|
The following list contains only selected spacecraft of interest to planetary science. It is far from complete (see below for more details). Much of the following was adapted from the sci.space FAQ.
(more info from NASA Spacelink)
(Apollo "home page"; Apollo Missions)
Pioneer 11's RTG power supply is dead. Its last communication with Earth was in November 1995. Pioneer 10 is still functioning (barely) but is no longer being tracked regularly due to budget cutbacks. The last data was received from it on 1997 March 31. They are heading off into interstellar space, the first craft ever to do so.
As the first two spacecraft to leave our solar system, Pioneer 10 & 11 carry a graphic message in the form of a 6- by 9-inch gold anodized plaque bolted to the spacecraft's main frame.
(Pioneer Project Home Page and more about Pioneer 10 and Pioneer 11 from NASA Spacelink; current status from NASA Ames)
Mercury in 1974. The probe
did return the first close-up images of the Venusian atmosphere in
ultraviolet, revealing previously unseen details in the cloud
cover,
plus the fact that the entire cloud system circles the planet in
four
Earth days. Mariner 10 eventually made three flybys of Mercury
from 1974
to 1975 before running out of attitude control gas. The probe
revealed
Mercury as a heavily cratered world with a mass much greater than
thought. This would seem to indicate that Mercury has an iron core
which
makes up 75 percent of the entire planet.
(more info from NASA Spacelink; and NSSDC a tutorial from UCLA)
orbit on June
19, 1976, and the lander set down on the western slopes of Chryse
Planitia on July 20, 1976. It soon began its programmed search for
Martian micro-organisms (there is still debate as to whether the
probes
found life there or not), and sent back incredible color panoramas
of
its surroundings. One thing scientists learned was that Mars' sky
was
pinkish in color, not dark blue as they originally thought (the
sky is
pink due to sunlight reflecting off the reddish dust particles in
the
thin atmosphere). The lander set down among a field of red sand
and
boulders stretching out as far as its cameras could image.
The last data from Viking (Lander 1) made its final transmission to Earth Nov. 11, 1982. Controllers at JPL tried unsuccessfully for another six and one-half months to regain contact with Viking Lander 1. The overall mission came to an end May 21, 1983.
An interesting side note: Viking 1's lander has been designated the Thomas A. Mutch Memorial Station in honor of the late leader of the lander imaging team. The National Air and Space Museum in Washington, DC is entrusted with the safekeeping of the Mutch Station Plaque until it can be attached to the lander by a manned expedition.
(more info (pdf) and an web page from JPL)
Between the two probes, our knowledge of the 4 giant planets, their satellites, and their rings has become immense. Voyager 1&2 discovered that Jupiter has complicated atmospheric dynamics, lightning and aurorae. Three new satellites were discovered. Two of the major surprises were that Jupiter has rings and that Io has active sulfurous volcanoes, with major effects on the Jovian magnetosphere.
When the two probes reached Saturn, they discovered over 1000 ringlets and 7 satellites, including the predicted shepherd satellites that keep the rings stable. The weather was tame compared with Jupiter: massive jet streams with minimal variance (a 33-year great white spot/band cycle is known). Titan's atmosphere was smoggy. Mimas's appearance was startling: one massive impact crater gave it the Death Star appearance. The big surprise here was the stranger aspects of the rings. Braids, kinks, and spokes were both unexpected and difficult to explain.
In contrast to Uranus, Neptune was found to have rather active weather, including numerous cloud features. The ring arcs turned out to be bright patches on one ring. Two other rings, and 6 other satellites, were discovered. Neptune's magnetic axis was also skewed. Triton had a canteloupe appearance and geysers. (What's liquid at 38K?)
If no unforeseen failures occur, we will be able to maintain communications with both spacecraft until at least the year 2030. Both Voyagers have plenty of hydrazine fuel -- Voyager 1 is expected to have enough propellant until 2040 and Voyager 2 until 2034. The limiting factor is the RTGs (radio-isotope thermal generators). The power output from the RTGs is slowly dropping each year. By 2000, there won't be enough power for the UVS (ultraviolet spectrometer) instrument. By 2010, the power will have dropped low enough such that not all of the fields and particles instruments can be powered on at the same time. A power sharing plan will go into effect then, where some of the F&P instruments are powered on, and others off. The spacecraft can last in this mode for about another 10 years, and after that the power will probably be too low to maintain the spacecraft.
(the Voyager Project Home Page from JPL; another nice "home page" at NSSDC; fact sheets and a web page from JPL; General Info from NASA/ARC)
In April, 1990, Giotto was reactivated. 3 of the instruments proved fully operational, 4 partially damaged but usable, and the remainder, including the camera, were unusable. On July 2, 1990, Giotto made a close encounter with Earth and was retargeted to a successful flyby of comet Grigg-Skjellerup on July 10, 1992.
Ground controllers have regained control of the spacecraft, however. Its potential future mission is being considered.
(for more information see the Clementine Mission Home page from USGS and the Clementine page from NASA PDS or The Clementine Mission from LPI.)
(more info (pdf), a web page and another web page from JPL; fact sheet from NSSDC)
Both Voyagers are using their ultraviolet spectrometers to map the heliosphere and study the incoming interstellar wind. The cosmic ray detectors are seeing the energy spectra of interstellar cosmic rays in the outer heliosphere
Voyager 1 has passed the Pioneer 10 spacecraft and is now the most distant human-made object in space.
(more info from JPL)
evidence of the interior of a gas giant.
Galileo has already returned the first resolved images of two asteroids, 951 Gaspra and 243 Ida, while in transit to Jupiter. It has also returned pictures of the impact of Comet SL9 onto Jupiter from its unique vantage point.
Efforts to unfurl the stuck High Gain
Antenna (HGA) have essentially been abandoned.
With its Low Gain Antenna
Galileo transmits data at about 10 bits per second.
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.
Long term
Jovian weather monitoring, which is imagery intensive, will
suffer the
most.
Galileo Schedule (times UTC)
----------------
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
07/13/95 - Probe Separation
07/20/95 - Orbiter Deflection Maneuver
12/07/95 - Jupiter Encounter
06/27/96 06:30 - Ganymede-1
09/06/96 19:01 - Ganymede-2
11/04/96 13:30 - Callisto-3
11/06/96 18:42 - Europa-3A ("non-targeted" flyby @32,000 km on the
same orbit as Callisto-3)
12/19/96 06:56 - Europa-4
01/20/97 01:13 - Europa-5A (flyby @27,400 km during solar
conjunction - counts for gravity - not science)
02/20/97 17:03 - Europa-6
04/04/97 06:00 - Europa-7A ("non-targeted" @23,200 km on the
Ganymede-7 orbit)
04/05/97 07:11 - Ganymede-7
05/06/97 12:12 - Callisto-8A ("non-targeted" @33,500 km on the
Ganymede-8 orbit)
05/07/97 15:57 - Ganymede-8
06/25/97 13:48 - Callisto-9
06/26/97 17:20 - Ganymede-9A ("non-targeted" @80,000 km on the
Callisto-9 orbit)
09/17/97 00:21 - Callisto-10
11/06/97 21:47 - Europa-11 (more
details)
Galileo's extended mission has been approved. If all goes well, it
will spend
another two years focusing primarily on Europa. (Education and Public Outreach (images!); Galileo Home Page; Galileo Probe Home Page and more info from JPL; newsletter; web page; NSSDC page; preliminary Galileo Probe Results from JPL and ARC and LANL)
Named for the American astronomer Edwin Hubble.
Much, much more information about HST and HST pictures are available at the Space Telescope Science Institute. HST's latest images are posted regularly. (Here is a brief history of the HST project. There's also some more HST info at JPL.)
(Ulysses Home Pages from JPL and ESA; yet more info from JPL)
The main scientific goal of the mission is to measure the mass, momentum and energy of the solar wind that somehow is transferred into the space environment around the Earth. Although much has been learned from previous space missions about the general nature of this huge transfer, it is necessary to gather a great deal of detailed information from several strategic regions of space around the Earth before scientists understand the ways in which the planet's atmosphere responds to changes in the solar wind.
The launch also marks the first time a Russian instrument will fly on an American spacecraft. The Konus Gamma-Ray Spectrometer instrument, provided by the Ioffe Institute, Russia, is one of two instruments on Wind which will study cosmic gamma-ray bursts, rather than the solar wind. A French instruments is also aboard.
At first, the satellite will have a figure-eight orbit around the Earth with the assistance of the Moon's gravitational field. Its furthest point from the Earth will be up to 990,000 miles (1,600,000 kilometers), and its closest point will be at least 18,000 miles (29,000 kilometers).
Later in the mission, the Wind spacecraft will be inserted into a special halo orbit in the solar wind upstream from the Earth, at the unique distance which allows Wind to always remain between the Earth and the Sun (about 930,000 to 1,050,000 miles, or 1,500,000 to 1,690,000 kilometers, from the Earth).
Launched on 1996 February 17 aboard a Delta 2 rocket, the NEAR spacecraft should arrive in orbit around asteroid 433 Eros in early January 1999. It will then survey the rocky body for a minimum of one year, at altitudes as close as 15 miles (24 kilometers). Eros is one of the largest and best-observed asteroids whose orbits cross Earth's path. These asteroids are closely related to the more numerous "Main Belt" asteroids that orbit the Sun in a vast doughnut-shaped ring between Mars and Jupiter.
(NEAR Home Page; more info from NSSDC; more from John Hopkins Univ.; Curriculum materials; more from JPL)
(MGS Home Page from JPL; Planned Missions from 1996 to 2003)
The scientific objectives include atmospheric entry science, long-range and close-up surface imaging, with the general objective being to characterize the Martian environment for further exploration. The spacecraft will enter the Martian atmosphere without going into orbit around the planet and land on Mars with the aid of parachutes, rockets and airbags, taking atmospheric measurements on the way down. Prior to landing, the spacecraft will be enclosed by three triangular solar panels (petals), which will unfold onto the ground after touchdown.
Mars Pathfinder was launched 1996 December 4 and landed successfully on Mars on 1997 July 4.
(info and MPF Home Page from JPL; more info from NSSDC; images and press releases from MSFC; Mars Watch, Linking Amateur and Professional Mars Observing Communities for Observational Support of the Mars Pathfinder Mission)
An earlier plan for an asteroid fly-by on the way out similar to the highly successful Galileo fly-bys of Ida and Gaspra was scrapped in order to reduce costs.
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.
Key Scheduled Dates for the Cassini Mission (VVEJGA Trajectory) ------------------------------------------------------------- 10/15/97 - Titan IV/Centaur Launch 04/26/98 - Venus 1 Gravity Assist 06/24/99 - Venus 2 Gravity Assist 08/18/99 - Earth Gravity Assist 12/30/00 - Jupiter Gravity Assist 07/01/04 - Saturn Arrival 11/06/04 - Probe Separation 11/27/04 - Titan Probe Entry 06/25/08 - End of Primary Mission
(Cassini Home Page from JPL; Huygens Home Page; another Cassini page from JPL; more info from JPL; from NASA Spacelink; info on the Doppler Wind Experiment on Huygens)
(home page; see also Europa Ocean Explorer)
Pluto-Kuiper Express
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 a 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.
There's an article about PFF by its designers in the Sep/Oct 1994 issue of The Planetary Report, the bimonthly newsletter from The Planetary Society.
Funding for this project is very much in doubt.
(more info from NASA; Pluto Express home page; Pluto Express Science)
This innovative mission will use new flight technology, including solar electric propulsion, to send a spacecraft to asteroid 4660 Nereus and deliver a JPL-developed rover, which measures about the size of a shoebox, to the asteroid's surface. The Muses-C spacecraft will also fire explosive charges into the asteroid, collect the samples that are ejected from the impacts, and return the samples to Earth in a capsule for laboratory analysis. The mission is scheduled for launch in 2002.
... Seeing
... Spacecraft
... Plea
... 
