HAM Radio 3/hamradioversion3.0examsandprograms1992.iso/news/amsat184/amsat184.txt

Text File | 1988-07-05 | 12.2 KB | 264 lines

SB ALL    @ AMSAT  $ANS-184.01
Final AO-13 Motor Burn 06 July

HR AMSAT NEWS SERVICE BULLETIN 184.01 FROM WA2LQQ
WARWICK, NY    July 2, 1988
TO ALL RADIO AMATEURS BT

AMSAT engineers estimate conditions will be right for the second and final
kick motor burn by early this week.  Wednesday, July 6, has now been pegged as
the actual firing day. The second motor burn should put AMSAT OSCAR 13 in its
final orbit now figured to have a slightly higher perigee than originally
planned.  The balance of the propellants will be expended in a "burn to
depletion" strategy.  About 85% of the propellants remain; enough for about 5
minutes of thrust.

After its letter-perfect launch June 15, AMSAT Controllers first successfully
fired AO-13's kick motor on June 22.  The result was an intermediate orbit
with perigee at 1081 km and inclination raised to 14.3 degrees.  The final
burn this week will raise perigee to about 2200 km and change the orbital
plane from its current 14.3 degree inclination to as high as 57 degrees.

Beginning immediately after the first burn, re-orientation and spin up
proceeded.  By Saturday, July 2, AO-13 had attained the desired second burn
attitude (-59 degrees longitude; -70 degrees latitude in the Bahn coordinate
system).  It is estimated that by Monday, July 4, the spin rate will actually
attain the desired 60 rpm.

If the final burn comes on Wednesday, July 6, it will occur at apogee of orbit
#47 at about 21:08 UTC.  Although the satellite will not be in view of North
America at the time, it will be easily viewed from Europe, Africa, the Middle
East and most of South America.

According to DB2OS, before and during the motor burn, the telemetry will be
switched to the Engineering Beacon (145.985 MHz).  It will then revert to the
General Beacon on 145.812 MHz. After the burn, earth and sun sensor
measurements will be made prior to beginning the re-orientation to the
operational attitude.

Getting the spin rate up to 60 rpm has taken considerable time due to the
attitude of AO-13 with respect to the geo-magnetic field.  Spinning up to the
relatively high rate of 60 rpm is done for at least two reasons.  First, the
gyroscopic effect of the spin will stabilize the spacecraft during motor
firing.  Second, the fuel in the tanks will be forced towards the exit ports
by the centrifugal force imposed on it by the spinning.  This will insure
most, if not all, of the fuel is expelled into combustion chamber. Once in its
final orbit, it will be easier to despin and re-orient due to the orientation
of the orbital plane with respect to the geo-magnetic field.

A short-term study of electron and proton density at 1500 and 3000 km
altitudes has been performed by the AMSAT DL team. It has been found neither
prospective perigee altitude offers and distinct advantage over the other. The
study was undertaken to ascertain whether changing the perigee target for
AO-13 would affect its radiation environment and thus its lifetime. With
neither perigee altitude showing a distinct advantage, it has been decided to
raise the target perigee altitude from its former 1500 km to a new target of
2200 km.  According to DJ4ZC, this will have two results: 1. It will add some
insurance altitude should the second burn be other than fully successful. 2.
It will improve coverage over the Southern Hemisphere.

/EX
SB ALL    @ AMSAT  $ANS-184.02
AO-13 Health Reported Good

HR AMSAT NEWS SERVICE BULLETIN 184.02 FROM WA2LQQ
WARWICK, NY    July 2, 1988
TO ALL RADIO AMATEURS BT

All the telemetry indications from AMSAT OSCAR 13 show this to be a healthy
satellite.  Power generation is excellent and temperatures are all within
expected ranges.  The main battery temperature is hovering between 12 and 13
degrees Celsius and the 2 meter power amplifier is running at a comfortable 16
degrees C.  The coldest reading monitored is in the Mode S transponder which
is not currently activated.  It's indicating a nominal 6 degrees Celsius.  In
general, all temperatures lie in a range of 6 to 19 degrees Celsius.

AO-13 telemetry is transmitted in three forms: PSK (phase shift keyed); RTTY;
CW.  The RTTY uses FSK (frequency shift keyed) tones spaced 170 Hz at a
signaling rate of 50 baud.  RTTY telemetry is sent at 15 and 45 minutes past
the hour.  CW telemetry is sent at 10 wpm at 0 and 30 minutes past the hour.
PSK telemetry is sent at other times at 400 baud.  The Mode B General Beacon
is at 145.812 MHz.  Telemetry reception in many areas has been hampered by FM
users many of whom are unaware 145.800 to 146.000 MHz is, by general
agreement, a sanctuary for weak signal, satellite operations.

Sixty four channels of telemetry are sent in PSK.  The first 60 of these are
sent in RTTY as well.  The revised telemetry equations are presented in ASR
#178 which is now in the mail.

Telemetry indicated effects from the huge solar flare last Saturday, June 25.
By Sunday, those monitoring AO-13 telemetry had already detected "hits" in
the satellite's computer.  Although no damage was expected and none occurred,
the intense burst of radiation from the sun registered on AO-13 when its
self-correcting devices were obliged to correct for radiation-induced errors
in the IHU.  These were seen as memory "soft errors" meaning a temporary upset
caused by radiation had occurred.  The AO-13 IHU and memory are extremely
radiation resistant, a least a thousand times more than AO-10, and so the
radiation hits are of academic interest but pose not real threat to its
health.  Watching the hits can, however, give an idea when solar radiation and
particles arrive in the vicinity of earth.

/EX
SB ALL    @ AMSAT  $ANS-184.03
AO-13 Comm Ops In 2 - 3 Weeks?

HR AMSAT NEWS SERVICE BULLETIN 184.03 FROM WA2LQQ
WARWICK, NY    July 2, 1988
TO ALL RADIO AMATEURS BT

With the second and final kick motor firing now slated for this coming week,
potential users are awaiting word on when the new bird will be available for
use.  With things going extremely well in all aspects, the answer could be
more sooner than later.

According to reliable sources, once the second and final kick motor burn is
accomplished, it will take about two weeks to re-orient the satellite and spin
it down to about 30 rpm for general operations.  Thus, if the motor burn
occurs later this week, AO-13 could be released for use beginning in late
July.

A detailed operating plan for AO-13 will evolve after initial operations
commence and will be based on operating experience including use levels.
Initially, Mode B will be used almost exclusively with Mode JL used in modest
proportions.  Then, depending on use patterns, Mode JL use, especially around
apogee will be gradually increased.  After a certain period, Mode JL operation
will likely predominate the operating schedule in order to take maximum
advantage of its broad bandpass.  Moreover, Mode JL will straddle apogee to
take advantage of the high gain, narrow beam 24 cm helix on the satellite. The
high gain antennas will be pointing directly at the geo-center when at apogee
once the spacecraft is properly oriented.

The narrow, 50 kHz, 2 meter J uplink in the 290 kHz Mode JL transponder, is
intended primarily for and recommended for Third World uplinks.

/EX
SB ALL    @ AMSAT  $ANS-184.04
Refined AO-13 Tracking Data

HR AMSAT NEWS SERVICE BULLETIN 184.04 FROM WA2LQQ
WARWICK, NY    July 2, 1988
TO ALL RADIO AMATEURS BT

The effort to refine the Keplerian elements for AO-13 continues with new
AMSAT-derived ranging data being combined with radar tracking data.  The
result is an extremely good fit.  Here is the latest set available which will
be more than adequate for tracking until the final kick motor burn this week.

Satellite: oscar-13
Catalog number: 19216
Epoch time:      88180.50000000
                 Tue Jun 28 12:00:00.0   1988 UTC
Element set:     mh6-28
Inclination:       14.3010 deg
RA of node:       241.4520 deg
Eccentricity:    0.7012999
Arg of perigee:   186.5090 deg
Mean anomaly:      21.9710 deg
Mean motion:    2.20041400 rev/day
Decay rate:              0 rev/day/day
Epoch rev:              29
Semi major axis: 24973.177 km
Anom period:    654.422304 min
Apogee:          36108.962 km
Perigee:          1081.402 km

New elements will be issued as soon as the new, post burn #2, orbit can be
ascertained.  A predicted post-KM#2 set may be issued early this coming week.

/EX
SB ALL    @ AMSAT  $ANS-184.05
Soviets Set For Phobos Mission

HR AMSAT NEWS SERVICE BULLETIN 184.05 FROM WA2LQQ
WARWICK, NY    July 2, 1988
TO ALL RADIO AMATEURS BT

Preparations are under way this week at the USSR's Baikonur Cosmodrome for the
first of two missions to Phobos, one of the two Martian moons.  Phobos-1 and
2, set for launch on July 7 and 12 respectively, will travel for 200 days
towards Mars where they will enter equatorial orbits around the "red planet"
prior to achieving a synchronous orbit with Phobos.  After some two months of
analysis and observations, the Phobos vehicles will start closing with the
Martian moon to a distance of 35 kilometers and finally to a height of 50
meters where they will "hover" above the lunar surface.

For a period of 15 minutes, a series of studies including television
transmissions, radioscopy of Phobos' internal structure, and laser and ion-ray
irradiation of the lunar surface will be conducted.  Nearly 150 laser pulses
will evaporate particles of the soil, which are expected to rise to a height
of over 50 meters.  The traps mounted on the orbiters, it is hoped, will
capture and analyze these particles with data being subsequently transmitted
back to earth.

Finally, the orbiters will drop two landing modules, one static and one a
mobile "leaping" device.  The leaping device will survey the surface as well
as send back television panoramas of Phobos' landscape.  The tiny, 27 km moon
of Mars has been described as looking like a "bitten apple."

In other Soviet space news, it is believed preparations are under way as well
for an August launch of the Soviet Space Shuttle.  Soviet space officials have
made no mention of the shuttle in recent weeks but the August date was
revealed during a media tour of the Cosmonaut training center at Star City in
May. This will be the first orbital test of the shuttle and only the second
test of the new, heavy lift launcher, Energia.

/EX
SB ALL    @ AMSAT  $ANS-184.06
Short Bursts

HR AMSAT NEWS SERVICE BULLETIN 184.06 FROM WA2LQQ
WARWICK, NY    July 2, 1988
TO ALL RADIO AMATEURS BT

Nominations for AMSAT-NA Director closed June 30.  Those nominated included:
Tom Clark, W3IWI; John Henry, VE2VQ; Phil Karn, KA9Q; Doug Loughmiller, KO5I;
Andy MacAllister, WA5ZIB; Vern Riportella, WA2LQQ.  Election materials will be
sent out next month to all current members.  There are four seats up for
election this year.

Handsome posters of AMSAT OSCAR 13 in orbit are now available from AMSAT HQ.
Call or write to obtain yours.

Here is the current AO-10 operating schedule:
Through July 31:       Mode B  MA 25 to MA 235
August 1 - August 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  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
JD = Digital mode
JA = Analog mode
D  = All systems off
DI = Systems off except CPU and memory
*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