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Terra (EOS AM-1) is a multi-national scientific research
satellite A satellite or an artificial satellite is an object, typically a spacecraft, placed into orbit around a celestial body. They have a variety of uses, including communication relay, weather forecasting, navigation ( GPS), broadcasting, scient ...
operated by
NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...
in a
Sun-synchronous A Sun-synchronous orbit (SSO), also called a heliosynchronous orbit, is a nearly polar orbit around a planet, in which the satellite passes over any given point of the planet's surface at the same local mean solar time. More technically, it is ...
orbit In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an ...
around the
Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...
. It takes simultaneous measurements of Earth's atmosphere, land, and water to understand how Earth is changing and to identify the consequences for life on Earth. It is the flagship of the
Earth Observing System The Earth Observing System (EOS) is a program of NASA comprising a series of artificial satellite missions and scientific instruments in Earth orbit designed for long-term global observations of the land surface, biosphere, earth's atmosphere, at ...
(EOS) and the first satellite of the system which was followed by Aqua (launched in 2002) and Aura (launched in 2004). Terra was launched in 1999. The name "Terra" comes from the
Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...
word for Earth. A naming contest was held by NASA among U.S. high school students. The winning essay was submitted by Sasha Jones of Brentwood, Missouri. The identifier "AM-1" refers to its orbit, passing over the equator in the morning.


Launch

The satellite was launched from
Vandenberg Air Force Base Vandenberg may refer to: * Vandenberg (surname), including a list of people with the name * USNS ''General Hoyt S. Vandenberg'' (T-AGM-10), transport ship in the United States Navy, sank as an artificial reef in Key West, Florida * Vandenberg S ...
on December 18th, 1999, aboard an Atlas IIAS vehicle and began collecting data on February 24th, 2000. It was placed into a near-polar, sun-synchronous orbit at an altitude of , with a 10:30am descending node. File:Orbit path - Terra ascending - night.png, Terra's ascending orbital path in 2021 File:Orbit path - Terra descending - day.png, Terra's descending orbital path in 2021


Instruments

Terra carries a payload of five remote sensors designed to monitor the state of Earth's environment and ongoing changes in its
climate Climate is the long-term weather pattern in a region, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteoro ...
system: * ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) ASTER creates high-resolution images of clouds, ice, water and the land surface using 3 different sensor subsystems. They are the Shortwave Infrared (SWIR); Thermal Infrared (TIR); and Visible and Near Infrared (VNIR). They cover 14 multi-spectral bands from visible to the thermal infrared. The SWIR stopped working in 2008. ASTER was provided by Japan's Ministry of Economy, Trade, and Industry. * CERES (Clouds and the Earth's Radiant Energy System) * MISR (Multi-angle Imaging SpectroRadiometer) *
MODIS The Moderate Resolution Imaging Spectroradiometer (MODIS) is a satellite-based sensor used for earth and climate measurements. There are two MODIS sensors in Earth orbit: one on board the Terra (EOS AM) satellite, launched by NASA in 19 ...
(Moderate-resolution Imaging Spectroradiometer) * MOPITT (Measurements of Pollution in the Troposphere) Data from the satellite helps scientists better understand the spread of pollution around the globe. Studies have used instruments on Terra to examine trends in global carbon monoxide and
aerosol An aerosol is a suspension (chemistry), suspension of fine solid particles or liquid Drop (liquid), droplets in air or another gas. Aerosols can be generated from natural or Human impact on the environment, human causes. The term ''aerosol'' co ...
pollution. The data collected by Terra will ultimately become a new, 15-year global data set.


Operations

After launch, operators observed that high energy protons like those found over the South Atlantic Anomaly or the poles could induce single-event upsets that would cause the Motor Drive Assembly (MDA) Built-In Test Equipment (BITE) to turn off the MDA. These false shut-downs occur 12–14 times a month and eventually the operations team automated the recovery to reduce the impact of these shut-downs. Starting in 2007, increased thermal resistance in the SWIR cryocooler of the ASTER instrument caused the temperature to gradually increase. By 2008, despite frequent attempts to recycle the cryocooler the data began to significantly degrade and on January 12, 2009, ASTER managers declared the SWIR no longer functional due to anomalously high SWIR detector temperatures. Data gathered after April 2008 was declared not usable. On October 13, 2009, Terra suffered a single battery cell failure anomaly and a battery heater control anomaly likely the result of a Micrometeoroid or Orbital Debris (MMOD) strike. On February 27, 2020, the Terra flight operations team conducted Terra's last inclination adjust maneuver due to the satellite's limited remaining fuel. With no more such maneuvers, Terra's mean local time has begun to drift starting in April 2021 and with it, its data quality. In October 2022, Terra is expected to reach and exceed a 10:15 AM MLT crossing which is expected to lead operators to initiate a constellation exit to a lower orbit altitude (694 km). Decommissioning would occur around 2025-26 followed by an un-controlled reentry several years later.


Malicious cyber activities

In June and October 2008 the spacecraft was targeted by hackers who gained unauthorized access to its command and control systems, but did not issue any commands.


Gallery of images by Terra

File:Firstmodisimage.jpg, The first image taken by Terra. File:Arctic eclipse.jpg, The Solar eclipse of August 1, 2008, over Russia, Norway, and the
Arctic Ocean The Arctic Ocean is the smallest and shallowest of the world's five oceanic divisions. It spans an area of approximately and is the coldest of the world's oceans. The International Hydrographic Organization (IHO) recognizes it as an ocean, ...
as seen from
NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...
's Terra satellite. File:Great Britain Snowy.jpg, The effects of the European winter storms of 2009–2010 on Great Britain, seen from Terra. File:Gulf of Mexico oil spill May 1 cropped.jpg, The
Deepwater Horizon oil spill The ''Deepwater Horizon'' oil spill was an environmental disaster off the coast of the United States in the Gulf of Mexico, on the BP-operated Macondo Prospect. It is considered the largest marine oil spill in the history of the petroleum in ...
oil slick as seen from space by
NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...
's Terra satellite on May 1, 2010. File:Gulf Oil Spill Creeps Towards Mississippi Delta.jpg, The Deepwater Horizon oil slick just off the Louisiana coast on April 30, 2010, visible from space. File:Hurricane Karl 2010-09-16 1720Z.jpg,
Hurricane Karl Hurricane Karl was the most destructive tropical cyclone on record to strike the Political divisions of Mexico, Mexican state of Veracruz. The eleventh tropical storm, sixth hurricane, and fifth and final major hurricane of the 2010 Atlantic hu ...
, the most destructive hurricane of the
2010 Atlantic Hurricane Season The 2010 Atlantic hurricane season was the first of three consecutive very active Atlantic hurricane seasons, each with 19 Tropical cyclone naming, named storms. This above average activity included 12 hurricanes, equaling the number t ...
, approaches Mexico on September 16. File:Satellite image of Sweden in March 2002.jpg, Satellite image of Sweden in March 2002. File:Ash distribution from Hunga Tonga over Australia.jpg, Satellite image of the Ash distribution over Australia from the 2022 Hunga Tonga–Hunga Ha'apai eruption. File:Animation of TERRA trajectory around Earth.gif, Animation of Terra's orbit around the Earth. Earth is not shown.


See also

*
Aqua (satellite) Aqua (EOS PM-1) is a NASA scientific research satellite in orbit around the Earth, studying the Precipitation (meteorology), precipitation, evaporation, and Water cycle, cycling of water. It is the second major component of the Earth Observing Sy ...
* Artificial structures visible from space *
Aura (satellite) Aura (EOS CH-1) is a multi-national NASA scientific research satellite in orbit around the Earth, studying the Earth's ozone layer, air quality and climate. It is the third major component of the Earth Observing System (EOS) following on Terra ...
* Fire Information for Resource Management System (FIRMS) – provides information on active fire locations as part of NASA's Earth Science Data Systems program


References


External links


NASA Terra site
{{Portal bar, Earth, Spaceflight Earth observation satellites of the United States NASA satellites orbiting Earth Spacecraft launched by Atlas rockets Spacecraft launched in 1999