More on the Mars Ice Cap

bfwebster writes "In a striking example of how a preliminary (but wrong!) scientific conclusion can persist for decades, Space.com has a story about how the south polar ice cap on Mars is mostly water, not mostly carbon dioxide (dry ice), as has been stated since the late 1960s. The new finding is based on analysis of Mars Observer readings that show that the souther polar ice cap is too warm at certain seasons to be dry ice. This finding has negative implications both for those claiming that liquid flow structures on Mars were caused by C02 instead of H20, as well as those who were hoping to use all that CO2 for terraforming."

Comments

Re:first spacecraft on Mars

[CuriousKangaroo]

The Mariner series of spacecraft went to Mars around that time period. I can't find a successful one in 1966, though. Here's the list:

• Mariner 4 Flyby, 14-Jul-1965
• Mariner 6 Flyby, 31-Jul-1969
• Mariner 7 Flyby, 06-Aug-1969
• Mariner 9 Orbit, 13-Nov-1971

Re:Spectrometer?

[torpor]

I dare say that they're not 'just' using this evidence, it's the only bit of evidence out of the datapool which makes for good press release.

If they say 'our spectrometer says that it is water', people won't know how that works or even why they believe it. But explaining the temperature difference between CO2 and H2O to the general public is a lot easier, so that's what we hear ...

I think MGO has a spectrometer or two aboard...

Re:Terraforming Mars

[Dr. Hohmannstein]

Sorry to be nitpicky, but:

Moon is only about 1/81 the mass of earth (it's surface gravitational force is one sixth of Earth's) and

Mars has (rather stable) seasons (see e.g. Season on Mars )

Re:Terraforming Mars

[FroBugg]

What are you talking about? The Earth has seasons because our axis is tilted 23.5 degrees from the ecliptic, and thus at different times of the year different hemispheres get either more or less direct sunlight. The moon has absolutely jack to do with this.

Mars has an inclination of about 25 degrees, just slightly more than us. Mars' seasons are actually more extreme than ours. It has a more eliptical orbit than Earth and makes its closest approach to the sun during Souther Summer, contributing greatly the global dust storms I'm sure you've heard about.

No, the main barrier to terraforming is the fact there's no atmosphere to speak of. In the long run, the low gravity and lack of tectonic activity will also be problems. These are major contributors to its current lifeless state.

Re:Spectrometer?

[JetJaguar]

It's a little trickier than that. Ices don't really have any spectroscopic features until you get into the far infrared. So you need an infrared spectrometer on board the probe. This isn't so easy to do, as any good infrared spectrometer needs a replenishable supply of liquid helium (which boils off fairly readily in the inner solar system).

It's far easier to take temperature measurement using other means, and those measurements are sufficient to show that it's too warm for CO2.

I'm not positive of this, but I would guess that ground based infrared spectrometers (like what's on NASA's IRTF) may not have the resolution nor the signal to noise capabilities to do the detection. No that I think of it, there are several plausible reasons why you can't do the detection from ground based telescopes, but I would need to check them out before sticking my neck out and posting them.