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Monday, August 28, 2023

India's Chandrayaan-3 Sends First Measured Temperatures

India's Chandrayaan-3 lunar lander Vikram and its rover Pragyan have sent back the first ever directly measured temperatures at the far southern latitude where it has landed, thanks to its instrument called ChaSTE (Chandra's Surface Thermophysical Experiment).  Not just at the surface but as far down as 80mm, or just over 3".

I see this as one of the most important reasons for the emphasis on landing near the south pole.  While the surface wouldn't be comfortable at (rough reading) 60C or 140F, the temperatures at the mid-latitudes where the Apollo missions landed were far beyond uncomfortable.  The midday temperatures at the lunar equator can reach 250F and plummet to nearly -210F at night.  

More importantly, the lunar soil or regolith must be a very effective insulator.  Just below the surface around 50mm, a mere two inches, the temperature dropped to 25C - the widely cited "room temperature" in thousands of applications - or 77F.   Another inch and a skosh deeper, 80mm down, and the temperature is -10C or 14F.  Unheard of in my part of Florida, but could be a pleasant winter day in much of the world.  Not bikini weather nor car washing weather but who's counting?

The race to the lunar south pole is on.  I've seen a number of published references to Chandrayaan-3 having landed AT the south pole.  No, it's around 70 degrees south latitude, the pole would be at -90.  Here in our southern hemisphere, 70 degrees south touches the northernmost land in Antarctica but the vast majority of Antarctica is south of 70 degrees (good, but small graphic at that Wikipedia link).  The reason for the emphasis on going to the south pole is primarily the water ice that has been been verified to be near both poles. 

Based upon SOFIA data, scientists estimated there could be as much as 12 ounces of water for every one cubic meter (just over 35 cubic feet) of lunar soil at the southern pole of the moon.

According to the Planetary Society, when considering Chandrayaan-1 and LRO data, the two lunar poles harbor over 600 million tons of water ice. That's enough to fill around 240,000 Olympic-sized swimming pools. 

And this, experts say, is a low-end estimate. 

In addition to being a survival necessity, water can be hydrolyzed to hydrogen and oxygen.  Oxygen is valuable itself; the two can be rocket fuel.  A secondary reason that seems to be a good thing is that insulating a habitat for living at the poles will be far easier than doing that at mid-latitudes.



11 comments:

  1. You don't honestly believe that they landed anything on the moon, do you?

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    1. Does "they" mean India? Sure. Why not?

      It's not like it's the first time they've sent something to the moon; that's what the "3" in the mission name means. Chandrayaan-2 had a software failure and they learned from their failure.

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  2. Let us please ignore the absolute stupid of the first commenter, who was kind enough not to inflict us with his name. As for this temperature graph, it is great news! I predict a gold-rush type of future for the lunar poles. Lunar regolith is obviously an incredible insulator, which will make habitation much more achievable.

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    Replies
    1. So you are gullible enough. LOL.

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    2. Anonymous, I'd recommend that you seek out a nice, comfy lunatic asylum. You'd be happier there.

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    3. Yeah, you'll be happier elsewhere. I blog about a lot of technical topics, mostly space of course, but also topics in radio, electronics, mechanical engineering and more. If the idea that rockets can go places beyond low Earth orbit bothers you, you'll find other places more enjoyable.

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  3. You want "For All Mankind"? Because this is how you get "For All Mankind".

    Yay!

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  4. If the lunar regolith is such a good insulator, poles vs. equator is a potentially negligible difference.

    Data should be obtained there, and in the middle latitudes as well.
    Besides pure solar energy capture, harnessing the extreme highs and turning it into an energy source could/should be the solution to putting a base anywhere we want it. Nuclear during the cold periods would be the obvious alternate source.

    It may be more easily done at the poles, but probably only slightly.
    The water there is the bigger argument, IMHO.
    Minerals elsewhere are the draw away from them.

    The question after that is suitability for subsurface mining operations, as tunneling under the surface both presents and potentially solves a host of problems with long term occupations.

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