Wednesday, July 8, 2015
I recall as a kid in elementary school a special presentation in the cafeteria during lunch. Someone from the Johnson Space Center gave a talk about Voyager passing by Jupiter. The slide that showed the relative size of earth next to the image from Jupiter was stunning. The volcanoes on Io were also amazing. It was huge.
Then Voyager 2 went on to complete the Grand Tour, a voyage of discovery likely never to be repeated in our solar system. Voyager 2 zoomed past Saturn the following year in 1980. I was in high school by the time Voyager 2 flew past Uranus. I was in college when she sailed by Neptune. That was a quarter century ago and those brief encounters are still all we have of 2 of our largest planets. At that time, the internet as we know it did not yet exist, so it was often months before a decent image could be seen in a magazine and over a year before interesting discoveries discussed.
What was missing in the Grand Tour was a visit to the 9th planet: Pluto. This is because Pluto has a strange orbit and it was too difficult to change Voyager 2's trajectory to reach it. Pluto orbits so far away from the sun it takes 248 years to complete 1 orbit. It was discovered during late spring-time 85 years ago, and now Pluto is just entering fall!
Pluto is known to have an atmosphere, and calculations made it seem possible that during winter the planet would get so far from the sun that the entire atmosphere would freeze onto the surface. That was one reason why there was a rush to send a spaceship out to photograph the planet while the atmosphere, surface, and amount of sunlight were all optimal. Missing this window would mean waiting 180 years to try again! Fortunately, NASA was up to the now-or-practically-never challenge. The Pluto Fast Flyby was proposed in 1992, but it was 10 years later when a mission was proposed that had the right amount of science for the right cost. New Horizons was launched in 2006. Even as the fastest spacecraft ever launched, it still takes a Jupiter assist and 9 years of waiting.,,,
But here we are! The doorstep of Pluto is already beginning to reveal its secrets and the flyby next week will finally finish what we started. Pluto may have changed its status from Planet to Dwarf, but in many ways Pluto is in a class of its own. It is sometimes called King of the Trans-Neptunian Objects, although Eris is larger. However, Pluto is unique in that it is our only known double-planet system; Charon is so large and close to Pluto, that the two orbit around a barycenter that is outside the radius of Pluto... they orbit empty space. Even more cool, Charon and Pluto may share an atmosphere, at least part of the time.
There are sure to be many more exciting space missions, some that have the potential to really shake things up (lets get to Europa already!!). But finally getting to see a map of Pluto is for me the finale of the original foray into our backyard.
Try downloading Eyes on the Solar System and virtually fly along with New Horizons as she speeds past Pluto and beyond. The preview mode is pretty cool, and its the next best thing to waiting 5 hours for the radio signal to reach home.
Thursday, May 21, 2015
Wow - another year has passed!
|Kentucky arrow darter: credit David Starovoytov|
Many species are endangered by one huge problem: habitat loss. A really unwise and shortsighted resolution passed by the Legislature this spring threatens to sell nearly all our public lands. There are economic, environmental, ecological, philosophical, and ethical reasons why this is a really bad idea and the article sums the problem up nicely. Our public lands are already economically important, and even our wildlife refuges do not restrict oil production or other resources extraction. It's very important to remember that most resource extraction is very short term economic impacts. Often, there are costs that industry does not portray, such as acid-mine drainage, soil erosion and land slides, water pollution, and many many other problems that are damages that short sighted profiteering does not consider.
These lands are our natural and historical heritage, and any politician that thinks selling them off to the highest bidder is in the best interest of the nation should reconsider their position carefully. Please consider voicing your opinion to your politician and let them know you consider our battlegrounds, historical trails, forests, rivers, grasslands, oceans, caves and other resources too important to sell off to a foreign company to strip mine or log. Sign a petition and get involved before this ill conceived idea goes one step further.
The good news is that my thesis research is forging ahead. I want to understand how "modern" plant communities have changed over time, particularly in response to drought and/or temperature. This is best accomplished via palynology: the study of microscopic planty things. Pollen is very tough stuff and fossilizes well, so it is often the best choice for reconstructing what an ancient ecosystem looked like. The problems with pollen is it doesn't tolerate drying out and its only produced when plants flower. Some plants reproduce vegetatively and may not produce pollen.
|Gus Engeling Wildlife Management Area|
I am conducting my research in North Central Texas. Texas is a big state, but it has no natural lakes. There are a few bogs and ephemeral ponds, but these are rare near SMU in Dallas. The closest bogs to Dallas are at Gus Engeling Wildlife Management Area, and I am coring the pitcher plant bog there to look for pollen. But when pollen can't be found, there is another trace plants leave behind... phytoliths!
Pytholiths are a bit of a mystery why plants produce them, but there are tiny crystals of opal-silica
By a stroke of luck, Dr. Reid Ferring serendipitously discovered one of the oldest archaeological sites in North America during the construction work of a reservoir spillway along the Elm Fork of the Trinity River. He discovered many Clovis era artifacts, fossil animals from the pleistocene, and in thin layered sediments from a small pond, pollen. As the last ice age faded 13,000 years ago, the spring feeding the pond dried up. Therefore, the pollen record does not continue forward into the Holocene. He has generously offered his research samples from 25 years ago for me to prospect for phytoliths! I'll write more about Dr. Ferring's research in my next blog.
Stay tuned as I spend the summer testing different places and layers of time for what plants grew when (and why it's important).