Rusty Schweickart & NEOShield Tweetup Transcript
Our co-founder and Chair Emeritus Rusty Schweickart was on hand to answer questions about asteroids, deflection and Sentinel. Here’s a transcript of the conversation. (Note: minor editing for punctuation, clarity/spelling and inclusion of names only.)
NEO (via Nick Howe @NickAstronomer): So much emphasis on asteroids, yet comets present a much bigger threat potentially. What realistically could humanity do given say a 1 year time from detection to impact, which could be a real scenario, for a 10+km wide comet?
Rusty: Not much… but comets are only 1% or less of the overall threat… so we are handling what we can deal with. Comets are also very difficult to track accurately since they outgas, etc. So we deal with the threat we can, which just happens to be 99% of it!
NEO (via Remco Timmermans @timmermansr): Is there a difference between asteroid and comet deflection methods? Or will any method serve both threats?
Rusty: Orbital mechanics is orbital mechanics… what applies to asteroids also applies to comets. However, that said, comets (long period comets anyway) come in from very far out in the solar system and therefore have much higher velocity. Plus we only detect them very late… so the deflection challenge is HUGE in comparison.
NEO (via Skip Morrow @skip_morrow): Is it just me or are we having more reported meteorite reportings this year? Maybe I am just paying more attention.
Rusty: It may not be you that is just now paying attention… the media is between you and reality. But the flux of NEOs is pretty constant… it’s just our knowledge of them that is improving. And the media is paying more attention, especially since Chelyabinsk.
NEO via Tom Hill on Facebook: Could a spacecraft stationed at Earth-Sun L1 provide constant monitoring and warning for Chelyabinsk(sp?)-style impactors?
Rusty: Good question. There is some looking at that as a potential last minute warning system for those small objects heading for impact “out of the Sun.” The L1 vantage point is interesting in that regard, but it would not give much warning.
NEO (via Jason Major @JPMajor): What are your thoughts on 1950 DA, which supposedly could impact Earth in 2880?
Rusty: We have to keep watching it. The question is what happens to the impact probability as we get better and better tracking of it over time. This is the monitoring process after we have discovered an NEO.
NEO (via Kyle @Stormdesk): With the high Fireball activity of late, is there anyway way to issue an advisory of such conditions? Been very active recently.
Rusty: Not really. Fireballs, by definition, are objects already coming through the atmosphere. That’s too late… and they are really too small to see before they get to the atmosphere.
Except, of course, when we happen to get very lucky, such as the case with 2008 TC3… a 3-4 meter object that we happen to see in space ~19 hours prior to impact. That one we tracked for a few hours and then predicted exactly when, where it would hit… and it did! And we then picked up bits & pieces on the desert floor (Sudan) afterward.
NEO (via Molly @MollyDenmark): Although they aren’t linked, what implications does NASA’s shutdown have on B612′s asteroid detection plans?
Rusty: The “system” that will actually enable us to pick up about half of the small objects just prior to impact (days, weeks) is called ATLAS… and NASA is now providing funding for its development. However that will not enable deflection… only last minute evacuation for those objects that it finds that are large enough to do harm.
None. B612 is independent of NASA… although if we were in operation with Sentinel now, then NASA tracking would be important.
We’re still in the design/build phase of Sentinel.
NEO (via Remco Timmermans @timmermansr): How will the @B612foundation Sentinel spacecraft help us detect asteroids earlier? When should it launch?
Rusty: Sentinel is designed to discover NEOs in their orbits around the sun… the total population.
We then calculate exact orbits for them and predict ahead for 100 years to see if there is an Earth impact. ATLAS only looks for those that are literally “on final approach” to an impact and provides a last minute warning…not a forecast of impact way ahead.
NEO (via Nick Howe @NickAstronomer): Would gov’t/space agencies sanction/use a last minute nuke strike if we only had days/hours notice as last resort?
Rusty: I hope not!! Such a bad idea could be much more likely to cause harm than save lives.
NEO (via @AsteroidInitiatives): Do you have any insight as to what ROSATOM and the US DOE are planning RE asteroid protection?
Rusty: To my knowledge they’re doing no planning. DOE has not been very much involved.
Los Alamos National Lab has been looking at the potential use of nukes for deflection, and they have been involved for some time. The current thinking is that nukes would be used only for cases where all other (benign) methods would not work.
NEO (via Leo @leot123): How accurate are NEO orbit calcs now? What level of confidence is needed before deflection attempt?
Rusty: Orbit accuracy is dependent on the level of tracking. If we’ve seen the NEO for many apparitions it is excellent. If only for a short period, pretty poor.
The level of confidence will have to be high to justify initiating a deflection campaign. This is why we need to “find ‘em early, find em early, find ‘em early!”
NEO (via SANEAlex @SANEAlex1): Could any of our existing satellites be quickly re-purposed to sacrifice themselves against city killer threats if time short?
Rusty: Not likely. They would have to already be in the exactly right orbit. No existing satellites have the capability to make large orbital changes… let alone intercepts!
The most efficient, and likely of success, would be to launch from the ground… with decades of early warning… you need to think predictions decades ahead of impact.
Last minute warning, a la ATLAS (or equivalent) is good for evacuation… not deflection. Deflection requires long early warning times… which is entirely possible and our primary effort.
NEO (via Nick Howe @NickAstronomer): Question for Rusty. Does @B612foundation excite you more or as much as your work on Apollo/Skylab?
Rusty: My work on NEOs is far more significant, in the long run. Apollo and Skylab were great experiences for me personally, but my NEO work may really save many, many lives… ultimately.
NEO via Tom Hill on Facebook: So the warning time would be dependent on the viewing angle around Earth and the minimum size visible would be dependent on the sensitivity of the IR detectors?
Rusty: RE warning time: think two separate strategies… completely separate. 1. find NEOs circling the sun and predict 100 years ahead, 2. look for NEOs just about to impact Earth and evacuate the impact zone.
And yes, minimum size visible (for an IR space telescope) depends on several factors… in addition to the sensitivity of the detectors… including size, temperature, and proximity.
NEO (via Matthias Carter @matthiascarter): What do you see as the biggest challenge; scientific/technical hurdles or convincing the public of genuine threat of NEOs?
Rusty: Excellent question! Interesting after Chelyabinsk. My thought is that the public does believe it to be a threat.
Rusty: OK… final thought. Based on the questions I think people need to understand that this is primarily an issue of looking ahead… decades… in order to prevent really serious calamities.
Yes, we can also put some effort into looking for only the last minute (overwhelmingly small) objects about to hit… and evacuate. But the really important issue is preventing the impact of city and nation killers… not just Chelyabinsk objects. Those take mapping ALL of the NEOs out there… that’s Sentinel’s VERY important job.
NEO: Thank you for your time, truly appreciate working with you and for all your support with NEOShield.