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Comment by pavel_lishin | Hacker News Reader

> ISRO announced the rover’s LIBS results definitively confirm the presence of sulfur at the landing site. Additionally, preliminary scans detect traces of aluminum, iron, calcium, chromium, titanium, manganese, silicon, and oxygen in the soil. Further hydrogen detection efforts are underway.

What about hydrogen? No hydrogen means no water where they're currently landed, right?

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The reason people think there will be water is that when water evaporates on the moon, it won't be instantly lost. Instead, it will bounce around for a while before it is (probabilistically) lost. If/when it hits a surface that's below freezing point in vacuum (~200K), it can instead freeze and stick to that surface.

There are believed to be such surfaces in permanently shadowed craters on the poles of the moon. They won't find any in any place where the rover can charge, but they might do short trips into shadowed spots, I don't know.

Probably elemental hydrogen.

They certainly won't find water on a 60C surface.

Why not?

Plenty of 60C water on the earth's surface.

The moon doesn't have an atmosphere. https://en.wikipedia.org/wiki/Phase_diagram#/media/File:Phas...

Ah nice, missed that thanks.

Is there? Hottest surface temp recorded on earth was 56.7C, no? And Death Valley isn't known for the presence of water (when it's anywhere close to that hot).

Hot springs in volcanically active areas?

Do you think that there might be hot springs on the Moon? Why not... our volcanoes on Earth bring water to the surface. That sounds like the kind of discovery that this mission is all about.

No hot springs without atmosphere, and we'd see vapor vents if there were something similar exposed to the surface, I think.

> Hottest surface temp recorded on earth was 56.7C, no?

Hottest air temperature at just above surface level; excluding several localized extremes like measurements around vulcanos or asphalt roads.

Asphalt surfaces can easily reach 60+°C on days with direct sunlight and little to no wind, and vulcanos supply new surface all the time with temperatures far north of 100°C.

And in both cases those surfaces would turn water into vapor, so no surface water.

but not in the vacuum. At 60C on the moon, the water is just gas and would leave the moon a long time ago.

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