SPACE/NEW_PROBES - Upcoming Planetary Probes - Missions and Schedules

Last-modified: $Date: 94/03/01 17:24:41 $


Information on upcoming or currently active missions not mentioned below
would be welcome. Sources: NASA fact sheets, Cassini Mission Design
team, ISAS/NASDA launch schedules, press kits.

ASCA (ASTRO-D) - Japanese (ISAS) Advanced Satellite for Cosmology and
Astrophysics. ASCA is an X-ray astronomy satellite launched into Earth
orbit on 2/20/93. Equipped with large-area wide-wavelength (1-20
Angstrom) X-ray telescope, X-ray CCD cameras, and imaging gas
scintillation proportional counters.

CASSINI - Saturn orbiter and Titan atmosphere probe. Cassini is a joint
NASA/ESA project designed to accomplish an exploration of the Saturnian
system with its Cassini Saturn Orbiter and Huygens Titan Probe. Cassini
is scheduled for launch aboard a Titan IV/Centaur in October of 1997.
After gravity assists of Venus, Earth and Jupiter in a VVEJGA
trajectory, the spacecraft will arrive at Saturn in June of 2004. Upon
arrival, the Cassini spacecraft performs several maneuvers to achieve an
orbit around Saturn. Near the end of this initial orbit, the Huygens
Probe separates from the Orbiter and descends through the atmosphere of
Titan. The Orbiter relays the Probe data to Earth for about 3 hours
while the Probe enters and traverses the cloudy atmosphere to the
surface. After the completion of the Probe mission, the Orbiter
continues touring the Saturnian system for three and a half years. Titan
synchronous orbit trajectories will allow about 35 flybys of Titan and
targeted flybys of Iapetus, Dione and Enceladus. The objectives of the
mission are threefold: conduct detailed studies of Saturn's atmosphere,
rings and magnetosphere; conduct close-up studies of Saturn's
satellites, and characterize Titan's atmosphere and surface.

One of the most intriguing aspects of Titan is the possibility that its
surface may be covered in part with lakes of liquid hydrocarbons that
result from photochemical processes in its upper atmosphere. These
hydrocarbons condense to form a global smog layer and eventually rain
down onto the surface. The Cassini orbiter will use onboard radar to
peer through Titan's clouds and determine if there is liquid on the
surface. Experiments aboard both the orbiter and the entry probe will
investigate the chemical processes that produce this unique atmosphere.

The Cassini mission is named for Jean Dominique Cassini (1625-1712), the
first director of the Paris Observatory, who discovered several of
Saturn's satellites and the major division in its rings. The Titan
atmospheric entry probe is named for the Dutch physicist Christiaan
Huygens (1629-1695), who discovered Titan and first described the true
nature of Saturn's rings.

Key Scheduled Dates for the Cassini Mission (VVEJGA Trajectory)
10/06/97 - Titan IV/Centaur Launch
04/21/98 - Venus 1 Gravity Assist
06/20/99 - Venus 2 Gravity Assist
08/16/99 - Earth Gravity Assist
12/30/00 - Jupiter Gravity Assist
06/25/04 - Saturn Arrival
01/09/05 - Titan Probe Release
01/30/05 - Titan Probe Entry
06/25/08 - End of Primary Mission
(Schedule last updated 7/22/92)

CLEMENTINE - Joint mission of the Strategic Defense Initiative
Organization and NASA to flight test sensors developed by Lawrence
Livermore for SDI. The spacecraft, built by the Naval Research Lab, was
launched on January 25 to a 400 km by 8300 km orbit of the Moon for a 2
month mapping mission. Instruments onboard include UV to mid-IR imagers,
including an imaging lidar that may be able to also obtain altimetric
data for the middle latitudes of the Moon. In early May the spacecraft
will be sent out of lunar orbit toward a flyby (11 km/sec ?) of the 4 km
x 1 km asteroid 1620 Geographos on August 31 at less than 100 km.

EARTH OBSERVING SYSTEM (EOS) - Multiple orbiting platforms to provide
long-term data of Earth systems science including planetary evolution.
First platform launch 1997?

GALILEO - Jupiter orbiter and atmosphere probe, in transit. Has returned
the first resolved images of an asteroid, Gaspra, while in transit to
Jupiter. Images of the August 1993 encounter with the asteroid Ida are
being returned slowly at present. Efforts to unfurl the stuck High Gain
Antenna (HGA) have essentially been abandoned. JPL has developed a
backup plan using enhancements of the receiving antennas in the Deep
Space Network and data compression (JPEG-like for images, lossless
compression for data from the other instruments) on the spacecraft. This
should allow Galileo to achieve approximately 70% of its original
science objectives with the much lower speed Low Gain Antenna. Longterm
Jovian weather monitoring, which is imagery intensive, will suffer the

Galileo Schedule
10/18/89 - Launch from Space Shuttle
02/09/90 - Venus Flyby
10/**/90 - Venus Data Playback
12/08/90 - 1st Earth Flyby
05/01/91 - High Gain Antenna (was to have) Unfurled
07/91 - 06/92 - 1st Asteroid Belt Passage
10/29/91 - Asteroid Gaspra Flyby
12/08/92 - 2nd Earth Flyby
05/93 - 11/93 - 2nd Asteroid Belt Passage
08/28/93 - Asteroid Ida Flyby
07/02/95 - Probe Separation
07/09/95 - Orbiter Deflection Maneuver
12/95 - 10/97 - Orbital Tour of Jovian Moons
12/07/95 - Jupiter/Io Encounter
07/18/96 - Ganymede
09/28/96 - Ganymede
12/12/96 - Callisto
01/23/97 - Europa
02/28/97 - Ganymede
04/22/97 - Europa
05/31/97 - Europa
10/05/97 - Jupiter Magnetotail Exploration

HITEN (MUSES-A) - Japanese (ISAS) lunar probe launched 1/24/90. Made
multiple lunar flybys and released Hagoromo, a smaller satellite, into
lunar orbit. This mission made Japan the third nation to orbit a
satellite around the Moon. Hiten impacted the lunar surface on 4/10/93.

MAGELLAN - Venus radar mapping mission. Has mapped almost the entire
surface at high resolution and is working on a global gravity map.
Magellan recently executed an 80-day aerobraking program to lower and
circularize its orbit.

MARS OBSERVER - Mars orbiter including 1.5 m/pixel resolution camera.
Launched 9/25/92 on a Titan III/TOS booster. Contact was lost with MO on
8/21/93 while it was preparing for entry into Mars orbit. The spacecraft
has been written off. Mars Surveyor, a replacement mission to achieve
most of MO's science goals, is scheduled to launch in November 1996.

TOPEX/Poseidon - Joint US/French Earth observing satellite, launched
8/10/92 on an Ariane 4 booster. The primary objective of the
TOPEX/POSEIDON project is to make precise and accurate global
observations of the sea level for several years, substantially
increasing understanding of global ocean dynamics. The satellite also
will increase understanding of how heat is transported in the ocean.

ULYSSES- European Space Agency probe to study the Sun from an orbit over
its poles. Launched in late 1990, it carries particles-and-fields
experiments (such as magnetometer, ion and electron collectors for
various energy ranges, plasma wave radio receivers, etc.) but no camera.

Since no human-built rocket is hefty enough to send Ulysses far out of
the ecliptic plane, it went to Jupiter instead, and stole energy from
that planet by sliding over Jupiter's north pole in a gravity-assist
manuver in February 1992. This bent its path into a solar orbit tilted
about 85 degrees to the ecliptic. It will pass over the Sun's south pole
in the summer of 1994. Its aphelion is 5.2 AU, and, surprisingly, its
perihelion is about 1.5 AU-- that's right, a solar-studies spacecraft
that's always further from the Sun than the Earth is!

While in Jupiter's neigborhood, Ulysses studied the magnetic and
radiation environment. For a short summary of these results, see
*Science*, V. 257, p. 1487-1489 (11 September 1992). For gory technical
detail, see the many articles in the same issue.

OTHER SPACE SCIENCE MISSIONS (various sources; corrections and updates
are solicited. Launch dates are usually tentative, and most shuttle
missions are not listed even when they have some science content).

1993 Missions
o ALEXIS [spring, Pegasus]
ALEXIS (Array of Low-Energy X-ray Imaging Sensors) is to perform
a wide-field sky survey in the "soft" (low-energy) X-ray
spectrum. It will scan the entire sky every six months to search
for variations in soft-X-ray emission from sources such as white
dwarfs, cataclysmic variable stars and flare stars. It will also
search nearby space for such exotic objects as isolated neutron
stars and gamma-ray bursters. ALEXIS is a project of Los Alamos
National Laboratory and is primarily a technology development
mission that uses astrophysical sources to demonstrate the
technology. Contact project investigator Jeffrey J Bloch
( for more information.

o Wind [Aug, Delta II rocket]
Satellite to measure solar wind input to magnetosphere.

o Total Ozone Mapping Spectrometer [Dec, Pegasus rocket]
Study of Stratospheric ozone.

o SFU (Space Flyer Unit) [ISAS]
Conducting space experiments and observations and this can be
recovered after it conducts the various scientific and
engineering experiments. SFU is to be launched by ISAS and
retrieved by the U.S. Space Shuttle on STS-68 in 1994.

o Space Radar Lab [April, Shuttle]
Gather radar images of Earth's surface.

o Polar Auroral Plasma Physics [May, Delta II rocket]
June, measure solar wind and ions and gases surrounding the

o IML-2 (NASDA) [July, Shuttle]
International Microgravity Laboratory (Spacelab mission).

o Space Radar Lab [August, Shuttle]
Followon to SRL-01.

Advanced Earth Observing Satellite.

o SL-M (Spacelab - MIR) [May, Shuttle, MIR]
Space Shuttle docking with Russian MIR station. Life sciences
mission (Spacelab).

o MUSES-B (Mu Space Engineering Satellite-B) [ISAS]
Conducting research on the precise mechanism of space structure
and in-space astronomical observations of electromagnetic waves.

Mars orbiter to study the structure and motions of the Martian
atmosphere and its interaction with the solar winds.

Discovery-class mission to rendezvous with near-Earth asteroid
Eros in 1998. Will orbit Eros for a year to determine size,
shape, mass, magnetic field, and measure composition and surface

o VSOP (VLBI Space Observatory Program) [NASDA]
Scheduled to be launched ~8/96. NASA is building 3 specialized
tracking stations to record the wideband radioastronomy data
that this spacecraft will produce.

o Mars Surveyor [November, NASA]
Replacement for Mars Observer including most MO instruments. To
be launched on a Delta II booster and begin Mars science
operations in 1/98. Followon landers and orbiters are planned
for launch about every 2 years for the following decade.

Elucidating the crust structure and thermal construction of the
moon's interior.

o RADIOASTRON [Russian space agency]
Same purpose as 1996 VSOP mission. NRAO is building similar
ground stations for tracking. These two spacecraft will
coobserve radio sources in conjunction with ground based VLBA
radio telescopes.

Asteroid flyby and comet rendezvous (potential target comets are
Schwassmann-Wachmann 3, Wirtanen, Finlay and Brooks 2 for a
launch in the time interval 2002-2004). After rendezvous,
the spacecraft will stay with the comet along its trajectory
into the inner solar system through perihelion (the orbital
point nearest to the Sun) to study the material that constitutes
the comet, and the cometary processes that evolve with the
decreasing distance from the Sun. A Surface Science Station will
be deployed onto the comets' nucleus surface to provide the
means for in-situ studies of the nucleus.

o FIRST (Far InfraRed Space Telescope) [ESA]
Large (3-meter mirror) space observatory.

Proposed Missions:
o Advanced X-ray Astronomy Facility (AXAF)
Possible launch from shuttle in 1995, AXAF is a space
observatory with a high resolution telescope. It would orbit for
15 years and study the mysteries and fate of the universe.

o Clementine II
Preliminary studies for a Clementine II mission have been done
by JPL. These studies envision a launch in July 1995, flyby of
the asteroid Eros on March 13, 1996, and flyby of the asteroid
Toutatis on October 4, 1996. Clementine would deply a probe to
impact Toutatis, and imagery and other measurements of the
impact crater and debris would help analyze the composition of
the asteroid.

o Pluto Fast Flyby (PFF)
Possible launch in 1999-2000 (if a 1996 new start is
authorized). Calls for launch of two ~110-150 kg spacecraft
using Titan IV/Centaur or Proton (both with additional solid
kick stages) in 1999-2000 and encounters with Pluto and Charon
around 2006-8. Flybys would be at 12-18 km/second; data would be
recorded onboard the probes during the short encounters and
returned to Earth slowly (due to low power, small antenna sizes,
and large distances) over the next year or so.

Science objectives include characterizing global geology and
geomorphology of Pluto and Charon, mapping both sides of each
body, and characterizing Pluto's atmosphere (the atmosphere is
freezing out as Pluto moves away from the Sun, so launching
early and minimizing flight time is critical for this
objective). The 7 kilogram instrument package might include a
CCD imaging camera, IR mapping spectrometer, UV spectrometer,
and radio science occultation experiments.

The PFF spacecraft would be highly miniaturized descendant of
the present class of outer solar system platforms, breaking the
trend of increasingly complex and expensive probes such as
Galileo and Cassini.

o Space Infrared Telescope Facility
Possible launch by shuttle in 1999, this is the 4th element of
the Great Observatories program. A free-flying observatory with
a lifetime of 5 to 10 years, it would observe new comets and
other primitive bodies in the outer solar system, study cosmic
birth formation of galaxies, stars and planets and distant
infrared-emitting galaxies

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This is a static and possibly incomplete copy of the USEnet SCI.SPACE Frequently Asked Questions (FAQ) document dated March 1994 (before the material was copyrighted). The official copyrighted and and up-to-date FAQ is maintained by Jon Leech ( and is posted to Network News and available via the World Wide Web . KSC's Hypertext converter last run Thursday June 15 10:23:25 EDT 1995