Three tracking stations are located on Earth to transmit messages to spacecraft and receive data concerning the status of the instruments and their results. These stations form the Deep Space Network (DSN), and are located in Goldstone, California (pictured here); Madrid, Spain; and Canberra, Australia. Each station has a 70-meter (230-foot) diameter antenna, and two 26-meter (85-foot) antennas.
Signals from the Viking Orbiters and Landers were received by the large antennnas of the Deep Space Network. Since the spacecraft transmissions were received as pulses of electrical energy, much work remained to be done to turn these signals into meaningful information.
When first received at one of the Deep Space Network's tracking stations, spacecraft data appears to be a meaningless stream of numbers. However, computers at the tracking stations and at the Jet Propulsion Laboratory in Pasadena, California are programmed to recognize certain sequences of numbers and convert the signals into useable data.
Viking pictures of Mars are not true photographs, but are "images" made up of individual small segments that are put together by computer. The numbers on the computer printout are each proportional to the level of light received by the camera for that individual segment.
magnified vs. original
A greatly magnified version of
a Viking Orbiter image shows the checkerboard pattern of individual
picture elements, or "pixels." On this image, the width of one pixel
is equal to meters on the ground.
Color images of Mars are made by combining pictures taken through red, green, and blue filters to form a scene similar to what we could see if we were standing on the surface. Color patches on the top of the Landers, and even the American flag, were used to calibrate the colors for returned pictures.
|Deep Space Network Programs|
|In addition to spacecraft tracking, the instruments of the Deep Space Network (DSN) are used for radio science investigations, such as radar studies of planetary surfaces, locating source regions for quasars and pulsars, and searching for extraterrestrial intelligence. The antennas of the DSN were enlarged to 70 meters (230 feet) in diameter, enabling them to record faint signals from spacecraft traveling farther and farther from our solar system.|
Touchdown on Mars ||
Laboratory on Mars || Deep
Space Network || Viking Lander Views
The Viking Mission
Exploring The Planets
©2002 National Air and Space Museum