Podcaster: Dr. Al Grauer
Title: Travelers in the Night Digest: Eps. 283 & 284: Micro Astronomy & Dark Trails
Organization: Travelers in The Night
Link : Travelers in the Night ; @Nmcanopus
Description: Today’s 2 topics:
- A single crystal of magnetite from a meteorite was examined by Dr. Tom Zega of the University of Arizona. The oxygen atoms they found came from the solar wind of another star than our Sun. It must have been part of the original star forming cloud that our solar system formed from.
- NASA’s Dr. Mark Fries (of the Planetary Science Institute) uses doppler radar to track the trails of meteorites and has led searchers to several fresh meteorite falls.
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Bio: Dr. Al Grauer is currently an observing member of the Catalina Sky Survey Team at the University of Arizona. This group has discovered nearly half of the Earth approaching objects known to exist. He received a PhD in Physics in 1971 and has been an observational Astronomer for 43 years. He retired as a University Professor after 39 years of interacting with students. He has conducted research projects using telescopes in Arizona, Chile, Australia, Hawaii, Louisiana, and Georgia with funding from NSF and NASA.
He is noted as Co-discoverer of comet P/2010 TO20 Linear-Grauer, Discoverer of comet C/2009 U5 Grauer and has asteroid 18871 Grauer named for him.
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Transcript:
283 -Micro Astronomy
The history of our spot in the Universe is written in the composition of meteorites and other samples of materials we have obtained from space. Even the smallest speck has a story to tell.
Recently Dr. Tom Zega and his collaborators analyzed a single crystal of the mineral magnetite obtained from a meteorite which was found on the LaPaz Icefield in Antarctica. This tiny grain of material measuring less than 1% of the diameter of the average human hair was selected with an ion beam scalpel and imaged with high powered electron microscopes. The oxygen in it’s molecules has a mixture of isotopes different from what we find on Earth. It is likely that these oxygen atoms were ejected in the solar wind of a star having about twice the mass of the sun. They appear to have combined with iron in the dust cloud surrounding this ancient star to form a crystal of magnetite. This tiny spec of material was included in the cloud of gas and dust which became our solar system some 4.5 billion years ago.
Currently Dr. Zega and his collaborators are creating a facility in the basement of the Lunar and Planetary Laboratory building at the University of Arizona in Tucson. The instruments they are installing are powerful enough to image single atoms. They will use them to analyze samples of the asteroid Bennu obtained by the OSIRIS-REx spacecraft. What these researchers find written in the composition and arrangement of atoms and molecules will have much to say about the origins of planet Earth and the life we find here.
284 – Dark Trails
A faint shooting star or meteor streaking across the sky is produced when a tiny bit of rock or dust enters the Earth’s atmosphere and burns up some 60 miles above us. Sometimes one is very bright and can be seen in the daytime. If it is as bright as the planet Venus it is called a fireball. Like it’s dimmer cousin the fireball stops being visible to the human eye sometimes after it breaks into pieces.
NASA scientist Dr. Marc Fries and his collaborators have used Doppler Weather Radar to track twenty meteor’s dark trails through the sky. In the past year or so they have used this technique to direct searchers on the ground to the probable location of freshly fallen meteorites. In three instances a total of two and a half pounds of freshly fallen meteorites were discovered near Creston, CA, Osceola, FL, and Mount Blanco, TX. In four other cases RADAR indicated the likelihood of meteorites near Locust Grove, CA, Rainsburg, PA, Black Earth, WI, and in the Atlantic Ocean off the coast of Florida but so far no meteorites from these falls have been found. Often vegetation, rough terrain, and the presence of terrestrial rocks make it difficult to find space rocks.
When a meteorite is shown to originate from a fireball which has been detected by NASA’s fireball network the data are used to calculate the object’s path through space before it entered the Earth’s atmosphere. This analysis reveals the part of the solar system that it came from and thus provides detailed information about the composition of an asteroid or comet from distant region of our solar system.
For Travelers in the Night this is Dr. Al Grauer.
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365 Days of Astronomy
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