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AO-40: Hibernation #2 - Final Report
- Subject: [amsat-bb] AO-40: Hibernation #2 - Final Report
- From: Peter Guelzow <peter.guelzow@xxxxxxxxxxxx>
- Date: Mon, 30 Apr 2001 16:45:57 +0100
AO-40 Hibernation #2
--------------------
by
James Miller G3RUH
2001 Apr 30
AO-40 entered "hibernation", a period when the Sun sensors cannot see the Sun,
and magnetorquing is not possible, on 2001 Apr 08, for a 3 week period.
This hibernation differed in one important respect to that previous; in
hibernation #2 we had measurements of alon throughout from the Earth
sensors. Through this it was discovered that the spacecraft experiences an
additional torque at perigee which re-orients it slightly.
Knowing this it was a straightforward matter to keep track of alon, the
"mystery effect", and by using the YACE camera on orbits 207, 216 and 225
measure alat, and thus create the Sun angle history, without actually having
a Sun sensor working.
Recordings were also made of a number of temperature points, and these
correlated sensibly with the estimated Sun angle.
The hibernation ended on orbit 228, exactly when expected.
Finally, attached is a plot of the temperatures, and appended the data
collected during hibernation.
ATTITUDE MEASUREMENTS:
Orbit alon alat Orbit alon alat
---------------------- ----------------------
202 141 * 216 106 13 **
203 138 * 217 - -
204 136 * 218 102 *
205 133 * 219 - -
206 132 * 220 98 *
207 128 14 ** 221 95 *
208 127 * 222 93 *
209 125 * 223 90 *
210 121 * 224 88 *
211 119 * 225 85 12 **
212 116 * 226 83 *
213 114 * 227 81 *
214 - - 228 79 *
215 109 *
---------------------- ----------------------
* alon based on ES stop(s)
** camera gives alon and alat
RMS error, fit on alon: 0.43°
ATTITUDE ESTIMATE and TEMPERATURE MEASUREMENTS:
Attitude | Batteries (deg.C)| Tanks (deg. C) | (deg. C) Panels
Orbit lon/lat SA | Main2 Aux1 Aux5 | MMH-3 N204+ NH3-2| IHU EPU 2-5
-----------------+------------------+-------------------+------------------
200 -41 | 29.8 33.1 21.1 | 19.3 17.3 31.8 | 9.4 19.9 9.0
201 -43 | 31.1 35.1 21.9 | 19.9 18.6 33.1 | 10.0 21.2 7.1
202 141 15 -47 | 33.8 37.1 22.6 | 20.6 19.3 35.7 | 10.0 21.9 1.8
203 138 14 -49 | 35.1 39.0 23.2 | 21.2 20.6 37.1 | 10.0 22.6
204 136 14 -51 | 36.4 39.7 23.9 | 21.2 21.2 38.4 | 10.0 23.2 -2.5
205 133 14 -53 | 37.1 41.0 23.9 | 21.2 21.2 39.0 | 10.0 23.2 -4.5
206 131 14 -56 | 37.7 41.7 23.9 | 21.2 21.2 39.7 | 9.4 23.2 -6.4
207 129 14 -58 | 37.7 41.7 23.2 | 20.6 20.6 39.7 | 8.7 22.6 -8.4
208 126 14 -59 | 37.1 41.0 21.9 | 19.9 19.3 39.0 | 8.1 21.9 -10.4
209 124 14 -61 | 37.1 40.4 21.9 | 18.6 17.9 38.4 | 6.7 20.6 -13.7
210 121 14 -62 | 36.4 40.4 21.2 | 18.4 17.3 38.4 | 6.1 19.9 -15.0
211 119 14 -64 | 35.7 39.7 20.6 | 16.6 16.6 37.7 | 5.4 19.3 -17.0
212 117 13 -65 | 35.7 39.0 20.6 | 16.6 16.0 37.7 | 4.8 18.6 -18.3
213 114 13 -65 | 35.1 39.0 19.3 | 15.3 15.3 37.1 | 4.1 17.9 -19.6
214 112 13 -65 | 35.1 39.0 19.9 | 15.3 14.7 37.1 | 4.1 17.9 -19.6
215 109 13 -65 | 35.1 39.0 20.6 | 16.0 14.7 37.1 | 4.1 17.9 -19.6
216 107 13 -65 | 35.1 39.0 20.6 | 16.0 14.7 37.1 | 4.1 17.9 -19.0
217 105 13 -64 | 35.1 39.0 19.9 | 16.0 14.7 37.1 | 4.1 18.6 -18.3
218 102 13 -63 | 35.1 39.0 20.6 | 16.0 15.3 37.1 | 4.8 18.6 -17.6
219 100 13 -62 | 35.1 39.0 20.6 | 16.6 15.3 37.1 | 4.8 18.6 -16.3
220 97 13 -60 | 35.7 39.0 21.9 | 17.3 16.0 37.7 | 6.1 19.9 -13.7
221 95 12 -59 | 35.7 39.7 22.6 | 17.9 16.6 37.7 | 6.7 20.6 -12.0
222 93 12 -57 | 36.4 40.4 23.2 | 19.3 17.3 38.4 | 8.1 21.2 -9.7
223 90 12 -55 | 36.4 40.4 23.9 | 19.9 17.9 38.4 | 8.7 21.9 -7.8
224 88 12 -52 | 37.1 41.0 24.5 | 21.2 19.3 39.0 | 10.0 23.2 -5.1
225 85 12 -50 | 37.1 41.0 24.5 | 21.2 19.3 39.0 | 10.7 23.9 -3.1
226 83 12 -48 | 37.1 41.0 26.5 | 22.6 19.9 39.0 | 11.4 24.5 -1.2
227 81 12 -45 | 37.1 41.0 27.2 | 23.2 20.6 39.0 | 12.0 25.2 0.8
228 78 12 -43 | 37.1 41.0 27.2 | 23.9 21.2 39.0 | 12.7 25.2 2.8
-----------------+------------------+-------------------+------------------
Rate of change of alon: -2.396°/perigee
Precession rate: -0.161
--------------------------------------
Mystery effect: -2.235°/perigee at 2.05 - 2.01 rpm and Hp ~ 315 km
--------------------------------------
<end>
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