General Information |
The encounter of Neptune by the Voyager 2 spacecraft in August of 1989 was a dramatic climax to the historic "Grand Tour" of the Solar System's giant outer planets. The Voyager Program, one of the most successful and exciting space projects ever flown, has revealed numerous surprises at each of its targeted planets, and it continues to provide new surprises as it explores the outer reaches of the solar system and searches for the boundaries between the plasmas, energetic charged particles, and magnetic fields of the solar system and those of the interstellar environment beyond the influence of the sun.
See the figures showing the Voyager 1 and 2 planetary encounter trajectories from launch through mid-1989, and the helioradii & heliographic latitudes and longitudes & spacecraft separation from launch through 2016.
The two Voyager spacecraft were launched in late 1977. Each had a close encounter with Jupiter in 1979, followed by encounters with Saturn in late 1980 and 1981 for Voyagers 1 and 2, respectively. After its Saturn encounter, Voyager 1 left the ecliptic plane and had no further close encounters with other planets of the Solar System. Voyager 2 continued on to encounter Uranus and Neptune in early 1986 and late 1989, respectively.
Throughout all of the dramatic Voyager events, JHU/APL has shared in the excitement as one of the instrument Principal Investigator institutions (PI: S. M. Krimigis). The Low Energy Charged Particle (LECP) instrument consists of two main subsystems: the Low Energy Particle Telescope (LEPT) and the Low Energy Magnetospheric Particle Analyzer (LEMPA).
The LECP is one of 11 instruments (including the radiotelemetry system, which served a dual purpose) that operated at the planetary encounters, and it is one of 5 instruments that explore the fields and charged particles environments of the solar system (along with the MAG, PLS, PWS, and CRS experiments). The positions of the LECP and other instruments on the spacecraft are shown in the spacecraft schematic.
The LECP instruments measure the intensity, energy spectra, composition, angular distributions, and spatial and temporal characteristics of ion and electrons that are encountered by the spacecraft. Charged particles with energies greater than about 20 keV are so characterized. Such particles are fundamental components of the interplanetary environment (through solar, galactic, and local acceleration processes) and of the space environments that surround the planets.
