NRC Hazardous NEO Mitigation Panel Meeting June 23-25, 2009, Woods Hole, Massachusetts

1. NRC Hazardous NEO Mitigation Panel MeetingJune 23-25, 2009, Woods Hole, Massachusetts Notes on our presentation and areas for further research (D. Hyland, June 26,2009)

2. Committee to Review Near-Earth Object Surveys and Hazard Mitigation Strategies – Mitigation Panel • Meeting Agenda: • June 23: • 8:30-12:00 noon: Closed session • 1:00 pm: Mitigation Proposal from Texas A&M – David Hyland, Texas A&M • 2:00 pm: NEODESYS Mitigation (via teleconference) – Brian Pitchford, Special Aerospace Services • 3:00 pm - 6:00 pm: Break and closed session • 6:00 pm - 8:00 pm: Dinner

3. Meeting Agenda, Continued • June 24: • 8:30 am- 10:15am: Closed session and break • International efforts on Near Earth Objects (via videoconference): Richard Crowther, UN COPUOS • Don Quijote (videoconference): Andres Galvez, ESA • 12:15 pm – 2:30 pm: Working Lunch and Closed session • 2:30 pm: International legal issues (teleconference): Frans von der Dunk, Univ. of Nebraska • 3:30 pm: Break • 3:45 pm: Disaster Management (videoconference): Karlene Roberts, U. C. Berkeley • 5:00 pm – 5:15 pm: Closed Session • June 25: • 8:30 am – 12:30 pm: Closed Session

4. Feedback on our proposal – Before Our Presentation (during lunch) • NRC Program Officer directing the study (Paul Jackson): • “Your proposal was the most coherent we received” • “In fact, it was viewed favorably, not only by the Hazard Mitigation panel, to whom you submitted, but also by the NEO Surveys Panel and even by the overall coordinating panel.” • One of the panelists: • “We see this as a very elegant solution.”

5. Next: Let me show you what I actually presented!

6. Q & A During the 1 Hr Presentation Period • I finished the presentation in 35 minutes (some slides were “hidden” – i.e., skipped over – but still retained in the PowerPoint file) • There were many questions (see next slides) – most of which I was able to put to rest. A few of the questions can’t be answered without further research (again, see below). There were some comments that were good suggestions for further work • At the end of the day, I (really AAA) got unanimous congratulations on a job well done – even from the two panelists who were strong and open advocates for the kinetic impactor approach. • I gave Paul Jackson a copy of the full presentation and promised we would deliver our Design Report to the Panel.

7. Reception of the Only Other Mitigation Technical Presentation • After our presentation, I was allowed to view the second presentation. • This was submitted by a company selling their kinetic impactor idea (having a rocket collide with Apophis). Their hardware cost alone was over $350M. • What was especially irritating to the panel was that whenever he was pressed for details (e.g., how much delta-V his rocket delivered to the asteroid), he would claim it was company-proprietary and refuse to answer. • The presenter was so slow, unconvincing and condescending that one panelist spoke out in a load voice: “Hey, you’re not talking to a bunch of grad students here. There’s really smart people in this room and we know what will and what won’t work. Not only that, you’re more than half-way through your time, but no where near half through your slides. Skip ahead and cut to the chase!” • …and cut to the chase he was forced to do. So much so, that his whole session was finished 15 minutes early. I used this time to continue talking about our proposal!

8. Substantive Questions/Comments During Our Presentation • Panelist: You do everything before 2029. I don’t think the public would buy this because they would fear that what you do might push Apophis into the keyhole and thus cause disaster. You should launch after 2029. • DCH: Our premier rule is “Do no harm”, and our process has many off-ramps. If we are just slightly uncertain about an orbit deflection technique, we refrain from implementing it. The degree of certainty is TBD by the community. • DCH: Suppose that we launch as proposed and we find that the keyhole will not be penetrated and we decide to do no mitigation. Then we still have an excellent exploration mission that resolves the orbit prediction uncertainties we have discussed in this presentation. On the other hand, what if the keyhole is pierced? Then our proposed system still has the means (at very little additional expense and with enough time) to forestall impact. How would the public react if they found we had no mitigation technique ready or we decided to launch after 2029?

9. Substantive Questions/Comments During Our Presentation - Continued 2) Panelist: Many of these asteroids are oblong and rotate rapidly – almost to the break-apart rate. So, at the end lobes, the net centripetal attraction is negative. How can your ACP deposition work in that case? • DCH: The primary mechanism in our deposition scheme is to ionize the ACPs and rely on (much stronger) electrostatic attraction to the sunlit surface. Of course, once the ACPs meet the surface the charge distributions are shorted out. However, we have asked our chemist (Dr. Rao) to design ACP materials that are adhere to the (relatively hot) sunlit regolith surface. So: Electrostatic attraction delivers the ACPs to the surface and chemical adhesion binds them.

10. Substantive Questions/Comments During Our Presentation - Continued 3) You have not taken account of surface roughness in determining how much ACPs you will need – because, when deposited on regolith, some ACPs will fall between the cracks and get hidden in the crevices. • Suggestion: Do a simple lab experiment. Try spray painting a box of sand, and see how much paint is required to get the same albedo change as on a flat surface. • One panelist said that JPL did a study that showed that of the NEOs that had highest probability of impacting Earth, very few of them would exhibit a sequence of close approaches prior to impact. • Relevance to our proposal is that we get much of the final orbit deflection by virtue of the magnifying effect of the 2029 encounter. • Implication: If most NEOs don’t have close-approaches before impact, then slow-push methods are irrelevant and one must use the kinetic impact method.

11. Response to Question 3 • The sandbox experiment is a good idea – let’s do it. • However, we must take account of the differential charging of the asteroid surface and the interaction with descending, negatively charged ACPs. • Solar wind ions and electrons flow onto the surface as two charging currents. • Solar UV and soft X-rays stimulate electron emission from sunlit surfaces by the photoelectric effect. • Electric resistivity of chondritic asteroids are > 1016-cm. • Result: sunlit areas are raised to positive potentials while shadowed areas accrete electrons and acquire negative potentials • Hypothesis: When traveling toward the surface, negatively charged ACPs are attracted to the sunlit rock surfaces and avoid the shadowed interstices and crevices. • If true, this means that the efficiency of the ACPs to change albedo is closer to what is achieved by deposition onto a flat surface, rather than a rough surface. • The proviso is that the cone angle of the spray nozzle should be slightly larger so as to give more diffuse deposition. This prevents the ACPs from clumping onto the sunlit faces.

12. Response to Question 4 • I found the JPL report alluded to:D.K. Yeomans, S. Bhaskaran, S.B. Broschart, S.R. Chesley, P.W. Chodas, T. H. Sweetser, “Deflecting a Hazardous Near-Earth Object”, 1st IAA Planetary Defense Conference: Protecting Earth from Asteroids, 27-30 April 2009, Granada, Spain • Very brief description, very little detail • Of the 990 NEOs considered over 30% of the population passes within 10 lunar distances during the 50-year interval prior to supposed impact, and about 4% of the population has keyholes with widths narrower than about 15 km. • Does not account for orbit prediciton uncertainties discussed by Giorgini et al. How many of the “impactors” will actually impact? • We will not be harmed by the “average” NEO, but by the one NEO that impacts. The one the “gets us” could well be an exceptional case (one of the 4%). Moreover, Apophis is the nearest-term case with some probability of impact. • Large uncertainties in KE method mean you have to have a second spacecraft to collect science data to provide terminal guidance • Our proposed mission: $350M (test Grav Tr & Yarkovski) • Our proposed sc plus impactor sc: >$1010M (test 3 methods)

13. Response to the Broader Implications of Question 4 • Question 4 was launched by an obvious advocate of the kinetic impactor approach. • This appears to be a strong faction – consisting of disappointed nuclear advocates ( no one now advocates the nuclear options) • We need to re-examine the impactor method. • The JPL report admits it’s risky. You have to know a lot about the asteroid to prevent the impactor from kicking up debris that escapes and carries away significant linear momentum. • Otherwise, there could be significant V errors. • We need to do simulations/calculations that examine this question. • If the above suspicions are verified, we need to get the word out ASAP. • If the impactor idea can be made to work, then we need to assimilate it. We don’t care which methods we use as long as we are the ones to do it!!

14. The Tasks Ahead • Press release needed on NRC announcement • We must finish the AEMP design report! • Follow-ons to the NRC Meeting • We still need to concentrate on the albedo change technology • Design, build, perform sandbox experiment • Build simulation of KE impact method – estimate risk • Help prepare the Lunar and NEO Science Institute charter – Mainly DCH, but help needed from the whole team. • We must begin the design of the albedo change flight experiment – and continuously provide inputs for the above tasks. • This could be the topic for Fall ’09 426. We need graduate student advisors. • We need to recruit more students! • We must generate two papers for the Malta conference. (a side trip to Dubai anyone?)

15. Tasks/Organization • Albedo change technology (ACT) – includes sandbox experiment • Justin Lopez (1) • Xiaoli Bai (1) • Julie Sandberg (4) • Neha Satak (3) • Zack Levin • Amrish Deep • KE Method study - Xiaoli • Woods Hole presentation • Comments on draft solicited from all. Need to finalize by Friday • Lunar & NEO Science Institute Definition • Julie Sandberg (1) • Xiaoli Bai (2) • Neha Satak (2) • Richard Margulieux • LEO Flight Demo of ACT • Neha Satak (1) • Julie Sandberg (3) • Zack Levin • Amrish Deep • Richard Margulieux • Justin Lopez • Paper writing for Malta conference • Xiaoli Bai (2) • Julie Sandberg (2) • Richard Margulieux • All of the above: Brian Young, Justin Doyle, Shen Ge