page_title: X band
section_title: Space communications
hierarchical_section_title: X band / Space communications
caption_attribution_description: English: View of 70m (230 ft.) spacecraft communication antenna at the Canberra Deep Space Communication Complex, located outside Canberra, Australia. It is one of the three complexes which comprise NASA's Deep Space Network. The other complexes are located in Goldstone, California, and Madrid, Spain. This is a parabolic antenna with Cassegrain feed. It operates on X band (8 - 12&#160;GHz) with extremely high gain of about 70&#160;dBi. The incoming microwaves bounce off the large dish and are focused on the small white convex secondary reflector, which reflects them into the feed horn at the center of the dish. The receiver uses extremely low noise amplifiers such as cryogenically cooled masers or parametric amplifiers to detect the faint signals from spacecraft in the outer reaches of the Solar System. The three flags in foreground are those of the nations hosting the three Deep Space Network sites.
context_page_description: The X band is the designation for a band of frequencies in the microwave radio region of the electromagnetic spectrum. In some cases, such as in communication engineering, the frequency range of the X band is rather indefinitely set at approximately 7.0–11.2 GHz. In radar engineering, the frequency range is specified by the Institute of Electrical and Electronics Engineers at 8.0–12.0 GHz. The X band is used for radar, satellite communication, and wireless computer networks.
context_section_description: Portions of the X band are assigned by the International Telecommunications Union (ITU) exclusively for deep space telecommunications. The primary user of this allocation is the American NASA Deep Space Network (DSN). DSN facilities are  in Goldstone, California (in the Mojave Desert), near Canberra, Australia, and near Madrid, Spain.
  These three stations, located approximately 120 degrees apart in longitude, provide continual communications from the Earth to almost any point in the Solar System independent of Earth rotation. DSN stations are capable of using the older and lower S band deep-space radio communications allocations, and some higher frequencies on a more-or-less experimental basis, such as in the K band.
  Notable deep space probe programs that have employed X band communications include the Viking Mars landers; the Voyager missions to Jupiter, Saturn, and beyond; the Galileo Jupiter orbiter; the New Horizons mission to Pluto and the Kuiper belt, the Curiosity rover and the Cassini-Huygens Saturn orbiter.
  The new European double Mars Mission ExoMars will also use X band communication, on the instrument LaRa, to study the internal structure of Mars, and to make precise measurements of the rotation and orientation of Mars by monitoring two-way Doppler frequency shifts between the surface platform and Earth. It will also detect variations in angular momentum due to the redistribution of masses, such as the migration of ice from the polar caps to the atmosphere.
  An important use of the X band communications came with the two Viking program landers. When the planet Mars was passing near or behind the Sun, as seen from the Earth, a Viking lander would transmit two simultaneous continuous-wave carriers, one in the S band and one in the X band in the direction of the Earth, where they were picked up by DSN ground stations. By making simultaneous measurements at the two different frequencies, the resulting data enabled theoretical physicists to verify the mathematical predictions of Albert Einstein's General Theory of Relativity. These results are some of the best confirmations of the General Theory of Relativity.
caption: DSS-43 70 meter X-band spacecraft communication antenna at the Canberra Deep Space Communication Complex, Australia.
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