NROL-76 elements from observations

From: Ted Molczan via Seesat-l <seesat-l_at_satobs.org>
Date: Sat, 3 Jun 2017 09:07:56 -0400
The following elements have been derived from observations by Leo Barhorst, Russell Eberst, David Hopkins, Marco
Langbroek, Alberto Rango and Mike Waterman:

USA 276                                                  388 X 411 km
1 42689U 17022A   17153.82560436  .00005488  00000-0  75944-4 0    03
2 42689  50.0056 114.2278 0016538 121.0056 239.2540 15.56240034    05
Arc 20170528.83-0602.84 WRMS resid 0.095 totl 0.011 xtrk

Below are updated conjunction estimates for the closest approaches on 2017 Jun 03 (today) with range <= ~100 km.

                   ISS sub-satellite point     USA 276 sub-sat point
                  -------------------------  ------------------------- 
  TCA      Range    Lat      Lon      Alt      Lat      Lon      Alt
  UTC       km      deg      deg      km       deg      deg      km
11:43:10   85.70  43.30 N 170.83 E   410.56  43.69 N 170.02 E   391.47
12:29:10   55.09  43.94 S  22.31 W   418.35  44.14 S  22.89 W   424.12
13:15:33   26.55  43.78 N 146.27 E   410.73  43.86 N 146.09 E   391.52
14:01:47   12.01  43.91 S  45.79 W   418.33  43.87 S  45.68 W   424.01
14:47:55   50.69  44.25 N 121.69 E   410.89  44.03 N 122.15 E   391.58
15:34:25   76.15  43.85 S  69.20 W   418.29  43.56 S  68.41 W   423.90
16:20:13  113.74  44.83 N  96.80 E   411.09  44.31 N  97.91 E   391.67

The above differ slightly from those I posted yesterday.

For USA 276, I used the above TLE. For ISS, I used NASA's current estimated TLE for June 3:

https://spaceflight.nasa.gov/realdata/sightings/SSapplications/Post/JavaSSOP/orbit/ISS/SVPOST.html

1 25544U 98067A   17154.59563486  .00016717  00000-0  10270-3 0  9023
2 25544  51.6395 106.0758 0004785 233.6024 126.4688 15.53983228 19632

If the intention is to perform an actual rendezvous, instead of, or in addition to a series of fly-bys, then USA 276
could manoeuvre to match the plane of ISS near one of the above times. If it is a no-show tonight in the above orbit,
then it would be prudent to look for it in close proximity to ISS, or somewhere along its track.

If delta-V is a significant constraint, then the minimum energy manoeuvre would occur on Jun 24, when USA 276 and ISS
would have the same RAAN, leaving only a 1.6 deg change of inclination.

Ted Molczan


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Received on Sat Jun 03 2017 - 08:08:31 UTC

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