Friday, March 30, 2007

Day 3: Stromato-whats?!?

[Sunrise over the Mojave]

(Ed: I've enabled comments from you non-Blogger members, although I get to moderate them to make sure you're not a spammer)

Wednesday was Media Day here. There were two webcasts scheduled for the morning. One in Spanish, one in English. Since many of the teachers had friends, family and students tuned in, there were only a couple of scheduled activities. Luckily one of them was the chance to play with a robotic rover. Now the rover that they had brought was nothing like those currently on Mars, and far less capable than the next generation rover. This one is based on an off-the shelf robotics kit, costing a "measley" $5000. The idea that Dr. Maite Trujillo was working on is to use the far less expensive rovers for "canaries" once the manned colonies on the Moon and Mars are occupied.

Since the rover is remotely operated, it can be sent out as an explorer to scout new areas, or to take simple readings, in lieu of a more expensive robot or Human explorer.

The rover also uses a standard external peripheral bus (USB), which means that a whole suite of different sensors, tools and other goodies could be attached on an as-needed basis. For our trials, the rover was only equipped with a USB camera as its sole sensor.

Our session with the rover team was realy just an introduction to tele-operated robotics, a chance to see a system in operation, and also an opportunity to see how such things can go wrong. The rover used a standard 802.11b network, which lost connection several times due to the construction of and locations of the buildings. Each of the four team members took a turn at driving the rover and trying to steer it toward a goal. I tried to drive it onto the back porch, and into the middle of the Spanish webcast (where Maite was about to be interviewed), but was foiled by the thickness of the building walls.

After lunch, I took advantage of another ad-hoc group. If you remember, the last one was Monday, when I hooked up with Jud and Mike, and had an absolutely awesome time setting sensor packs in the caves. This time, Dr. Rafael Novarro-González needed to take a small group out to a number of geologic sites to retrieve samples of stone and rock in order to compare mineral content to other samples he had taken in the Atacama, Rio Tinto, in Spain and several locations in Antarctica among others.

Our first destination was a field of stromatolites, located above an abandoned talc mine in a band of sedimentary upthrust. We had a bit of a drive, and I was in the back seat of a van full of spanish-speaking scientists. If you think sitting in a room full of scientists results in unintelligible conversation, try one where they are all speaking another language. My two years of high school spanish was far outclassed...I took a nap. ;)

I awoke to the now familiar feel of a bumpy, gravel road, and the sight of the bright white tailings of an old talc mine. The mine was a short hike from the road, so with our approximate directions for the location of the stromatolite field, we set off bravely for the stromatolite field.

Note how I used the word "approximate" to describe our knowledge of the field...That's right, only one of us had been there before, and he was just part of one of the previous trips, not a guide. We found the mine pretty easily, but the field eluded us. Ready to admit defeat, we headed back to our van.

Once again, luck played a hand. Rafael remembered that he had a set of pictures of the field and its location. Breaking out his files, we were able to place the field relative to the mine, and made the trek to the mine, once again. In this case, I didn't complain about the hike, because with all I had learned over the last few days, I was walking through an incredible variety of desert pavement, varnish, lava and other interesting geologic fields, as well as enjoying a beautiful, cloudless afternoon.

We got to the field, and they were everything I had hoped to see.

For those of you who have been thinking "Stromato-whats?!?", stromatolites are a combination biologic and sedimentary structure. Mats of cyanobacteria (formerly known as blue-green algae), grow in a shallow ocean or pool. Occasionally, a thin layer of sediment will be deposited on top of the mat. Since cyanobacteria is photosynthetic, the majority of the covered mat will die off. However, enough of the cyanobacteria survive to begin re-forming the mat, on top of the layer of sediment. Since the sediment is not deposited evenly, the new mat has more of an uneven appearance. The process repeats many, many times. Over thousands of years, layer upon layer of alternating sediment and mats build up a field full of small "towers". These towers are stromatolites.

The picture of my two samples show how a flat mat slowly changes into a mounded structure. The effect is most obvious in the sample on the left.

The field was located in an area where we were allowed to take samples, and I was lucky enough to grab the two you see above. The two came from different strata, separated by about 20 feet in vertical direction, and probably several million years (at least) in age. The one with lighter sediment comes from the older strata, the gray sediment comes from the same as the main field that we came to see.

The fossilized field in the rock strata has a very well defined layer where the thick, dark, iron-rich material was deposited on top of a field of stromatolite towers. You can see the obvious horizontal band, outlining the rounded towers in this picture.

Stromatolites are important, because they provide our most early fossil evidence of life on our planet. This particular field is between 1 and 1.5 BILLION years old. There are many other stromatolite deposits worldwide, that are older. The earliest fossils of other life are half that age or younger. The earliest dinosaur fossils are about a quarter the age of the stromatolites we were looking at.

With our little "approximate" location error, we weren't able to visit other sites that afternoon, but it was still another winning day!


Ann L said...

Amazing variety of experiences you are having.

Ann L said...
This comment has been removed by a blog administrator.
Mike Lum said...

It has been a real whirlwind tour. I owe a huge debt to Dr. Kress' astrobiology class. We have covered much of the same topics in class, so I have a real leg up on the research going on here, which has made my experience all that much better.

BTW: I removed your double post.