David Morrison (NASA Ames & SSERVI) has given an excellent history of asteroid impact research and planetary defense. The basic motivation for detection and deflection of potentially hazardous asteroids is public safety. This is a societal issue as well as a scientific one, and this video is one that everyone should watch.

Click here to watch the recording of David’s talk

Click here to download a copy of David’s slides

Impacts are the only natural hazard that can, in principle, be eliminated. How can we protect our planet and ourselves? Key to any defense effort is early detection. Surveys are the front line. The first task is to find hazardous asteroids and calculate their orbits long before they hit. Then, we could develop the technology to change asteroid orbits. Earth moves its own diameter in 6 minutes — thus to avoid a collision we need only change the arrival time of the asteroid by 6 minutes. Technologies considered to change orbits include ballistic impact, gravity tractor, and nuclear explosives.

This raises several questions about Planetary Defense. Should we develop this technology now, or wait until a specific threat is identified? Should this be an international effort? If so, how should it be organized? How much should we spend to protect our planet? Who can be trusted with this responsibility, and how do we ensure that asteroid defense systems are not misused?

In studying the dinosaur’s, we can see that they were big and strong and beautiful creatures and they were even pretty intelligent. They occupied environments all over the planet – on land and sea and air, and they ruled the world for more than 100 million years… BUT they didn’t have telescopes and they didn’t have a space program.

“If some day in the future we discover well in advance that an asteroid that is big enough to cause a mass extinction is going to hit the Earth, and then we alter the course of that asteroid so that it does not hit us, it will be one of the most important accomplishments in all of history…” –U.S. Congressman George Brown (1993)

Perhaps asteroids are nature’s way of checking on the robustness of our space program!

About the Asteroid Grand Challenge
Curious about the NASA Asteroid Grand Challenge to “discover all asteroids that could threaten human populations and find out how to deal with them”? NASA is sponsoring a series of virtual seminars on the properties of Near Earth Asteroids (NEAs) and what is being done to learn more about the hazards and the opportunities they may pose for us here on Earth. The purpose is to inform interested astronomers (both amateur and professional), students, teachers, and others who are potentially interested in contributing to studies of NEAs.

Each seminar will focus on some aspect of the asteroid population, how we discover and track NEAs, and what we need to know about them if we are ever required to change the orbit of a NEA that is an impact threat.

The seminar format will be a 40-minute talk by an asteroid expert followed by 20 minutes for questions from the audience. They will be broadcast over the Internet. The audience will watch, listen and post questions by Adobe Connect using an Internet connection and a web browser.

The seminars will be held on the second and fourth Fridays of each month at 11:00 am Eastern time, which will allow live audience participation over most of the United States, Europe, and Africa.

The schedule for the first five seminars is as follows:

- Feb 14 David Morrison (NASA Ames & SSERVI):
History of impacts research and planetary defense

- Feb 28 Lindley Johnson (NASA Headquarters):
NASA’s NEA programs

- Mar 14 Paul Chodas (NEO Program Office at JPL):
NEA discovery, orbit calculation and impact probability assessment

- Mar 28 Alan Harris (JPL retired):
NEA populations and impact frequency

- Apr 11 Dan Britt (University of Central Florida):
Physical properties of NEAs

If there is sufficient interest, the virtual seminar series will continue with talks on asteroid deflection strategies, the new International Warning Network, characterizing hazardous asteroids, radar studies of NEA orbits and surfaces, and finding destinations for robotic and human missions to asteroids.

This virtual seminar series is sponsored by the NASA Asteroid Grand Challenge (AGC) Office, in collaboration with the NASA Near Earth Object Observations (NEOO) Program and the NASA Solar System Exploration Research Virtual Institute (SSERVI).

How to Join
This seminar series can be viewed online by clicking here, or by going to the following URL:


Please “Enter as a Guest” and use your full name. Audio will be heard through your computer speakers, while questions will be accepted in the room’s chat window. If you have any technical difficulties or questions, please contact one of our Technical Systems Specialists: [Ricky Guest] or [Ashcon Nejad]

System requirements for viewing this seminar series are:
1. An up-to-date web browser (e.g. Safari, Firefox, Internet Explorer).
2. The latest version of Adobe Flash Player [Click here for the latest version]

Posted by: Soderman/SSERVI staff

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