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Making Sure We Don't Get Hit

By Keith Cowing
NASA Watch
March 27, 2012
Filed under , ,

Evacuation? Surely we can do better!, B612 Foundation
“The other day we had a couple of small asteroids narrowly miss hitting the Earth, and we only discovered them about a day before they flew by. This is actually a fairly common occurrence (and these particular asteroids are like most of these cases quite small and relatively harmless). But consider what would happen if a larger asteroid like the one that hit Tunguska in 1908 was found to be on a collision course just a day or so ahead of impact. Our only option would be to evacuate the impact area.”

NASA Watch founder, Explorers Club Fellow, ex-NASA, Away Teams, Journalist, Space & Astrobiology, Lapsed climber.

22 responses to “Making Sure We Don't Get Hit”

  1. Hallie Wright says:
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    Smart and rational comments from a respected organization. Wonderful to see this advocacy for better detection, instead of a reflexive plea for human visits to NEOs to achieve some measure of asteroid defense. Go to one to mine it, to colonize it, or to just plant a flag on it, but don’t tell me that visit to a random asteroid is going to tell me what I need to know to defend myself against that other one that’s aimed at me.

  2. DTARS says:
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     The B612 Foundation pleading for money to do something that should have been done years ago or be first on the to do plate. Shame Jwst can’t find these dangerous rocks. I know lets use asteroid fear to spend tons of money to soak Mr. and Ms.tax payer again!
    A very important project that like cheaper lift to LEO should be first  priority.

    doesn’t take a rocket scientistt

  3. Joe Cooper says:
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    Why spend money up there when we’ll have asteroids to study down here?

  4. Anonymous says:
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    It should be noted that the Large Synoptic Survey Telescope (LSST), one of whose science missions is to detect NEO’s, is already under construction.  
    With a fast, 3.2GByte camera and a relatively wide field of view, LSST will image approximately the entire visible (to the telescope) night sky every 3 days with the ability to resolve small, dim objects much farther away than we can now.  Best of all, data from LSST will be available to the public virtually immediately.  LSST will image from the NUV to the NIR.  It may not be the best possible solution, but it will much better than what we have now by at least 2 orders of magnitude.

    It’s not necessary to employ fear mongering, and I don’t think it is being employed by the astronomy community at all.  We have a geological record that tells us that the odds of a significant NEO impact on Earth are not negligible.  We now, however, have what no one else had when Tunguska hit in 1908 or what other living creatures had before impact caused mass extinction events: we have the technology to try to do something about it.

    It should be noted that the B612 Foundation is not “soaking Mr. and Ms. tax payer again.”  Their site plainly states they are looking for donations.  Alleging as much is as misguided as fear mongering is.  It is possible to have more than one priority, and that’s certainly the case with NEO detection and manned space flight.  They are not mutually exclusive.   It does not take a rocket scientist or an astronomer to see that.  If we do keep up the invective or non-constructive dialogue (as we see our government doing), we can guarantee that neither priority gets done.

    • DTARS says:
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      PsiSquared
      Thanks for the facts. I did not mean to Allege any fear mongering, But I am wondering why the B612 foundation should  need to look for donations? Seems a program as important as this shouldn’t be wanting of money?
      Should we have a vehicle always in orbit or built and ready to launch to devert any small or medium size NEOs?

      You are Right of course Richard.

      But I’m glad my comment got some facts out of Mr. PsiSquared

      • Paul Roberts says:
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        >>Should we have a vehicle always in orbit or built and ready to launch to devert any small or medium size NEOs?

        I’m afraid that today we can’t have such a spacecraft on call because we don’t know how to divert anything big enough to cause trouble. The ones that are dangerous, even the least dangerous of the ones that might cause a very few deaths on Earth are in the 10s of meters in diameter (smaller ones break up high in the atmosphere & little debris gets through to the ground) and are too massive for anything we could currently launch and fly to them to have any effect with the currently known technologies. There are lots of ideas, but none of them has been tried even once. We, as a species, have only visited a couple asteroids and have actually touched only one.

        Before you can divert something you have to know a fair amount about it. Things like how much force can you put on it, how can you control it, will you spin it rather than nudge it, etc. All with spacecraft that today, by the time they get to a reachable asteroid, are generally only the size of a large chest freezer with very little fuel.

        I’m not saying it’s not a very good use of NASA money, but we have to realise that an actual plan to create an asteroid deflection capability would cost a LOT of money, require the development of new technologies, require visits to many asteroids to gather target data and take a very long time, decades at even accellerated funding levels.

        “Armageddon” we can’t do.

        Paul

    • erinleeryan says:
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      Excuse me? LSST, while advocated in the last Decadal Survey yet again, is no where near being started on construction (and in fact can’t be constructed until ALMA is finished as NSF only has so much money). The LSST plan as it currently stands *does not* do UV, nor NIR, as they only plan to use the Sloan set of filters (~3543 to ~9134 Angstroms) and the filter coverage will not be consistent across the sky. The moving object program which encompasses Near Earth Asteroids, asteroids in the main belt, and commets is effectively doomed to failure as the current SciBook for LSST still states that only 2 epochs of data for any sky position will be obtained each night- only 2 epochs of data is insufficent to derive predictive orbital tracklets, as the Pan-STARRS team learned in one very painful way (yet the LSST has not updated the observing strategy, and those of us who do solar system which have tried to join the LSST collaboration during the “open calls” via NOAO have been told to take a long walk off a short pier). God help us if any of the projected paths along the sky goes across the galactic plane as well as that as been defined as a zone of avoidance for LSST due to saturation concerns, which is also total science fail when it comes to monitoring potential supernova progenitors or possible extreme variable sources.

      The B612 strategy is more useful than LSST data, as they’ll be using mid-IR data in addition to optical which will allow them to actually constrain the geometric albedos and *diameters* of asteroids, something you can’t just do with optical data. Yes, you can use a mean geometric albedo and optical magnitude to estimate a diameter, but you can also be off by a factor of 4 in terms of diameter which is not so insignificant, especially given that it means your mass can be off by a factor 64!

      • Hallie Wright says:
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        Agreed. LSST is very good, but hardly the godsend to asteroid mitigation efforts. What B612 is advocating, which is a well thought out strategy, is an IR telescope in a Venus orbit. The advantage of that over LSST is manyfold. (1) sensitivity to dangerous objects, and (2) effective observation at 1AU, which is not quite “night sky” to LSST. A WISE-like system might be optimal, though ideally with a longer cryogenic lifetime. As noted, a shared facility for this work is also hardly optimal. The money for LSST would largely come from NSF astronomy, so asteroid detection will inevitably not be a high priority in system design and definition.

    • Stuart J. Gray says:
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       Well I happen to know about one proposal to make a Kepler-like spacecraft with IR capability in a Venus-like orbit.

      This would allow the spacecraft to look outward for NEOs in Earth crossing and/or trojan orbits.

      This would allow us to find objects that are difficult or impossible to see from the surface of the Earth.
      Lets just hope the (private) funding surfaces……

  5. Andrew_M_Swallow says:
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    Do we have sufficient information to estimate how much danger we are in?

    What statistical curve does size V. frequency of NEO follow?  Normal?  Poisson?  Non-random?

    • erinleeryan says:
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      If you ignore things that fall prey to observing completeness at the moment, the size-frequency distribution of asteroids (all of them including the NEAs) is an inverse power-law as a function of size- effectively more rocks the smaller you get.

      • Andrew_M_Swallow says:
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        Thank you.   The good old 80-20 rule.
        <url>

      • erinleeryan says:
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        Yes, so part of the problem is whose power law do you believe. The ones based on optical data are nice, but how bright things are in optical light is both a function of surface reflectance and diameter. If you only have optical data, the error bars on the diameter are pretty awful and then mass mis-estimates will totally bite you in the backside when it comes to planetary defense. Infrared is better, but the wavelengths we’d want to use are also where the atmosphere is opaque, so trying to do this with ground based telescopes is really a lost cause in those wavelengths.

        • Andrew_M_Swallow says:
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           It may be the power law of things that actually hit the Earth.  Meteors that do not cross Earth orbit are not a danger.

          Different rules may apply to spacecraft.

  6. Delta_v says:
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    B612 is seeking donations because like many other small nonprofits with important missions, they don’t get the benefit of feeding at the government trough. 

    Andrew: ASE did a study on this very question: you can read our report Asteroid Threats: A Call for Global Response. Not sure if Keith will let me post the link, but the report is here: http://www.space-explorers….
    (click through to the ATACGR tab).

  7. dogstar29 says:
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    Does Spitzer have any capability to spot NEO’s in infrared?

    • erinleeryan says:
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      Spitzer did, however in it’s current warm mission only the 3.5 and 4.5 micron channels are available and those are really insufficent for thermal model fitting to derive accurate diameters and albedos. . . .unless we test some theories, but thus far the science review panels have been less than warm to such proposals.

  8. DTARS says:
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    Paul
    “All with spacecraft that today, by the time they get to a reachable asteroid, are generally only the size of a large chest freezer with very little fuel.
    I’m not saying it’s not a very good use of NASA money, but we have to realise that an actual plan to create an asteroid deflection capability would cost a LOT of money, require the development of new technologies, require visits to many asteroids to gather target data and take a very long time, decades at even accellerated funding levels.
    “Armageddon” we can’t do.”
    SOOO
    If we had a plan to build an inner solar system railroad which got fuel depots up into space and we had robot spaceships that could leave leo with FUEL. Building that space capablity plus better asteroid mapping could very possiblity save earth from a few disasters in the future, Likely tsunami s I’m guessing.
     
    old adage
     
    An ounce of prevention is worth a pound of cure.
     
    Joe Tax Payer