Mars

The planet Mars is exciting quite a lot of interest right now. Robotic exploration has been underway for about 20 years and our understanding is increasing. What makes Mars particularly interesting is that there is a possibility that extra-terrestrial life will be found there.  Dismiss any thought of little green men immediately; we are talking about very primitive life at the bacterial level. The announcement of the discovery of life in the 1990’s on a meteorite from Mars was made with great hoo-ha by then President Clinton. It is now understood that this was at best very premature and was probably wrong. Essentially it rested on the discovery of what were thought to be micro fossils but are now thought to be likely inorganic in origin.

 Mars is the most earth like planet in the solar system. While it is the most similar this doesn’t mean it is very earth like in in its properties. It is much smaller than earth and is the next planet out from the sun. It is a rocky planet and most planets further away still from the sun are gas giants. Mercury the closest to the sun is too hot as is Venus which has suffered run away climate change . Earth is nearly ideal in the next position  but Mars is further still away. It’s remoteness from the sun means it gets much less sunlight so it is rather cold. Although summer equatorial temperatures are rather similar to earth days mostly the surface temperature of Mars is cold; colder than the Arctic.

Because it is only about 40% the size of earth the surface gravity is also about 40% that of earth. Because Mars rotates only slightly slower than earth a Mars day , called a sol, is only about 25 hours. However because Mars is much further away from the sun its orbit around the sun takes a lot longer and Martian seasons are roughly twice as long as on earth. Mars has a very thin atmosphere; less than 1% of the atmosphere of Earth. It is composed almost entirely of carbon dioxide. The very low pressure of the atmosphere means that men would need to live in a pressurised suit or habitat. It is thought that the low pressure is a result of evaporation into space due to the small size and exposure to the solar wind..

Mars lacks the strong magnetic field of Earth which means charged particles of radiation, which are deflected around Earth, hit its surface.  With such a thin atmosphere the radiation which on earth is absorbed by the air also reaches the surface. This means that the surface of Mars is bathed in radiation. Any living organism would need radiation protection on the surface but a metre or two below ground should be alright.

Mars is rather dry at present; most is rather like a very arid Earth desert. The polar regions contain water ice which can sublime ( ie. change straight into water vapour ) in summer. This is very interesting as there is good evidence Mars once contained a lot of water on its surface which over many thousands of years has been lost to space. All the features associated with water on Earth exist even down to surface ripples which are seen on Mars. Generally it is thought that water doesn’t exist on the Martian surface except possibly as very, very briny patches in summer.

Exploration of Mars is by robotic survey. Firstly there are artificial satellites around Mars. These not only give information about Mars but also act as radio relay stations between surface robots and Earth. There have been 3 main robotic wheeled surveyors. The first, Mars Pathfinder was quite small, not much larger than a wheeled garden stool. The importance of Pathfinder was more that it landed successfully and explored. Space launches to Mars until then had been very problematic with a high failure rate. Pathfinder pioneered a new type of landing where the spacecraft hit the surface still falling at fair speed but surrounded by balloon type air bags so that it is bounced around cushioned against the fall. After Pathfinder came Spirit and Opportunity; two identical but larger rovers now wheelbarrow sized. These two were extremely successful. Rather than the few months life expected this became years and one is has only just stopped functioning. It was expected that the solar arrays providing power would become dusty and eventually cease. However it was found that there is sufficient Martian wind to blow away the dust. This does mean that gigantic dust storms can arise and it was one such which ended the life of Opportunity although it had survived for 15 years to succumb recently. Spirit became stuck in sand in 2010.

The latest Rover, Curiosity, a small car sized vehicle carrying many experiments had to land by retro rockets because of its size and weight. It is at present continuing Martian exploration.  The most recent fixed lander is Insite which has seen the first Mars earthquake.

The search for Martian life continues with some tantalising clues emerging but nothing definite as yet.

Human visits to Mars are planned by several groups. Space X has the most ambitious with mid to late 2020’s timing and NASA is talking 2030-5. It remains to be seen whether robotic exploration will decide the existence or not of life before then.

There are a lot of jokes along the lines of why are computers male/female such as in order to get their attention you have to turn them on.

Not quite in this genre-

How does a woman stop her husband from reading her emails

Rename the file “Instruction Manuals”