Monday, May 13, 2013
The Voyager program is an American scientific program that launched two unmanned space missions, the probes Voyager 1 and Voyager 2. These were launched in 1977 to take advantage of a favorable alignment of the planets during the late 1970s. Although they were designated officially to study just the planetary systems of Jupiter and Saturn, the space probes were able to continue their mission into the outer solar system, and they are expected to push through the heliosheath in deep space.
These two space probes were built at the Jet Propulsion Laboratory in Southern California, and they were paid for by the National Aeronautics and Space Administration (NASA), which also paid for their launchings from Cape Canaveral, Florida, their tracking, and everything else concerning the space probes.
As of April 2013, Voyager 1 is the farthest manmade object that has ever been sent from the Earth. On 15 June 2012, scientists at NASA reported that Voyager 1 might be very close to entering interstellar space and becoming the first manmade object to leave the Solar System.
Both of these scientific missions into outer space have gathered large amounts of data about the gas giants of the solar system, and their orbiting satellites, about which little had been previously known. In addition, the trajectories of the two spacecraft have been used to place limits on the existence of any hypothetical trans-Neptunian planets.
The Voyager spacecraft weighs 773 kilograms. Of this, 105 kilograms are scientific instruments. The identical Voyager spacecraft use three-axis-stabilized guidance systems that use gyroscopic and accelerometer inputs to their attitude control computers to point their high-gain antennas towards the Earth and their scientific instruments pointed towards their targets, sometimes with the help of a movable instrument platform for the smaller instruments and the electronic photography system.
The diagram at the right shows the high-gain antenna (HGA) with a 3.66 meter diameter attached to the hollow decagonal electronics container. There is also a spherical tank that contains the hydrazine monopropellant fuel.
The Voyager Golden Record is attached to one of the bus sides. The angled square panel to the right is the optical calibration target and excess heat radiator. The three radioisotope thermoelectric generators (RTGs) are mounted end-to-end on the lower boom.
Two 10-meter whip antennas, which study planetary radio astronomy and plasma waves, extend from the spacecraft's body diagonally below the magnetometer boom. The 13-meter long Astromast tri-axial boom extends diagonally downwards left and holds the two low-field magnetometers (MAG), and the high-field magnetometers remain close to the main antenna.
The instrument boom extending upwards holds, from bottom to top: the cosmic ray subsystem (CRS) left, and Low-Energy Charged Particle (LECP) detector right; the Plasma Spectrometer (PLS) right; and the scan platform that rotates about a vertical axis.
The scan platform comprises: the Infrared Interferometer Spectrometer (IRIS) (largest camera at top right); the Ultraviolet Spectrometer (UVS) just above the UVS; the two Imaging Science Subsystem (ISS) vidicon cameras to the left of the UVS; and the Photopolarimeter System (PPS) under the ISS.
Only five investigation teams are still supported, though data is collected for two additional instruments. The Flight Data Subsystem (FDS) and a single eight-track digital tape recorder (DTR) provide the data handling functions.
The FDS configures each instrument and controls instrument operations. It also collects engineering and science data and formats the data for transmission. The DTR is used to record high-rate Plasma Wave Subsystem (PWS) data. The data is played back every six months.
The Imaging Science Subsystem, made up of a wide angle and a narrow angle camera, is a modified version of the slow scan vidicon camera designs that were used in the earlier Mariner flights. The Imaging Science Subsystem consists of two television-type cameras, each with eight filters in a commandable Filter Wheel mounted in front of the vidicons. One has a low resolution 200 millimeter wide-angle lens with an aperture of f/3 (the wide angle camera), while the other uses a higher resolution 1.500 meter narrow-angle f/8.5 lens (the narrow angle camera).