LOCATION

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LOCATION
Preparations for the start of LAGEOS 1
LAGEOS 2 leaves Columbia's payload bay . The IRIS upper stage with the engine nozzle is clearly visible.

LAGEOS ( Laser Geodynamics Satellite ) is the name of two of the most important laser satellites in higher geodesy . This outlines the main areas of application : the determination of tectonic plate movements and regional crustal displacements , the determination of polar movement and earth rotation parameters as well as the definition of a geodetic reference system .

The LAGEOS satellites have the shape of a sphere with 426 laser reflectors . These reflect incident light exactly in the direction of incidence and, by means of Satellite Laser Ranging (SLR), allow precise distance measurement between terrestrial observatories and the satellite. The transit time measurement used is carried out after the light echo has been received through a telescope through an interval counter triggered by the photons .

LAGEOS-1 has an orbit height between 5845 and 5955 km. Thanks to a solid brass core, it has a mass of 411 kg. Together with the small diameter of about 60 cm, non-gravitational disruptive forces have only a minor influence on the orbit . Therefore, its orbit is extremely stable and can be used for the precise determination of higher-level survey points and the fundamental system of geodesy and astronomy. The orbital time around the earth is 225 minutes.

Of the approximately 20 other laser satellites, the French Starlette is the next most important. It has a similar structure and weighs 47 kg.

LOCATION 1

The first LAGEOS satellite built by NASA was launched into orbit on May 4, 1976 from Cape Canaveral on a Delta-2913 . The satellite itself was housed in a protective housing, on which a Star 24 - apogee was to circularize the orbit.

LOCATION 2

The second LAGEOS satellite was built by the Italian space agency ASI and is an almost exact copy of the first LAGEOS satellite. It has a diameter of 60 cm and a slightly lower weight of 405 kg. The satellite was launched into space by NASA on October 22, 1992 , together with the Italian senior level IRIS, as part of the space shuttle mission STS-52 .

The LAGEOS badges

The LAGEOS badges, designed by Carl Sagan

Due to the high and extremely stable orbit of the LAGEOS satellites, they will only leave orbit after about eight million years. For this reason, both satellites are carrying a stainless steel badge 18 cm wide and 10 cm high, which depicts the continental drift and is intended to give any finder information about the purpose of the satellite in the future. There is also a counting system based on binary numbers and a human handprint on the badges .

Others

The analysis of the orbit data of the LAGEOS satellites also provided knowledge for the detection of the Lense-Thirring-Effect .

See also

Web links

Commons : LAGEOS  - collection of images, videos and audio files

Individual evidence

  1. ↑ a b orbit data according to LAGEOS 1. N2YO, January 7, 2019, accessed on January 7, 2019 (English). The height above the earth's surface depends on the definition of the earth figure.
  2. ↑ SP-4012 NASA Historical Data Book: Volume III
  3. ↑ LAGEOS Phase B Technical Report (PDF file; 2.16 MB)
  4. ↑ https://www.heise.de/tp/features/Orbitale-Zeitkapsel-fuer-die-fernste-Zukunft-3385593.html
  5. ^ As World Turns it Drags Time and Space nasa.gov, accessed May 6, 2011