information we need?

We've all used "search engines" to find information on the Internet. These devices use forms of artificial intelligence: computer programs that emulate certain aspects of the way we search for and assimilate information.

In a similar way, we use software assistance to search out what we need from our rapidly growing pile of data we are accumulating about the universe we live in.

However, it will be a while before we completely eliminate the need to dig around in the data ourselves, because it is very difficult to program in all the questions we might possibly ask, and research essentially involves asking questions that have never been asked before.

  • Mars is still conspicuous in the southern sky.
  • Saturn lies low in the south
  • Jupiter is very low in the southwest after sunset.
  • The moon will reach Last Quarter on Oct. 2 and be new on Oct. 8.


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Life on Saturn's moon?

Carbon is an unusual element. Its atoms can join directly together to form huge molecules consisting of long chains and other structures.

As my high school science teacher said, "carbon atoms are four-armed things." When linked together in a chain, they have two spare "arms," which they can use to grab onto other sorts of atom, such as hydrogen, oxygen, phosphorus, nitrogen etc., or to other carbon atoms.

In cosmic clouds and other places, chains of up to half a dozen or so carbon atoms can come together, forming chemicals such as amino acids, the building blocks of life.

However, the only place other than the laboratory or plastic manufacturer where we find molecules containing tens, hundreds or thousands of carbon atoms joined directly together is in living things.

This is why we refer to the chemistry of all but the simplest carbon-based molecules as organic chemistry.

Organic means, "to do with life." This provides us with a powerful tool in our search for life. If we find complex carbon molecules (CCMs), living things had something to do with it, either now or in the past.

For example, coal and oil are loaded with CCMs, because they formed, millions of years ago, from buried plant remains. If we take a sample of seawater from any of our oceans, we will find CCMs.

They could be from the decay of dead things, skins or scales moulted off, by-products of life processes, or small creatures unlucky enough to get caught up in the sample.

We are pretty sure life got started in Earth's oceans. For most living things, the sun's light and warmth are crucial to their survival.

However, in the cold, deep oceans there are huge communities of exotic creatures surviving on the hot, mineral-laden water spewing out of hydrothermal vents. Sunlight plays no role in the life of these animals, which raises an interesting possibility.

There are moons of the giant planets Jupiter and Saturn, so far from the sun their surfaces are cold and covered with ice, but which we believe to have oceans of liquid water beneath those icy crusts.

These oceans are kept liquid by the huge amounts of heat released by the tidal "kneading" those moons experience as they orbit their respective giant planets. This heat will, almost certainly, drive hydrothermal vents.

One great advantage those oceans have over ours is that they are heated from the bottom, so convection passes the heat throughout the water.

On Earth, our oceans are heated from the top, and as we go down deeper, they get cold, not far above freezing. Except for around the hydrothermal vents, the population per square kilometre of deep ocean bottom is low.

A good way to search for life in the oceans on those tidally heated moons is to look for CCMs in the water. That is, if we can get at the water.

With Enceladus, one of the moons of Saturn, we have been lucky. The tidal heating is so strong, there are geysers of liquid water coming up through the ice and rising high into space.

While it was exploring Saturn and its moons, the Cassini spacecraft observed these geysers. It has just been discovered there are traces of CCMs in that ejected water. The early results look encouraging.
 
Europa, one of the moons of Jupiter, is an object of particular interest. It has an icy envelope covering a tidally heated ocean.

Images from spacecraft show an ice cover that is continually breaking up and healing, with some of the ocean water finding its way onto the surface, where it evaporates, leaving its chemicals behind.

There is a proposed experiment for a spacecraft to look at Europa's surface for the infrared signatures of CCMs. But more exciting is the plan to land a spacecraft on Europa, to drill down through the ice, lower a robot submarine and have a direct look at what might be swimming around down there.

  • During the evening Mars, the red planet, is conspicuous low in the southeast.
  • Saturn lies low in the south and Jupiter very low in the southwest.
  • The moon will be reach last quarter on the 2nd.


More Skywatching articles

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About the Author

Ken Tapping is an astronomer born in the U.K. He has been with the National Research Council since 1975 and moved to the Okanagan in 1990.  

He plays guitar with a couple of local jazz bands and has written weekly astronomy articles since 1992. 

Tapping has a doctorate from the University of Utrecht in The Netherlands.

[email protected]



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The views expressed are strictly those of the author and not necessarily those of Castanet. Castanet does not warrant the contents.

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