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")
Pioneer 11's RTG power supply is dead. Its last communication with Earth was in November 1995. Pioneer 10 continues to gather valuable scientific data but will be shut down on March 31, 1997 due to budget cutbacks. 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)
(more from JPL and JPL)
(more info from NASA Spacelink; a tutorial from UCLA)
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 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)
(Vega Mission Home page
(Phobos Mission Home page
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.
(more info from NSSDC)
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, a web page and another web page from JPL; Magellan page from NASA PDS; 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
It is now estimated that Voyager 1 will pass the Pioneer 10 spacecraft in January 1998 to become the most distant human-made object in space.
(more info from JPL)
As of December 1 1994, Voyager 1 was 8.7 billion kilometers (5.4 billion miles) from Earth traveling at 61,200 km/hr (39,000 mph) and Voyager 2 was 6.7 billion kilometers (4.2 billion miles) from Earth traveling at 57,600 km/hr (36,000 mph).
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
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)The magnetotail passage occurs on the long orbit between Callisto 9 and 10. Galileo will also obtain a few images of Jupiter's ring system and some of its smaller satellites.
Galileo passed by Jupiter at a distance of only 214,000 km from the cloud tops on its first "perijove" on 7-Dec-1995
No images of Io and Europa were returned from the intial orbit due to concerns with the tape recorder. An additional close pass by Io may be added late in the mission.
The date from the probe has been safely returned to Earth and the last major manouver completed successfully. New software has been uploaded which (among other things) uses data compression techniques to improve the effective data transmission rate by a factor of 8.
(Education and Public Outreach (images!); Galileo page from NASA PDS; the 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; a Fact Sheet from JPL; 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; Curriculum materials; more from JPL)
Mars Global Surveyor will be a polar-orbiting spacecraft at Mars designed to provide global maps of surface topography, distribution of minerals and monitoring of global weather.
Launched with a Delta II expendable vehicle from Cape Canaveral, Fla., on November 7 1996, the spacecraft is now in its 10-month cruise phase; it will arrive at Mars on September 12, 1997, where it will be initially inserted into an elliptical capture orbit. During the following four months, thruster firings and aerobraking techniques will be used to reach the nearly circular mapping orbit over the Martian polar caps. Aerobraking, a technique pioneered by the Magellan mission, which uses the forces of atmospheric drag to slow the spacecraft into its final mapping orbit, will provide a means of minimizing the amount of fuel required to reach the low Mars orbit. Mapping operations are expected to begin in late January 1998.
The spacecraft will circle Mars once every two hours, maintaining a "sun synchronous" orbit that will put the sun at a standard angle above the horizon in each image and allow the mid-afternoon lighting to cast shadows in such a way that surface features will stand out. The spacecraft will carry a portion of the Mars Observer instrument payload and will use these instruments to acquire data of Mars for a full Martian year, the equivalent of about two Earth years. The spacecraft will then be used as a data relay station for signals from U.S. and international landers and low-altitude probes for an additional three years.
International participation, collaboration and coordination will enhance all missions of the program. Landers in future years -- 1998, 2001, 2003 and 2005 -- will capitalize on the experience of the Mars Pathfinder lander mission to be launched in 1996. Small orbiters launched in the 1998 and 2003 opportunities will carry other instruments from the Mars Observer payload and will serve as data relay stations for international missions of the future.
The Mars Global Surveyor spacecraft will be acquired from industry through a competitive procurement. The science payload will be provided as government-furnished equipment that was built to duplicate the instruments flown on Mars Observer. The payload includes the Mars orbital camera, thermal emission spectrometer, ultra-stable oscillator, laser altimeter, magnetometer/electron reflectometer and Mars relay system.
The Jet Propulsion Laboratory will manage the project for NASA's Solar System Exploration Division and will provide the mission design, navigation, and conduct mission operations. Tracking and data acquisition will be provided by a 34-meter subnetwork of the worldwide Deep Space Network.
Project costs for the Mars Global Surveyor through 30 days after launch will be approximately $155 million.
(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 will arrive at Mars 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) ------------------------------------------------------------- 10/06/97 - 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 11/06/04 - Probe Separation 11/27/04 - Titan Probe Entry 06/25/08 - End of Primary Mission
(Cassini Home Page from JPL; another Cassini page from JPL; Cassini page from NASA PDS; more info from JPL; fact sheets from NASA Spacelink; info on the Doppler Wind Experiment on Huygens)
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)
Hermes is a joint effort between JPL and TRW. If it is approved, it will be launched in 1999.
Bill Arnett; last updated: 1997 Jan 13