Satellite laser ranging

Satellite laser ranging

In satellite laser ranging (SLR) a global network of observation stations measure the round trip time of flight of ultrashort pulses of light to satellites equipped with retroreflectors. This provides instantaneous range measurements of millimeter level precision which can be accumulated to provide accurate measurement of orbits and a host of important scientific data.

Satellite laser ranging is a proven geodetic technique with significant potential for important contributions to scientific studies of the Earth/Atmosphere/Oceans system. It is the most accurate technique currently available to determine the geocentric position of an Earth satellite, allowing for the precise calibration of radar altimeters and separation of long-term instrumentation drift from secular changes in ocean topography.

Its ability to measure the variations over time in the Earth’s gravity field and to monitor motion of the station network with respect to the geocenter, together with the capability to monitor vertical motion in an absolute system, makes it unique for modeling and evaluating long-term climate change by:
* Providing a reference system for post-glacial rebound, sea level and ice volume change
* Determining the temporal mass redistribution of the solid Earth, ocean, and atmosphere system
* Monitoring the response of the atmosphere to seasonal variations in solar heating.

SLR provides a unique capability for verification of the predictions of the theory of General Relativity, such as the frame-dragging effect.

SLR stations form an important part of the international network of space geodetic observatories, which include VLBI, GPS, DORIS and PRARE systems. On several critical missions, SLR has provided failsafe redundancy when other radiometric tracking systems have failed.

History

Laser ranging to a near-Earth satellite was first carried out by NASA in 1964 with the launch of the Beacon-B satellite. Since that time, ranging precision, spurred by scientific requirements, has improved by a factor of a thousand from a few metres to a few millimetres, and more satellites equipped with retroreflectors have been launched.

Several sets of retroreflectors were installed on the Earth's moon as part of the American Apollo and Soviet Lunokhod space programs. These retroreflectors are also ranged on a regular basis, providing a highly accurate measurement of the dynamics of the Earth/Moon system.

During the subsequent decades, the global satellite laser ranging network has evolved into a powerful source of data for studies of the solid Earth and its ocean and atmospheric systems. In addition, SLR provides precise orbit determination for spaceborne radar altimetre missions mapping the ocean surface (which are used to model global ocean circulation), formapping volumetric changes in continental ice masses, and for land topography. It provides a means for subnanosecond global time transfer, and a basis for special tests of the Theory of General Relativity.

The International Laser Ranging Service was formed in 1998 by the global SLR community to enhance geophysical and geodetic research activities, replacing the previous CSTG Satellite and Laser Ranging Subcommission.

Uses of SLR data

SLR data has provided the standard, highly accurate, long wavelength gravity field reference model which supports all precision orbit determination and provides the basis for studying temporal gravitational variations due to mass redistribution. The height of the geoid has been determined to less than ten centimeters at long wavelengths less than 1500 km.

SLR provides mm/year accurate determinations of tectonic drift station motion on a global scale in a geocentric reference frame. Combined with gravity models and decadal changes in Earth rotation, these results contribute to modeling of convection in the Earth’s mantle by providing constraints on related Earth interior processes. The velocity of the fiducial station in Hawaii is 70 mm./year and closely matches the rate of the background geophysical model.

ource

*cite web|url=http://ilrs.gsfc.nasa.gov/docs/slrover.pdf|title=Satellite Laser Ranging and Earth Science|publisher=NASA Internal Laser Ranging Service|format=PDF (public domain)"

See also

* LAGEOS
* LIDAR

External links

* [http://ilrs.gsfc.nasa.gov/ International Laser Ranging Service] website
* [http://www.csr.utexas.edu/mlrs/ McDonald Laser Ranging Station]
* [http://nercslr.nmt.ac.uk/ NERC Space Geodesy Facility]
* [http://physics.ucsd.edu/~tmurphy/apollo/lrrr.html Retroreflectors on the Moon]
* [http://monoptec.com/ Fixed Shutter Dome (FSD) for SLR]


Wikimedia Foundation. 2010.

Поможем решить контрольную работу

Look at other dictionaries:

  • Satellite Laser Ranging — Laser Ranging System des geodätischen Observatoriums Wettzell in Bayern. Satellite Laser Ranging (Abkürzung SLR, deutsch etwa: Satelliten Distanzmessung) ist eine hochpräzise Methode der Satellitengeodäsie, bei der, mit Hilfe der Laufzeit eines… …   Deutsch Wikipedia

  • Satellite laser ranging — Saltar a navegación, búsqueda El Satellite Laser Ranging (SLR) o Mediciones Láser a Satelites es un método muy preciso de medición de distancias realizado mediante la emisión de pulsos de Luz Láser a Satélites de acuerdo con el principio de pulso …   Wikipedia Español

  • Lunar Laser Ranging — Retroreflektor der Apollo 11 Mission Beim Lunar Laser Ranging (kurz: LLR) werden, von Bodenstationen auf der Erde ausgehend, Laufzeitmessungen von Laserpulsen zum Mond nach dem Puls Echo Verfahren durchgeführt. LLR Messungen liefern Informationen …   Deutsch Wikipedia

  • Apache Point Observatory Lunar Laser-ranging Operation — APOLLO shooting a laser at the Moon. The laser pulse is reflected from the retroreflectors on the Moon (see below) and returned to the telescope. The round trip time tells the distance to the Moon to great accuracy. In this picture the Moon is… …   Wikipedia

  • Laser-Entfernungsmesser — Dieser Artikel oder Abschnitt bedarf einer Überarbeitung. Näheres ist auf der Diskussionsseite angegeben. Hilf mit, ihn zu verbessern, und entferne anschließend diese Markierung. Die optische Abstandsmessung ist die Distanzmessung anhand der… …   Deutsch Wikipedia

  • Laser Geodynamics Satellite — LAGEOS LAGEOS (Laser Geodynamics Satellite) ist der Name zwei der wichtigsten Lasersatelliten der höheren Geodäsie. Die LAGEOS Satelliten haben die Gestalt einer Kugel, die 426 Laserreflektoren trägt. Diese werfen auftreffendes Licht genau in die …   Deutsch Wikipedia

  • Laser — Demonstrationslaser: In der Mitte ist das Leuchten der Gasentladung zu sehen, die das Lasermedium anregt. Der Laserstrahl ist rechts als roter Punkt auf dem weißen Schirm zu erkennen. Laser [ˈleɪzə] (Akronym für engl. Light Amplification by… …   Deutsch Wikipedia

  • Satellite de Taille Adaptée avec Réflecteurs Laser por les Etudes de la Terre — Starlette (französisch Satellite de Taille Adaptée avec Réflecteurs Laser por les Etudes de la Terre) ist der Name eines französischen Satelliten, der am 6. Februar 1975 mit einer Diamant B P4 vom Centre Spatial Guyanais in Kourou aus für Zwecke… …   Deutsch Wikipedia

  • Laser rangefinder — A laser rangefinder is a device which uses a laser beam in order to determine the distance to a reflective object. The most common form of laser rangefinder operates on the time of flight principle by sending a laser pulse in a narrow beam… …   Wikipedia

  • Satellite geodesy — is the measurement of the form and dimensions of the Earth, the location of objects on its surface and the figure of the Earth s gravity field by means of satellite techniques. In other words, geodesy by means of satellites. It belongs to the… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”