[X] My Assistant

[pumpkinpie]

Does there exist a list of all the evidence of water on Mars, listed by spacecraft?

Ideally, it would be a list with a short description and a link to a story or news release. For example:

Mars Global Surveyor: NASA Images Suggest Water Still Flows in Brief Spurts on Mars http://www.nasa.gov/mission_pages/mars/new...s-20061206.html
Phoenix: NASA Spacecraft Confirms Martian Water, Mission Extended http://www.nasa.gov/mission_pages/phoenix/...x-20080731.html
Opportunity: NASA Mars Rover Finds Mineral Vein Deposited by Water http://www.nasa.gov/mission_pages/mer/news/mer20111207.html

I know I could spend some time and extend the list that I've started above, but if someone or some organization has already done it I'd hate to reinvent the wheel!

Thank you.

[pumpkinpie]

Thanks for the reply!

I think I should have been a little more specific in my post. Sometimes I forget that people can't read everything I think about when I am typing.

I work in a planetarium, so I do shows on Mars for the public and for schools. I would love to have just a highlights list--what scientists and/or NASA E/PO think are the (for example) 10, 20, 50 "best" discoveries of evidence of water on Mars. Every month it seems there is a new release saying "best evidence yet!" so that makes me think, ok, what was the last "best evidence yet!" and the one before, and the one before, etc.

I would use it a number of ways. For my own background information, so I am ready to answer the question from a student or general public "how do we know there is/was water there?" in 30 seconds or less. That applies for my student employees, too. They wouldn't have the same time to dedicate to learning about this topic as I do, so I would want to give them a simple list. It would also be great to include in handouts I give to teachers.

I may be asking a lot, with the only answer being "do it yourself and use your best judgement."

[JRehling]

There are a few different parts of the answer, broken down by ice/liquid/vapor, and past/present. And past includes many past eras.

Phoenix took a photo of the ice like a hockey rink in the polar subsurface, so that's about as direct evidence as you could ask for regarding the ice/present combination. That was no great surprise after Mars Odyssey showed the extent of subsurface ice by detecting where neutrons were absorbed by hydrogen (which is a component of virtually no other mineral than water ice).

Pointers to other key evidence are:

MGS and MRO: Orbital observation of gullies formed in the present.

MRO: Orbital detection of minerals that are likely formed only in water.

Opportunity: In situ detection of minerals and geomorphology that indicates standing (acidic) water.

This is far from exhaustive, but if you only have 30 seconds, you can only say so much.

[mcaplinger]

This is far from exhaustive, but if you only have 30 seconds, you can only say so much.

Water vapor was detected and globally mapped by the Viking Orbiter MAWD instrument, and the residual north polar cap was confirmed to be water ice by Viking as well.

There was some Earth-based spectroscopy in the 1950s that suggested the polar caps were water ice, but I'm not sure how definitive those were.

[mwolff]

Water vapor was detected and globally mapped by the Viking Orbiter MAWD instrument, and the residual north polar cap was confirmed to be water ice by Viking as well.

There was some Earth-based spectroscopy in the 1950s that suggested the polar caps were water ice, but I'm not sure how definitive those were.

Water vapor was identified in 1963:

Spinrad H, Münch G, Kaplan LD. 1963. Letter to the Editor: the Detection of Water Vapor on Mars. Astrophysical Journal 137: 1319


Water ice in clouds in 1973:

Curran RJ, Conrath BJ, Hanel RA, Kunde VG, Pearl JC. 1973. Mars: Mariner 9 Spectroscopic Evidence for H<SUB>2</SUB>O Ice Clouds. Science 182: 381-3

[JRehling]

On a meta-level, I recall that Earth-based spectroscopy of the planets has a long history that began with inappropriately low standards of calibration, so water vapor may have been "detected" in the atmosphere of Mars a long time before it was actually detected. It may be hard to know now which early efforts actually observed water vapor in Earth's atmosphere and simply attributed it to Mars. But certainly the time came when these studies were done right.

[mcaplinger]

...I recall that Earth-based spectroscopy of the planets has a long history that began with inappropriately low standards of calibration...

Hence my caveat about Earth-based detection upthread. I didn't do any research on Mike Wolff's citation of Spinrad 1963 to form an opinion about whether it was certainly right or just happened to match reality. I'm fairly sure there was no credible result to 1950 or so; see http://en.wikipedia.org/wiki/History_of_Mars_observation for an incomplete survey of this.