# Send Home a Postcard!

Written by Dr. Klaus L.E. Kaiser

by Dr. Klaus L.E. Kaiser

The planet Mars is Earth’s next of kin; just a little further out from the Sun. President Obama thinks we should go there with a manned mission. I wonder why? Is there a reason to visit Mars, other than to mark your bucket list with “been there, done that?”

The Idea

The idea that mankind should “conquer” Mars has been around for a while, i.e. one hundred years plus. The idea that it is worth exploring Mars, similar to Earth’s Moon was proposed by President Obama in 2010, to be achieved in the 2030’s. Russia and possibly other countries have similar thoughts.

No doubt, sending astronauts to Mars and having them return safely to Earth would be a major technological achievement. One may ask though to what purpose and is the effort really worth it?

Some of you may remember President Kennedy back in the 1960’s announcing his plan to send astronauts to the Moon by 1970. That goal was achieved well within time. The glory was great and a few small samples of moon rocks were retrieved which can now be seen in museums here and there, mostly collecting dust.

The main benefit of the Apollo (moon) program was to demonstrate US superiority in the race to develop advanced materials and technology. However, whether or not a similar excursion to Mars would produce similar results in innovation is rather questionable.

Characteristics

Mars and Earth share similar characteristics. The data in Table 1 illustrate my point. Their diameter, distance from the Sun, tilt of the orbit, length of day and number of moons are quite comparable. In terms of mass, Mars has only 11% of that of Earth but, in planetary scales that is still quite comparable.

Table 1. Size, distance and other characteristics of the Earth and Mars, all data in “Earth units:”

 Planet Distance from Sun Diameter Tilt, relative to orbit [angle, deg.] Length of year Length of day Mass Number of moons Earth 1.00 1.00 23 1.00 1.00 1.00 1 Mars 1.52 0.53 25 1.88 1.03 0.11 2

With similar basic parameters, how do some other comparative data stack up? Let’s look at table 2, which shows the composition of the atmosphere on each planet. That’s where some major differences come to the fore.

Atmospheres

Table 2. Atmospheric compositions of Earth and Mars, units as stated.

 Planet Atmospheric CO2 [ppm] Atmospheric Oxygen [%] Surface Temperature (day side, C) Surface Temperature (night side, C) Air pressure [Earth units] Earth 400 20 +30 +10 1.0 Mars 950,000 ~nil +30 -145 0.6

As is apparent from Table 2, when it comes to the composition of the atmospheres and the surface temperatures (at least on the night side), Earth and Mars are vastly different from each other. To begin with, the atmosphere of Mars lacks any meaningful level of molecular oxygen, which is the stuff we need to breathe to live. The Earth’s atmosphere contains approximately 400 ppm (parts per million) or 0.04% of carbon dioxide (CO2). We live by breathing in air with 400 ppm CO2, consuming a large portion of the oxygen and then exhaling air with approximately 50,000 ppm (or 5%) CO2.

Compare that with Mars. Its atmosphere consists almost entirely of CO2, namely 950,000 ppm (or 95%) being CO2 to begin with. Any creature from Earth would quickly suffocate in the atmosphere on Mars, due to both the high level of CO2 and lack of free oxygen. Of course, the lower air pressure would also cause a problem for us.

As an aside: despite the high CO2 level, the Martian surface temperature on its sunny side is quite similar to that of Earth. If you were to believe the computer models showing the (Earth’s) atmospheric temperature to be strongly influenced by the CO2 content, Mars ought to be “just cookin;” which, clearly is not the case.

Water and Biota

The most important difference is the distribution of water, hence biota, as shown in table 3. Life as we know it is predicated upon the presence of water and the photo-synthesis process. For all intents and purposes neither exists on Mars.

Table 3. Critical differences between Earth and Mars.

 Planet Free water Photo-synthesis Life Polar caps Earth prevalent prevalent prevalent water Mars absent absent absent carbon dioxide

Table 3 shows the most important and critical differences between Earth and Mars. To begin with, Mars has no free water, actually no water at all except for some trace amounts bound in minerals and rocks. The polar “ice caps” on Mars consist not of frozen water, but of pure solid carbon dioxide, also known as “dry ice.” In contrast, more than three quarters of the Earth is covered with water in the oceans, freshwater lakes and rivers all of which harbor abundant life. No such things on either the Moon or Mars as they are barren places with sand and rock not unlike the most extreme deserts on Earth. So let me close with a note to the missionaries-to-be.

Note to Sons

It’s a long way to Tipperary. When you finally get to Mars, don’t forget to mark your diary with “been there, done that;” and please send home a postcard!