LARES (Laser Relativity Satellite) is a

passive satellite {{about, the satellite by its functional type, the satellite by its orbital parameters, :Satellites by orbit Categories by type ...

system of the Italian Space Agency.

Mission

LARES 1

LARES 1 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, and ...

rocket from the ESA

Centre Spatial Guyanais The Guiana Space Centre (; CSG), also called Europe's Spaceport, is a spaceport to the northwest of Kourou in French Guiana, an Overseas departments and regions of France, overseas region of France in South America. Kourou is located approxim ...

in Kourou,

French Guiana French Guiana, or Guyane in French, is an Overseas departments and regions of France, overseas department and region of France located on the northern coast of South America in the Guianas and the West Indies. Bordered by Suriname to the west ...

Composition

The satellite is made of THA-18N, a

tungsten Tungsten (also called wolfram) is a chemical element; it has symbol W and atomic number 74. It is a metal found naturally on Earth almost exclusively in compounds with other elements. It was identified as a distinct element in 1781 and first ...

alloy, and houses 92 cube-corner retroreflectors, 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 (also known as orbital revolution) 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 ...

near and an inclination of 69.49 degrees. The satellite is tracked by the

International Laser Ranging Service Satellite laser ranging (SLR) is a method to measure the distance to satellites in a geocentric orbit. It consists of an astronomical observatory equipped with a laser that sends ultrashort pulses of light. The pulses hit the satellite and boun ...

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 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 as Einstein's theory of gravity, is the differential geometry, geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of grav ...

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, ...

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 and COVID pandemic), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), began with an disease outbreak, outbreak of COVID-19 in Wuhan, China, in December ...

. LARES 2 may improve the accuracy of the

frame-dragging Frame-dragging is an effect on spacetime, predicted by Albert Einstein's General relativity, general theory of relativity, that is due to non-static stationary distributions of mass–energy. A stationary Field (physics), field is one that is ...

effect measurement to 0.2%.''A new laser-ranged satellite for General Relativity and space geodesy: I. An introduction to the LARES2 space experiment'' Concerns about the actual possibility of reaching this goal were raised. 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