Terra (satellite)

Terra
Terra (EOS AM-1)
Mission type Climate research
Operator NASA
COSPAR ID 1999-068A
SATCAT no. 25994
Website terra.nasa.gov
Mission duration Elapsed: 18 years, 10 months, 5 days
Spacecraft properties
Manufacturer NASA
Launch mass 4,864 kilograms (10,723 lb)
Start of mission
Launch date December 18, 1999, 18:57:39 (1999-12-18UTC18:57:39Z) UTC
Rocket Atlas IIAS AC-141
Launch site Vandenberg SLC-3E
Contractor ILS
Orbital parameters
Reference system Geocentric
Regime Low Earth
Semi-major axis 7,080.0 kilometers (4,399.3 mi)
Eccentricity 0.0001392
Perigee 708.7 kilometers (440.4 mi)
Apogee 710.6 kilometers (441.5 mi)
Inclination 98.2098°
Period 98.8 minutes
RAAN 251.3130 degrees
Argument of perigee 83.7699 degrees
Mean anomaly 276.3654 degrees
Mean motion 14.57110250
Epoch 25 June 2016, 02:58:27 UTC
Revolution no. 87867

Terra (EOS AM-1) is a multi-national NASA scientific research satellite in a Sun-synchronous orbit around the Earth.[1] It is the flagship of the Earth Observing System (EOS). The name "Terra" comes from the Latin 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 on December 18, 1999, aboard an Atlas IIAS vehicle and began collecting data on February 24, 2000. It was placed into a near-polar, sun-synchronous orbit at an altitude of 705 km, with a 10:30am descending node.

Mission

Terra carries a payload of five remote sensors designed to monitor the state of Earth's environment and ongoing changes in its climate system:[2]

  • ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer)[3] 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 (Moderate-resolution Imaging Spectroradiometer)[4]
  • MOPITT (Measurements of Pollution in the Troposphere)[5]

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 pollution.[6] The data collected by Terra will ultimately become a new, 15-year global data set.

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.[7]

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.[8]

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.[7]

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.[9]

See also

References

  1. ↑ "NASA: TERRA (EOS AM-1)". nasa.gov. Retrieved 2011-01-07.
  2. ↑ Maurer, John (November 2001). "Overview of NASA's Terra satellite". hawaii.edu (University of Hawai'i). Retrieved 2011-01-07.
  3. ↑ Stevens, Nicki F.; Garbeil, Harold; Mouginis-Mark, Peter J. (2004-01-22). "NASA EOS Terra ASTER: Volcanic topographic mapping and capability" (PDF). Hawai'i Institute of Geophysics and Planetology. Retrieved 2011-01-07.
  4. ↑ "MODIS Terra Satellite Images". ucar.edu(National Center for Atmospheric Research: Earth Observatory Laboratory). Retrieved 2011-01-07.
  5. ↑ "MEASUREMENTS OF POLLUTION IN THE TROPOSPHERE (MOPITT)". acd.ucar.edu (NESL's Atmospheric Chemistry Division). Archived from the original on 2011-01-28. Retrieved 2011-01-07.
  6. ↑ "NASA's Terra Satellite Tracks Global Pollution". gsfc.nasa.gov (Goddard Space Flight Center). 2004-05-18. Archived from the original on 2010-11-24. Retrieved 2011-01-07.
  7. 1 2 Kelley, Angelita. "Terra mission operations: Launch to the present (and beyond)" (PDF). Retrieved 5 April 2018.
  8. ↑ "ASTER SWIR Alert". Retrieved 5 April 2018.
  9. ↑ "2011 REPORT TO CONGRESS of the U.S.-CHINA ECONOMIC AND SECURITY REVIEW COMMISSION, page 216" (PDF). uscc.gov. Archived from the original (PDF) on 2013-02-15. Retrieved 2012-10-09.
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