Re: USA 193 debris situation

From: Robert Holdsworth (robbonz1@xtra.co.nz)
Date: Sun Mar 02 2008 - 17:50:39 UTC

  • Next message: David Brierley: "DMB Obs March 2 a.m."

    I note that at this stage neither the ATV nor the shuttle have been delayed, 
    even though something the size of a football at orbital speeds would 
    literally appear to literally have a significant impact :-)
    
    That is probably as far as I can go without sliding OT re that comparison 
    but you can draw your own conclusions.   Suffice it to say that I have been 
    hit by volleyball at non orbital speeds and it was not a pleasant 
    experience!  (although it is accepted that for decaying pieces it probably 
    means that  they are not of significant size.)
    
    I have commented earlier on the particular interest for this region there 
    will be for the ATV launch assuming it does go ahead, more on this later 
    assuming launch remains on schedule.
    
    Robert
    
    
    
    ----- Original Message ----- 
    From: "Ted Molczan" <ssl2molcz@rogers.com>
    To: <seesat-l@satobs.org>
    Sent: Monday, March 03, 2008 4:26 AM
    Subject: USA 193 debris situation
    
    
    > Of the less than 3,000 fragments of USA 193 reportedly detected by US 
    > STRATCOM,
    > the vast majority should have decayed within hours or a few days of the
    > intercept on 2008 Feb 21 UTC. To my knowledge, the total number remaining 
    > in
    > orbit has not been published; my guess is that it does not exceed a few 
    > hundred,
    > and could well be much less.
    >
    > Dr. T.S. Kelso has made decay predictions, as plotted near the bottom of 
    > the
    > following page:
    >
    > http://celestrak.com/events/usa-193.asp
    >
    > Dr. Kelso's 20 cm plot is similar to results I have obtained using Satevo 
    > v0.51.
    > Basically, most of the remaining debris will decay by the end of March.
    >
    > As far as I can tell, the debris situation is unfolding much as I 
    > described soon
    > after plans to intercept USA 193 were announced:
    >
    > http://satobs.org/seesat/Feb-2008/0256.html
    >
    > As has been reported on the list, NROL-28 is being delayed due to concerns 
    > about
    > the USA 193 debris. This was the NRO's statement, issued on Feb 27:
    >
    > "The NRO will postpone its launch of mission NROL-28 approximately two 
    > weeks as
    > a precautionary move to avoid possible debris from the NRO experimental
    > satellite which was intercepted last Wednesday, 20 Feb 2008. When 
    > established,
    > the revised date will be posted."
    >
    > Some may see this as an indication that the orbital debris situation is 
    > more
    > severe than the public is being told; however, my intuition is that it is 
    > simply
    > caution on the part of those managing the launch. As shown in Dr. Kelso's
    > analysis, at least half of the debris now in orbit will decay within two 
    > weeks.
    > Also, the remaining debris will have spread out over a planar swath some 
    > 2.5
    > times wider than at present. So, there would much less debris, spread much 
    > more
    > thinly.
    >
    > Another possibility is that it was taking longer than expected to complete 
    > the
    > orbital analysis of the USA 193 debris, resulting in less complete and/or
    > confident collision-avoidance analyses than required, hence the decision 
    > to
    > delay the launch.
    >
    > The delay may seem overly cautious, given the small number of fragments 
    > likely
    > remaining in orbit, but not unusually so, given the well known phenomenon 
    > of
    > bureaucratic CYA. Absent strong evidence to the contrary, I prefer this
    > interpretation over more dramatic ones.
    >
    > Ted Molczan
    >
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