LARES (Laser Relativity Satellite) is a
passive satellite system of the
Italian Space Agency
The Italian Space Agency ( it, Agenzia Spaziale Italiana; ASI) is a government agency established in 1988 to fund, regulate and coordinate space exploration activities in Italy. The agency cooperates with numerous national and international entit ...
.
Mission
Launch
LARES was launched into orbit on 13 February 2012 at 10:00:00 UTC. It was launched on the first
Vega
Vega is the brightest star in the northern constellation of Lyra. It has the Bayer designation α Lyrae, which is Latinised to Alpha Lyrae and abbreviated Alpha Lyr or α Lyr. This star is relatively close at only from the Sun, an ...
rocket from the
ESA
, owners =
, headquarters = Paris, Île-de-France, France
, coordinates =
, spaceport = Guiana Space Centre
, seal = File:ESA emblem seal.png
, seal_size = 130px
, image = Views in the Main Control Room (1205 ...
Centre Spatial Guyanais in
Kourou
Kourou () is a commune in French Guiana, an overseas region and department of France in South America. Kourou is famous for being the location of the Guiana Space Centre, the main spaceport of France and the European Space Agency (ESA). It i ...
,
French Guiana
French Guiana ( or ; french: link=no, Guyane ; gcr, label=French Guianese Creole, Lagwiyann ) is an overseas departments and regions of France, overseas department/region and single territorial collectivity of France on the northern Atlantic ...
.
Composition
The satellite is made of THA-18N, a
tungsten
Tungsten, or wolfram, is a chemical element with the symbol W and atomic number 74. Tungsten is a rare metal found naturally on Earth almost exclusively as compounds with other elements. It was identified as a new element in 1781 and first isolat ...
alloy, and houses 92 cube-corner
retroreflectors
A retroreflector (sometimes called a retroflector or cataphote) is a device or surface that reflects radiation (usually light) back to its source with minimum scattering. This works at a wide range of angle of incidence, unlike a planar mirro ...
, which are used to
track the satellite via laser from stations on Earth. LARES's body has a diameter of about and a mass of about .
LARES was inserted in a nearly circular
orbit
In celestial mechanics, an orbit 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 object or position in space such as a p ...
near and an inclination of 69.49 degrees. The satellite is tracked by the
International Laser Ranging Service
In satellite laser ranging (SLR) a global network of observation stations measures the round trip time of flight of ultrashort pulses of light to satellites equipped with retroreflectors. This provides instantaneous range measurements of milli ...
stations.
The LARES satellite is the densest object known orbiting the Earth.
The high density helps reduce disturbances from environmental factors such as solar radiation pressure.
Scientific goals
The main scientific target of the LARES mission is the measurement of the
Lense–Thirring effect with an accuracy of about 1%, according to principal investigator
Ignazio Ciufolini
Ignazio Ciufolini (born 1951) is an Italian physicist active in the field of gravitational physics and general relativity.
Biography
Ignazio Ciufolini graduated magna cum laude in 1980 at Sapienza University of Rome, and received a PhD in Physic ...
and the LARES scientific team,
[
*
*
*
*
*
*
*
* ] but the reliability of that estimate is contested.
In contrast, a recent analysis of 3.5 years of laser-ranging data reported a claimed accuracy of about 4%. Critical remarks appeared later in the literature.
Beyond the project's key mission, the LARES satellite may be used for other tests of
general relativity
General relativity, also known as the general theory of relativity and Einstein's theory of gravity, is the geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of gravitation in modern physics ...
as well as measurements in the fields of
geodynamics
Geodynamics is a subfield of geophysics dealing with dynamics of the Earth. It applies physics, chemistry and mathematics to the understanding of how mantle convection leads to plate tectonics and geologic phenomena such as seafloor spreading, mo ...
and
satellite geodesy
Satellite geodesy is geodesy by means of artificial satellites—the measurement of the form and dimensions of Earth, the location of objects on its surface and the figure of the Earth's gravity field by means of artificial satellite techniques. ...
.
LARES 2
A second satellite, LARES 2, was launched into orbit on 13 July 2022 at 13:13:43 UTC on a
Vega-C
Vega ( it, Vettore Europeo di Generazione Avanzata, or french: Vecteur européen de génération avancée, or en, European Vector of Advanced Generation, meaning "Advanced generation European carrier rocket") is an expendable launch system in ...
. It was originally due to launch in mid-2021. The launch was delayed to mid-2022 due to continuing impacts from the
COVID-19 pandemic
The COVID-19 pandemic, also known as the coronavirus pandemic, is an ongoing global pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The novel virus was first identif ...
.
LARES 2 may improve the accuracy of the
frame-dragging
Frame-dragging is an effect on spacetime, predicted by Albert Einstein's general theory of relativity, that is due to non-static stationary distributions of mass–energy. A stationary field is one that is in a steady state, but the masses cau ...
effect measurement to 0.2%.
[''A new laser-ranged satellite for General Relativity and space geodesy: I. An introduction to the LARES2 space experiment'' ] LARES 2 is made of a nickel alloy instead of a tungsten alloy.
See also
*
LAGEOS
LAGEOS, Laser Geodynamics Satellite or Laser Geometric Environmental Observation Survey, are a series of two scientific research satellites designed to provide an orbiting laser ranging benchmark for geodynamical studies of the Earth. Each satel ...
similar satellites launched in 1976
*
List of laser ranging satellites
In satellite laser ranging (SLR) a global network of observation stations measures the round trip time of flight of ultrashort pulses of light to satellites equipped with retroreflectors. This provides instantaneous range measurements of milli ...
*
List of passive satellites
List of passive satellites is a listing of inert or mostly inert satellites, mainly of the Earth. This includes various reflector type satellites typically used for geodesy and atmospheric measurements.
Passive satellites
*Calsphere
**Calspher ...
*
PAGEOS
PAGEOS (PAssive Geodetic Earth Orbiting Satellite) was a balloon satellite which was launched by NASA in June 1966.
Design
PAGEOS had a diameter of exactly , consisted of a thick mylar plastic film coated with vapour deposited aluminium enc ...
*
Project Echo
Project Echo was the first passive communications satellite experiment. Each of the two American spacecraft, launched in 1960 and 1964, were metalized balloon satellites acting as passive reflectors of microwave signals. Communication sign ...
*
Vega flight VV01
Vega flight VV01 (called officially Vega qualification flight VV01) is the maiden flight of the Vega (rocket), Vega launcher. It occurred from the Guiana Space Centre, Centre Spatial Guyanais (CSG) on 13 February 2012 at 10:00:00 UTC.
Payload ...
References
External links
LARES Mission official Web Site of LARES Mission.
LARES - Testing of General Relativityon ASI's page.
LARES - Pronto al via!article with images of LARES on ASI's site (in Italian).
LARES page on the ILRS Web Site.
{{DEFAULTSORT:Lares (Satellite)
2012 in Italy
Satellites orbiting Earth
Italian Space Agency
Laser ranging satellites
Satellites of Italy
Spacecraft launched by Vega rockets
Spacecraft launched in 2012