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Skywatching

Red Planet still alluring

The latest flotilla of spacecraft to arrive at Mars must make that world the most-visited planet in the Solar System.

There are two reasons for this group visit. The missions were timed to be when Mars was particularly close to us. A shorter trip and an easier rendezvous means a given launcher can accommodate a bigger and more capable spacecraft.

Since our current method for travelling between planets involves a big shove followed by "falling all the way there,” the laws of orbital dynamics apply, which requires the launches to fall within a restricted window of time.

It is like throwing a baseball into the air and then throwing another one so that it gently nudges it.

We want to arrive at Mars with a low enough relative velocity to require just a small rocket shove to enter orbit or to dive into the atmosphere at the right angle.

The second reason is that Mars is a candidate for being the most fascinating object in the Solar System.

Even today, as a cold desert world with a thin atmosphere, out of all the planets in the Solar System, it is the one most like ours, and one we could live on for long periods, with a lot of technical help, of course.

Then there is the discovery that Mars was once a warmer, wetter world, with a thick atmosphere. There are dry watercourses, canyons, lakes and seas over most of the surface. The dry riverbeds are floored with water-worn pebbles and little round pellets of salts precipitated as the water disappeared.

Actually, today there is a lot of water on Mars, as layers of ice below the surface. On a really warm, summer day, close to the equator, temperatures may reach 20 C.

This melts some of the underground ice, causing short-lived water flows down sandy slopes. Even on those summer days, the temperature dives to far below zero at night. This raises the next fascinating issu: billions of years ago, when Mars was warmer and wetter, was there life?

We know that life appeared on our world very early, around 3.5 billion years ago, more or less as soon as our world had cooled enough for liquid water to accumulate on its surface.

Why could it not have been the same for Mars too?

We are looking hard for traces of that ancient life, or even better, some it its hard-bitten descendants eking out a tough existence somewhere below soil level.

Thanks to our robot explorers, we are learning about Martian geology and weather, and are piecing together what happened to Mars, and just as important, why it didn't happen here.

In addition to our scientific curiosity, we have a special cultural attachment to the Red Planet.

Ever since Percival Lowell mapped the canals, which were actually a combination of wishful thinking and poor observing conditions, and launched the idea of the Martians working hard to sustain life on a dying planet, we got the idea that the Martians might just want to come here.

This launched a stream of novels, movies and radio plays. We were usually saved by sheer luck. In War of the Worlds, it was our bacteria, to which the Martians were not immune. In Mars Attacks, it was the lucky discovery that Martians could not tolerate yodelling country music.

Actually, it is unlikely that Martian life had a chance to evolve to the point of achieving interplanetary travel. Until around 500 million years ago, life here was single-celled bacteria and algae. Then things started to happen, with complex life forms appearing.

It looks as though Mars became the hostile place it is today, more than a billion years ago. Since Earth and Mars formed at the same time, it is reasonable that if life appeared on Mars, it happened at the same time as it did here, but never had time to get past the bacterial and algal stage.

We could be wrong!

These videos of Mars are well worth watching:

https://www.youtube.com/watch?v=7zpojhD4hpI

https://www.youtube.com/watch?v=0NRFk_jNhek

  • Mars is high in the southwest after dark.
  • The Moon will be Full on the 27th.

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



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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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