Podcaster: Dr. Al Grauer
Title: Travelers in the Night Digest: Potentially Hazardous Asteroids From Catalina Sky Survey
Organization: Travelers in The Night
Link : Travelers in the Night
Description: Today’s 2 topics:
- Catalina Sky Survey member Greg Leonard discovered 3 PHAs!
- Aten asteroids have an orbit that’s inside Earth’s orbit. Rose Matheney discovered 2016 CL136, a PHA.
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:
230 – Hot Hand
Every year asteroid hunters discover about a hundred objects which are larger than 450 feet in diameter and come closer than 20 times the Moon’s distance from us. We call these potentially hazardous asteroids. In 2015 my group the Catalina Sky Survey discovered 21 of them. It was thus exiciting news to our team, when, recently, our newest team member Greg Leonard discovered three of them in rapid succession.
Two of Greg’s discoveries are a thousand feet in diameter while the third is approximately 1,800 feet in diameter. Fortunately none of them are on a collision course with planet Earth. The Congress of the United States has directed NASA to discover large, potentially dangerous asteroids like these since if one should impact the Earth it would release several times the energy of the largest hydrogen bomb ever exploded. Asteroid hunters’s goal is to prevent such a disaster by discovering an Earth bound asteroid at least 50 years before it hits. Serious engineering studies are being conducted to determine the best way to deflect an asteroid which appears to be on a collision course with Earth. One proposal involves changing the path of a threatening asteroid by striking it with a high velocity impacting space craft. Another involves using a “gravity tractor” to exert a tiny force for a long time causing the asteroid to miss the Earth. A third involves setting off a nuclear blast adjacent to the asteroid to vaporize a portion of its surface. This will produce a rocket type of thrust to change the threatening object’s trajectory.
The goal of the NASA Near Earth Object program is to provide the early detection critical to any of these mitigation techniques.
231-Dangerous Aten
About one in twenty Earth approaching objects that asteroid hunters discover has a path which is mostly inside of the Earth’s orbit around the Sun. We call them Atens. They are hard to discover since they spend much of their time shrouded by solar glare. A large percentage of Aten asteroids are economically attractive. Some of them are likely to contain nickel, cobalt, gold, and platinum.
Recently my Catalina Sky Survey teammate Rose Matheny discovered a potentially hazardous Aten asteroid now called 2016 CL136. Rose was able to discover this object when it emerged from the solar glare traveling at 12 miles per second. Humans were able to observe Rose’s space rock for another month until it became too faint to detect. 2016 CL136 orbits the Sun every 227 days on a path that takes it from inside the orbit of the planet Mercury to 18% farther from the the Sun than the planet Earth. It must be made out of tough rocky metallic stuff, since when it is closest to the Sun its surface temperature is likely to be above 800F and it is traveling 45 miles per second relative to our star. Rose’s 580 foot diameter discovery will make 16 close approaches to planet Earth in the next 50 years with the closest being in 2021 when it will be about 13 times the Moon’s distance from humans.
Like the rest of the more than 1,700 known potentially hazardous asteroids, asteroid hunters will continue to track 2016 CL136.
For Travelers in the Night this is Dr. Al Grauer.
End of podcast:
365 Days of Astronomy
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