A couple of recent articles in the science section of the BBC have caught my eye lately.

The first one I read a few days ago or so ago concerned the atmosphere of Mars. It turns out that over time, most of the Martian atmosphere has been lost into space (how, I’m not too sure) but what caught my eye was the method used to determine the rate of loss of gas in the atmosphere to space.

I have written about a similar method in an earlier blog that has been used here, on Earth. It’s a method that looks at the ratio of isotopes. In this case, it is the ratio of Argon 36 and 38.

Argon 36 will escape the Martian atmosphere at a higher rate than the 38 isotope. Why? Well, it has just got a lower mass, meaning it is lost more easily. The gas is lost constantly, as the Martian atmosphere is dragged into space by the solar wind.

Curiosity, the Mars rover on the surface is able to measure the ratio of these isotopes. Maven, a satellite in orbit around the red planet can measure the ratio of these isotopes as well. A comparison of the ratio of isotopes at the surface and the ratio of isotopes in the upper atmosphere gives an indication of how much of the atmosphere has been lost over time.

Argon is used as it is inert. If another gas were sampled (eg, carbon dioxide and there is plenty of that on Mars) then the results would not be reliable as the CO2 could have reacted with something.

When you start thinking about this, the implications are huge. It is possible to predict how much atmosphere there was on Mars and even how much CO2 there was … which then allos a prediction to be made about the temperature that the surface of the planet could have got up to which has implications about if the water on Mars was liquid or ice which has further implications on the possibility that there was once life on Mars. Pretty cool (or warm) in my opinion!


By ESA – European Space Agency & Max-Planck Institute for Solar System Research for OSIRIS Team ESA/MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA – http://www.esa.int/spaceinimages/Images/2007/02/True-colour_image_of_Mars_seen_by_OSIRIS, CC BY-SA 3.0-igo, https://commons.wikimedia.org/w/index.php?curid=56489423

The full article can be read here:


The other article is more syllabus related and involves the use of a grapheme filter to turn sea water into drinking water by sieving out the sodium and chloride ions. This would be a nano filter and it is pretty amazing to think that this degree of filtering could occur.

It sounds as if some clever engineering needs to go on to ensure the holes are smaller enough for water but large enough to block the ions. What I want to know is what happens to the filtered ions – would they form solid sodium chloride? And would they very quickly clog up the filter?

If you have any suggestions, please post them below – it would be great to read your thoughts.

The full article can be found here: