Of all the planets we've seen so far, Mars is most like Earth

Photo: Contributed

Out of all the worlds around the Solar System we have so far looked at, Mars is the most like ours. The geological and geographic resemblance to ours is striking. It does look like a place where we could live, that is, with a lot of technical help.

When we go to an exotic place, what we will need depends on the length of our proposed stay. For example, a fit person can stay underwater, holding his or her breath for maybe two minutes. For longer than that we need a supply of air, and if we stay more than a few hours, we will need food, a warm, secure habitat and somewhere to sleep. Since using current space technology means it will take months to get to Mars, we expect to stay a while. For example, we might need to wait until Mars and Earth are in the right relative positions for our return trip. This means we will need some sort of habitat suitable for long-term residence, providing everyone with enough individual living space, and a supply of food, water and energy. There are ways to persuade Mars to help us with these. However, although it looks a lot like Earth, there are important differences we must face.

Firstly, Mars' atmosphere is very thin. The pressure at ground level is around 0.4 kilopascals, as opposed to about 100 kilopascals on the Earth's surface. To survive in such a low pressure will require almost a complete space suit. Experience with the International Space Station shows we can provide a long-term, "shirt sleeve" environment in the vacuum of space, and we know such technologies will work on the surface of Mars. In Earth orbit the space station experiences huge temperature variations as it moves between direct sunlight and the shadow of the Earth. The thin atmosphere of Mars provides almost no insulation or greenhouse effect. A summer's day on the equator might bring temperatures as high as 20 degrees Celsius, but during that summer night the temperature can fall far below zero. This is less extreme than what the space station experiences, and even better, on Mars, there is an option for minimizing that variation: we can bury the habitat.

Except during the occasional dust storms, days are sunny, and there is enough sunlight to make solar energy useful for providing heat and electricity. In many cases there is water ice below the ground. This can be melted for drinking and broken up by electrolysis to provide breathable oxygen. If the habitat is buried in or over permafrost, we will have to take precautions to prevent the heat from the habitat from melting it.

The Earth's atmosphere screens out most of the harmful ultraviolet radiation from the Sun. Mars' atmosphere is too thin. If we are wearing space suits when outside the habitat, this won't be too much of a problem for us. However, it has loaded the soil with lots of chemicals that would be toxic to anything we want to grow in it. So agriculture will require more than just putting up a greenhouse.

For long-term life on Mars, things get a lot more complicated. As we live we interact with our environment. For example, we release water droplets, skin cells, hair, and we are covered with bacteria and other things. This is not normally a problem in our everyday lives because the ecosystem we live in handles such things. Over longer periods, this interaction becomes more complex. How much of that environment do we need to take to Mars with us to ensure our long-term health? This is why long-term visits to the International Space Station are so important. If anything goes wrong, safety is only hours away. On Mars it's months. Getting to Mars and back again is only a small part of the problem of exploring and living safely on the Red Planet. Living on the planet would be easier for us if we were to terraform it. However, we would first need to make absolutely sure there are no Martians.

Venus lies low in the sunset glow. At the same time Jupiter and Saturn are rising in the southeast. The Moon be Full on the 20th.

Ken Tapping is an astronomer with the National Research Council's Dominion Radio Astrophysical Observatory in Penticton.

This article is written by or on behalf of an outsourced columnist and does not necessarily reflect the views of Castanet.