[meteorite-list] Asteroid may be set to slam Mars in Jan.

From: Göran Axelsson <axelsson_at_meteoritecentral.com>
Date: Fri, 21 Dec 2007 22:31:09 +0100
Message-ID: <476C309D.9080201_at_acc.umu.se>

Big foot in mouth... Well, I only managed to prove my inability to
understand orbital calculations. It is of course easier to measure speed
and position orthogonally to the plane of the planet system.

Thanks for giving the necessary explanation to kick my brain in the
right orbit.

:-)

Regards, G?ran

lebofsky at lpl.arizona.edu wrote:
> Hi G?ran:
>
> It is all in the timing. If I remember correctly, when orbits are
> calculated, the greatest uncertainty is in the time of perihelion passage
> (where it is in its orbit). So, while they know the inclination of the
> orbit (where it will be when it crosses the orbit of Mars), the greatest
> question is will Mars still be there (or not there yet). That is the
> greatest uncertainty.
>
> With a better orbit (and better timing), the untertainty goes down and so
> the "target ellipse" gets smaller. When it is big, there is a greater
> likelihood that Mars will be in it. When the ellipse gets smaller, the
> likelihood is that Mars will not be in it.
>
> Larry
>
> On Fri, December 21, 2007 1:13 am, G?ran Axelsson wrote:
>
>> "Scientists say the object currently has a 1-in-75 chance of colliding
>> with the planet, but that probability is expected to go down over the next
>> month as more observations are made."
>>
>> Let me guess... it has a 74 in 75 probability to go down and 1 in 75
>> chance to go up?
>>
>> I'm always amused over this formulation. It always appears like a
>> reassuring message, "Don't worry, it will go away."
>>
>> "If the asteroid does smash into Mars, it'll likely aim near the
>> equator, ..." What? They don't know if it will hit, but if it hit Mars it
>> will do it near the equator. Is this a statistical centre of where it will
>> hit because the equator lies halfway between the poles.
>>
>> Okay, maybe the error in the predicted orbit is really small and just
>> overlaps Mars at one side of the planet....
>>
>> Anyhow, a really interesting scenario and I hope I will be able to see a
>> major impact on Mars with my own eyes through the big telescope in the
>> local observatory.
>>
>> /G?ran
>>
>>
>> tracy latimer wrote:
>>
>>> http://www.msnbc.msn.com/id/22350742/
>>>
>>>
>>> Watch the skies! We may be getting (okay a LONG time down the road)
>>> more Martian meteorites...:)
>>>
>>> Tracy Latimer
>>>
>>>
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>
Received on Fri 21 Dec 2007 04:31:09 PM PST