Definitive proof would be given by telescope observations. This page shows images by a 1 meter scope of Mir and ISS at around 400 km altitude: Gallery - Artificial Satellites. http://www.tsm.toyama.toyama.jp/curators/aroom/satellite/index.htm These space stations are around 30 to 40 meters wide at their widest dimensions. So at 2000 km altitude and 1/5th the size, the object in question would appear 1/25th the size of the stations in these images. You could probably resolve its shape. Of course a 2 meter scope could do better. Bob Clark --- Ted Molczan <molczanssl@rogers.com> wrote: > Robert Clark asked: > > > My reading of the discussion on the "Misty" type > satellites > > suggests they are difficult to track visually. > > So how are these orbital elements so accurately > determined > > to the degree that the amount of orbital decay > they are > > experiencing can be determined? > > The object in question is readily tracked because is > not a Misty satellite. It > is either debris or a decoy resulting from the > launch of what is now believed to > be Misty 2 (1999-028A / 25744), which was launched > in May 1999. > > In June 1999, hobbyists began tracking an object > from that launch that was > fairly intrinsically bright, in a 63.4 deg, 2700 km > x 3100 km orbit, which > seemed like it might be the payload. Initial > speculation was that it was an > IMINT satellite of KH-11 lineage, sent into a higher > than usual orbit, to obtain > increased dwell-time and wider area coverage of > targets, at reduced resolution - > a need that had been identified as a result of > experience during Operation > Desert Storm. > > This theory began to fall apart in 2002, with the > discovery of the object's high > area-to-mass ratio, which makes it more likely to be > debris than a payload, as I > reported in the following post, which I believe you > have read: > > http://satobs.org/seesat/Aug-2002/0045.html > > In the above post, I also discussed the object's > other debris-like > characteristic: it rotates, unlike most payloads, > which are 3-axis stabilized. > > Initially, its period of brightness variation was > about 150 s, which had > decreased to 116 s after three years. By the summer > of 2005, it had decreased > below 80 s; since then it appears to have been > increasing: > > http://satobs.org/seesat_ref/99028C_period_of_var/99028C_period_of_var_3.jpg > > If the object were a spin-stabilized payload, then I > would expect its rate of > rotation to remain much more nearly constant. > > In late 2005, we changed our designation of the high > object from 1999-028A / > 25744 to 1999-028C / 25746, in recognition that it > could not be the primary > payload, and most likely is debris, or a decoy, > intended to draw attention away > from Misty 2, which most likely would have gone to a > quasi 65 deg, 700 - 800 km > orbit, like that of its predecessor. > > We should have made the switch sooner, but finally > acted when it became clear > that using the original ID was creating confusion > among those not familiar with > the evolution of our understanding of this object. > > Based on its observed brightness, 99028C probably > has a cross-sectional area of > about 50 m^2. Assuming it presents an equivalent > area to the sun, then its mass > is about 560 kg, based on its area-to-mass ratio of > about 0.09 m^2/kg, derived > from analysis of solar radiation pressure > perturbations. > > For the object to be a primary Titan IV-B class > payload, it would have to be > very massive, and have a large surface area facing > the sun, to account for its > area-to-mass ratio. > > I estimate that a manoeuvrable Titan IV-B payload in > excess of 10,000 kg (dry > mass) could reach the 63.4 deg, 2700 km x 3100 km > orbit of 99028C, which would > require a sun-facing surface area of about 900 m^2. > I cannot imagine an NRO > spacecraft so-configured. > > The JWST (James Webb Space Telescope), has a mass of > 6200 kg, and a sunshield of > 220 m^2, resulting in a sun-facing A/m of 0.035 > m^2/kg, well short of 99028C's > value. Of course, unlike NRO telescopes, JWST is > designed for ultra-high IR > sensitivity, requiring it to have the large > sunshield. Also, JWST is 3-axis > stabilized. > > Ted Molczan > > ------------------------------------------------------------------------- > Subscribe/Unsubscribe info, Frequently Asked > Questions, SeeSat-L archive: > http://www.satobs.org/seesat/seesatindex.html > > __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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