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MISSION: GALILEO
Mission Start Date : 1977-10-01
Mission Stop Date : 1997-11-11
Mission Alias Name : JUPITER ORBITER-PROBE (JOP)
Mission Phases
==============
GALILEO ORBITER EARTH EARTH-EARTH CRUISE
----------------------------------------
Spacecraft Id : GO
Target Name : EARTH
Mission Phase Start Time : 1991-04-29T00:00:0
Mission Phase Stop Time : 1993-04-12T00:00:0
Spacecraft Operations Type : FLYBY
Description
-----------
Interplanetary cruise from Earth, around the sun, and back
to and past the Earth a second time. This phase includes
both the encounter with the asteroid Gaspra and the second
Earth encounter.
GALILEO ORBITER EARTH EARTH1 ENCOUNTER
--------------------------------------
Spacecraft Id : GO
Target Name : EARTH
Mission Phase Start Time : 1990-11-08T00:00:0
Mission Phase Stop Time : 1990-12-16T00:00:0
Spacecraft Operations Type : FLYBY
Description
-----------
Following Voyager's Neptune encounter in 1989, every planet
in the solar system had been encountered and explored from
deep space by an Earth-launched spacecraft except Pluto and
Earth. The first Earth encounter by Galileo in December 1990
left only Pluto thus unexplored. The spacecraft trajectory
took Galileo virtually up the Earth's magnetotail, providing
unprecedented opportunity for fields and particles
measurements of the magnetotail. The plasma science
experiment results brought into question the validity of the
previous assumption that the bulk flows of the ion and
electron plasmas in the distant magnetotail are identical.
Spectral mapping observations of Australia and Antarctica
were made by the near infrared mapping spectrometer. A first
ever time lapse movie, in six colors, of the rotating Earth
over a period slightly greater than one day was made by the
solid state imaging experiment. Multispectral imaging of the
western nearside and eastern farside of the Moon were
obtained by the SSI. This data showed that Orientale Basin
ejecta deposits are similar to typical highlands deposits
such as the soils at the Apollo 16 site, while observations
of the South Pole-Aitken basin interior contain
characteristics that appear distinctively different from
that of nearside maria, thus providing new information on
mare deposits on the limb and farside of the Moon. (Refer to
Clarke, 1988; Clarke and Fanale, 1989; Fanale, 1990; Head et
al, 1991; Chapman, 1991; Ingersoll, 1991; Frank, 1991; and
O'Neil, 1991).
GALILEO ORBITER EARTH VENUS-EARTH CRUISE
----------------------------------------
Spacecraft Id : GO
Target Name : EARTH
Mission Phase Start Time : 1990-02-19T00:00:0
Mission Phase Stop Time : 1991-04-29T00:00:0
Spacecraft Operations Type : FLYBY
Description
-----------
Interplanetary cruise from Venus, around the sun, and back
to and past the Earth. This phase includes the first Earth
encounter.
GALILEO ORBITER GASPRA GASPRA ENCOUNTER
---------------------------------------
Spacecraft Id : GO
Target Name : GASPRA
Mission Phase Start Time : 1991-10-29T00:00:0
Mission Phase Stop Time : 1991-10-29T00:00:0
Spacecraft Operations Type : FLYBY
Description
-----------
On 29 October 1991 Galileo passed Gaspra at a distance of
approximately 1,600 km and a speed of approximately 30,000
km per hour. Color and black and white images were taken of
Gaspra as well as measurements to indicate composition and
physical properties. The data were stored on the spacecraft
tape recorder and later played back to Earth.
GALILEO ORBITER JUPITER INTERPLANETARY CRUIS
--------------------------------------------
Spacecraft Id : GO
Target Name : JUPITER
Mission Phase Start Time : 1989-10-19T00:00:0
Mission Phase Stop Time : 1995-10-08T00:00:0
Spacecraft Operations Type : FLYBY
Description
-----------
The trajectory of the spacecraft from Earth to Jupiter was
dictated by the limited propulsion capability allowed within
the Space Shuttle to boost the spacecraft from earth orbit
to an interplanetary trajectory. This limit prevented a
direct trajectory from Earth to Jupiter; instead a 'VEEGA'
trajectory was used to achieve the energy necessary to send
Galileo to Jupiter. The acronym VEEGA is from the trajectory
description: Venus-Earth- Earth Gravity Assist. In this
trajectory, Galileo passes Venus once, then flies by Earth
twice, thus obtaining three gravity assists before heading
toward Jupiter. (Refer to D'Amario, et al, Space Science
Reviews, 1992.)
GALILEO ORBITER MOON EARTH1 ENCOUNTER
-------------------------------------
Spacecraft Id : GO
Target Name : MOON
Mission Phase Start Time : 1990-11-08T00:00:0
Mission Phase Stop Time : 1990-12-16T00:00:0
Spacecraft Operations Type : FLYBY
Description
-----------
Following Voyager's Neptune encounter in 1989, every planet
in the solar system had been encountered and explored from
deep space by an Earth-launched spacecraft except Pluto and
Earth. The first Earth encounter by Galileo in December 1990
left only Pluto thus unexplored. The spacecraft trajectory
took Galileo virtually up the Earth's magnetotail, providing
unprecedented opportunity for fields and particles
measurements of the magnetotail. The plasma science
experiment results brought into question the validity of the
previous assumption that the bulk flows of the ion and
electron plasmas in the distant magnetotail are identical.
Spectral mapping observations of Australia and Antarctica
were made by the near infrared mapping spectrometer. A first
ever time lapse movie, in six colors, of the rotating Earth
over a period slightly greater than one day was made by the
solid state imaging experiment. Multispectral imaging of the
western nearside and eastern farside of the Moon were
obtained by the SSI. This data showed that Orientale Basin
ejecta deposits are similar to typical highlands deposits
such as the soils at the Apollo 16 site, while observations
of the South Pole-Aitken basin interior contain
characteristics that appear distinctively different from
that of nearside maria, thus providing new information on
mare deposits on the limb and farside of the Moon. (Refer to
Clarke, 1988; Clarke and Fanale, 1989; Fanale, 1990; Head et
al, 1991; Chapman, 1991; Ingersoll, 1991; Frank, 1991; and
O'Neil, 1991).
GALILEO ORBITER VENUS EARTH-VENUS CRUISE
----------------------------------------
Spacecraft Id : GO
Target Name : VENUS
Mission Phase Start Time : 1989-10-19T00:00:0
Mission Phase Stop Time : 1990-03-05T00:00:0
Spacecraft Operations Type : FLYBY
Description
-----------
End of Launch sequence to March 5, 1990. This phase includes
the encounter with the planet Venus.
GALILEO ORBITER VENUS LAUNCH
----------------------------
Spacecraft Id : GO
Target Name : VENUS
Mission Phase Start Time : 1989-10-18T00:00:0
Mission Phase Stop Time : 1989-10-19T00:00:0
Spacecraft Operations Type : FLYBY
Description
-----------
Galileo was launched on October 18, 1989 at 1654 GMT aboard
the Space Shuttle Atlantis (OV-104), flight STS-34. An
Inertial Upper Stage (IUS-19) placed Galileo on its
Earth-to-Venus trajectory. Following the IUS burn, Galileo
configured itself for solo flight and separated from the IUS
on October 19, 1989 at 0107 GMT. (Refer to O'Neil, 1991).
GALILEO ORBITER VENUS VENUS ENCOUNTER
-------------------------------------
Spacecraft Id : GO
Target Name : VENUS
Mission Phase Start Time : 1990-02-06T00:00:0
Mission Phase Stop Time : 1990-02-16T00:00:0
Spacecraft Operations Type : FLYBY
Description
-----------
A 10 day single load sequence provided the sequencing
resources for the Venus encounter. The data gathered was put
entirely onto the onboard tape recorder, since the high gain
antenna had to remain furled behind its sunshade during this
near-sun activity, and the low gain antenna did not have the
performance for real-time science data transmission to Earth
during the Venus encounter. The Venus encounter data was
played back to Earth in November 1990, when Galileo was
close enough to Earth that science data rates could be
achieved over the low gain antenna. Upstream energetic
particles were detected, bowshock crossings were indicated,
and the plasma wave instrument saw evidence of lightning
discharges. Eighty-one images by the Solid State Imaging
experiment were taken, which proved useful in atmospheric
motion studies. (Refer to O'Neil, 1991).
Mission Description
===================
The Galileo mission utilizes a single launch of a combined
Orbiter and Probe using the space shuttle Atlantis and an
inertial upper stage (IUS) to inject the Galileo spacecraft
on its interplanetary trajectory to Jupiter. The launch
window occurs from October 12, 1989 to November 21, 1989.
Since the IUS does not have the energy to inject Galileo on
a direct trajectory to Jupiter, the spacecraft will instead
be launched first towards Venus for the first leg of its
Venus-Earth-Earth gravity assist (VEEGA) trajectory to
Jupiter. Target-of-opportunity science observations will be
made at Venus (closest approach February 10, 1990), the
first Earth encounter (closest approach to Earth and Moon
December 8, 1990), the asteroid Gaspra (closest approach
October 29, 1991), the second Earth encounter (closest
approach to Earth and Moon December 8, 1992), and the
asteroid Ida (closest approach August 28, 1993).
At about 150 days before Galileo arrives at Jupiter, the
Probe is separated from the Orbiter. From this moment in
time, the Probe is on a ballistic trajectory to the Probe
entry point, about 6 degrees north latitude, into the
atmosphere of Jupiter. Using its 400 Newton engine for the
first time, the Orbiter executes an Orbiter deflection
maneuver to keep from following the Probe into the
atmosphere of Jupiter, and to retarget the Orbiter to the
proper encounter conditions required for the Jupiter Orbit
Insertion phase of the mission.
A close flyby (about 1,000 kilometer altitude) of the Jovian
satellite Io occurs in this phase for the purpose of science
observations as well as to slow the Orbiter down relative to
Jupiter by nearly 200 meters/second in order to reduce the
propellant required during the Jupiter Orbit Insertion (JOI)
400 Newton engine burn to capture Galileo into Jupiter's
orbit. Perijove of about 4 Jupiter radii occurs about 4
hours after Io encounter. A few minutes after perijove
passage, the Probe entry and beginning of the relay of data
from the Probe to the Orbiter occurs.
The Probe mission and data relay lasts 75 minutes, after
which JOI is performed, slowing the Orbiter down relative to
Jupiter by about 630 meters/second. The initial orbit period
is about 200 days. A large 400 Newton engine burn is
performed at the first apojove in order to raise perijove
from 4 Jupiter radii to about 9 Jupiter radii, thus allowing
at least 11 orbits with 10 targeted satellite encounters to
be completed by the Orbiter without exceeding the allowed
total accumulated radiation exposure at the spacecraft. Only
three orbits would be allowed before exceeding this limit if
perijove were allowed to stay at 4 Jupiter radii, where the
radiation environment is very severe. Also during this
perijove raise maneuver, Galileo is targeted to the
satellite Ganymede, the first of its Galilean satellite
encounters following JOI.
At this point, the targeting to satellite encounters begins,
such that a satellite tour consisting of a minimum of 10
targeted satellite encounters is achieved within the 23
month period allotted for the satellite tour. During the
course of the satellite tour, the orientation, shape and
size of the spacecraft orbits around the Jovian system,
referred to as petals because of how the spacecraft orbits
appear on a plan view of the Jovian satellite tour
trajectory, is controlled almost exclusively by gravity
assists of the satellites themselves. The orbit periods are
pumped down by successive encounters with the satellites
from the initial 200 days to approximately 35-40 days
between encounters. At the 8th orbit, when the orbit petal
orientation is approximately in the anti-sun direction, the
period is again pumped up to about 100 days, allowing one of
the primary objectives, probing the Jovian magnetotail, to
be accomplished. After this magnetotail orbit, the period is
again pumped down, by gravity assist encounters with the
Jovian satellites, to 35-40 days for the final 2-3 targeted
encounters. (Refer to O'Neil, 1991; the Galileo Science
Requirements Document, PD 625-50; and Wolf, et al, IOM
GLL-NAV-92-90, May 12, 1992).
Mission Objectives Summary
==========================
The Galileo mission has three major and co-equal general
science objectives. They are (1) to investigate the chemical
composition and physical state of Jupiter's atmosphere, (2)
to investigate the chemical composition and physical state
of the Jovian satellites, and (3) to investigate the
structure and physical dynamics of the Jovian magnetosphere.
(Refer to Galileo Project Plan, PD 625-1).
Reference
=========
Journal: EOS TRANSACTIONS
Publication Date: 1991-04-23
Reference Key ID: CHAPMAN1991
Authors
-------
CLARK R. CHAPMAN
Citation
--------
Galileo Encounter With the Planet Earth: Imaging Results,
AGU-MSA 1991 Spring Meeting, EOS Transactions, American
Geophysical Union, April 23, 1991
Reference
=========
Journal: N/A
Publication Date: 1988-08-01
Reference Key ID: CLARKE1988
Authors
-------
THEODORE C. CLARKE
Citation
--------
Earth and Moon Encounters by the Galileo Jupiter Orbiter,
Proceedings of IGARSS '88 Symposium, Edinburgh, Scotland,
September 13-16, 1988, ESA SP-284, August 1988
Reference
=========
Journal: THE PLANETARY REPORT
Publication Date: 1989-09-01
Reference Key ID: CLARKE1989
Authors
-------
FRASER P. FANALE
THEODORE C. CLARKE
Citation
--------
Galileo: the Earth Encounters, The Planetary Report, Volume
9, number 5, The Planetary Society, September 1989
Reference
=========
Journal: EOS TRANSACTIONS
Publication Date: 1990-11-20
Reference Key ID: FANALE1990
Authors
-------
FRASER P. FANALE
Citation
--------
Galileo's Earth-Moon Encounter Set for December 8, EOS
Transactions, Volume 71, number 47, American Geophysical
Union, November 20, 1990
Reference
=========
Journal: N/A
Publication Date: 1991-04-23
Reference Key ID: FRANK1991
Authors
-------
K. L. ACKERSON
LOUIS A. FRANK
W. R. PATERSON
Citation
--------
Plasma Measurements at Earth With the Galileo Spacecraft,
AGU Spring Meeting, Baltimore, Maryland, May 1991
Reference
=========
Journal: N/A
Publication Date: 1992-05-12
Reference Key ID: GLLIOM1992
Authors
-------
AARON A. WOLF
Citation
--------
Jet Propulsion Laboratory Interoffice Memorandum
GLL-NAV-92-90, Satellite Tour 92-14A Data Package, May 12,
1992
Reference
=========
Journal: N/A
Publication Date: 1991-01-01
Reference Key ID: GLLMS1991
Authors
-------
WILLIAM J. O'NEIL
Citation
--------
Project Galileo Mission Status, 42nd Congress of the
International Astronautical Federation, IAF-91-468, Oct
5-11, 1991
Reference
=========
Journal: N/A
Publication Date: 1985-01-01
Reference Key ID: GLLPP1985
Authors
-------
JOHN R. CASANI
Citation
--------
Galileo Project Plan, PD 625-1 Revision C, JPL D-1284,
January 1985
Reference
=========
Journal: N/A
Publication Date: 1989-01-18
Reference Key ID: GLLSRD1989
Authors
-------
CLAYNE M. YEATES
THEODORE C. CLARKE
Citation
--------
Galileo Science Requirements Document 625-50, Rev. C, Jet
Propulsion Laboratory, Pasadena, California, January 18,
1989
Reference
=========
Journal: EOS TRANSACTIONS
Publication Date: 1991-04-23
Reference Key ID: HEAD1991B
Authors
-------
JAMES W. HEAD
Citation
--------
Galileo Solid State Imaging Experiment Results for the Moon,
AGU- MSA 1991 Spring Meeting, EOS Transactions, American
Geophysical Union, April 23, 1991
Reference
=========
Journal: EOS TRANSACTIONS
Publication Date: 1991-04-23
Reference Key ID: INGERSOLL1991
Authors
-------
A. INGERSOLL
R. THOMPSON
Citation
--------
A Global View of Earth From Galileo, AGU-MSA 1991 Spring
Meeting, EOS Transactions, American Geophysical Union, April
23, 1991
Reference
=========
Journal: SPACE SCIENCE REVIEWS
Publication Date: 1992-05-01
Reference Key ID: SSR1992
Authors
-------
AARON A. WOLF
C.M. YEATES
LARRY E. BRIGHT
LOUIS A. D'AMARIO
R. YOUNG
T.V. JOHNSON
Citation
--------
Space Science Reviews, Volume 60 Numbers 1-4, 1992, The
Galileo Mission, Kluwer Academic Publishers, 1992.
__________________________________________________________________________
SPACECRAFT: GALILEO ORBITER
Spacecraft Information
======================
Launch Date : 1989-10-18
Instrument Host Name : GALILEO ORBITER
Instrument Host Type : SPACECRAFT
Mission Information
===================
Mission Start Date : 1977-10-01
Mission Stop Date : 1997-11-11
Mission Alias Name : JUPITER ORBITER-PROBE (JOP)
Targets
=======
MOON
EARTH
VENUS
GASPRA
JUPITER
Spacecraft Description
======================
The Galileo spacecraft consists of two parts, an orbiter
(SPACECRAFT_ID = 'GO') and a probe (SPACECRAFT_ID = 'GP').
Spacecraft power is provided by two radioisotope
thermoelectric generators. Propulsion is accomplished via a
bipropellant system of twelve 10- newton thrusters and one
400 newton engine. The command and data subsystem consists
of multiple microprocesors and a high-speed data bus.
Galileo is the first spacecraft to operate in a dual-spin
mode. The orbiter uses a dual-spin attitude stabilization
system consisting of a spun section (the rotor, which spins
at approximately three rpm) and a despun section (the
stator, which maintains a fixed orientation in space). This
design accommodates the different requirements of the two
types of instruments on board: the stator contains the
remote sensing instruments and the rotor contains the fields
and particles instruments as well as spacecraft engineering
subsystems.
There are eleven subsystems on the orbiter and nine
scientific scientific instruments. The orbiter weighs 2,380
kilograms (which includes 1089 kilograms of propellant). It
can transmit data to Earth at data rates ranging from 10 bps
to a maximum rate of 134 kilobits per second at S-band and
X-band frequencies. The rotor has one 4.8 meter high-gain
antenna and two low-gain antennas. The stator contains a
radio relay antenna operating at the L band for receiving
data from the atmospheric probe. The rotor and stator are
connected by the spin bearing assembly, which conducts power
via slip rings and data signals via rotary transformers.
(Refer to Yeates, et al, 1985; Johnson, et al, 1992.)
Platform Descriptions
=====================
Platform ROTOR
--------------
The rotor is the spinning section of the orbiter which
contains the high-gain communications antenna, the
propulsion module, flight computers, and most support
systems. The rotor contains two booms which were unfurled
and extended automatically after launch. The science boom,
which extends to a distance of three meters from the
spacecraft centerline, is the mounting platform for the
energetic particles detector (EPD), the dust detector (DDS),
the heavy ion counter (HIC), and the plasma detector (PLS).
The magnetometer boom extends outward eleven meters from the
centerline and is attached to the science boom. It contains
the plasma wave antenna (PWS) and two magnetometer sensors
(MAG), one at the midpoint of the boom and the other at its
outboard end. The extreme ultraviolet spectrometer (EUV) is
mounted on the spacecraft bus. (Refer to Yeates, et al,
1985; Johnson, et al, 1992.)
Platform STATOR
---------------
The stator is the despun section of the orbiter. It is
turned via an electric motor opposite to the rotation of the
rotor, so that it maintains a stable orientation in space.
Attached to the stator is a moveable scan platform which
contains the remote sensing instruments: the
photopolarimeter radiometer (PPR), the near-infrared mapping
spectrometer (NIMS), the solid-state imaging camera (SSI),
and the ultraviolet spectrometer (UVS). The probe and the
probe relay antenna are also attached to the stator. (Refer
to Yeates, et al, 1985; Johnson, et al, 1992.)
Reference
=========
Journal: N/A
Publication Date: 1985-01-01
Reference Key ID: GLL1985
Authors
-------
C. M. YEATES
D. M. HUNTEN
F. P. FANALE
L. COLIN
L. FRANK
T. V. JOHNSON
Citation
--------
Galileo: Exploration of Jupiter's System, NASA SP-479,
1985.
Reference
=========
Journal: SPACE SCIENCE REVIEWS
Publication Date: 1992-05-01
Reference Key ID: SSR1992
Authors
-------
AARON A. WOLF
C.M. YEATES
LARRY E. BRIGHT
LOUIS A. D'AMARIO
R. YOUNG
T.V. JOHNSON
Citation
--------
Space Science Reviews, Volume 60 Numbers 1-4, 1992, The
Galileo Mission, Kluwer Academic Publishers, 1992.
__________________________________________________________________________