“Finding Them Early is NOT Enough” — Professor Joel Marks on Asteroid Detection

I’ve gotten a lot of nice emails from fans of the Last Policeman books, but most of them are not from people who have spent years studying the fascinating (and terrifying) real science of asteroids. I couldn’t resist asking Professor Joel Marks to contribute to my Reverse Blog Tour

Here’s his bio: 

“Joel Marks is professor emeritus of philosophy at the University of New Haven, a Bioethics Center Scholar at Yale University, and an amateur astronomer. His Website is www.docsoc.com. He wishes to express his indebtedness to the GaiaShield Website athttp://gaiashield.com/two.htmlHe also notes that this is the twentieth anniversary of his having seen with his own eyeballs Comet Shoemaker-Levy 9 striking the planet Jupiter.”

And now here’s the professor: 


UNH Faculty and Staff Portraits April 11, 2012Aside from being a page-turning thriller of detective and science fiction, Ben Winters’Last Policeman trilogy is a case study of a very real threat. What is that threat? It may seem obvious that I am referring to Armageddon by asteroid. But that is not quite what I have in mind. I think Winters’ tale points us to a crucial gap in humanity’s current preparations for planetary defense. For despite extraordinary gains in recent decades in our knowledge of what space rocks could do to us and of their near-Earth population, we are wedded to a strategy that guarantees failure sooner or later.

The strategy I am talking about is usually attributed to Donald Yeomans, NASA/JPL, to wit: “There are only three ways to increase our chances against an asteroid aimed at Earth: ‘Find it early; find it early; find it early’.”  The reasoning behind this seems straightforward enough, although it contains several components. One (alluded to in Winters’ books) is that just blowing up an incoming rock of sufficient size to do us serious damage is not likely to help matters; in place of one monster rock we might just end up with several humongous rocks, with total worldwide damage the same. Another part of the argument is that we would need to know the specifics of an incoming object – composition, speed, direction, etc. – in order to be able to counter it. But most important: Whatever known technologies we could employ would require a great deal of advance warning to apply to the threat at hand: not just months but years, decades, possibly even a century. The widely touted gravity tractor, for instance, could only nudge a Mount Everest size object a teeny bit per year into an orbit that would eventually bypass the Earth.

Nevertheless there is optimism in the planetary defense community because the vast majority of large near-Earth objects have already been discovered and none of them is on course to collide with the Earth in the next century. But here is where the reasoning becomes flawed: doubly so. First is that one of those small-minority-not-yet-discovered rocks could turn out to have our name on it. The other is that a completely different kind of threat could suddenly appear: a comet targeting Earth. (The doomsday object in Winters’ trilogy is really an amalgam of these two, as the 75-year orbit of his asteroid is more suggestive of a short-period comet. However, my main concern is long-period comets.)

The asteroid 253 Mathilde.

Yeomans and everyone else working to protect us know this. But they have reasons for acting as if these were not pressing concerns. As regards asteroids: Projects like B612’s Sentinel space telescope may soon reveal all of the current crop of NEOs. (Please donate to the B612 Foundation to help make this a reality.)  As regards comets: They are much rarer than asteroids in the inner solar system where we reside, and their early detection would require a far more extensive undertaking than anything contemplated or budgetarily feasible in the current political climate.

The problem with this reasoning, however, is that the apparition of a comet is a completely random event, and so its statistical rarity does not tell that the next one won’t happen for millions of years. It could happen tomorrow. And once a comet does appear and enter the domain of near-Earth objects, it will be too late to do anything about it, because, unlike asteroids, which have fairly circular orbits around the Sun, comets coming from beyond Neptune have highly eccentric orbits that assure a much quicker closing time with our planet. In his 2013 book Near-Earth Objects: Finding Them before They Find Us, Yeomans tells us that a comet discovered at the typical distance of Jupiter’s orbit could reach us in nine months. And as if called to order, Comet C/2013 A1 (Siding Spring), discovered only in January of last year and originally thought to be dinosaur-killer size, will narrowly miss colliding with Mars this coming October (on the 19th, not the 3rd!!). Had it been heading towards Earth instead, we could be living The Last Policeman.

Comet image from the Jet Propulsion Lab.

What to do? I see two implications: (1) “Find it early” needs to be reconceived to encompass comets as well as asteroids, thereby requiring a greatly enhanced detectioninfrastructure; and (2) “Find it early” needs to be understood as a necessary but not a sufficient means of planetary defense, since we must also begin development and deployment of a deflection infrastructure prior to detecting (“finding”) the next killer comet.But all of that will take money, which in turn will require political will, which in turn will require an informed electorate, and, in general, a greater sense of urgency about the threat. And surely one way to instill that urgency will be to encourage the widest possible circulation of books like the Last Policeman trilogy, for they show that “Find it early” is worse than useless advice if there is nothing you can do about “it” once you’ve found it!


Thank you so much, Professor Marks! I wholeheartedly agree, as I do with any scientific hypothesis that leads to more people reading my books. I also heartily second the suggestion to donate to the B612 Foundation; Rusty Schweickart, a former astronaut and one of the founders of that organization, was hugely helpful to me in writing The Last Policeman.


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1 comment

  1. I agree wholeheartedly with this analysis. It explains why we need to get out to Mars-like-distances within a month or two…..with nuclear explosive equipped rockets that can impart a momentum change (by ablating a thin layer of one side of the object), thereby causing a course change….deflection. To do this requires better rocket engines…faster ones. This means restarting the old nuclear fission engine capability NOW (for a factor of 2x speed boost), and for the long term, working on 20x faster nuclear fusion engines.

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