[CraigS]

Hi Orestis;

So, you know that I mentioned that its Ok to believe something but its always good to keep the facts separated from your beliefs ?

Well, answering your question requires me to separate what I would like to believe, and the facts. So, I'm going to try and give you a balanced answer. Here goes ..

Originally Posted by orestis

Thanks Craig for the explanation .

So have they done any tests on the composition of the polar ice caps?

Yes. As far as I'm aware, the most direct measurements taken from orbit of the southern polar region were taken by the Mars Express 'MARSIS' instrument which used primarily, ground penetrating radar as its detection mechanism. The radar could penetrate to considerable depths, but at the end of the day, the chemical composition of the material being penetrated is still 'inferred' (you may have to look this word up). Having said this, the lander samples are clearly not inferred. Carl and I had posts on this in the past.

The Mars Global Surveyor and Mars Odyssey also did high resolution and thermal imaging of the polar caps from orbit. From these (images only), it was concluded that the polar caps were made from mostly water ice with layers of about one metre to 8 metres of dry ice (CO2) over the top. Here's a page to read up on this.

The Phoenix lander also confirmed by direct measurements from the TEGA instrument, (Thermal and Evolved-Gas Analyzer), which is a very accurate mass spectrometer, the existence of water vapour from a scoop sample taken in 2008. I recall that they were unable to repeat this measurement/result again.

Clearly, there is H2O on Mars. The quantity of it is still approximated using models and inferred results, rather than by direct measurements. Large volumes of frozen CO2 have not been entirely discounted as a possibility as the origin of some of the geological formations on the surface. As they look more into this aspect, some of the geological evidence supporting the large volumes of liquid H2O theory may, (or may not), erode the supporting case.

It Would be interesting to know how much water there really is on mars.

I agree. It seems that direct sampling using spectrometers and other chemical sampling methods, over a wide geographical polar area might be the best method to come up with an accurate answer to this question.

It would be very interesting to know what had really happened in Mars's past. It could of been very much like Earth, something must of went terribly wrong in its distant past.

The so called Mars 'devastation' theory depends on the inferred results of the above mentioned data, which leads to the conclusion that there was a lot of liquid H2O on Mars in the past. The possibility that there wasn't a lot of H2O is not inconsiderable, which is why I still have doubts. I can keep my doubts separated from the facts, however. I continue to look for more data to satisfy my questions about it all. Let me know if you find any.

I Wouldn't mind volunteering to go to mars to see it all for myself yet i think it is a little inhospitable right now .

I wouldn't be going there without a lot of water. Its pretty dry and humans need water to survive.

Your questions are right on the mark. Keep 'em coming.

Cheers and Regards.