The Jason 1 satellite altimeter is a science project to measure the ocean surface topography, and the successor to the TOPEX/Poseidon satellite. Image File history File links Artists Drawing of Jason1, based on NASAs image http://topex-www. ... A satellite is any object that orbits another object (which is known as its primary). ... An altimeter is an active instrument used to measure the altitude of an object above a fixed level. ... The worlds oceans as seen from the South Pacific Ocean (from Okeanos, Greek for river, the ancient Greeks noticed that a strong current flowed off Gibraltar, and assumed it was a great river); covers almost three quarters (71%) of the surface of the Earth, and nearly half of the... Surface of the Earth Topography, a term in geography, has come to refer to the lay of the land, or the physiogeographic characteristics of land in terms of elevation, slope, and orientation. ... The TOPEX/Poseidon satellite altimeter is a science project to measure the ocean surface topography. ...

It is a joint project between the NASA (United States) and CNES (France) space agencies. It was launched on December 7, 2001 aboard a Boeing Delta II. During the first months Jason 1 shared an almost identical orbit to TOPEX which allowing for cross calibration. At the end of this period TOPEX was moved to a new orbit midway between each Jason ground track. Like TOPEX, Jason has a repeat cycle of 10 days. NASA Logo Listen to this article · (info) This audio file was created from the revision dated 2005-09-01, and does not reflect subsequent edits to the article. ... The Centre National dÉtudes Spatiales is the French government space agency (administratively, a public establishment of industrial and commercial character). Its headquarters are located in central Paris. ... December 7 is the 341st day (342nd in leap years) of the year in the Gregorian calendar. ... 2001: A Space Odyssey. ... The Boeing Company NYSE: BA is leading: American aircraft and aerospace manufacturer, headquartered in Chicago, Illinois, with its largest production facilities in Everett, Washington, about 30 miles north of Seattle, Washington. ... A Delta II rocket launches from Cape Canaveral carrying a GPS satellite The Boeing IDS Delta II family of launch vehicles has been in service since 1989 and has successfully launched 115 projects (through August, 2004) including the last six NASA missions to Mars: Mars Global Surveyor in 1996 Mars...

The program is named after the Greek mythological hero Jason. Jason (Greek: Ίασων, Etruscan: Easun) is a hero of Greek mythology. ...

It contains 5 instruments:

• Poseidon 2 - Nadir pointing Radar Altimeter using C band and Ku band for measuring height above sea surface.
• Jason Microwave Radiometer (JMR) - measures water vapor along altimeter path to correct for pulse delay
• DORIS (Doppler Orbitography and Radiopositioning Integrated by Satellite) for orbit determination to within 10 cm or less and ionospheric correction data for Poseidon 2.
• BlackJack Global Positioning System receiver provides precise orbit ephemeris data
• Laser retroreflector array works with ground stations to track the satellite and calibrate and verify altimeter measurements.

The nadir (from Arabic nazir, opposite) is the astronomical term for the point in the sky directly below the observer, or more precisely, the point in the sky with an altitude of -90°. Geometrically, it is the point on the celestial sphere intersected by a line drawn from the observer... This long range radar antenna (approximately 40m (130ft) in diameter) rotates on a track to observe activities near the horizon. ... An altimeter is an active instrument used to measure the altitude of an object above a fixed level. ... C band (compromise band) is a portion of electromagnetic spectrum in the microwave range of frequencies ranging from 4 to 6 GHz. ... The Ku band (kay-yoo kurz-under band) is a portion of the electromagnetic spectrum in the microwave range of frequencies ranging from 11 to 18 GHz. ... Sunset at sea Look up Sea on Wiktionary, the free dictionary Look up maritime on Wiktionary, the free dictionary. ... This page is about the radiation; for the appliance, see microwave oven. ... A Radiometer is a device used to measure the radiant flux or power in Electromagnetic radiation. ... Water vapor or water vapour, also aqueous vapour, is the gas phase of water. ... Sound waves emanating from an ambulance moving to the right. ... A satellite is any object that orbits another object (which is known as its primary). ... The ionosphere is the part of the atmosphere that is ionized by solar radiation. ... It has been suggested that Gps tracking be merged into this article or section. ... In physics, an orbit is the path that an object makes, around another object, whilst under the influence of a source of centripetal force, such as gravity. ... An ephemeris (plural: ephemerides) (from the Greek word ephemeros= daily) was, traditionally, a table providing the positions (given in a Cartesian coordinate system, or in right ascension and declination or, for astrologers, in longitude along the zodiacal ecliptic), of the Sun, the Moon, and the planets in the sky at... A retroreflector is a device that sends light or other radiation back where it came from regardless of the angle of incidence, unlike a mirror, which does that only if the mirror is exactly perpendicular to the light beam. ...

Use of information

A number of satellites (See links) use exotic dual-band radar altimeters to measure height from a spacecraft. That measurement, coupled with orbital elements (possibly from GPS), enables determination of the topography. The two lengths of radio waves permit the altimeter to automatically correct for varying delays in the ionosphere. This long range radar antenna (approximately 40m (130ft) in diameter) rotates on a track to observe activities near the horizon. ... Ariane 5 lifts off with the Rosetta space probe on March 2, 2004. ... In physics, an orbit is the path that an object makes, around another object, whilst under the influence of a source of centripetal force, such as gravity. ... Over fifty GPS satellites such as this NAVSTAR have been launched since 1978. ... Surface of the Earth Topography, a term in geography, has come to refer to the lay of the land, or the physiogeographic characteristics of land in terms of elevation, slope, and orientation. ... The ionosphere is the part of the atmosphere that is ionized by solar radiation. ...

Over water, detailed satellite altitude information has proven amazingly useful. Humps in the water indicate gravitational concentrations, permitting a computer program to construct a maps of undersea features such as mountains. The altimeters can also measure wave heights, wave directions, and wave spectra. This information permits computer programs to measure the speed of ocean currents and produce detailed maps of wind speeds and directions at the surface, even in extremely stormy conditions. Gravitation is the tendency of massive objects to accelerate towards each other. ...

This is a great article!

See also

• Argo, a project to measure the temperature and salinity of the upper 2 km of the water column.
• Seasat- an early radar altimeter satellite
• TOPEX/Poseidon- the immediate predecessor to Jason 1.

Argo is a network of oceanic robotic probes coverig the Earths oceans, with a total of 3000 probes planned. ... Seasat (Courtesy NASA/JPL-Caltech) Seasat was the first Earth-orbiting satellite designed for remote sensing of the Earths oceans and had onboard the first spaceborne synthetic aperture radar (SAR). ... The TOPEX/Poseidon satellite altimeter is a science project to measure the ocean surface topography. ...

External links

• Jason site at CNES
• TOPEX/Jason site at NASA

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