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sugarplumkittyI have (oh darn! lol) to attend two seminars at NASA/Ames this quarter and write papers on them. I want to go to them anyway and will probably attend more than two if I can manage it. Yesterday at 4pm, I attended my first one for this quarter. I'm trying to find some of the images he used because they really illustrated his points. So far I've only found a few. I've linked to the webpages.
COLLOQUIUM ON "ROLE OF WATER ON MARS" given by Philip Christensen
Water in the Geologic Record of Mars is being debated.
Was Mars:
Dry?
Wet?
Warm?
Cold?
How has the environment changed over time?
The answer is Mars has been all of the above, at different times and places.
First of all, the measurements for elements needs to be explained. Spectroscopic images are being taken by a special camera named Themis in orbit around Mars measures the brightness of different surfaces in a range of 6 to 50 microns. Different elements reflect back different amounts of light. Themis also takes infrared photos to pick up the amount of heat being generated. Smaller granules like sand don't retain the heat as well as larger objects like rocks. The day vs night infrared images help discover how solid any surface or object is as well as how big it is.
On Earth, different minerals have been tested to get their spectroscopic wave forms. The minerals listed on the slide with their waveforms as being on Mars are:
Quartz
Feldspar
Pyroxene
Hornblende
Clay
Olivine
Calcite
When the spectrograpic wave form is analyzed, they can find the combination of minerals by combining the wave forms from the different known minerals to see what combination makes a matching wave form from the spectrograph.
The same thing has been done with infrared here on Earth so we can tell from the amount of retained heat combined with the results of the spectrographic image what mineral or mix of minerals is in any one area. The results have been verified with the Mars Rovers in the areas they've been able to access for testing.
An example area used for the lecture is Gusev Crater. The Themis images have told us the rocks on the surface are primary volcanic in nature. They haven't deteriorated much since they were spewed from the volcano. There are dunes in the crater as well, most likely formed from dust blown by the wind storms.
Ganges Chasma was also studied. A night photo of the area shows Olivene basalt on the surface. This is a fragile type of basalt that deteriorates when exposed to liquid water. On Earth, it turns to serpentine in about 100,000 years. The Olivene on Mars is still in prime condition despite being much older than that.
Another area studied was Ares Vallis. A major feature is another old channel of Olivene basalt. Ares Valles is a collapsed cauldera with a small volcano inside it. The old lava flows from the small volcano appear to be pristine olivene with a few impact craters in it. One special characteristic of this small volcano is an old flow of Dacite lava which is a glassy type of basalt. Glass is especially subject to deterioration by liquid water. The sheer age of this area and the pristine state of the basalt is a clear indication that little or no liquid water has flowed in this area of Mars for billions of years.
The summary of part 1 was:
Mars is fundamentaly volcanic
Unstable minerals have survived billions of years on the surface, proof that Mars is predominantly dry.
We still need to reconcile how the channels were created with
- Limited chemical weathering
- Mechanical weathering (wind) is orders of magnitude faster than chemical weathering.
- Water frozen most of the time with occasional short-lived periods when liquid water is stable. (Segura paper, 2002)
The arguments for a wet history of Mars:
Meridiani Crater
There is an abundance of hematite "blueberries" over a large lake bed. Hematite forms mostly in water. A collapsed area within the lake bed shows sedimentary layers that are rich in sulfates. Water dissolved the deposits and as it evaporated, the spheres formed. Aolean basaltic dunes and rippled basalt follow the same pattern as water-formed dunes and ripples here on Earth. The exposed 10 foot layer examined by the rover Opportunity is clearly composed of sedimentary layers which suggests a very wet environment.
Rocks in the lake include El Capitan, which clearly shows sedimentary layers.
The hematite bearing area is slightly lower than the old basalt and follows a shoreline. This shows that both water and gravity were part of the formation process for the hematite spheres and granules. The layer of hematite is stacked in a layer on older materials that in Earth lakes, takes up to 10,000 years to form.
We know the area with the hematite is quite old based upon the number of impact craters counted there.
Orego Vallis is another hematite lake.
Aram Chaos
The Omega Experiment shows sulfates in the areas where hematite is also found. These are all in sedimentary rock and the combination is only found within 10 degrees of the equator.
Ophir / Candor Chasma
In the far North of Mars, sulfates are found without hematite. In that area, today's temperatures range from 280k during the day to 170k at night. The color blue is the coldest, red is the hottest.
picture and short explanation
Chasma Canyon in infrared
Summary of part 2:
There are places with minerals that form in warm water and places without them. This means a locally wet Mars.
Modern Mars
Softened terrains are from dust storms.
Deuteronilus Mensae, north of Arabia
This is a newer area with fine grained material slowly moving over bedrock of olivene. It looks like several bluffs that are slowly crumbling and spreading in soft circles over the bedrock. The shape of the flows suggest ice laden material, turning to slush on occasion and then refreezing. It has to be newer than other areas because it isn't completely homogenized yet. The flows haven't covered the bedrock.
In either hemisphere, the slopes facing the poles are protected from the dust storms that flare up from the middle of the planet. Only on these slopes are areas that appear to be "pasted" onto the hills. The upper edges of the pasted on areas are scalloped. They reach almost to, but not quite up to the peaks of the slopes they're on. They also all end at about the same elevation. The flow of the material down the slope shows compression ridges, exactly like glaciers here on Earth.
This next part is being hotly debated by the scientists.
As they deteriorate, gullies appear beneath them. Others suggest Mars has underground aquifers that are extruding from the rock face and create the gullies by breaking the rock on the way out
Philip disagrees about the underground aquifiers. Because the olivene basalt exposed is 3 to 4 kilometers beneath the regular surface of Mars, he says that indicates underground aquifers don't exist. If Mars had active underground aquifers, the olivene basalt wouldn't be pristine everywhere it's exposed because the water would have degraded it.
Philip thinks they're snow accumulations and that the melting of the snow creates the gullies.
Dirty snow will melt because the dirt absorbs the heat from the sun then sinks through the snow, creating a trickle of water underneath. The snow acts as a protective barrier from the cold atmosphere and prevents the water from refreezing right away. The trickle forms the gullies.
Icy dirt won't melt because it doesn't have the protective blanket of snow. Snow also dissipates.
He thinks these pasted on areas are patches of dust-covered snow.
A scientist named Feldman mapped the ice and water on Mars. Water vapor on Mars is only 2% of the atmosphere.
Traces of carbonates have been found by the rovers. Carbonates usually form from the interaction of water with carbon dioxide. Minor carbonates are found in dust. Scientists named Booth and Kieffer formed carbonates in similar abundance from water dust interactions. The dust on Mars consists of granules of basalt.
Only small amounts of clay have been found on Mars. It isn't common there because it takes a lot of water to create clay. Arizona, one of our dryest areas on Earth consists of 50% to 60% clay.
Conclusion:
Mars has lots of near surface water.
It has been cold and frozen most of its history.
Local hot spots have happened in the past.
Minor carbonates formation happened from interaction of water vapor with dust.
There are large deposits of snow and ice in mid- to high-latitudes today.
COLLOQUIUM ON "ROLE OF WATER ON MARS" given by Philip Christensen
Water in the Geologic Record of Mars is being debated.
Was Mars:
Dry?
Wet?
Warm?
Cold?
How has the environment changed over time?
The answer is Mars has been all of the above, at different times and places.
First of all, the measurements for elements needs to be explained. Spectroscopic images are being taken by a special camera named Themis in orbit around Mars measures the brightness of different surfaces in a range of 6 to 50 microns. Different elements reflect back different amounts of light. Themis also takes infrared photos to pick up the amount of heat being generated. Smaller granules like sand don't retain the heat as well as larger objects like rocks. The day vs night infrared images help discover how solid any surface or object is as well as how big it is.
On Earth, different minerals have been tested to get their spectroscopic wave forms. The minerals listed on the slide with their waveforms as being on Mars are:
Quartz
Feldspar
Pyroxene
Hornblende
Clay
Olivine
Calcite
When the spectrograpic wave form is analyzed, they can find the combination of minerals by combining the wave forms from the different known minerals to see what combination makes a matching wave form from the spectrograph.
The same thing has been done with infrared here on Earth so we can tell from the amount of retained heat combined with the results of the spectrographic image what mineral or mix of minerals is in any one area. The results have been verified with the Mars Rovers in the areas they've been able to access for testing.
An example area used for the lecture is Gusev Crater. The Themis images have told us the rocks on the surface are primary volcanic in nature. They haven't deteriorated much since they were spewed from the volcano. There are dunes in the crater as well, most likely formed from dust blown by the wind storms.
Ganges Chasma was also studied. A night photo of the area shows Olivene basalt on the surface. This is a fragile type of basalt that deteriorates when exposed to liquid water. On Earth, it turns to serpentine in about 100,000 years. The Olivene on Mars is still in prime condition despite being much older than that.
Another area studied was Ares Vallis. A major feature is another old channel of Olivene basalt. Ares Valles is a collapsed cauldera with a small volcano inside it. The old lava flows from the small volcano appear to be pristine olivene with a few impact craters in it. One special characteristic of this small volcano is an old flow of Dacite lava which is a glassy type of basalt. Glass is especially subject to deterioration by liquid water. The sheer age of this area and the pristine state of the basalt is a clear indication that little or no liquid water has flowed in this area of Mars for billions of years.
The summary of part 1 was:
Mars is fundamentaly volcanic
Unstable minerals have survived billions of years on the surface, proof that Mars is predominantly dry.
We still need to reconcile how the channels were created with
- Limited chemical weathering
- Mechanical weathering (wind) is orders of magnitude faster than chemical weathering.
- Water frozen most of the time with occasional short-lived periods when liquid water is stable. (Segura paper, 2002)
The arguments for a wet history of Mars:
Meridiani Crater
There is an abundance of hematite "blueberries" over a large lake bed. Hematite forms mostly in water. A collapsed area within the lake bed shows sedimentary layers that are rich in sulfates. Water dissolved the deposits and as it evaporated, the spheres formed. Aolean basaltic dunes and rippled basalt follow the same pattern as water-formed dunes and ripples here on Earth. The exposed 10 foot layer examined by the rover Opportunity is clearly composed of sedimentary layers which suggests a very wet environment.
Rocks in the lake include El Capitan, which clearly shows sedimentary layers.
The hematite bearing area is slightly lower than the old basalt and follows a shoreline. This shows that both water and gravity were part of the formation process for the hematite spheres and granules. The layer of hematite is stacked in a layer on older materials that in Earth lakes, takes up to 10,000 years to form.
We know the area with the hematite is quite old based upon the number of impact craters counted there.
Orego Vallis is another hematite lake.
Aram Chaos
The Omega Experiment shows sulfates in the areas where hematite is also found. These are all in sedimentary rock and the combination is only found within 10 degrees of the equator.
Ophir / Candor Chasma
In the far North of Mars, sulfates are found without hematite. In that area, today's temperatures range from 280k during the day to 170k at night. The color blue is the coldest, red is the hottest.
picture and short explanation
Chasma Canyon in infrared
Summary of part 2:
There are places with minerals that form in warm water and places without them. This means a locally wet Mars.
Modern Mars
Softened terrains are from dust storms.
Deuteronilus Mensae, north of Arabia
This is a newer area with fine grained material slowly moving over bedrock of olivene. It looks like several bluffs that are slowly crumbling and spreading in soft circles over the bedrock. The shape of the flows suggest ice laden material, turning to slush on occasion and then refreezing. It has to be newer than other areas because it isn't completely homogenized yet. The flows haven't covered the bedrock.
In either hemisphere, the slopes facing the poles are protected from the dust storms that flare up from the middle of the planet. Only on these slopes are areas that appear to be "pasted" onto the hills. The upper edges of the pasted on areas are scalloped. They reach almost to, but not quite up to the peaks of the slopes they're on. They also all end at about the same elevation. The flow of the material down the slope shows compression ridges, exactly like glaciers here on Earth.
This next part is being hotly debated by the scientists.
As they deteriorate, gullies appear beneath them. Others suggest Mars has underground aquifers that are extruding from the rock face and create the gullies by breaking the rock on the way out
Philip disagrees about the underground aquifiers. Because the olivene basalt exposed is 3 to 4 kilometers beneath the regular surface of Mars, he says that indicates underground aquifers don't exist. If Mars had active underground aquifers, the olivene basalt wouldn't be pristine everywhere it's exposed because the water would have degraded it.
Philip thinks they're snow accumulations and that the melting of the snow creates the gullies.
Dirty snow will melt because the dirt absorbs the heat from the sun then sinks through the snow, creating a trickle of water underneath. The snow acts as a protective barrier from the cold atmosphere and prevents the water from refreezing right away. The trickle forms the gullies.
Icy dirt won't melt because it doesn't have the protective blanket of snow. Snow also dissipates.
He thinks these pasted on areas are patches of dust-covered snow.
A scientist named Feldman mapped the ice and water on Mars. Water vapor on Mars is only 2% of the atmosphere.
Traces of carbonates have been found by the rovers. Carbonates usually form from the interaction of water with carbon dioxide. Minor carbonates are found in dust. Scientists named Booth and Kieffer formed carbonates in similar abundance from water dust interactions. The dust on Mars consists of granules of basalt.
Only small amounts of clay have been found on Mars. It isn't common there because it takes a lot of water to create clay. Arizona, one of our dryest areas on Earth consists of 50% to 60% clay.
Conclusion:
Mars has lots of near surface water.
It has been cold and frozen most of its history.
Local hot spots have happened in the past.
Minor carbonates formation happened from interaction of water vapor with dust.
There are large deposits of snow and ice in mid- to high-latitudes today.
