Podcaster: Dr. Al Grauer
Title: Travelers in the Night Eps. 87E & 88E: Peppered By Space Rocks & Where Extension Cords Can’t Reach
Organization: Travelers in The Night
Link : Travelers in the Night ; @Nmcanopus
Description: Today’s 2 topics:
- NASA NEO Observations Program Executive Lindley Johnson stated “We now know that Earth’s atmosphere does a great job of protecting Earth from small asteroids”.
- Solar panels work well for powering spacecraft out to the orbit of Mars. Beyond that the use of radioactive isotope power generators has enabled exploration…
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:
87E: Peppered By Space Rocks
Recently my, University of Arizona, Catalina Sky Survey, teammate, Jess Johnson, was searching for Earth Approaching asteroids when he discovered a faint slow moving object in the night sky. Six nights of followup observations revealed that this new object’s path is out near the planet Neptune. It takes approximately 173 years for it to travel once about the Sun so it will take observations over the next few years to pin down its orbit. With a diameter of approximately 43 miles it is much larger than the Earth approaching objects we normally encounter.
The Minor Planet Center has classified it as a Centaur.
Centaurs are named for the mythical beings which are half horse and half human.They are small cold worlds that share the characteristics of both asteroids and comets. Humans have discovered less than 200 of the more than 40,000 of them which are likely to be traveling amongst the outer planets.
A Centaur’s orbit about the Sun changes as it crosses paths with the giant planets Jupiter, Saturn, Uranus, and Neptune. Sometimes one is perturbed to move it closer to the Sun, be warmed, and give off a cloud of gas. At that point a Centaur may be impossible to distinguish from a faint comet.
Centaurs are so far from us that we don’t know much about their surface features. By studying the light that is reflected from them we know that they contain carbon, organic molecules, and ices of various substances.
How many Centaurs have collided with the Earth over the eons and enriched our planet remains a mystery.
88E: Where Extension Cords Can’t Reach
Marie Curie’s discovery of radioactivity started humans on a path which so far has skirted annihilation and has led to cures for cancer and the exploration of the distant regions of our solar system.
Solar panels work well for powering spacecraft out to the orbit of Mars. Beyond that the use of radioactive isotope power generators has enabled the exploration of Mars, Jupiter, Neptune, Uranus, and soon a mission to Pluto. One of these power plants enables Voyager I, the most distant, human made, traveler in the night,to operate and communicate with Earth. It continues to operate more than 37 years after it was launched.
Radioisotope Power Systems provide heat and electricity to operate spacecraft by using the natural radioactive decay of plutonium-238. This potentially dangerous substance is carefully protected. Over the past 50 years radioisotope power systems have been flown on 27 missions. No member of the public or NASA employee has ever been injured by one of these units.
Radioisotope Power Systems work well where solar panels are impractical. At Saturn, for example, a solar panel would receive only 1% of the Sun’s energy that it would receive in Earth Orbit.
If you want to get an idea about what our knowledge of the solar system would be like without Radioisotope Power Systems, go to a used bookstore or the library and find an Astronomy text book from the mid 1970’s and well as a current one. Look up the planets in both.
For Travelers in the Night this is Dr. Al Grauer.
End of podcast:
365 Days of Astronomy
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