Re: [Fwd: [AR] First Torrino Scale 2 object...]

Sean R. Lynch wrote:

> Donald Qualls wrote:
>
>> David Weinshenker wrote:
>>
>>>> From arocket... -dw
>>>
>>>
>>>
>>> Paul Breed wrote:
>>>
>>>> http://neo.jpl.nasa.gov/risk/
>>>>
>>
>> That's a very low velocity object with a small estimated diameter -- 
>> I wonder if it isn't another "lost" upper stage that's been in an 
>> almost-congruent orbit for a long time and just now getting 
>> synchronized again enough to come close.  The white paint on those 
>> rocket stages makes them look much, much larger than they are if you 
>> have an assumption they're almost black like a chondrite asteroid.
>>
> I've started running the orbit backwards. I've found a close encounter 
> on April 15, 1998 so far. I'll keep going.

I should have mentioned that the 1998-04-15 encounter was 0.11 AU, not 
all that close. Here are the other close encounters I've found:

0.11 AU (42.8 Rmoon) 1998-04-15 (Lunar Prospector 1998-01-07)
0.0585 AU (22.8 Rmoon) 1985-12-22  (Giotto 1985-07-02)
0.116 AU (45.1 Rmoon) 1975-04-15
0.185 AU (72.0 Rmoon) 1973-12-22 (Mariner 10 1973-10-03)
0.0731 AU (28.4 Rmoon) 1967-03-31 (Venera 4? When was that launched?)
0.113 AU (44.0 Rmoon) 1959-01-26 (Luna-1 1959-01-02)

I worked from <http://my.execpc.com/~culp/space/timeline.html>. There 
may be more complete lists.

I would say that Lunar Prospector is practically out of the question 
because a 0.11 AU error that recent doesn't make sense. Giotto 
<http://sci.esa.int/science-e/www/area/index.cfm?fareaid=15> seems 
pretty plausible. Venera 4, being 37 years ago with a fairly close 
approach, and Luna 1, being so close in date to the date of the 
approach, also seem like candidates.

Someone who knows more about orbital mechanics will have to check my 
work here  :)

Perhaps I should port orbfit to Python and write an integrator in Pyrex :)

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