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 enti ...

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, a ...

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 (120 ...

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 department/region and single territorial collectivity of France on the northern Atlantic coast of South America in the Guianas. ...

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 isol ...

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 ...

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. 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 identi ...

. 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 ca ...

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.

References

External links

LARES Mission
official Web Site of LARES Mission.
LARES - Testing of General Relativity
on 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