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Ham Radio CD-ROM (Emerald Software) (1995).ISO
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amsat177
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amsat177.txt
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1988-06-27
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SB ALL @ AMSAT $ANS-177.01
AO-13 Kick Motor Fired OK
HR AMSAT NEWS SERVICE BULLETIN 177.01 FROM WA2LQQ
WARWICK, NY June 25, 1988
TO ALL RADIO AMATEURS BT
AMSAT Ground controllers have successfully fired AMSAT OSCAR 13's kick motor
in orbit. The result is a successful intermediate orbit one or two steps away
from the final, desired AO-13 orbit. A second kick motor firing could come
within a week setting the stage for general communications operations in a few
weeks.
After reviewing the AO-13 attitude and spin rate, DJ4ZC gave the OK for a kick
motor firing last Wednesday. The firing took place at 18:57 UTC, Wednesday,
June 22. The burn coincided almost exactly with apogee of orbit number 16.
The IHU was loaded with a firing routine for a 50 second burn by AO-13's 400
Newton bi-propellant kick motor.
Prior to the burn decision, criteria had been established to maneuver to an
attitude, in Bahn coordinates, of 90 degrees longitude and -60 degrees
latitude with an angular velocity (spin rate) of 30 to 40 rpm. However,
looking at various considerations such as the overall schedule and visibility
of the satellite over the next week, the decision was taken at about 1630 UTC
to execute the burn two and one half hours later. Estimated attitude and spin
rate of AO-13 at the time of motor burn were found to be within tolerance for
a burn and so it was executed.
According to an analysis by Phil Karn, KA9Q, the change in AO-13 velocity due
to the kick motor burn was 159.6 meters per second. This value is about 14.4%
higher than the 139.5 meters per second predicted from W4PUJ's figures for
spacecraft mass, motor performance, and propellant flow rates. Based on the
direction of the delta-velocity vector, the attitude of the spacecraft in
pre-burn Bahn coordinates was: longitude 66.7 deg (vs 75 predicted) and
latitude 57.7 deg (vs 55 predicted). The difference is well within the
uncertainty range predicted by DJ4ZC, Karn said
"Bahn coordinates" is a special coordinate system based on the orbit of the
spacecraft and will be addressed in an upcoming Amateur Satellite Report
newsletter.
Apparently the performance of the kick motor exceeded expectations in terms of
thrust. KA9Q points out the delta V on AO-10 was also larger than predicted
(by about 11%), even after the longer burn time due to the LIU (Liquid
Ignition Unit) wiring error was taken into account. According to Dick
Daniels, W4PUJ, the flow rates for both spacecraft were measured on the ground
in the same fashion using isopropyl alcohol in place of real propellants. The
difference in viscosity between alcohol and the actual propellants could
easily account for increased flow rates (and thus increased thrust) on both
spacecraft.
KA9Q points out these data are important since they "calibrate" the motor's
actual performance, helping plan the next maneuvers more accurately.
/EX
SB ALL @ AMSAT $ANS-177.02
AO-13 Motor OK For More Burns
HR AMSAT NEWS SERVICE BULLETIN 177.02 FROM WA2LQQ
WARWICK, NY June 25, 1988
TO ALL RADIO AMATEURS BT
The AO-13 kick motor burn was the second in-orbit burn performed by any AMSAT
spacecraft but the first fully successful one. AO-10's first and only motor
burn in 1983 was longer than planned due to a hardware problem. Perigee rose
to 3900 km versus the desired 1500 km as a result. Later, due to a Helium
leak through a seal, a second burn was found to be impossible.
Last week's AO-13 kick motor burn, on the other hand, went perfectly with no
deviations except for the higher than expected kick motor performance.
Telemetry indicates the pressure loss experienced on AO-10 has not recurred
with AO-13. Telemetry channels 09 and, 0D in particular confirm the
satisfactory performance. Channel 09 (Helium high pressure) was at about 735
Bars and Channel 0D (Helium low side pressure) was about 14 Bars.
Further refinement of AO-13's orbit should now be possible. A second and
possibly a third burn can be accomplished whenever the required attitude
maneuvers are completed.
/EX
SB ALL @ AMSAT $ANS-177.03
AO-13 Ranging Proves Accurate
HR AMSAT NEWS SERVICE BULLETIN 177.03 FROM WA2LQQ
WARWICK, NY June 25, 1988
TO ALL RADIO AMATEURS BT
AMSAT's team of ground controllers has begun precise ranging of AO-13 in order
to determine its new orbit after the first kick motor burn accomplished last
Wednesday. The result is a set of successively more accurate orbital element
sets. The data has proved sufficiently accurate to be adopted by official
government satellite tracking agencies.
AMSAT's orbital determination process begins with range measurements from
various command stations using round trip delay time measurements from the
earth to the satellite and back. Stations making such measurements at present
include KA9Q, DJ4ZC, DB2OS, ZL1AOX and VK5AGR.
Once the range data is acquired, a complex number-crunching process begins. A
Keplerian element set results which is then checked for "fit" with other
tracking data and with AOS/LOS observation reports.
Here is a recent product of this process:
Satellite: oscar-13
Catalog number: 19216
Epoch time: 88176.00000000
Fri Jun 24 00:00:00.0 1988 UTC
Element set: ka9q-3
Inclination: 14.4344 deg
RA of node: 242.9507 deg
Eccentricity: 0.7012359
Arg of perigee: 183.8892 deg
Mean anomaly: 57.3505 deg
Mean motion: 2.20055906 rev/day
Decay rate: 0 rev/day/day
Epoch rev: 19
Semi major axis: 24972.204 km
Anom period: 654.379166 min
Apogee: 36105.470 km
Perigee: 1082.659 km
/EX
SB ALL @ AMSAT $ANS-177.04
Ariane Launcher Tribute
HR AMSAT NEWS SERVICE BULLETIN 177.04 FROM WA2LQQ
WARWICK, NY June 25, 1988
TO ALL RADIO AMATEURS BT
Another key step towards resumption of the U.S. Space Shuttle flights was
taken June 14 with the test firing of a version of Morton-Thiokol's redesigned
solid rocket booster (SRB) engine. One final test remains before Space Shuttle
flights can resume.
June 14th's test firing, fourth of the five required, lasted the required 122
seconds and provided the usual spectacular show as the 126 foot long rocket
shook the ground and sent grayish-brown smoke billowing thousands of feet into
the Utah skies. Royce Mitchell, Solid Rocket Program Manager for NASA, pegged
the test "Extremely Good."
Officials for Morton-Thiokol said that, unlike the previous three test
firings, no intentional flaws had been introduced into this test rocket motor.
They went on to confirm that the final full-scale test firing is planned for
late July. The SRB manufacturer plans to introduce several flaws into the
joint sections to test the system to its limits.
The June 14th test was unique for another reason. It was the first on the
newly built $22 million test stand. Hydraulic struts have been added to
duplicate steering, flight turbulence and other flight stresses. Data seems to
indicate that the engine successfully withstood the simulated worst-case
stresses, similar to those experienced in past shuttle flights. A full report
is expected within two weeks.
Officials said the testing has gone so well that Discovery's two SRB's were
mated to an external fuel tank two weeks ago. Discovery was mated to its
liquid fuel tank late this past week. If progress continues apace, officials
say late August or early September will mark flight resumption.
(Story by NW2T)
/EX
SB ALL @ AMSAT $ANS-177.05
Short Bursts
HR AMSAT NEWS SERVICE BULLETIN 177.05 FROM WA2LQQ
WARWICK, NY June 25, 1988
TO ALL RADIO AMATEURS BT
AMSAT Director Harry Yoneda, JA1ANG, celebrated his 69th birthday on the day
AO-13 was born, June 15. Happy Birthday to both.
AMSAT Director Bill Tynan, W3XO, is back at home after a couple of days in
hospital for angioplasty measures. Bill listened to the AO-13 launch on WA3NAN
from his hospital room. Feeling reasonably well, he sends thanks to all who
sent him get-well cards/QSLs.
Mike Parisey, WD0GML, says he has now completed preparations and placed his
new dial-up computer BBS in operation. According to Mike, it will be
available full-time on 314-447-3003 and carry the latest AMSAT bulletins and
orbital data. It will run the same BBS system used at the W0RPK system Mike
says. Operating at 300 or 1200 baud at present, set your modem for even
parity, 7-bit word with 1 stop bit full duplex. There is no charge for this
service.
Handsome posters of AMSAT OSCAR 13 in orbit are now available from AMSAT HQ.
Call or write to obtain yours.
Here is the AO-10 operating schedule:
Through June 30 Mode B MA 30 to MA 230
July 1 to July 31 Mode B MA 25 to MA 235
Aug. 1 to Aug. 15 Mode B MA 30 to MA 240
The satellite will be unavailable for use beginning August 16 because of
predicted insufficient solar illumination and reduced battery charge. If
"FMing" of signals occur sooner that August 15, DO NOT USE AO-10 please. As
always, please use minimum power required for communications. Listen to your
nets for later updates, or to AMSAT OSCAR 13 beacons beginning in late July
for any changes to this schedule.
Here is the FO-12 operating schedule.
Mode From (UTC)
----------------
JA Jun 25 0318 JD = Digital mode
D 27 0131 JA = Analog mode
JA 29 0143 D = All systems off
D Jun 30 0049 DI = Systems off except CPU and memory
JA Jul 02 0103
D 04 0116
JD* 07 1530
JD 07 1935
DI 08 0143
JD 09 0049
DI 09 2355
JA 13 1409
D 14 1315
JA 16 1328
D 17 1235
JD 20 1356
DI 21 1301
JD 23 1141
DI 24 1020
JD 26 1033
DI 27 1141
JD 30 1100
DI Jul 31 1006
*From 1530 to 1732 UTC, July 7, acquisition of telemetry will be every 2
seconds. The mailbox will be disabled during this interval.
The transponders will be off at other times. The actual operating schedule may
change due to unexpected situations such as variations in available power.
/EX