--------------------------------------------------------- NSSDC Master Catalog Display Spacecraft --------------------------------------------------------- Pioneer 11 NSSDC ID: 73-019A Other Name(s) * Pioneer-G * 06421 --------------------------- Launch Date/Time: 1973-04-06 at 02:11:00 UTC On-orbit dry mass: 259.00 kg Nominal Power Output: 165.00 W --------------------------- Description This was the second mission to investigate Jupiter and the outer solar system and the first to explore the planet Saturn and its main rings. Pioneer 11, like Pioneer 10, used Jupiter's gravitational field to alter its trajectory radically. It passed close to Saturn and then it followed an escape trajectory from the solar system. The spacecraft was 2.9 m long and contained a 2.74-m diameter high-gain antenna of aluminum honeycomb sandwich material whose feed was topped with a medium-gain antenna. A low-gain, omnidirectional antenna was mounted below the high-gain dish. The spacecraft contained two nuclear electric-power generators, which generated 144 W at Jupiter, but decreased to 100 W at Saturn. There were three reference sensors: a star (Canopus) sensor, and two sun sensors. Attitude position could be calculated from the reference direction to the earth and the sun, with the known direction to Canopus as backup. Pioneer 11's star sensor gain and threshold settings were modified, based on experience gained from the settings used on Pioneer 10. Three pairs of rocket thrusters provided spin-axis control (maintained at 4.8 rpm) and change of the spacecraft velocity. The thrusters could be either fired steadily or pulsed, by command. Communications were maintained via the omnidirectional and medium-gain antennas, which operated together, connected to one receiver, while the high-gain antenna was connected to the other receiver. The receivers could be interchanged by command. Two radio transmitters, coupled to two traveling-wave tube amplifiers, produced 8 W power each in S-band. Communication uplink (earth to spacecraft) operated at 2110 MHz, and downlink (spacecraft to earth) at 2292 MHz. At Jupiter's distance, round-trip communication time took 92 min. Data were received at the Deep Space Network (DSN). The spacecraft was temperature-controlled to between -23 and +38 deg C (-10 to +100 deg F). An additional experiment, a low-sensitivity fluxgate magnetometer, was added to the Pioneer 11 payload. Instruments studied the interplanetary and planetary magnetic fields; solar wind properties; cosmic rays; transition region of the heliosphere; neutral hydrogen abundance; distribution, size, mass, flux, and velocity of dust particles; Jovian aurorae; Jovian radio waves; the atmospheres of planets and satellites; and the surfaces of Jupiter, Saturn, and some of their satellites. Instruments carried for these experiments were magnetometer, plasma analyzer (for solar wind), charged-particle detector, ionizing detector, non-imaging telescopes with overlapping fields of view to detect sunlight reflected from passing meteoroids, sealed pressurized cells of argon and nitrogen gas for measuring penetration of meteoroids, UV photometer, IR radiometer, and an imaging photopolarimeter, which produced photographs and measured the polarization. Further scientific information was obtained from celestial mechanics and occultation phenomena. This spacecraft, like Pioneer 10, contains a plaque that has a drawing depicting man, woman, and the location of the sun and earth in the galaxy. During its closest approach, December 4, 1974, Pioneer 11 passed to within 34,000 km of Jupiter's cloud tops. It passed by Saturn on September 1, 1979, at a distance of 21,000 km from Saturn's cloud tops. The spacecraft has operated on a backup transmitter since launch. Instrument power sharing began in February 1985 due to declining RTG power output. Science operations and daily telemetry ceased on September 30, 1995 when the RTG power level was insufficient to operate any experiments. As of the end of 1995 the spacecraft was located at 44.7 AU from the Sun at a nearly asymptotic latitude of 17.4 degrees above the solar equatorial plane and was heading outward at 2.5 AU/year. ------------------- Discipline(s) Astronomy Planetary Science Space Physics Sponsoring Agencies/Countries NASA-Office of Space Science Applications/United States --------------------------------------------------------- NSSDC Master Catalog Display Spacecraft Launch/Orbital Information --------------------------------------------------------- Pioneer 11 NSSDC ID: 73-019A Launch Information Launch Date/Time: 1973-04-06 at 02:11:00 UTC Launch Site/Country: Cape Canaveral, United States Launch Vehicle: Atlas-Centaur Orbital Information Orbit: Interplanetary cruise Central Body: Sun Epoch start date/time: 1973.095:14:11:00 (05 Apr.) Epoch end date/time: 1974.336:17:22:00 (02 Dec.) Periapsis: 1.00 AU ------------------- Orbit: Flyby Central Body: Jupiter Epoch start date/time: 1974.336:17:22:00 (02 Dec.) Inclination: 51.80 degrees Periapsis: 1.60 RJ Apoapsis: 51.80 RJ ------------------- Orbit: Interplanetary cruise Central Body: Sun Epoch start date/time: 1974.336:17:22:01 (02 Dec.) Epoch end date/time: 1979.244:16:31:00 (01 Sep.) Inclination: 6.60 degrees Periapsis: 4.90 AU Apoapsis: 6.60 AU ------------------- Orbit: Flyby Central Body: Saturn Closest approach date/time: 1979.244:16:31:00 (01 Sep.) Periapsis: 1.34 RS ------------------- Orbit: Solar system escape Central Body: Sun Epoch start date/time: 1979.244:16:31:00 (01 Sep.) Inclination: 12.60 degrees Periapsis: 9.40 AU Apoapsis: 12.60 AU ------------------- --------------------------------------------------------- NSSDC Master Catalog Display Spacecraft Telecommunications Information --------------------------------------------------------- Pioneer 11 NSSDC ID: 73-019A Telemetry rates: 0.016 - 2.048 kbps Effective Telemetry Rate: 0.450 kbps Telemetry support via Deep Space Network (DSN) Description The DSN supported the Pioneer spacecraft deep space tracking, uplink commands, and downlink data acquisition during the mission with 26-m, 34-m, 64-m, and 70-m antennas at Goldstone, Madrid, and Canberra. Overlapping coverage by two stations was used to prevent loss of data. The spacecraft carried three antennas for reception and transmission - low gain (omnidirectional), medium gain, and high gain (beamed) - with pairs of redundant transmitters and receivers, so the ground uplink and downlink DSN antennas could be switched between the different antenna sizes to accommodate telemetry demands from other missions. Downlink telemetry bit rates were at a maximum of 2048 bps enroute to Jupiter and 1024 bps at Jupiter but were maintained at 1024 bps out to Saturn's orbit due to increases in DSN antenna sensitivity. Reduced bit rates were required during superior conjunctions with the Sun. Pioneer 11 could receive uplink commands from 34-m antennas at 36 AU from the Sun in mid-1992, and the downlink could be maintained at 32 bps on the 70-mt antennas. ------------------- --------------------------------------------------------- NSSDC Master Catalog Display Spacecraft Personnel --------------------------------------------------------- Pioneer 11 NSSDC ID: 73-019A Program Manager Dr. James B. Willett Code SS NASA Headquarters Washington, DC 20546 Electronic Mail WILLETT@USRA.EDU (INTERNET) NHQVAX::JWILLETT (NSI/DECNET) ----- Program Scientist Dr. W. Vernon Jones Code SR NASA Headquarters Washington, DC 20546 Electronic Mail WVJONES@NHQVAX.DNET.NASA.GOV (INTERNET) NHQVAX::WVJONES (NSI/DECNET) ----- Project Manager Mr. Richard O. Fimmel Mail Stop 244-8 NASA Ames Research Center Moffett Field, CA 94035 ----- Project Scientist Dr. Palmer Dyal Mail Stop 200-7 Astrophysics Branch NASA Ames Research Center Moffett Field, CA 94035 ----- NSSDC Contact Dr. John F. Cooper GSFC-Code 632 Electronic Mail JCOOPER@NSSDCA.GSFC.NASA.GOV (INTERNET) NCF::JCOOPER (NSI/DECNET) ----- --------------------------------------------------------- NSSDC Master Catalog Display Spacecraft Selected References --------------------------------------------------------- Pioneer 11 NSSDC ID: 73-019A 1. Fimmel, R. O., Swindell, W., and Burgess, E., Pioneer odyssey encounter with a giant, NASA, SP-349, Washington, D.C., 1974. 2. Fimmel, R. O., Van Allen, J. A., and Burgess, E., Pioneer first to Jupiter, Saturn and beyond, NASA, SP-466, Washington, D.C., 1980. 3. Northrop, T. G., Opp, A. G., and Wolfe, J. H., Pioneer 11 Saturn encounter, J. Geophys. Res., 85, No. A11, 5651-5652, Nov. 1980. --------------------------------------------------------------------------- For questions about this mission, please contact: Dr. John F. Cooper, jcooper@nssdca.gsfc.nasa.gov, (301)286-1193 GSFC-Code 632 For questions about the NSSDC's information systems, please contact: Dr. James Thieman, thieman@nssdca.gsfc.nasa.gov, (301)286-9790 National Space Science Data Center, Code 633.2 NASA/Goddard Space Flight Center, Greenbelt, MD 20771 --------------------------------------------------------------------------- NASA Official: J. H. King, king@nssdca.gsfc.nasa.gov Last Updated: 1996-08-29 Output Generated: 1996-09-15 Programming by: E. V. Bell, II