Пионер-11: Исследование Юпитера и Сатурна

Space probe launched by NASA in 1973

Pioneer 11 (also known as Pioneer G) is a NASA robotic space probe launched on April 5, 1973, to study the asteroid belt, the environment around Jupiter and Saturn, the solar wind, and cosmic rays. Pioneer 11 was built by TRW and managed as part of the Pioneer program by NASA Ames Research Center. A backup unit, Pioneer H, is currently on display in the "Milestones of Flight" exhibit at the National Air and Space Museum in Washington, D. C. Many elements of the mission proved to be critical in the planning of the Voyager program.

The Pioneer 11 bus measures deep and with six panels forming the hexagonal structure. The bus houses propellant to control the orientation of the probe and eight of the twelve scientific instruments. The spacecraft has a mass of 259 kilograms. hydrazine monopropellant thrusters: pair one maintains a constant spin rate of 4.8 rpm, pair two controls the forward thrust, pair three controls attitude. Information for the orientation is provided by performing conical scanning maneuvers to track Earth in its orbit, a star sensor able to reference Canopus, and two Sun sensors. Helium Vector Magnetometer (HVM) Measures the fine structure of the interplanetary magnetic field, mapped the Jovian magnetic field, and provides magnetic field measurements to evaluate solar wind interaction with Jupiter. Quadrispherical Plasma Analyzer Peer through a hole in the large dish shaped antenna to detect particles of the solar wind originating from the Sun. Charged Particle Instrument (CPI) Detects cosmic rays in the Solar System. Cosmic Ray Telescope (CRT) Collects data on the composition of the cosmic ray particles and their energy ranges. Geiger Tube Telescope (GTT) Surveys the intensities, energy spectra, and angular distributions of electrons and protons along the spacecraft's path through the radiation belts of Jupiter and Saturn. Trapped Radiation Detector (TRD) Includes an unfocused Cerenkov counter that detects the light emitted in a particular direction as particles passed through it recording electrons of energy, 0.5 to 12 MeV, an electron scatter detector for electrons of energy, 100 to 400 keV, and a minimum ionizing detector consisting of a solid state diode that measured minimum ionizing particles (<3 MeV) and protons in the range of 50 to 350 MeV. Meteoroid Detectors Twelve panels of pressurized cell detectors mounted on the back of the main dish antenna record penetrating impacts of small meteoroids. Asteroid/Meteoroid Detector (AMD) Meteoroid asteroid detector looks into space with four non imaging telescopes to track particles ranging from close by bits of dust to distant large asteroids. Ultraviolet Photometer Ultraviolet light is sensed to determine the quantities of hydrogen and helium in space and on Jupiter and Saturn. Imaging Photopolarimeter (IPP) The imaging experiment relies upon the spin of the spacecraft to sweep a small telescope across the planet in narrow strips only 0.03 degrees wide, looking at the planet in red and blue light. These strips are then processed to build up a visual image of the planet. Infrared Radiometer Provides information on cloud temperature and the output of heat from Jupiter and Saturn. Triaxial Fluxgate Magnetometer Measures the magnetic fields of both Jupiter and Saturn. This instrument is not carried on Pioneer 10.

The Pioneer 11 probe was launched on April 6, 1973, at 02:11:00 UTC, by the National Aeronautics and Space Administration from Space Launch Complex 36A at Cape Canaveral, Florida aboard an Atlas Centaur launch vehicle, with a Star 37E propulsion module. Its twin probe, Pioneer 10, had been launched on March 3, 1972. Pioneer 11 was launched on a trajectory directly aimed at Jupiter without any prior gravitational assists. In May 1974, Pioneer was retargeted to fly past Jupiter on a north–south trajectory, enabling a Saturn flyby in 1979. The maneuver used of propellant, lasted 42 minutes and 36 seconds, and increased Pioneer 11's speed by 230 km/h. It also made two mid course corrections, on April 11, 1973 and November 7, 1974.

Pioneer 11 flew past Jupiter in November and December 1974. During its closest approach, on December 2, it passed above the cloud tops.

By 1995, Pioneer 11 could no longer power any of its detectors, so the decision was made to shut it down. On September 29, 1995, NASA's Ames Research Center, responsible for managing the project, issued a press release that began, "After nearly 22 years of exploration out to the farthest reaches of the Solar System, one of the most durable and productive space missions in history will come to a close." It indicated NASA would use its Deep Space Network antennas to listen "once or twice a month" for the spacecraft's signal, until "some time in late 1996" when "its transmitter will fall silent altogether." NASA Administrator Daniel Goldin characterized Pioneer 11 as "the little spacecraft that could, a venerable explorer that has taught us a great deal about the Solar System and, in the end, about our own innate drive to learn. Pioneer 11 is what NASA is all about – exploration beyond the frontier." Besides announcing the end of operations, the dispatch provided a historical list of Pioneer 11 mission achievements. NASA terminated routine contact with the spacecraft on September 30, 1995, but continued to make contact for about two hours every two to four weeks.

Timeline of travel Date Event 1973 04 06 Spacecraft launched at 02:11:00. 1974 04 19 Passage through the asteroid belt. 1974 11 03 Start Jupiter observation phase. Time Event 1974 12 02 Encounter with Jovian system. 08:21:00 Callisto flyby at 786,500 km. 22:09:00 Ganymede flyby at 692,300 km. 1974 12 03 03:11:00 Io flyby at 314,000 km. 04:15:00 Europa flyby at 586,700 km. 05:00:21 Jupiter shadow entry. 05:01:01 Jupiter occultation entry. 05:21:19 Jupiter closest approach at 42,828 km. 05:33:52 Jupiter shadow exit. 05:43:03 Jupiter occultation exit. 22:29:00 Amalthea flyby at 127,500 km. 1975 01 01 Phase stop. 1979 07 31 Start Saturn observation phase. Time Event 1979 08 29 Encounter with Saturnian system. 06:06:10 Iapetus flyby at 1,032,535 km. 11:53:33 Phoebe flyby at 13,713,574 km. 1979 08 31 12:32:33 Hyperion flyby at 666,153 km. 1979 09 01 14:26:56 Descending ring plane crossing. 14:50:55 Epimetheus flyby at 6,676 km. 15:06:32 Atlas flyby at 45,960 km. 15:59:30 Dione flyby at 291,556 km. 16:26:28 Mimas flyby at 104,263 km. 16:29:34 Saturn closest approach at 20,591 km. 16:35:00 Saturn occultation entry. 16:35:57 Saturn shadow entry. 16:51:11 Janus flyby at 228,988 km. 17:53:32 Saturn occultation exit. 17:54:47 Saturn shadow exit. 18:21:59 Ascending ring plane crossing. 18:25:34 Tethys flyby at 329,197 km. 18:30:14 Enceladus flyby at 222,027 km. 20:04:13 Calypso flyby at 109,916 km. 22:15:27 Rhea flyby at 345,303 km. 1979 09 02 18:00:33 Titan flyby at 362,962 km. 1979 10 05 Phase stop. 1979 10 05 Begin Pioneer Interstellar Mission. 1990 Passed the orbit of Pluto. 1995 09 30 Routine daily mission operations stopped. Pioneer 11 is 6.5 billion km from Earth. 1995 11 24 Last signal received.

Due to power constraints and the vast distance to the probe, the last routine contact with the spacecraft was on September 30, 1995, and the last good engineering data was received on November 24, 1995. As of January 20, 2023, Pioneer 11 is estimated to be from the Earth and from the Sun. It was traveling at relative to the Sun and traveling outward at about 2.36 AU per year. The spacecraft is heading in the direction of the constellation Scutum near the current position (January 2023) RA 18h 54m dec 8° 59' (J2000.0), close to Messier 26. In 928,000 years, it will pass within of the K dwarf TYC 992 192 1 and will pass near the star Lambda Aquilae in about four million years. Pioneer 11 has now been overtaken by the two Voyager probes launched in 1977, and Voyager 1 became the most distant object built by humans and will remain so for the foreseeable future, as no probe launched since Voyager has the speed to overtake it.

Analysis of the radio tracking data from the Pioneer 10 and 11 spacecraft at distances between 20 and 70 AU from the Sun had consistently indicated the presence of a small but anomalous Doppler frequency drift. The drift can be interpreted as due to a constant acceleration of (8.74 ± 1.33) × 10−10 m/s2 directed towards the Sun. Although it was suspected that there was a systematic origin to the effect, none was found. As a result, there has been sustained interest in the nature of this so called "Pioneer anomaly". Extended analysis of mission data by Slava Turyshev and colleagues determined the source of the anomaly to be asymmetric thermal radiation and the resulting thermal recoil force acting on the face of the Pioneers away from the Sun.

Pioneer 10 and 11 both carry a gold anodized aluminum plaque in the event that either spacecraft is ever found by intelligent lifeforms from other planetary systems. The plaques feature the nude figures of a human male and female along with several symbols that are designed to provide information about the origin of the spacecraft.

In 1991, Pioneer 11 was honored on one of 10 United States Postage Service stamps commemorating uncrewed spacecraft exploring each of the then nine planets and the Moon. Pioneer 11 was the spacecraft featured with Jupiter. Pluto was listed as "Not yet explored".