MAGELLAN STATUS REPORT           May 25, 1993        8:30 PM PDT

The Magellan spacecraft started its Transition Experiment this
morning at 10:31 AM PDT with an Orbit Trim Maneuver which lowered its 
periapsis (closest approach to Venus) to 149.4 km. Telemetry indicated 
that the 11.3 minute burn of the thrusters was normal, and the resulting 
periapsis altitude was 149.7 km. Following the first atmospheric drag 
pass, all subsystems were reported to be nominal.  Temperatures of the 
solar panels increased by about 7 to 9 degrees C as a result of 
atmospheric friction.  This is about half the expected value.  The 
attitude control system generated about 2800 thruster pulses as the 
control shifted from reaction wheel control to thrusters and back during 
the pass.  Much of this activity is caused by the residual momentum from 
the wheels being transferred to the body of the craft. Power and Telecom 
were nominal. Nearly identical telemetry measurements were received 
following the next two drag passes (Orbits 7628, 7629). During the next 
four days a series of walk-in trim maneuvers will further lower the 
periapsis until the spacecraft is in the desired corridor. Based on the 
present navigation and spacecraft data, the next two OTMs (Orbit Trim 
Maneuvers) will be the "double down" magnitude.  The first of the corridor
-adjustment OTMs is scheduled for 5:46 AM PDT tomorrow.
Ron Baalke  Jet Propulsion Lab   Pasadena, CA 91109



MAGELLAN STATUS REPORT     May 27, 1993    3:00 PM PDT
The Magellan Transition Experimet continues as the flight team carefully 
maneuvers the spacecraft toward the desired aerobraking corridor.  The 
second "double down" trim maneuver was performed at 2:07 PM PDT today to 
lower the periapsis to 143 km.  At the Mission Director meeting early this 
afternoon, a "single down" OTM was approved for execution on Saturday.   
This will lower the periapsis by 1.6 km.  All spacecraft subsystems 
continue to report nominal performance. There have been some difficulties 
with transfer of 1200 bps telemetry between JPL and Denver. On the incident 
of orbit 7638 last night, Attitude Control estimates that the spacecraft 
performed the drag pass about 120 deg.off the proper attitude. Spacecraft 
systems responded as designed and there was no damage to the craft.  The 
solar panels were facing the sun and stayed near 85 degrees C.(instead of 
cooling to 25 and then warming to 39 during the drag pass).  Attitude 
control stayed in phase plane D, and used about 0.046 kg of fuel during 
the pass.  From orbit 7639 on the spacecraft performance has been normal.
Ron Baalke   Jet Propulsion Lab  Pasadena, CA 91109



MAGELLAN STATUS REPORT      May 27, 1993    10:00 AM PDT

The Magellan Transition Experiment continues as the flight team
carefully maneuvers the spacecraft toward the desired aerobraking corridor.  
The spacecraft has now made fifteen atmospheric drag passes with periapsis 
below 150 km and all subsystems were reported to be nominal.  As the 
spacecraft approaches the low part of the orbit, the attitude control 
system switches from reaction wheel control to the thrusters.  Depending 
on the amount of attitude error when this switch occurs, the thrusters 
have used from 0.013 to 0.023 kg of fuel to maintain the position within 
10! of the velocity vector.  The expected fuel consumption is 0 to 0.3 kg 
per orbit.  Shortly before orbit 7638 last night, an update to the 
periapsis time table was sent to Magellan.  An error in the coded data was 
rejected by the on-board computer, and the spacecraft apparently went 
through the atmospheric drag pass in the wrong attitude.  Spacecraft 
systems responded as designed and there was no damage to the craft.  The 
solar panels were facing the sun and stayed near 60 degrees C.(instead of 
cooling to 25 and then warming to 39 during the drag pass).  Attitude 
control stayed in phase plane D, and used about 0.046 kg of fuel during 
the pass.  From orbit 7639 on the spacecraft performance has been normal.  
Based on the present navigation and spacecraft data, the next OTM (Orbit 
Trim Maneuver) will be the "double down" magnitude.  The second of the 
corridor-adjustment OTMs is scheduled for 2:07 PM PDT today.

Ron Baalke     Jet Propulsion Lab    Pasadena, CA 91109





PUBLIC INFORMATION OFFICE  JET PROPULSION LABORATORY  CALIFORNIA
INSTITUTE OF TECHNOLOGY  NATIONAL AERONAUTICS AND SPACE ADMINISTRATION  
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011

PLANETARY MISSION STATUS                           May 27, 1993

GALILEO:  The spacecraft is now en route to Jupiter, scheduled to
enter orbit December 7, 1995.  Spacecraft performance and condition are 
excellent except that the high-gain antenna is only partly deployed; 
science and engineering data are being transmitted via the low-gain 
antenna.  The mission team is planning to use the low-gain antenna for 
the Jupiter mission and for the encounter August 28, 1993 with asteroid Ida.  
Galileo was launched October 18, 1989, flew by Venus in 1990 and Earth in 
1990 and 1992 for gravity assists, and flew by asteroid Gaspra in October 
1991 for scientific observation. Contact: Jim Wilson, (818) 354-5011.

MAGELLAN: The Magellan spacecraft has concluded its eight-month
survey of the gravitational field of Venus from its elliptical orbit.  
On May 25, flight controllers began an 80-day program to lower and 
circularize the spacecraft's orbit by aerobraking, dipping into Venus's 
upper atmosphere each orbit.  Magellan was launched May 4, 1989 and 
radar-mapped more than 98 percent of Venus's surface from September 1990 
to September 1992. Contact: Jim Doyle, (818) 354-5011.

MARS OBSERVER:  Spacecraft health and performance are normal, after 
several episodes in which it entered contingency mode, a safe state 
triggered by the spacecraft computer because of attitude-reference 
anomalies.  A software fix has solved the problem.  Mars Observer is 
scheduled to enter Mars orbit August 24, 1993; it will be moved into a 
mapping orbit by November 8 and science operations are planned to start 
November 22.   Mars Observer was launched September 25, 1992.  
Contact: Diane Ainsworth, (818) 354-5011.

TOPEX/POSEIDON:  The satellite is healthy, and all scientific instruments 
are performing normally, typically providing three playbacks per day.  The 
mission is mapping ocean circulation. TOPEX/Poseidon was launched August 
10, 1992. Contact: Mary Hardin, (818) 354-5011.

ULYSSES: The spacecraft is in a highly inclined solar orbit now 31.7 
degrees south relative to the Sun's equator, in transit from its Jupiter 
gravity assist in February 1992 toward its solar polar passages (about 80 
degrees south and north) in 1994 and 1995.  Spacecraft condition and 
performance are excellent, with Ulysses gathering data on the heliosphere 
-- the realm dominated by the solar wind, a stream of charged particles 
flowing from the Sun.  The Ulysses spacecraft was built by the European 
Space Agency and launched October 6, 1990. 
Contact: Diane Ainsworth, (818) 354-5011.

VOYAGER 1 and 2: The two Voyager spacecraft have detected low-frequency 
radio emissions believed to originate at the boundary between the solar 
wind and the interstellar medium, called the heliopause. Detection and 
measurement of this boundary is the principal goal of the Voyager 
Interstellar Mission. Voyager 1, launched September 5, 1977, is currently 
7.8 billion kilometers (4.8 billion miles) from the Sun after flying by 
Jupiter and Saturn in 1979 and 1980; Voyager 2, launched August 20, 1977, 
to fly by Jupiter (1979), Saturn (1981), Uranus (1986) and Neptune (1989), 
is now 6 billion kilometers (3.7 billion miles) from the Sun.  
Contact: Mary Hardin, (818) 354-5011.

Ron Baalke       Jet Propulsion Lab        Pasadena, CA 91109                 


VOYAGER HELIOPAUSE DIAGRAM                    May 28, 1993                  
A GIF image of the Voyager heliopause diagram is now available at the JPL 
Info public access site.  Note that the image is in GIF89a format, so make 
sure your display software supports this format (as opposed to the older 
GIF87a format).  The image is available by dialup modem at 
+1 (818) 354-1333, up to 9600 bps, parameters N-8-1 (will be moved to 
the images directory in 30 days)         file:  vgrhelio.gif

Ron Baalke       Jet Propulsion Lab      Pasadena, CA 91109                   