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Rusty Schweickart, Tuesday, 5-1-12 May 2, 2012

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Rusty Schweickart, Tuesday, 5-1-12


Guest:  Rusty Schweickart.   Topics:  Planetary Defense, NEO deflection.  You are invited to comment, ask questions, and discuss the Space Show program/guest(s) on the Space Show blog, https://thespaceshow.wordpress.com. Comments, questions, and any discussion must be relevant and applicable to Space Show programming. Transcripts of Space Show programs are not permitted without prior written consent from The Space Show (even if for personal use) & are a violation of the Space Show copyright. We welcomed back Rusty Schweickart to update us on the latest with planetary defense and NEO risk assessment.  Rusty started our discussion with an examining of the asteroid 2011 AG5 which if it goes through the keyhole in 2023, would be likely to hit Earth in 2040.  During much of this first segment, our guest explained asteroid orbital issues, the keyhole and why it is so important to understand it, Earth’s gravity impact on NEOs, and the different deflection techniques.  He talked about the need for a dual mission which would include an observer satellite plus the kinetic impact deflector.  The observer satellite would be needed to confirm the hit and if the deflection was sufficient to miss the keyhole.  He estimated the cost for such a mission from $500 million to a billion or more!  We also learned that the keyhole for AG5 is about 300 KM wide and that is a much easier deflection than trying to do it once AG5 goes through the keyhole. Then we would be looking at a deflection roughly equal to the Earth’s diameter of 20,000 km which is a much harder deflection to accomplish requiring significantly more energy and costs.  Other issues talked about in this segment included the state of our existing technology to accomplish a deflection, the risks associated with AG5, the issue of who pays for the cost of such a mission, the role of a heavy lift launcher in deflection, and asteroid finding space telescopes.

In our second segment, we talked about different scenarios for deflection and the cost of deflection compared to the cost of an evacuation of people from the impact zone.  Rusty talked about knowing the impact zone and why we can evaluate this much further in advance of impact than when working with space debris.  A listener asked about using a nuclear bomb in space for mitigation. Rusty took us through the nuclear analysis and when as a last resort, a nuke might be needed.  In this analysis, he again went over the kinetic impact and then talked about the gravity tractor concept which he said was slow but very precise.  In his analysis, he used an interesting analogy to baseball, pitching the fastball, & the point at which the batter must act given the speed of the ball.  Don’t miss it.  We talked more on telescopes and he mentioned the University of Hawaii ATLAS project (www.fallingstar.com). Another important point discussed in this segment was the fact that NASA has no official responsibility to protect us from a hit.  We talked about the consequences of this policy, changing the policy to officially give NASA this responsibility, and funding it through the budget process.  During our discussion, Rust outlined several steps that listeners could take if interested in this issue.  Rusty offered specific recommendations all of us could do that would be beneficial to planetary defense.

Please post your comments/questions on The Space Show blog.  If you want to send Rusty a note, please do so through me.



1. Alistair - May 10, 2012

Good show.

Only nit I have is the portrayal of the risk. There are two aspects to assessing any hazard, the probability AND the severity. Thus, something that is relatively low risk (e.g. 1 in 500), should not be dismissed purely because it is low risk; given the consequences of an impact over even this smallish asteroid, the consequences can be quite high. Thus the overall risk would be considered medium. Similarly, a high probability, low consequence hazard is also medium (albeit on the low end). Typical risk matrices are 4×4 -> 5×5.
This concept was sort of implied, but not really explicit in the discussion on the show.

Regardless, it was a good show. Wish I could have listened live and called in.

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