Voyager LECP Pages
An Analysis of the Performance of the Magnetic
in the Voyager Low Energy Charged Particle Experiment
by Sheela Shodhan
The Voyager mission is a major element of NASA's strategy for the exploration of the outer solar system. Results from the Voyager Low Energy Charged Particle (LECP) instrument have been described elsewhere .
Voyager 2 is scheduled to arrive at Neptune on 24 August 1989. The gravitational force of Neptune will veer the spacecraft sharply towards its moon Triton. The Voyager spacecraft will then continue into the outer reaches of the solar system to the heliopause and beyond.
The large complement of scientific instruments aboard each Voyager allows the investigation of particles and fields as well as the broad coverage of the electromagnetic spectrum .
launch date (1977)
Jovian system (1979)
Uranian system (1986)
|Voyager 2||20 Aug.||09 July||26 Aug.*||24 June|
|Voyager 1||05 Sept.||05 March||12 Nov.**|
Table 2.1. The launch dates and the dates of closest approach to the planetary systems. Note: * indicates 1981, ** 1980
2.2 The Low Energy Charged Particle Experiment (LECP)
2.2.1 Objectives of the experiment
The above stated objectives are met by a single instrument which utilizes 23 solid state detectors configured in two distinct detector subsystems, each of which is optimized for a particular energy/intensity range and/or group of particle species. These are:
It is important to determine the particle anisotropies and since the Voyager spacecraft has a fixed orientation, both the subsystems are mounted on a rotating platform that is stepped through eight 45 deg. sectors in periods ranging from 48 seconds to 48 minutes.
The detectors in the LEMPA subsystem are designed for:
LEMPA uses two primary identification methods:
2.2.4 BETA and GAMMA detectors
These are designed to measure the low and intermediate portions of the electromagnetic spectrum respectively, primarily to measure low energy ( ³ 15 keV) electrons. They are also designed to measure large fluxes in the Jovian magnetosphere and at the same time to be capable of measuring interplanetary electrons such as those emitted in solar particle events. Energy spectra available from these detectors during the planetary encounters will be crucial in examining in depth particle acceleration and loss processes associated with satellite interactions in the planetary magnetospheres.
The table showing the areas of the Beta and the Gamma detectors for Voyager 1 and Voyager 1 :
Table 2.2. Areas of the Beta and the Gamma detectors for Voyager 1 and Voyager 2
The nominal LECP/LEMPA electron characteristics for Voyager 1 and Voyager 2 are :
Table 2.3. Nominal LECP/LEMPA Electron Characteristics for Voyager 1
Table 2.4. Nominal LECP/LEMPA Electron Characteristics for Voyager 2
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Last modified 12/9/02, Tizby Hunt-Ward