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Mars - A Small Red Planet
Tell me about Mars
It is often called the “Fourth Rock from the Sun” and is the last of the solid planets before we encounter the gas giants of Jupiter, Saturn, Neptune and Uranus. Although we have no evidence either way, there is no reason to believe that rocky planets always occur close to suns and gas giants always further away. That is just the way that our particular solar system is arranged.
While Mars only possesses 11% of Earth’s mass, its compact size gives it over a third of Earth’s Gravity. It lacks a magnetic field, so compasses would be useless there. That is because its smaller size has allowed it to cool and slow enough that its core no longer acts like Earth’s magnetic dynamo. That has also stopped the vulcanism, which built one of the mightiest volcanoes in the entire solar system, called Olympus Mons (Mount Olympus) at twenty-two kilometers (13.75 miles) in height.
Mars, through early telescopes, was thought to have evidence of engineering on its surface in the form of canals, presumed to move water from the poles to the warmer equatorial climate for its inhabitants. Now, sadly, we know there are no such inhabitants and that Mars is actually a rather dreary place. Its atmosphere is so thin that you would need a pressure suit to survive; it’s so cold that you would need thermal gear everywhere except the equator in high summer; and it’s so dusty that contamination of everything would be a constant worry. Few people would choose to live there in its current state.
There are great seas of sand dunes, rock outcroppings that, in a particular light, look like faces (except when examined closely), dry river valleys, volcanoes and the Valles Marineris a 4000 km (2500 mi) long canyon that dwarfs our Grand Canyon on Earth by being five times longer and four times deeper! The entire canyon is about the same size as the entire width of the United States from East to West… Now that is a Grand Canyon!
There are also depressions in the surface of Mars that are deep enough that atmospheric pressure passes what is called the Triple Point of Water. Water is volatile, a word which is often mistaken to mean flammable or capable of exploding, but which actually mean that it can evaporate. Most liquids are volatile at some temperature or pressure where they can become gaseous.
At low air pressure, such as on a high mountain top on Earth, water boils at such a low temperature that mountaineering expeditions have had difficulty making tea with the boiling-cold water. If the pressure at Hellas Planitia (a crater seven kilometers below “sea level” on Mars) was typically at 1,155 Pa and above 0° Celsius, it is possible for liquid water to exist.
This Triple Point occurs when water can become gaseous, freeze and liquefy all at the same time, hence the name Triple point. In science demonstrations we show this in a vacuum jar with water boiling, freezing and becoming liquid at 607 Pa (4.57 mm Hg) and 0.0098 degrees Celsius.
Recent photos have been examined and show rather clearly that there is liquid water on the surface of Mars. This is a stunning revelation since the atmosphere is too thin to permit liquid water to exist for long, and the planet is simply too cold for pure water not to freeze in very short order. The explanation may be complex.
First, the water appears only at the equator where, in Martian summer, temperatures can approach 20°C (70°F), well-above the freezing point of water. Second, this is not some gushing brook, or raging torrent – it is surface that gets darker as what appears to be underground ice liquefies and dampens sand, rock or soil that is downhill from the source. Nothing else fits the observations…it’s water. But not just a tiny bit. These markings broaden out like the dendritic patterns of a Mississippi river delta, so there is a fair quantity there – just not a river.
Could There be Life on Mars?
The consequences of water on Mars might be staggering. This thing we call life is a brazen and bold thing. You give it the tiniest chance in the worst possible conditions of Earth, and there it is, defying the odds and persisting where it seems totally ridiculous to do so. And what does Mars offer? Water, carbon dioxide, iron, magnesium, sodium, potassium, chlorine and living room temperatures!
On Earth we have a type of life called extremophiles which live in environments such as deep sea volcanic vents with super-heated water well above the boiling point at standard temperature and pressure. They live using sulfur to exchange electrons, instead of oxygen. At the opposite end of the spectrum we have extremophiles in the arctic deserts that live a few millimeters below the surface of rock, eating minerals and photosynthesizing energy. This latter type might very well survive on Mars with little difficulty.
We’re anxious to visit this area and see what we discover, but it will involve a great deal of additional effort. The equipment and robot explorer will have to be utterly sterilized before launch and kept pristine until it gets there. We can take no Earthly contaminants with us in fear of damaging any life we might find, or polluting the results of our research. And if we do find life it could prove one, or possibly two, things: First that life will arise wherever the conditions exist, making it much more likely that the Universe is filled with life; or second, that we Earthlings are actually Martians!
Mars was once warm and watery and had an atmosphere long before the Earth had cooled enough for life to begin. Eons later, as Mars was dying because it had lost its magnetic field and its atmosphere was being stripped away by the solar wind, it was also being bombarded by meteors, and debris was being thrown up into space. If life had arisen on Mars, it’s almost certain that some of it left Mars’ surface with this debris.
To this day we regularly get meteorite impacts on Earth of rocks that undoubtedly come from Mars; hundreds are on exhibit all over the world with well-established histories. And we know from experiments in the Long Term Exposure Facility on the International space station that bacteria and such survive in space with little to no damage, flourishing immediately when given the right environment. Those rocks may very well have carried life to Earth where conditions then were just becoming hospitable to life. It was like a Martian lifeboat carrying its microscopic representatives to a new world, there to thrive and grow, someday to return to the planet of their origin! Hello, fellow Martian!
The Weather on Mars
Mars has weather, too. In September 2014, the Curiosity Rover managed to record this sequential .gif image (courtesy NASA/JPL) of the sky showing distinct clouds passing overhead. They are likely composed of ice-crystals and/or super-cooled droplets of water. As little as 1.8 billion years ago, Mars quite probably experienced rain. Prior to that, it is absolutely certain that rain was common.
Of course we have had pictorial evidence of snow since 2008 when the Phoenix Rover recorded the event, but we were relatively certain of that years before we had conclusive evidence. Similar to Earth, Mars’ atmosphere will tend to transport vapor to its poles and drop it off. Its icecaps grow and recede just like ours do every year (although Mars’ year is twice as long as ours). Whether it freezes out or goes through deposition (when gas changes from a gaseous state to a solid state without being liquid at any point) makes little difference – the atmosphere works similarly to ours.
But even if there is no present day rain, Mars still has weather. Dust storms are a common phenomenon, sometimes planet wide, obscuring the surface for months. Although the atmosphere is only about one percent of the density of Earth’s, it has been blowing so fast, for so long, that the surface dust had been worn down to crystals smaller than the finest beach sand. In fact, the name of this micro-dust is “fines” and it will be a problem when people finally get there. It likes to worm it’s way into everything.
When we someday have habitats on Mars, coming in from outside will mean passing through an airlock and undergoing some serious cleaning before entering your home or any other building. The fines are more like talcum powder than dust. If you’re not careful, it will get everywhere, including your lungs if you breathe it, or your digestive tract if it gets in the food supply; it could potentially cause something like miner’s black lung disease, silicosis or even something akin to mesothelioma. The low gravity of Mars, the lack of humidity and the tiny size of the particles could keep it suspended in indoor air for a very long time.
While it is true the high-speed winds would not have much effect on a person standing on the surface of Mars, at only one percent of Earth’s atmospheric density, it is adequate for transporting the fines. That might make it hard to see sometimes. So where do these winds come from?
Carbon Dioxide goes through deposition and solidifies (the opposite of sublimation) in winter at the poles. When Spring rolls around, the CO2 sublimates back to a gas very quickly creating 400 km/h (250 mph) winds and disperses back into the atmosphere. In Autumn the process is reversed, albeit a bit more slowly, so lighter winds are generated.
The composition and chemistry of the soil give us some distinct clues about how Mars has evolved in its lifetime. Sulphates on top with chlorates beneath indicate that, contrary to the theory that had prevailed for decades, water actually fell from the sky, and did not well up from below when the soil was formed. If you put sodium chloride (table salt), potassium chloride, or other salts on a bed of soil, and put some sulphates or sulphides with them, and then apply rain-like water to them, the chlorates will dissolve more readily than the sulphates and consequently penetrate further into the soil. And this is what we are now finding on Mars. If the source of the water was from below, in the form of an upwelling, the chlorates would be higher in the soil, near the surface and the sulphates would below them. Since we see the former scenario and not the latter, it is now very clear that the water came from above, not below.
Tips for Observing Mars with a Telescope
If it is your first time observing Mars through a telescope you will want to lower your expectations – it won’t appear with the same detail as is does in magazine articles. However, all is not lost, with a telescope with at least a 3” objective lens and a quality mount you can see some of the most obvious features of the planet, such as, the white polar cap and variations in the surface colors. Every 26 months the orbits of Mars and Earth reach their closet approach, this is called opposition, during this period of time Mars is much more enjoyable to observe because it’s apparent diameter in the sky in much larger than when Mars and the Earth on opposite sides of the Sun. Even when Mars and Earth at their closest approaches, the diameter of Mars in the sky is still many times smaller than that of a full Moon. This favorable viewing condition has already occurred in 2014 and the next favorable viewing season is in 2016.
There are few things you can do to see more of the surface features of Mars. First, a telescope of at least a 3” objective lens and a quality mount that is steady and will track the motion of Mars across the sky during the evening is your starting point. Take the telescope outside at least an hour before you plan to observe so the telescope reaches the temperature of the outside air. When the telescope and the surrounding air are at the same temperature this minimizes air turbulences within the telescope. Rapid motion of air within the telescope can limit your “seeing” capability of the telescope. Where you observe can also have a large effect on your view of Mars. Just like air turbulence within the telescope the air is constantly in motion in the sky. You can less this effect by not viewing over, for example, a large concrete parking lot. The concrete in the parking lot cools at a different rate than the ground and this creates large amounts of air turbulence which hampers your viewing experience. If you can find an open field to observe this is much preferred to an area with many structures. Due to the small diameter of Mars in the sky, you will need to use at least 100 power on your telescope. The more power you use on your telescope the quality of the optics and mount become much more important. You can also add color filters to your eyepiece that will bring out different features of the planet. Last, but not least, is observe regularly. As you become a more experienced observer you start being able to pick out more detail and the whole experience is much more enjoyable.