AMSAT OSCAR 40 Briefing


Maggie Leber K3XS
AMSAT Area Coordinator
Editor, Phil-Mont Mobile Radio Club The Blurb
k3xs@arrl.net


Why is AO-40 different?

It's Big

This illustrates the relative sizes of AO-40 and previous recent amateur radio spacecraft. You can see that there's room for a lot more on AO-40, and that room was all used.

Overall Systems Status Summary

The big spaceframe and large amounts of available power made it possible to include a lot of systems in Phase 3D design. ("Phase 3D" was the pre-launch designation for the satellite that was designated AMSAT OSCAR 40 upon acheiving orbit)

Here's a matrix with an entry for every major system on the spacecraft, with an indication of its staus as of this writing. You can see that AO-40 was a very ambitious design...and the large number of systems marked "+" for "functional/operational" show us that AO-40 is far from dead.

(Cheerfully stolen from http://www.amsat.de)
IHU-1 computer  + RF-RX  ? V-TX  - RUDAK-A  +
IHU-2 computer  + V-RX  + U-TX  # RUDAK-B  +
Magnetorque Coils  + U-RX  + S1-TX  # SCOPE-A Camera  +
Earth/Sun-Sensors  + L1-RX  + S2-TX  + SCOPE-B Camera  +
Momentum Wheels  \ L2-RX  + X-TX  - YACE Camera  +
400N Thruster  / S1-RX  + K-TX  + Cedex  +
ATOS Thruster  / S2-RX  - Laser  ? GPS  +
Solar Array.  + C-RX  - LEILA-1  + RF-Exp  ?
Omni Antennas  # IF-Matrix  + LEILA-2  + Smart Node  +

It took a big ride to a big orbit

A "Molniya" high eccentricity orbit gives long pass times and low angular rates vs. Low Earth Orbit (LEO) birds. A typical "good" LEO pass is less than 15 minutes horizon to horizon AO-40 will hang in your sky for many hours at a time.

(diagram of eccentricity and inclination)

The 400n thruster was intended to reshape the basically equitorial geosychronous transfer orbit (GTO) provided by the Ariane V booster to an orbit with more inclination angle--about 63 degrees--to the equator, resulting in the satellite moving further to the north and south. The apogee was planned to be around 47,700 km and the perigee 400-10,000 km. This would have resulted in an "orbital mean" of 16 hours, resulting in a ground observer getting approximately the same pass every 16 hours. Three-axis stabilization provided byinertia wheel attitude control would provide three-axis stabilization, resulting in optimum pointing of spacecraft antennas and the solar panel array.

Unfortunately this design orbit isn't what we ended up with.

"The most successful satellite that ever blew up..."

AO-40 experienced an on-board explosion shortly after the first use of an on-board rocket engine. This disabled a number of on-board systems, and resulted in a spacecraft that was significantly less capable than originally hoped. Nonetheless, there's still more bandwidth available through AO-40 than in all the other amateur satellites put together.

The period of AO-40's orbit is about 19 hours 6.5 minutes. In four days a total of just over five orbits complete, and, at the observer, it appears that almost the same conditions exist as four days previously. The sub satellite point at apogee is oscillating between 7.6 north and 7.6 south. far from the 68 inclination originally desired.

What still works?

What is still being worked on?

What do you need to work AO-40?

Telemetry

Telemetry is useful to ops for...

A blocks:

A "Message of the Day", followed by 128 analog and 128 digital telemetry channels

A  HI, THIS IS AMSAT OSCAR-40       2003-05-11  20:53:14  #0975 
+--------------------------------------------------------------+
|  Hgt: 57420 km   Lon: -146  Lat: -1   ALON: 330  ALAT: 24    |
+--------------------------------------------------------------+
..........$@.?)b,)+.....&&.....CCM.4Q....MH)&...........wM..-Nw.
}......!..}yf{{{zg..}@.......@..@~}}}......}...}311112112""Z""""
..........@......Z.e m.....5.2...M..%j....5.-$..................
~_~_~_Q......p..X........B...x..u...... ............. .0.@.P.d.p

The telemetry channels are more easily understood when decoded with software, but are probably of interest mostly to the command team and deep AO-40 fans:

+---------------------------- STATUS ----------------------------+
|Day 9261   UTC 20:57:42.94  Orbit 1161  MA 107  frac 9479       |
|Mem.err.: 6  Emergency:                                         |
|Equipment:   IHU-2 ARU Instr LIU EPU Armed                      |
|Equipment:   Rudak GPS MonRX CamA CamB Cede| -ctl Laser         |
+----------------------------------------------------------------+
 Source: file T030511.RAW                             
 Block:   22/82     Decode:  A  E  wrongCRC     
+-------------- TX/RX/MATRIX ---------------++---------- TEMPERATURES ----------+
|RX:   AGC:                                 ||----TX----+---Frame---+---Tanks---|
|21/24     -|----:----|----|----|----|----| ||V     23.2|Top    97.0|MMH-3  22.6|
|V o       -:----|----|----|----|----|----| ||U     22.6|Bottom 97.0|N2O4+  20.6|
|U     -1.3-|----:----|----|----|----|----| ||U-PA  25.9|Back   97.0|N2O4-  97.0|
|L1     0.7-|----|----|----|----|----|----: ||S1    18.6|Side2  16.0|NH3-2  33.8|
|L2        -|----|----|----|----|----:----| ||S2    21.2|Side4  15.3|He     97.0|
|S1        -|----|----:----|----|----|----| ||X       - |S ant  14.7|---Solar---|
|S2/C      -|----|----|----|----|----|----: ||TWT     - |-Heatpipes-+Pnl1   -2.5|
|GB  =EB   -|----|----|----:----|----|----| ||----RX----+1+X-Y  25.9|Pnl2   11.4|
|MB        ----------------#----|----:----| ||U/V   17.3|2+X+Y  23.2|Pnl3   11.4|
|EB        -|----|----|----:----|----|----| ||L1    18.6|2+X-Y  23.9|Pnl4   11.4|
|Rudak-1   -:----|----|----|----|----|----| ||L2    21.9|2-X    97.0|Pnl5   10.7|
|Rudak-2   -|----|----|----|----:----|----| ||S1/H  22.6|3+X    19.9|Pnl6   -1.8|
|Leila-1   -|----|----:----|----|----|----| ||S2/C  23.2|3-X    20.6|-Batteries-|
|Leila-2   -|----|----|----|----:----|----| ||-Modules--+4+X+Y  17.3|Main2  31.1|
|           |    |    |    |    |    |    | ||IHU   13.3|-Bat.Reg.--+Main4  97.0|
|      TX:  V   Uo   S1  S2/K   X  Lei1 Lei2||SEU   12.7|BCR1   17.9|Main6  94.4|
|     PWR:              119       |  8 |  2 ||EPU   24.5|BCR2   24.5|Au|1   36.4|
|     ALC:               77       |NJ S|NJ S||           BCR3   21.2|Au|5   27.2|
+-------------------------------------------++----------------------------------+
+----------- NAVIGATION ------------++-------------- POWER ---------------+
|Mode: spin             ---400 N----||-Status--+----Volts----+----Amps----|
|--Magnet---+Spin SunS.kLIUpwr:  OFF||Main bat |Main bat 28.2|Tot.bat  0.8|
|Off        |SS1cnt 255|Valve closed||Au|. bat |Au|.bat   0.1|Main bus 2.2|
|M-Soll   77|SS2cnt 218|Hi pr:   -  ||Charger  |Bat.ofs 28.08|28v-S   0.43|
|--Panels---+Angle-37.9|Lo pr:   -  ||Heater   |28V bus  27.9|BCR      3.0|
|stowd stowd|Thr.  1.5v|---ArcJet---||---BCR---1-----2-----3-+SEU      179|
|Earth Sens.|Flags    3|Cnf 00000000||V-in   13.2  21.2  20.7|EPU      0.2|
|Sensi.:  64|Spin   2.1|EPUpwr:  OFF||I-SA   17.3  17.3  17.3|--TX Amps---|
|Pntng: side| Raw#  185|Flow:    128||I-SA   17.3  17.3  17.3|S 28V    1.1|
|Edge:   neg|3-A| SunS.kMtr flow  - ||V-ofs  21.5  20.4  20.4|S 10V     90|
|Lockout: 10|Y/25:   - |Cur.Set 10.3||I-10vC        2.1   2.1|Xheli|  3.0m|
|ES1 top:   |Y/45:   - |Tankpr:   - ||U-10vC       10.5  10.5|K         34|
| Cnt  53   |Z/25:   - |Mtr.pr:   - |+------------------------------------+
| MA:      9|Z/45:   - |   -     -  |
| Orb:  1161|Up-X: 88.2|---Wheels---|
|ES2 bottom:|Up-Y: 88.2| on sync rpm|
| Cnt  50   |Dn-X: 88.2|1:- -    0.0|
| MA:      8|Dn-Y: 88.2|2:- -    0.0|
| Orb:  1161|U/D Z: Dwn|3:- -    0.0|
+-----------------------------------+                                           

E blocks

carry data as per A-block, but are historic events, a snapshot of the sensor state when a channel goes out of predefined limits.

K: Whole-orbit data (WOD):

One sensor channel recorded for the duration of one orbit
K  Whole Orbit Data V1.2   Samples: 1    Captured Channel: #019B
gggggg..........................................................
.......................................;;;....;;................
...............    ............;;...;;.....;.;.;.;;.............
................................................................
........................;;;...;;....wwwwww................gg....
.......                                                         

L, M, N blocks are message blocks

M  QST AMSAT OSCAR-40                                2003 May 11
                                                                
  ALON/ALAT ~ 330/25.  Holding ALON and slowly lowering ALAT.   
      Passband off for ~ 1 more week.  Beacon remains ON.       
                                                                
         The AO-40 team would like your telemetry files!        
Please "zip" compress your daily telemetry files and e-mail to: 
                      ao40-archive@amsat.org                    

N is used to publish the transponder schedule, showing what systems are operating in what part of the orbit, expressed in "mean anomaly" 0->255, zero being perigee.

N  QST AMSAT AO-40          SCHEDULE                2003-03-25
               MA      010   120   240   244   010
               ---------7-----1-----5-----0-----7
               S2/K-Tx  |  S  |  S  |  S  |  S  |
               MB       |  *  |  *  |  *  |  *  |
               RUDAK    |     |     |     |     |
               V/U-Rx   |  U  |  U  |  U  |  V  |
               Uplink   |     | UL  |     |     | 
	       

X blocks

-- IHU boot progress messages

D blocks

-- downlinked file transfer -- often camera images