First Odyssey report!! - Finally! :)

Josh Cryer · 2002-03-02 00:51:12

Hey guys, sorry for not being around much lately. Interestingly it's the southern hemisphere that has the most water! Anyway, to the juicy stuff!

Observation of large amounts of ice on Mars
Basis of observation:
The evidence for large amounts of ice in the southern hemisphere of Mars comes from three different instruments in the Gamma-Ray Spectrometer (GRS) instrument suite on board the 2001 Mars Odyssey spacecraft: the Gamma Ray Sensor, the Neutron Spectrometer (NS), and the High-Energy Neutron Detector (HEND). Each of these instruments has detected the signal expected from a large amount of ice in the surface, or regolith, of Mars. The presence of ice is indicated by signals due to hydrogen, one of the major constituents of water, which has the chemical formula H2O. This formula signifies that water is made up of two atoms of hydrogen combined with one atom of oxygen. We determine the amount of hydrogen in the soil by two different techniques. One relies on the ability of hydrogen to slow down, or moderate, neutrons and the other relies on the fact that hydrogen can absorb a neutron and then emit a gamma ray of a specific and characteristic energy. We have seen both of these effects in the initial data from the Mars Odyssey GRS.

Here's a smaller image of the first GRS data:

Source: http://mars.jpl.nasa.gov/odyssey....al.html

The blue areas indicate where water is.

Other sources:
GRS (Gamma Ray Spectrometer) press conference: http://grs.lpl.arizona.edu/results/presscon1/
JPL press conference (Real Player link): http://realserver1.jpl.nasa.gov:8080/ramgen....compact

rgcarnes · 2002-03-03 17:40:09

Can someone, who has already had the time confirm it, determine that the patch of strong hydrogen signal in the northern hemisphere is located coincident with the Sirtus Majoris feature? If it is, I'm celebrating. You may note that the color coding in the image indicates that the signal is very intense near the center of this feature.

Rex G. Carnes

Josh Cryer · 2002-03-03 22:30:43

I don't have time! But this is too much. Woo.

Anyway, the dark blue patch you refer to is actually too far north to be Syrtus Major, its location above Olympus Mons would put it around Arcadia Planitia as far as I can tell (you can make out Olympus Mons and Tharsis Montes, and even Elysium Mons if you look closely, which I'm sure you noticed). Syrtus Major would be three to four sectors from the left near the equator in the GRS image I posted.

I have not been able to find any close up images of Milankovic (a large crater, which was probably a lake at one time, in the Arcadia Planitia region), but I am sure that it will be an interesting candidate now for future rover missions. (You can actually see the crater if you look hard enough, it's right above the little green bit in the blue patch above Olympus Mons.)

Shaun Barrett · 2002-03-04 06:28:52

I think Josh is right, Rex. But why would you be celebrating the possible discovery of water ice at Syrtis Major? Unless that would fit in with a pet theory of yours(?).
All this stuff from Odyssey is certainly exciting, but are these results pretty much accurate and complete? Or might they discover more water ice if they look harder?
The point of these questions is that, to be honest, I'm just a little bit disappointed with Mars' northern hemisphere! Sure, the southern hemisphere discovery is a revelation of enormous importance. But could there be more?
Is it possible that the sediment on Vastitas Borealis is just too thick to allow detection of an underground ocean of water ice with the instruments aboard Odyssey?
And one more question: Could something other than water be giving us these results? I guess liquid ammonia (NH3) or liquid methane (CH4) could theoretically give a strong hydrogen signal, though its nearly impossible to hypothesise a source for such compounds, I admit! And they wouldn't remain in solid or liquid form under Martian conditions either. But is there ANYTHING else that could even remotely fit the bill? I don't want to break out the champagne and then be told we're actually dealing with underground lakes of hydrochloric acid (HCl) instead of water!!
Anybody want to put my mind at rest and reassure me? I want to believe! But I'm almost afraid to!
???

Josh Cryer · 2002-03-04 07:00:37

Well, I could be wrong, a 'lil bit. I'm not quite sure where Syrtus Major is with regard to that GRS image, but I'm positive that large blue patch in the northern hemisphere is not Syrtus Major (I double checked just now, just to be sure).

rgcarnes, I'm wondering why you'd be excited about water (mind you, water ice) in Syrtus Major. Care to clue us in? (I'm a little forgetful when it comes to general news, are there interesting indications of life there?)

All this stuff from Odyssey is certainly exciting, but are these results pretty much accurate and complete? Or might they discover more water ice if they look harder?

With further investigation we'll know how much water is there with an astounding degree of accuracy, but the preliminary GRS image we're seeing now won't change much. Just like with the MOLA data. It became more detailed, but it didn't change much visually. The regions we're seeing now have water ice, and a lot of it. The continuing mapping phase will try to determine how much.

The point of these questions is that, to be honest, I'm just a little bit disappointed with Mars' northern hemisphere! Sure, the southern hemisphere discovery is a revelation of enormous importance. But could there be more?

I'm not disappointed at all, I'm actually quite pleased. I mean, this is very early data and it's showing us a lot of stuff we never knew about before. The interesting thing is that Mars' north polar cap doesn't show up in these images. We'll have to see what pans out, I am tempted to email the GRS guys and bug them about this intereting paradigm.

Is it possible that the sediment on Vastitas Borealis is just too thick to allow detection of an underground ocean of water ice with the instruments aboard Odyssey?

You know, I hope so. And it's possible, I think. The data itself is extremely preliminary, so don't be surprised if the Vastitas Borealis starts to turn blue over time as more and more data comes in.

And I think you can be assured that this is H2O hydrogen we're picking up.

Adrian · 2002-03-04 10:05:12

I'm not disappointed at all, I'm actually quite pleased. I mean, this is very early data and it's showing us a lot of stuff we never knew about before. The interesting thing is that Mars' north polar cap doesn't show up in these images. We'll have to see what pans out, I am tempted to email the GRS guys and bug them about this intereting paradigm.

According to what I've read, the northern polar ice cap is composed of water ice with a layer of carbon dioxide on top. Since winters in the southern hemisphere are both longer and colder than in the north, the northern polar ice cap is regularly completed vaporised into the atmosphere, whereas the southern polar ice cap merely shrinks a bit.

What's required (and I'm sure will be made) is a series of surveys of hydrogen amounts on Mars over a long period of time.

Shaun Barrett · 2002-03-04 23:50:09

I was surprised to read Adrian's comment: " ... the northern polar ice cap is regularly completely vaporised into the atmosphere ..".
I always thought that a large residual cap remained, even at the height of the northern summer (?).
So, does the northern cap vanish entirely every summer and then reform every winter? What about the energy required to vaporise 300,000 cubic miles of super-cold ice.
Surely Adrian must be referring to the superficial frozen CO2 layer disappearing completely each summer; not the water ice (?). Or does he have access to new information I've been too slow to keep up with?

:0

Josh Cryer · 2002-03-05 00:56:13

The other water thread we have going here discusses this in length... and the north residual cap (what's speculated to be water ice) is quite large (about four times larger than the south). However, since it's winter on the north cap, there is upwards of 2 meters of CO2 ice covering the risidual cap, it's possible the CO2 ice is masking the H2O that is there!

Ah, all becomes clear now. ^_^;

Source: http://ltpwww.gsfc.nasa.gov/tharsis/snow_paper.html

Adrian · 2002-03-05 11:47:29

Ah, I suspect I was reading an overly simplified account of the way in which the north pole changes in shape according to the seasons. Does anyone have a good online reference to exactly how the mass and composition of the poles changes with time?

RobS · 2002-03-05 17:25:30

The various news reports all noted that the data for the northern polar regions is not accurate for water because of the seasonal CO2 cap covering the permafrost. So we have to wait for northern hemisphere summer to get that data.

If you have a map of Mars at home, you can read the multicolored map pretty easily if you remember the vertical line down the middle of the map is the 180 degree line. The map starts with zero degrees on the right and increases to 359 on the left (or maybe it's the other way around; I don't have a map here at work). The lines you can just barely see on the map are every 30 degrees of latitude or longitude. The three Tharsis volcanoes (Arsia, Pavonis, Ascraeus) and Olympus Mons are quite distinct one quarter from the right edge.

-- RobS

AndyM · 2002-03-06 12:09:06

Its worth noting that the maximum depth of investigation of the gammar ray sensor is about one foot while for the neutron detector it is about three feet. In other words, Odyssey isn't able to see any water below three feet of the surface. There could still be significant deposits of ice below the surface that the Odyssey just can't see.

RobS · 2002-03-07 18:38:19

For those who enjoy technical reading, the November 2001 issue of *Icarus* is now on the web--well, the abstracts, anyway--and the theme of the issue is water on Mars. The URL is http://www.idealibrary.com/links/toc/icar/154/1/0.

-- Robert Stockman

RobS · 2002-03-07 18:38:27

For those who enjoy technical reading, the November 2001 issue of *Icarus* is now on the web--well, the abstracts, anyway--and the theme of the issue is water on Mars. The URL is http://www.idealibrary.com/links/toc/icar/154/1/0.

-- Robert Stockman

Josh Cryer · 2002-03-09 03:35:30

Thanks RobS, this is interesting indeed.

rgcarnes · 2002-03-15 00:31:04

Thanks to those of you who asked why I would be celebrating in regards to the Odyssey press releases and the Syrtus Major feature. I'm not celebrating. I certainly hope that some more definitive information will be forthcoming. It may not be given the advertised lateral resolution of the various instruments.

I applaud the release of information that shows that a significant amount of water is available on the planet's surface. To be more useful, potential visitors to Mars need to be able to access the water nearer the equator than the poles.

The depths to which a couple of the Odyssey instruments can detect hydrogen, probably water, have been mentioned by AndyM.

What may be more important, I hope, is the lateral resolution of the various instruments. A brief and not comprehensive list includes the Odyssey visible imager at 20 meters, and MOLA at 400 meters. This compares to the Mars Global Surveyor highest resolution images at 1.5 meters. So the Odyssey imager is over one order of magnitude worse and the MOLA is more than two orders of magnitude worse.

To make a comparison with an image that has been on the news in the last year or so, the P3 Orion on the end of the runway in China was imaged at about one meter resolution, a little better but comparable to the MGS. The aircraft has dimensions of around 35 meters length and width, especially considering the nose job it was given before making the landing. This cross-shaped object, even if it had the highest possible contrast with its background, would have been imaged by the Odyssey imager as, if we were lucky, a slightly different tint, or grey scale value in so few pixels as to be indistinguishable from its surroundings.

The images produced by the MOLA and the Odyssey units are useful as wide area survey tools, but as anyone who has spent time examining the MGS images can testify, the surface takes on a very much more interesting character at highest resolution. The MGS is still the most detailed show available.

Ice and perhaps even water?? may be visible in the MGS archives if one really looks for them. In fact I have gone out on limb and pointed out a few candidate image details in the past.

Rex G. Carnes

Shaun Barrett · 2002-04-12 01:00:25

Does anyone know what Odyssey is up to these days? There was an initial rush of information and now ... nothing!
Didn't they promise to release stuff pretty much as it happens? (I know there have been pictures released, but they're only at resolutions somewhere between Viking and MGS. What purpose does a backward step in visual resolution serve anyhow? )
I don't know about you, but I'm more than ready for some more interesting data! ???

Josh Cryer · 2002-04-13 23:54:39

There really isn't much in the way of info. Basically what you have is a bunch of scientists downloading data. The analysis process won't happen until everything is archived in the PDS. (As far as I can tell, there isn't an Odyssey Press Release scheduled for the next two weeks... but you never can tell, they might find something surprising.)

You can see daily Themis images here though: http://themis.asu.edu/latest.html

I think after the GRS boom is deployed we'll get some really cool information, especially since a success like that would warrent a press release.

Here's hoping for the next few weeks. ???

BTW, NASA has and does release stuff often, that's what the PDS is there for. The only reason they hold back anything initally is probably so they can take credit for any discoveries made (when [liquid] water was found by scientists studying the MGSS MOC data, NASA took responsiblity for it, even though it wasn't their direct discovery).

Shaun Barrett · 2002-04-15 01:45:58

Is there anything wrong with the GRS boom? Am I right in thinking that I read somewhere about a problem with its deployment? :0

Josh Cryer · 2002-04-15 05:14:02

Nah, it just hasn't happened yet. I think they're on schedule though. They're just taking it slowly but surely.

dicktice · 2002-11-02 13:20:57

I'm shocked (having just joined) at how old these comments are. Here, it is the 1st of November 2002, and no-one has anything to say about the dirth of nighttime infrared imagery from Odyssey! Anyone? Dick Tice.

Josh Cryer · 2002-11-02 16:29:20

Hehehe, the night time infrared images were just made to pacify the conspiracy theoreists.

Shaun Barrett · 2002-11-12 01:28:51

We are well and truly into the northern Martian summer now. The CO2 'hood', which covers the north of Mars in winter, must have disappeared by this time and the instruments on Odyssey should have been in a position to take readings of hydrogen in the upper regolith.
Why have we heard nothing?
The northern plains must surely have at least as much water in the top metre as the southern highlands, and I'm keen to see some results!

Does anyone know what's going on? ???

Josh Cryer · 2002-11-12 03:48:54

Good question. I just checked out the Odyssey site, and I noticed that they're going to be having a press conference and a Q&A on the 14th. So I suspect we'll find out then. I can't access the PDS currently, but I was going to go see when the latest GRS data was put there. It would be interesting to find that the data is very recent.

I suggest you go to the Odyssey site, and check out the news conference the 14th. It'll be on NASA TV, of course, but you'll be able to view it online. I think we might actually get a total watershed figure! That would be very interesting, indeed!

Bleh, I hope it doesn't go as bad as that last netcast I saw, though. I was disappointed when they showed off the 2003 ?rover.? The whole job was botched very bad. You couldn't see the scientists out in the Arizona desert, and the rover they actually showed off wasn't the actual one, just an old prototype they've been using for awhile. I just hope this next Odyssey thing isn't as botched (can't imagine that it would be, though; just complaining for no good reason).

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#1 2002-03-02 00:51:12

Re: First Odyssey report!! - Finally! :)

#2 2002-03-03 17:40:09

Re: First Odyssey report!! - Finally! :)

#3 2002-03-03 22:30:43

Re: First Odyssey report!! - Finally! :)

#4 2002-03-04 06:28:52

Re: First Odyssey report!! - Finally! :)

#5 2002-03-04 07:00:37

Re: First Odyssey report!! - Finally! :)

#6 2002-03-04 10:05:12

Re: First Odyssey report!! - Finally! :)

#7 2002-03-04 23:50:09

Re: First Odyssey report!! - Finally! :)

#8 2002-03-05 00:56:13

Re: First Odyssey report!! - Finally! :)

#9 2002-03-05 11:47:29

Re: First Odyssey report!! - Finally! :)

#10 2002-03-05 17:25:30

Re: First Odyssey report!! - Finally! :)

#11 2002-03-06 12:09:06

Re: First Odyssey report!! - Finally! :)

#12 2002-03-07 18:38:19

Re: First Odyssey report!! - Finally! :)

#13 2002-03-07 18:38:27

Re: First Odyssey report!! - Finally! :)

#14 2002-03-09 03:35:30

Re: First Odyssey report!! - Finally! :)

#15 2002-03-15 00:31:04

Re: First Odyssey report!! - Finally! :)

#16 2002-04-12 01:00:25

Re: First Odyssey report!! - Finally! :)

#17 2002-04-13 23:54:39

Re: First Odyssey report!! - Finally! :)

#18 2002-04-15 01:45:58

Re: First Odyssey report!! - Finally! :)

#19 2002-04-15 05:14:02

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#20 2002-11-02 13:20:57

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#21 2002-11-02 16:29:20

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#22 2002-11-12 01:28:51

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#23 2002-11-12 03:48:54

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