Quote from: kevin-rf on 10/16/2017 10:36 amDo you need to be logged in or something? Reply 637 in that thread no longer has the picture. At least on a mobile device.Yes sorry. Because I am always logged in I forgot.Apparently another poster said the same model featured in a 60 minutes documentary two years back so it obviously isn’t as intriguing as thought.
Do you need to be logged in or something? Reply 637 in that thread no longer has the picture. At least on a mobile device.
On the evening of 2017 Nov 02 UTC, Russell Eberst made new observations of the bright UNID he spotted on the morning of 2017 Oct 03 UTC, that we suspect is OTV 5.The following circular orbit fits Russell's timed positions, one each on Oct 03 and Nov 02:OTV 5 suspect 403 X 404 km1 77203U 77203A 17306.77911249 .00000000 00000-0 00000-0 0 082 77203 63.5883 190.6553 0001000 0.0010 0.1122 15.54162386 02It should be recovered easily in the above orbit. The eccentricity could be somewhat greater, in which case there will be small time and cross-track errors.I would like to perform a bit more analysis to assure myself this is OTV 5, before I assign the ID: OTV 5 (USA 277), 2017-052A / 42932. OTV 5 most likely was inserted into an approximately 43 deg parking orbit. My guess is that the second stage of its Falcon 9 booster performed the manoeuvre to change the inclination, which I intend to attempt to verify.Russell's relevant observation reports:http://satobs.org/seesat/Oct-2017/0007.htmlhttp://satobs.org/seesat/Nov-2017/0007.htmlRussell, what was its approximate magnitude on Nov 02, prior to entry into the penumbra?Ted Molczan
63.588 deg inclination if this one is correct. Unexpected, but an interesting inclination - not far from Molniya orbit inclinations (63.4 deg), though obviously those satellites are in 12 hour orbits versus OTV-5's likely 1.5 hour orbit. - Ed Kyle
Quote from: edkyle99 on 11/03/2017 07:01 pm63.588 deg inclination if this one is correct. Unexpected, but an interesting inclination - not far from Molniya orbit inclinations (63.4 deg), though obviously those satellites are in 12 hour orbits versus OTV-5's likely 1.5 hour orbit. - Ed KyleBut doesn’t any orbit at 63.4 degrees inclination have a fixed argument of perigee, where the apogee and perigee do not roll around the orbit, as it is not a function of semi-major axis (orbit altitude)? Even if the orbit is only slightly elliptical the apogee could remain over a fixed latitude. You could get a somewhat longer “hang time” or a somewhat lower perigee over a specific target once a day with that inclination. Do we need a better determined orbit to see what the apogee and perigee are over?
I did an attempt this evening. Unfortunately, the sky deteriorated rapidly aftersunset. Quite hazy conditions, but stars visible on the photographs and video.Video (WATEC + 1.8/50 mm) and photo camera registered nothing around the 18:20UT pass. I had shadow ingress predicted for 50 degrees elevation in the N-NWnear 18:21:00 UT.If weather cooperates, new attempts tomorrow and the day after tomorrow (when Ishould have a good near-zenith pass).- Marco
HYDROPAC 3033/2017 (GEN) WESTERN SOUTH PACIFIC.SOUTHERN INDIAN OCEAN.1. HAZARDOUS OPERATIONS SPACE DEBRIS 071754Z TO 072226Z SEP, ALTERNATE 081754Z TO 082226Z AUG IN AREA BOUND BY 51-00S 077-10E, 44-44S 160-09E, 58-59S 161-33E, 65-20S 078-27E.2. CANCEL THIS MSG 082326Z SEP 17.( 051942Z SEP 2017 )
Yaogan and NOSS, etc., the multisatellite SIGINT formations that orbit around 1,000 km or so circular, are around the same inclination (63.4 deg). This orbit is used to avoid a "gradual increase in orbital eccentricity" caused by perturbations in Earth's gravity, according to Wiki. Perhaps a strong hint at whatever test payload(s) is/are on board. - Ed Kyle
How much delta-v would the 2nd stage have to expend to change orbital inclination from 43 deg. to 63.6 deg.?
The search orbit I posted for the 63.6 deg inclined OTV 5 suspect is too far in plane from the estimated 43 deg parking orbit of OTV 5, to have been manoeuvred there by the Falcon 9 second stage. The burn angle would have been nearly 45 deg, requiring an orbital manoeuvre with delta-V in excess of 5800 m/s.
Russell Eberst and David Hopkins report that the OTV 5 suspect was a no-show in the search TLE that I posted, which casts serious doubt on the reliability of that orbit.
Russell has suggested that his Nov 02 UTC sighting may have been of an old NOSS object. NOSS 1-7 (E) (86014E / 16624) appears to correlate.
QuoteHow much delta-v would the 2nd stage have to expend to change orbital inclination from 43 deg. to 63.6 deg.?delta-v = v * sin (alpha) , alpha is the angular change in inclination. delta-v = v * sin(20.6 deg)delta-v = v * 0.36, approximately.so it depends on the slowest velocity that the second stage reached which happens at apogee.
Quote from: aero on 11/06/2017 03:55 amQuoteHow much delta-v would the 2nd stage have to expend to change orbital inclination from 43 deg. to 63.6 deg.?delta-v = v * sin (alpha) , alpha is the angular change in inclination. delta-v = v * sin(20.6 deg)delta-v = v * 0.36, approximately.so it depends on the slowest velocity that the second stage reached which happens at apogee.I agree with your numeric result, for a manoeuvre at the equator in a circular orbit. [But...]For the above case, alpha would have been about 44.7 deg, requiring delta-V of about 76% of initial velocity, or more than 5800 m/s.
Is the X37 from this SpaceX Launch still in orbit? I havent heard anything about the X37 project in a while.