Podcaster: Dr. Al Grauer
Title: Travelers in the Night Digest: Eps.431 & 432: Tough Space Rocks & Close Space Rocks
Organization: Travelers in The Night
Link : Travelers in the Night ; @Nmcanopus
Description: Today’s 2 topics:
- Most small asteroids are likely to be rubble piles of small rocks and dust loosely held together. A few are solid objects which may contain metals like iron and nickel as well as gold, silver, and platinum.
- In 2017 my team the Catalina Sky Survey discovered 17 space rocks that can come closer than the communication satellites to the surface of planet Earth. Three quarters of them are less than 50 feet in diameter and would produce a harmless exciting light show if they ever enter our atmosphere.
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:
430 – Tough Space Rocks
Most small asteroids are likely to be rubble piles of small rocks and dust loosely held together by their weak force of gravity while others may be made of ices of various substances. A few are solid objects which may contain metals like iron and nickel as well as gold, silver, and platinum. As they whiz by us it is hard to tell much about them from their overall brightness and distance from us. In 2017 my team the Catalina Sky Survey found 21 asteroids having an average diameter of 750 feet which pass closer to the Sun than the planet Mercury. They must be made of very tough rocky material since they regularly receive more solar energy than heats the surface of Mercury to 800F. Over the centuries this repeated baking has likely removed all of their water and other volatile materials leaving only rocky metallic minerals. The largest of this group of tough guys is the half mile in diameter asteroid 2017 VV14 which orbits the Sun once every 3.4 years and can come to about 20 times the Moon’s distance from us. The smallest is the 30 foot diameter tiny asteroid 2017 RQ17 which orbits the Sun once every 214 days on a path that brings it close to Mercury, Venus, Earth, and Our Moon. Based on known terrestrial deposits many of the key elements required for modern industry and food production such as phosphorus, antimony, silver, gold, and copper could be exhausted on Earth in the next 50 to 60 years. Perhaps in the future humans will mine tough asteroids for the materials they need.
432 – Close Space Rocks
In 2017 my team the Catalina Sky Survey discovered 17 space rocks that can come closer than the communication satellites to the surface of planet Earth. Three quarters of them are less than 50 feet in diameter and would produce a harmless exciting light show if they ever enter our atmosphere. Another very close approaching asteroid, 2017 YZ1, is a different story. It was discovered by my Catalina Sky Survey teammate Carson Fuls using our 60 inch telescope on Mt. Lemmon, Arizona and on it’s present path can theoretically come to about 30,000 miles from the surface of planet Earth. Fortunately asteroid hunters are sure that it will not impact the Earth in the next few hundred years. An asteroid like 2017 YZ1 strikes the Earth every 66,000 years or so releasing the energy 7 large hydrogen bombs. According to the Purdue University Impact Calculator, if 2017 YZ1 were to be made of dense rock and entered our atmosphere at about 7 miles per second it would make a crater about 2 miles in diameter and 1,500 feet deep in sedimentary rock. If you were 100 miles away from ground zero, 32 seconds after impact it would feel like a Richter Scale 6.3 magnitude Earth quake. Eight minutes later you would experience a 15 mph breeze and a sound as loud as heavy traffic. Rest easy, there are no known asteroids currently on a collision course with Earth. Additionally, my team the Catalina Sky Survey scans the sky with 4 telescopes to discover any space rocks coming our way.
For Travelers in the Night this is Dr. Al Grauer.
End of podcast:
365 Days of Astronomy
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