Re: Hitomi: evidence of more than one debris-shedding

From: George Herbert via Seesat-l <>
Date: Sat, 2 Apr 2016 11:09:32 -0700
That almost matches my estimate of center of mass to end of extensible boom distance, about ten meters.

One point - dynamically, if you have a tethered mass less than main mass, spinning together, and release/break tether, it will carry away angular momentum and slow down main object spin.  So roughly, given that release velocity, 9.5 meter orig CG to boom instruments distance, it would be spinning say 30% faster, 3.7 or so sec/rev, 16 vs 11 RPM, then the separation would slow the main body down to about 11.

This is totally BOTE, if I have time later will try and get actual main body CG and boom instruments masses.

George William Herbert
Sent from my iPhone

> On Apr 2, 2016, at 10:49 AM, Ted Molczan via Seesat-l <> wrote:
> Conjunction analyses between Hitomi (16012A / 41337) and the first two TLEs of 16012K / 41441, reveal that the two
> objects separated on 2016 Mar 26 around 02:35 UTC to 02:45 UTC. That was about one hour later than JSpOC's initial
> estimate of the time of the debris-shedding: 01:42 UTC +/- 11 min. Several of the other fragments appear to have
> separated from Hitomi in the vicinity of 01:42 UTC; therefore, the later time of 16012K's separation is evidence of more
> than one debris-shedding event.
> 16012K separated when Hitomi happenned to be close to the perigee of its 568 X 584 orbit. 16012K is in a 533 X 570
> orbit, differing from Hitomi in argument of perigee by very roughly 180 deg, with minimal planar differences; therefore,
> it was ejected in approximately opposite the direction of Hitomi's motion, at a relative velocity of roughly 14 m/s.
> Assuming Hitomi was tumbling, then it seems possible for 16012K to have been flung off of it due to the rotation. Based
> on Brad Young's observation on Apr 02 UTC that Hitomi was flashing with a period of 2.589 s, I estimated that its period
> of rotation was about 5.2 s. With that period, an object about 11.6 m from the axis of rotation would have a speed of 14
> m/s.
> Ted Molczan
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