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Re: {MPML} Asteroid 2012 DA14

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  • Alan W Harris
    Somehow, the criterion of whether or not an asteroid will pass inside of the the geosynchronous satellite distance captures the imagination of the public and
    Message 1 of 12 , Mar 26 12:02 PM
      Somehow, the criterion of whether or not an asteroid will pass inside of
      the the geosynchronous satellite distance captures the imagination of the
      public and the press, I suppose out of worry that such an asteroid might
      plow into one of the satellites stationed at that distance. This is an
      utterly stupid red herring, however. Not only are the odds astronomically
      small, but a rock the size of a marble would be quite sufficient to kill a
      satellite; it doesn't take a rock bigger than the satellite. Marble-sized
      rocks pass within geosynchronous distance at a rate of about once per
      second -- around 100,000 per day (I actually worked that out roughly). So
      yes, there is a meteoroid hazard to satellites, but it comes overwhelmingly
      from the marbles, not the mountains.

      At 11:39 PM 3/25/2012, Jean Meeus wrote:
      >As is well-known, asteroid 2012 DA14, discovered on 2012 Feb 23,
      >will pass close to the Earth on 2013 Feb 15.
      >A few days after its discovery, based on an observed arc of only
      >7 days, the minimum distance to the Earth's center on 2013 Feb 15
      >was calculated to be 0.0001873 AU, yielding a least distance of
      >about 21642 kilometers to the Earth's surface, bringing the object
      >closer to the Earth than the geostationary satellites.
      >Five days later, based on an observed 12-day arc, the distance to the
      >Earth's center was revised to 0.0003149 AU, or 40730 kilometers to
      >the surface.
      >And now, with an observed arc of 30 days, those numbers are revised to
      >0.0004653 AU and 63230 km, so the object will remain well OUTSIDE the
      >orbits of the geostationary satellites.
      >
      >(Numbers given in the "List of close approaches" of the Minor Planet
      >Center).
      >
      >Jean Meeus
      >
      >
      >[Non-text portions of this message have been removed]
      >
      >
      >
      >------------------------------------
      >
      >~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      >
      >Posts to this list or information found within may be freely used, with
      >the stipulation that MPML and the originating author are cited as the
      >source of the information.Yahoo! Groups Links
      >
      >
      >
      *****************************************************************************
      Alan Harris Phone: 818-790-8291
      4603 Orange Knoll Ave.
      La Cañada, CA 91011-3364
      email: harrisaw@...
      *****************************************************************************
    • amaury@spaceobs.com
      Jean s message reminds us too that this field is the only scientific (or is it ?) field where people publish things on lousy data. Most real scientists would
      Message 2 of 12 , Mar 26 1:02 PM
        Jean's message reminds us too that this field is the only scientific
        (or is it ?) field where people publish things on lousy data. Most
        real scientists would wait till they have good data before publishing...
        In fact it's so scary :), they should think of some kind of other
        italian city scale, Padua scale ? for the incredible risks we have of
        loosing valuable satellites :)
        Alain


        Alan W Harris <harrisaw@...> a écrit :

        > Somehow, the criterion of whether or not an asteroid will pass inside of
        > the the geosynchronous satellite distance captures the imagination of the
        > public and the press, I suppose out of worry that such an asteroid might
        > plow into one of the satellites stationed at that distance. This is an
        > utterly stupid red herring, however. Not only are the odds astronomically
        > small, but a rock the size of a marble would be quite sufficient to kill a
        > satellite; it doesn't take a rock bigger than the satellite. Marble-sized
        > rocks pass within geosynchronous distance at a rate of about once per
        > second -- around 100,000 per day (I actually worked that out roughly). So
        > yes, there is a meteoroid hazard to satellites, but it comes overwhelmingly
        > from the marbles, not the mountains.
        >
        > At 11:39 PM 3/25/2012, Jean Meeus wrote:
        >> As is well-known, asteroid 2012 DA14, discovered on 2012 Feb 23,
        >> will pass close to the Earth on 2013 Feb 15.
        >> A few days after its discovery, based on an observed arc of only
        >> 7 days, the minimum distance to the Earth's center on 2013 Feb 15
        >> was calculated to be 0.0001873 AU, yielding a least distance of
        >> about 21642 kilometers to the Earth's surface, bringing the object
        >> closer to the Earth than the geostationary satellites.
        >> Five days later, based on an observed 12-day arc, the distance to the
        >> Earth's center was revised to 0.0003149 AU, or 40730 kilometers to
        >> the surface.
        >> And now, with an observed arc of 30 days, those numbers are revised to
        >> 0.0004653 AU and 63230 km, so the object will remain well OUTSIDE the
        >> orbits of the geostationary satellites.
        >>
        >> (Numbers given in the "List of close approaches" of the Minor Planet
        >> Center).
        >>
        >> Jean Meeus
        >>
        >>
        >> [Non-text portions of this message have been removed]
        >>
        >>
        >>
        >> ------------------------------------
        >>
        >> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        >>
        >> Posts to this list or information found within may be freely used, with
        >> the stipulation that MPML and the originating author are cited as the
        >> source of the information.Yahoo! Groups Links
        >>
        >>
        >>
        > *****************************************************************************
        > Alan Harris Phone: 818-790-8291
        > 4603 Orange Knoll Ave.
        > La Cañada, CA 91011-3364
        > email: harrisaw@...
        > *****************************************************************************
        >
        >
      • Gerald McKeegan
        Alan, I m not sure that the possibility of satellite destruction is the main reason for public & media fascination with asteroids coming closer that
        Message 3 of 12 , Mar 26 1:07 PM
          Alan,

          I'm not sure that the possibility of satellite destruction is the main reason for public & media fascination with asteroids coming closer that geosynchronous satellites, although that it is certainly a factor. In my experiences when talking with the public and media about asteroid close approaches, the sense I get is that they see the geosynchronous orbit distance as a sort of arbitrary boundary between "close" and "REALLY close." Most people seem to recognize that, in astronomical terms, satellites orbiting the Earth, even geosynchronous ones, are pretty close. So when you tell them an asteroid will pass closer to the Earth than geosynchronous satellites, it seems to heighten their sense that we're really dodging a bullet if it comes that close and still misses us. There is no question that it's completely arbitrary, but it's something the public and media can relate to.

          Gerald


          -----Original Message-----
          >From: Alan W Harris <harrisaw@...>
          >Sent: Mar 26, 2012 12:02 PM
          >To: Jean Meeus <jmeeus@...>, MPML <mpml@yahoogroups.com>
          >Subject: Re: {MPML} Asteroid 2012 DA14
          >
          >Somehow, the criterion of whether or not an asteroid will pass inside of
          >the the geosynchronous satellite distance captures the imagination of the
          >public and the press, I suppose out of worry that such an asteroid might
          >plow into one of the satellites stationed at that distance. This is an
          >utterly stupid red herring, however. Not only are the odds astronomically
          >small, but a rock the size of a marble would be quite sufficient to kill a
          >satellite; it doesn't take a rock bigger than the satellite. Marble-sized
          >rocks pass within geosynchronous distance at a rate of about once per
          >second -- around 100,000 per day (I actually worked that out roughly). So
          >yes, there is a meteoroid hazard to satellites, but it comes overwhelmingly
          >from the marbles, not the mountains.
          >
          >At 11:39 PM 3/25/2012, Jean Meeus wrote:
          >>As is well-known, asteroid 2012 DA14, discovered on 2012 Feb 23,
          >>will pass close to the Earth on 2013 Feb 15.
          >>A few days after its discovery, based on an observed arc of only
          >>7 days, the minimum distance to the Earth's center on 2013 Feb 15
          >>was calculated to be 0.0001873 AU, yielding a least distance of
          >>about 21642 kilometers to the Earth's surface, bringing the object
          >>closer to the Earth than the geostationary satellites.
          >>Five days later, based on an observed 12-day arc, the distance to the
          >>Earth's center was revised to 0.0003149 AU, or 40730 kilometers to
          >>the surface.
          >>And now, with an observed arc of 30 days, those numbers are revised to
          >>0.0004653 AU and 63230 km, so the object will remain well OUTSIDE the
          >>orbits of the geostationary satellites.
          >>
          >>(Numbers given in the "List of close approaches" of the Minor Planet
          >>Center).
          >>
          >>Jean Meeus
          >>
          >>
          >>[Non-text portions of this message have been removed]
          >>
          >>
          >>
          >>------------------------------------
          >>
          >>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          >>
          >>Posts to this list or information found within may be freely used, with
          >>the stipulation that MPML and the originating author are cited as the
          >>source of the information.Yahoo! Groups Links
          >>
          >>
          >>
          >*****************************************************************************
          >Alan Harris Phone: 818-790-8291
          >4603 Orange Knoll Ave.
          >La Cañada, CA 91011-3364
          >email: harrisaw@...
          >*****************************************************************************
          >
          >
          >
          >------------------------------------
          >
          >~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          >
          >Posts to this list or information found within may be freely used, with the stipulation that MPML and the originating author are cited as the source of the information.Yahoo! Groups Links
          >
          >
          >
        • Alan W Harris
          Well, when it was announced that Apophis would pass closer than geosynchronous distance from the Earth, there was enough media feather-fluffing that JPL saw
          Message 4 of 12 , Mar 26 1:37 PM
            Well, when it was announced that Apophis would pass "closer than
            geosynchronous distance" from the Earth, there was enough media
            feather-fluffing that JPL saw fit to issue a press release to point out
            that while the path could take it closer than geosynchronous distance, it
            would be far out of the Earth's equatorial plane at that distance and that
            it would actually pass through the equatorial plane, where the
            geosynchronous satellites reside, well outside of the geosynchronous
            distance. That seemed to put an end to the brouhaha, which as I noted in
            my first message, was an utter and total red herring right from the
            start. About 5,000 equally deadly (to satellites) "NEAs" (of the marble
            size) have passed by that close since I sent my last message an hour and a
            half ago.

            At 01:07 PM 3/26/2012, Gerald McKeegan wrote:
            >Alan,
            >
            >I'm not sure that the possibility of satellite destruction is the main
            >reason for public & media fascination with asteroids coming closer that
            >geosynchronous satellites, although that it is certainly a factor. In my
            >experiences when talking with the public and media about asteroid close
            >approaches, the sense I get is that they see the geosynchronous orbit
            >distance as a sort of arbitrary boundary between "close" and "REALLY
            >close." Most people seem to recognize that, in astronomical terms,
            >satellites orbiting the Earth, even geosynchronous ones, are pretty
            >close. So when you tell them an asteroid will pass closer to the Earth
            >than geosynchronous satellites, it seems to heighten their sense that
            >we're really dodging a bullet if it comes that close and still misses
            >us. There is no question that it's completely arbitrary, but it's
            >something the public and media can relate to.
            >
            >Gerald

            *****************************************************************************
            Alan Harris Phone: 818-790-8291
            4603 Orange Knoll Ave.
            La Cañada, CA 91011-3364
            email: harrisaw@...
            *****************************************************************************
          • Robert Warren
            Sirs,I agree with you about how the distance of an asteroids passage, such as Apophis or any other especially if that distance is at the geosync orbits is not
            Message 5 of 12 , Mar 27 6:49 AM
              Sirs,I agree with you about how the distance of an asteroids passage, such as Apophis or any other especially if that distance is at the geosync orbits is not anything to really worry about. However, I must point out one simple fact. Most of the people involved in astronomy, and more specifically asteroidal studies tend to associate with others of like mind and training, and experience. Out in the real world though, most average people even Americans, know next to nothing about miss distances, or orbital mechanics, or asteroids and comets. If you walk any street in America and carried a sign saying that you were an astronomer, most of the people would ask you about their horoscopes, not about the science. So most people are more concerned in their daily lives with paying the bills, having a roof over their heads, driving while texting or on their cell phone, and a million other seemingly mundane things that never even comes close to science. Most of those people have no comprehension as to what a scientist does for a living. Most of those people still think that when we sent man to the Moon that we were sending tons of money to the Moon, without understanding that the money involved had been spent right here on the Earth to buy raw materials, pay workers, pay for studies on how to do things, and to ay for the hardware and the fuels. That is why many people are still complaining that we should spend the money here on the Earth to solve the social problems, or to creat jobs. But that is exactly what the money was being spent on, jobs for the people who designed and built the rockets and spacecraft that went to the moon. That meant those people were spending that money out on the economy. So many people on the streets do not think about that. It is the same way with any close approaching asteroid. They don't think about what 22,000 miles means. They are thinking in terms of how a passage through the geosync belt might disrupt their monday night football because maybe the satellites would have their orbits disrupted, which is still a possiblity if any object with a gravitational field of its own passed close to or through the geosync belt.I knows many people who just llve to look at and admire the photos taken of deep space objects by the Hubble Telescope, but they all turn around and complain about the waste of the money being spent on space research. Most people simply do not care about educating themselves into what is really going on, or what might happen and what the ramifications are if something like a close passage did occur. That my friends is the real world out here.
              respectfully,


              Bob
              To: geraldspace@...
              CC: mpml@yahoogroups.com
              From: harrisaw@...
              Date: Mon, 26 Mar 2012 13:37:54 -0700
              Subject: Re: {MPML} Asteroid 2012 DA14




























              Well, when it was announced that Apophis would pass "closer than

              geosynchronous distance" from the Earth, there was enough media

              feather-fluffing that JPL saw fit to issue a press release to point out

              that while the path could take it closer than geosynchronous distance, it

              would be far out of the Earth's equatorial plane at that distance and that

              it would actually pass through the equatorial plane, where the

              geosynchronous satellites reside, well outside of the geosynchronous

              distance. That seemed to put an end to the brouhaha, which as I noted in

              my first message, was an utter and total red herring right from the

              start. About 5,000 equally deadly (to satellites) "NEAs" (of the marble

              size) have passed by that close since I sent my last message an hour and a

              half ago.



              At 01:07 PM 3/26/2012, Gerald McKeegan wrote:

              >Alan,

              >

              >I'm not sure that the possibility of satellite destruction is the main

              >reason for public & media fascination with asteroids coming closer that

              >geosynchronous satellites, although that it is certainly a factor. In my

              >experiences when talking with the public and media about asteroid close

              >approaches, the sense I get is that they see the geosynchronous orbit

              >distance as a sort of arbitrary boundary between "close" and "REALLY

              >close." Most people seem to recognize that, in astronomical terms,

              >satellites orbiting the Earth, even geosynchronous ones, are pretty

              >close. So when you tell them an asteroid will pass closer to the Earth

              >than geosynchronous satellites, it seems to heighten their sense that

              >we're really dodging a bullet if it comes that close and still misses

              >us. There is no question that it's completely arbitrary, but it's

              >something the public and media can relate to.

              >

              >Gerald



              *****************************************************************************

              Alan Harris Phone: 818-790-8291

              4603 Orange Knoll Ave.

              La Ca�ada, CA 91011-3364

              email: harrisaw@...

              *****************************************************************************


















              [Non-text portions of this message have been removed]
            • Jean Meeus
              How close will asteroid 2012 DA14 approach the Earth on 2013 February 13? It is interesting to look at the values given by the Minor Planet Center in its list
              Message 6 of 12 , Apr 13, 2012
                How close will asteroid 2012 DA14 approach the Earth on
                2013 February 13? It is interesting to look at the values
                given by the Minor Planet Center in its list of "Forthcoming
                Close Approaches To The Earth". The second column gives the
                least distance to the CENTER of the Earth in astronomical units,
                while the last column gives the least distance to the SURFACE
                of the Earth in kilometers.

                Observed
                arc (days)

                7 0.0001973 23138
                7 1873 21642
                10 3429 44919
                11 2285 27805
                12 3149 40730
                30 4653 63230
                35 5374 74016
                37 4835 65953
                49 3166 40985

                Jean Meeus


                [Non-text portions of this message have been removed]
              • Jaime Nomen
                ... As not an expert on orbital computation and risk asssestment I can only try to imagine which would be our uncertainty knowledge and when would be the
                Message 7 of 12 , Apr 14, 2012
                  >How close will asteroid 2012 DA14 approach the Earth on
                  >2013 February 13? It is interesting to look at the values

                  As not an expert on orbital
                  computation and risk asssestment
                  I can only try to imagine which would
                  be our uncertainty knowledge and
                  when would be the last posssible
                  prediction and how accurate, if an
                  object/orbit very similar to 2012 DA14
                  would have some real chances
                  to hit the Earth , instead of miss more or
                  less close to us. It is a real case...
                  We are at 10 months it comes back,
                  and mangitude is fading every day
                  (last possibility for new astrometry maybe will
                  be along this current dark run...?)...
                  and then wait... until?
                  According MPC ephemeris for one month before
                  of the closest date 2013 feb 15, the object would
                  be at -68º declination and mag 23.9, one
                  week later, on 2013 Jan 22 at magnitde 23.5
                  and still at -68º declination, but moon
                  will be close to full. Which telescope at these
                  low latitudes is able to spot it there with such
                  a big moon ... Moon that will be reaching full on
                  Jan 27th.

                  It seems to me that the object would not
                  be recovered before 10 days - 1 week it closest
                  date, so the uncertainty until the end...?

                  Jaime




                  [Non-text portions of this message have been removed]
                • Aldo Vitagliano
                  ... Although the stretching of the uncertainty on the position of 2012DA14 at the date of the close approach is quite bigger of the predicted nominal
                  Message 8 of 12 , Apr 14, 2012
                    --- In mpml@yahoogroups.com, "Jaime Nomen" <jnomen@...> wrote:
                    >
                    > >How close will asteroid 2012 DA14 approach the Earth on
                    > >2013 February 13? It is interesting to look at the values
                    >
                    > As not an expert on orbital
                    > computation and risk asssestment
                    > I can only try to imagine which would
                    > be our uncertainty knowledge and
                    > when would be the last posssible
                    > prediction and how accurate, if an
                    > object/orbit very similar to 2012 DA14
                    > would have some real chances
                    > to hit the Earth ...

                    Although the "stretching" of the uncertainty on the position of 2012DA14 at the date of the close approach is quite bigger of the predicted nominal distance, the chance that it might hit Earth is zero, due to the "trail shape" of the cloud representing the uncertainty.

                    The linked figure is a view of the approach, with the point of view set on Jupiter, because in this view the miss is clearly seen.

                    http://www.webalice.it/alvitagl/Figures/DA14_app.gif

                    Regards
                    Aldo Vitagliano
                  • Jaime Nomen
                    Dear Aldo, Thanks a lot to let us see this clearing chart. My question was more referred to the hypothetical case of a very similar object/orbit/observing
                    Message 9 of 12 , Apr 14, 2012
                      Dear Aldo,
                      Thanks a lot to let us see this clearing chart.
                      My question was more referred to the "hypothetical" case
                      of a very similar object/orbit/observing circumstances
                      but with some chances to hit us.. and how, how much
                      and when, given the limited future observing window could be
                      possible to discart a so close 10 months impact for a such similar
                      object as 2012 DA14 according the same uncertainty that it seems
                      could remain for it from now (this dark run) until maybe only 10 days to
                      one week before it comes again and should be recovered. In such
                      hypothetical scenario I guess would not require (by size) / allow
                      (by uncertainty?-time a head?) to delimit any regional evacuation/
                      prevention (tsunamis etc) in case of confirmed Earth impact, but
                      when, if so, and where if all the same but only few more meters
                      across.

                      Jaime

                      _____

                      De: mpml@yahoogroups.com [mailto:mpml@yahoogroups.com] En nombre de Aldo
                      Vitagliano
                      Enviado el: Saturday, April 14, 2012 13:56
                      Para: mpml@yahoogroups.com
                      Asunto: {MPML} Re: Asteroid 2012 DA14






                      --- In mpml@yahoogroups.com <mailto:mpml%40yahoogroups.com> , "Jaime Nomen"
                      <jnomen@...> wrote:
                      >
                      > >How close will asteroid 2012 DA14 approach the Earth on
                      > >2013 February 13? It is interesting to look at the values
                      >
                      > As not an expert on orbital
                      > computation and risk asssestment
                      > I can only try to imagine which would
                      > be our uncertainty knowledge and
                      > when would be the last posssible
                      > prediction and how accurate, if an
                      > object/orbit very similar to 2012 DA14
                      > would have some real chances
                      > to hit the Earth ...

                      Although the "stretching" of the uncertainty on the position of 2012DA14 at the
                      date of the close approach is quite bigger of the predicted nominal distance,
                      the chance that it might hit Earth is zero, due to the "trail shape" of the
                      cloud representing the uncertainty.

                      The linked figure is a view of the approach, with the point of view set on
                      Jupiter, because in this view the miss is clearly seen.

                      http://www.webalice.it/alvitagl/Figures/DA14_app.gif

                      Regards
                      Aldo Vitagliano






                      [Non-text portions of this message have been removed]
                    • Aldo Vitagliano
                      ... Probably there won t be much to do, except that perhaps a bigger object would be less faint and could be tracked for a longer time ... However in such a
                      Message 10 of 12 , Apr 14, 2012
                        --- In mpml@yahoogroups.com, "Jaime Nomen" <jnomen@...> wrote:
                        >
                        > Dear Aldo,
                        > Thanks a lot to let us see this clearing chart.
                        > My question was more referred to the "hypothetical" case
                        > of a very similar object/orbit/observing circumstances
                        > but with some chances to hit us.. and how, how much
                        > and when, given the limited future observing window could be
                        > possible to discart a so close 10 months impact for a such similar
                        > object as 2012 DA14 according the same uncertainty that it seems
                        > could remain for it from now (this dark run) until maybe only 10
                        > days to one week before it comes again and should be recovered.


                        Probably there won't be much to do, except that perhaps a bigger object would be less faint and could be tracked for a longer time ...

                        However in such a case it should be possible to know 10 months in advance in which narrow geographic "corridor" the object might hit ...

                        I dealed with this subject in a recent article about 2011 AG5 written for an italian amatorial astronomy webmagazine:
                        http://www.eanweb.com/2012/2011-ag5-a-dangerous-course-correction/

                        Aldo
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