[meteorite-list] Large (future) impact
From: Matson, Robert <ROBERT.D.MATSON_at_meteoritecentral.com>
Date: Thu Apr 22 10:31:29 2004 Message-ID: <AF564D2B9D91D411B9FE00508BF1C86904EE59FD_at_US-Torrance.mail.saic.com> This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. ------_=_NextPart_001_01C3FD75.5216961E Content-Type: text/plain; charset="iso-8859-1" Hi All, A couple inputs on the future-large-impact subject. Dirk Ross opined: > NO GOVERNMENT in its right mind would give advance warning even > if scientists do detect the object in time. Whether the "government" chose to provide advance warning or not, nearly everyone with a computer would know, and thus I feel confident that most governments WOULD make a formal statement, if only for fear of being accused of withholding information that could have saved lives. How would everyone with a computer know? Because there are a large enough number of amateurs with good equipment that are perfectly capable of making asteroid measurements themselves and computing orbits, and they are not the sort of people that would keep quiet about it. When a suspected NEO is detected and its astrometric measurements are sent to the Minor Planet Center, a preliminary orbit is computed and quickly made publically available on the NEO Confirmation Page. This is to facilitate recovery of the object by other observers with the goal of improving the accuracy of the orbital solution. Naturally, the more measurements you have from different locations, and the longer period of time those measurements span, the better the solution. If it turns out that impact is only a few days to a week away, it won't take long to compute a fairly accurate time and location of impact. This knowledge can definitely save lives, just as a tornado or hurricane warning can. On the subject of the aftermath of a large impact -- specifically the duration of "nuclear winter", Stan wrote: > "In the event of a large impact, we would need to build an enclosure that > protects food crops from the environment, and provides an alternate source > of energy to the crops. Rice isn't going to grow if the sun is blacked out for > 1000 years because of a comet induced nuclear winter." An impact that doesn't kill everyone and everything within hours should not have effects lasting anywhere near that long. Months to a few years, I would guess, depending on the size and velocity of the impactor. It's a very difficult thing to estimate since the only contemporary, large energy releasing events we have to compare to are many orders of magnitude smaller in energy. Krakatoa's four explosions on August 27, 1883, for instance, are estimated to have released the energy equivalent of around 200 megatons of TNT. They gave us red sunsets for more than a year and lowered global temperatures as much as 1.2 C. The only modern events that can provide some insight were the Shoemaker- Levy 9 impacts on Jupiter. The 2- or 3-km diameter G-fragment hit with the energy of 6 billion megatons (30 million times the energy of Krakatoa!) The black spots from these impacts are long gone, but perhaps there are other still measurable effects from these impacts today. (Anyone?) --Rob ------_=_NextPart_001_01C3FD75.5216961E Content-Type: text/html; charset="iso-8859-1" <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1"> <META content="MSHTML 6.00.2800.1106" name=GENERATOR></HEAD> <BODY> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>Hi All,</FONT></SPAN></DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2></FONT></SPAN> </DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>A couple inputs on the future-large-impact subject. Dirk Ross opined:</FONT></SPAN></DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2></FONT></SPAN> </DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>> </FONT></SPAN>NO GOVERNMENT in its right mind would give advance warning even<SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2> </FONT></SPAN></DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>></FONT></SPAN> if scientists do detect the object in time.<SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2> </FONT></SPAN></DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2></FONT></SPAN> </DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>Whether the "government" chose to provide advance warning or not, nearly</FONT></SPAN></DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>everyone with a computer would know, and thus I feel confident that most</FONT></SPAN></DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>governments WOULD make a formal statement, if only for fear of being</FONT></SPAN></DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>accused </FONT></SPAN><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>of withholding information that could have saved lives. How would</FONT></SPAN></DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>everyone </FONT></SPAN><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>with a computer know? Because there are a large enough number</FONT></SPAN></DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>of </FONT></SPAN><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>amateurs with good equipment that are perfectly capable of making</FONT></SPAN></DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>asteroid </FONT></SPAN><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>measurements themselves and computing orbits, and they are</FONT></SPAN></DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>not the sort </FONT></SPAN><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>of people that would keep quiet about it.</FONT></SPAN></DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2></FONT></SPAN> </DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>When a suspected NEO </FONT></SPAN><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>is </FONT></SPAN><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>detected and its astrometric measurements are</FONT></SPAN></DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>sent to the Minor Planet </FONT></SPAN><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>Center, a preliminary orbit is computed and quickly</FONT></SPAN></DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>made publically available on the NEO Confirmation Page. </FONT></SPAN><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>This is to facilitate</FONT></SPAN></DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>recovery of the object by other </FONT></SPAN><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>observers with the goal of improving the</FONT></SPAN></DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>accuracy of the orbital solution. Naturally, the more measurements you</FONT></SPAN></DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>have from </FONT></SPAN><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>different locations, and the longer period of time those measurements</FONT></SPAN></DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>span, the better the solution. If it turns out that impact is only a few days to</FONT></SPAN></DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>a week away, it won't take long to compute a fairly accurate time and location</FONT></SPAN></DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>of impact. This knowledge can definitely save lives, just as a tornado or</FONT></SPAN></DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>hurricane warning can.</FONT></SPAN></DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2></FONT></SPAN> </DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>On the subject of the aftermath of a large impact -- specifically the duration of</FONT></SPAN></DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>"nuclear winter", Stan wrote:</FONT></SPAN></DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2></FONT></SPAN> </DIV> <DIV><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>> "</SPAN><SPAN class=054433319-27022004>In the event of a large impact, we would need to build an enclosure that</SPAN></FONT></FONT></FONT></DIV> <DIV><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>> protects</SPAN></FONT></FONT></FONT><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2> food crops from the environment, and provides an alternate source</FONT></SPAN></DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>> of energy to</FONT></SPAN><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2> the crops. Rice isn't going to grow if the sun is blacked out for</FONT></SPAN></DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>> 1000 years because</FONT></SPAN><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2> of a comet induced nuclear winter."</FONT></SPAN></DIV> <DIV><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004><FONT face=Arial size=2></FONT></SPAN></FONT></FONT></FONT> </DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>An impact that doesn't kill everyone and everything within hours should not</FONT></SPAN></DIV> <DIV><SPAN class=054433319-27022004><FONT face=Arial color=#0000ff size=2>have </FONT></SPAN><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>effects lasting </SPAN><SPAN class=054433319-27022004>anywhere near that long. Months to a few years, I would</SPAN></FONT></FONT></FONT></DIV> <DIV><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>guess, </SPAN></FONT></FONT></FONT><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>depending on the size and velocity of the impactor. It's a very difficult</SPAN></FONT></FONT></FONT></DIV> <DIV><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>thing </SPAN></FONT></FONT></FONT><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>to estimate since the only contemporary, large energy releasing events</SPAN></FONT></FONT></FONT></DIV> <DIV><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>we have to compare to are many orders of magnitude smaller in energy.</SPAN></FONT></FONT></FONT></DIV> <DIV><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>Krakatoa's </SPAN></FONT></FONT></FONT><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>four explosions on August 27, 1883, </SPAN></FONT></FONT></FONT><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>for instance, are estimated</SPAN></FONT></FONT></FONT></DIV> <DIV><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>to have released </SPAN></FONT></FONT></FONT><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>the </SPAN></FONT></FONT></FONT><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>energy equivalent of around </SPAN></FONT></FONT></FONT><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>200 megatons of TNT. They</SPAN></FONT></FONT></FONT></DIV> <DIV><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>gave us </SPAN></FONT></FONT></FONT><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>red sunsets </SPAN></FONT></FONT></FONT><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>for more than a year and lowered global temperatures as</SPAN></FONT></FONT></FONT></DIV> <DIV><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>much </SPAN></FONT></FONT></FONT><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>as 1.2 C.</SPAN></FONT></FONT></FONT></DIV> <DIV><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004></SPAN></FONT></FONT></FONT> </DIV> <DIV><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>Th</SPAN></FONT></FONT></FONT><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>e only modern events that can provide some insight were the </SPAN></FONT></FONT></FONT><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>Shoemaker-</SPAN></FONT></FONT></FONT></DIV> <DIV><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>Levy 9 impacts on </SPAN></FONT></FONT></FONT><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>Jupiter. The 2- or 3-km diameter G-fragment hit with the</SPAN></FONT></FONT></FONT></DIV> <DIV><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>energy of 6 billion </SPAN></FONT></FONT></FONT><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>megatons (30 million </SPAN></FONT></FONT></FONT><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>times the energy of Krakatoa!) The</SPAN></FONT></FONT></FONT></DIV> <DIV><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>black spots from these </SPAN></FONT></FONT></FONT><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>impacts are long gone, but perhaps there are other</SPAN></FONT></FONT></FONT></DIV> <DIV><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>still </SPAN></FONT></FONT></FONT><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>measurable effects from these </SPAN></FONT></FONT></FONT><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>impacts today. (Anyone?)</SPAN></FONT></FONT></FONT></DIV> <DIV><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004></SPAN></FONT></FONT></FONT> </DIV> <DIV><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004>--Rob</SPAN></FONT></FONT></FONT></DIV> <DIV><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN class=054433319-27022004></SPAN></FONT></FONT></FONT> </DIV></BODY></HTML> ------_=_NextPart_001_01C3FD75.5216961E-- Received on Fri 27 Feb 2004 04:04:42 PM PST |
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