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Altimeter Satellites: Topex/Poseidon, Jason, ERS-1, ERS-2, and EnviSat (

Aqua ( -Latin for water , is a NASA Earth Science satellite mission named for the large amount of information that the mission will be collecting about the Earth's water cycle, including evaporation from the oceans, water vapor in the atmosphere, clouds, precipitation, soil moisture, sea ice, land ice, and snow cover on the land and ice. Additional variables also being measured by Aqua include radiative energy fluxes, aerosols, vegetation cover on the land, phytoplankton and dissolved organic matter in the oceans, and air, land, and water temperatures.

    Moderate Resolution Imaging Spectrometer ( MODIS (or Moderate Resolution Imaging Spectroradiometer) is a key instrument aboard the Terra (EOS AM) and Aqua (EOS PM) satellites. Terra's orbit around the Earth is timed so that it passes from north to south across the equator in the morning, while Aqua passes south to north over the equator in the afternoon.

Defence Meteorological Satellite Program DMSP ( DMSP was designed to provide high-quality weather images to our military. Since the beginning of program, Aerospace has provided systems engineering and integration support. In 1998 DMSP was incorporated into the National Polar Orbiting Operational Environmental Satellite System (NPOESS), creating a joint civil-military weather system.

Envisat ( In March 2002, the European Space Agency launched Envisat, an advanced polar-orbiting Earth observation satellite which provides measurements of the atmosphere, ocean, land, and ice. The Envisat satellite has an ambitious and innovative payload that will ensure the continuity of the data measurements of the ESA ERS satellites. Envisat data supports earth science research and allows monitoring of the evolution of environmental and climatic changes.

Gravity Recovery and Climate Experiment GRACE ( GRACE, twin satellites launched in March 2002, are making detailed measurements of Earth's gravity field which will lead to discoveries about gravity and Earth's natural systems. These discoveries could have far-reaching benefits to society and the world's population.

    From GeoForschungsZentrum Potsdam Germany (in English) (

    From Center for Space Research University of Texas Austin (

Jason-1 Satellite from NASA Jet Propulsion Laboratory ( Jason-1 is the first follow-on to the highly successful TOPEX/Poseidon mission that measured ocean surface topography to an accuracy of 4.2 cm, enabled scientists to forecast the 1997-1998 El Nino, and improved understanding of ocean circulation and its effect of global climate. The joint NASA- CNES program will launch a French spacecraft on an American Delta II from an American base. Like TOPEX/Poseidon, the payload will include both American and French instruments. Jason-1 altimeter data will be part of a suite of data provided by other JPL-managed ocean missions--the GRACE mission will use two satellites to accurately measure Earth's mass distribution, and the QuikSCAT scatterometer mission will measure ocean-surface winds.


    Geostationary Operational Environmental Satellites GOES ( GOES satellites provide the kind of continuous monitoring necessary for intensive data analysis. They circle the Earth in a geosynchronous orbit, which means they orbit the equatorial plane of the Earth at a speed matching the Earth's rotation. This allows them to hover continuously over one position on the surface. The geosynchronous plane is about 35,800 km (22,300 miles) above the Earth, high enough to allow the satellites a full-disc view of the Earth.

    Polar Orbiting Environmental Satellites POES ( The POES satellite system offers the advantage of daily global coverage, by making nearly polar orbits roughly 14.1 times daily. Since the number of orbits per day is not an integer the sub orbital tracks do not repeat on a daily basis, although the local solar time of each satellite's passage is essentially unchanged for any latitude.

    Satellite Information Gateway ( The NOAASIS provides essential information for NOAA satellite direct readout station operators and users of NOAA environmental satellite data. While the emphasis is on the U.S. NOAA and GOES series of satellites, limited information is also provided for the satellites operated by other countries and entities. General background information about the U.S. satellites, suitable for all users, is also available on this site. Links to some products from U.S. satellite data are also available. This page will get the user started on finding what information is available on the NOAASIS.

QuickSCAT ( NASA's Quick Scatterometer (QuikSCAT) was lofted into space at 7:15 p.m. Pacific Daylight Time on Saturday (6/19/99) atop a U.S. Air Force Titan II launch vehicle from Space Launch Complex 4 West at California's Vandenberg Air Force Base. The satellite was launched in a south-southwesterly direction, soaring over the Pacific Ocean at sunset as it ascended into space to achieve an initial elliptical orbit with a maximum altitude of about 800 kilometers (500 miles) above Earth's surface.

Terra ( Terra is a multi-national, multi-disciplinary mission involving partnerships with the aerospace agencies of Canada and Japan. Managed by NASA's Goddard Space Flight Center, the mission also receives key contributions from the Jet Propulsion Laboratory and Langley Research Center. Terra is an important part of NASA's Science Mission, helping us better understand and protect our home planet.

    Advanced Spaceborn Thermal Emission and Reflection Radiometer ASTER ( The Advanced Spaceborne Thermal Emission and Reflection Radiometer obtains high-resolution (15 to 90 square meters per pixel) images of the Earth in 14 different wavelengths of the electromagnetic spectrum, ranging from visible to thermal infrared light. Scientists use ASTER data to create detailed maps of land surface temperature, emissivity, reflectance, and elevation.

    Clouds and Earth's Radiant Energy System CERES ( There are two identical CERES instruments aboard Terra that measure the Earth's total radiation budget and provide cloud property estimates that enable scientists to assess clouds' roles in radiative fluxes from the surface to the top of the atmosphere. One CERES instrument will operate in a cross-track scan mode and the other in a biaxial scan mode.

    Moderate Resolution Imaging Spectrometer (

Topex/Poseidon from NASA Jet Propulsion Laboratory ( Launched in 1992, TOPEX/Poseidon is a joint venture between CNES and NASA to map ocean surface topography. While a 3-year prime mission was planned, with a 5-year store of expendables, TOPEX/Poseidon has delivered an astonishing 10+ years of data from orbit.

Revised on: 4 February, 2005