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LARES (Laser Relativity Satellite) is a passive satellite with laser mirrors for the study of the Earth gravitational field and general relativity measurements (Lense-Thirring effect).

LARES is basically a solid sphere made of Tungsten with a diameter of 376 mm and a mass of 400 kg. The surface of the sphere is covered by 92 Corner Cube Reflectors (CCR). To achieve its scientific objectives, LARES will be injected into a circular orbit at 1200 km altitude with an inclination of 71°.

As LARES orbits the Earth, laser beams are emitted from a number of ground stations around the Earth, the International Laser Ranging Service, and reflected by the CCRs on LARES to the ground stations. The time delay between emission and arrival of the laser beam provides a measure of the round-trip distance to LARES, allowing a highly accurate orbit determination. Correcting for a number of effects, most importantly the deviation of the Earth gravitational field from an ideal sphere, yields the frame-dragging effect.

The main scientific objectives of the LARES mission are:

  • High precision tests of Einstein's theory of general relativity, in particular:
    • A measurement of the Lense-Thirring effect due to the Earth's angular momentum and a high precision test of the Earth's gravitomagnetic field. The Lense-Thirring effect is a tiny shift of the orbit of a test particle. Gravitomagnetic field and Lense-Thirring effect are theoretical predictions of Einstein's theory of general relativity.
    • An improved, high precision, test of the inverse square law for very weak-field gravity and test of the equivalence principle.
    • A measurement of the general relativistic perigee precession of LARES and a high precision measurement of the corresponding combination of the PPN (Parametrized-Post-Newtonian) parameters beta and gamma. The PPN parameters beta and gamma test Einstein's theory of gravitation versus other metric theories of gravitation.
    • Other tests of general relativity and gravitation.
  • Measurements and improved determinations in geodesy and geodynamics.

On February 7, the ASI board approved funding for the LARES mission, that will be launched with Vega's maiden flight.

LARES is deployed from the LARES-A&H/SS equipment mounted on the AVUM upper stage of the Vega launch vehicle.

Nation: Italy
Type / Application: Basic research, Geodesy
Operator: ASI
Contractors: Carlo Gavazzi Space SpA
Equipment: 92 cube corner reflectors
Configuration: 37,6 cm sphere
Propulsion: None
Power: None
Mass: ~ 400 kg
Orbit: 1200 km × 1200 km, 71°
Satellite COSPAR Date LS Launch Vehicle Remarks
LARES 2012-006A 13.02.2012 Ko ELV Vega with ALMASat 1, e-st@r, Goliat, MaSat 1, PW-Sat 1, ROBUSTA, UniCubeSat-GG, XaTcobeo, LARES-A&H/SS


Further LARES missions:

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