LARES (satellite)
Encyclopedia
LARES is an Italian Space Agency
scientific satellite
to be launched with the new European launch vehicle Vega.
LARES will be launched by Vega's maiden flight, scheduled for 2011.
with 1400 kilometres (870 mi) of perigee
, an inclination from 60 to 86 degrees and reduced eccentricity. The satellite should be tracked by the International Laser Ranging Service stations. but, at present, it does not result in the list of the approved future missions with retroreflectors.
, with an accuracy of about 1%, according to its proponent. In fact, doubts have been raised concerning the reliability of such an estimate: the realistic total accuracy may be orders of magnitude larger. This would be due to the fact that LARES will be launched in a lower orbit with respect to the existing LAGEOS satellites, being, thus, more sensitive to a larger number of even zonal harmonic coefficients of the multipolar expansion of the Newtonian part of the terrestrial gravitational potential which account for the non-sphericity of the Earth because of its diurnal rotation. The proponent of the LARES mission, I. Ciufolini, does not agree with such criticisms. Other goals of the mission, which were later dismissed because of a change in the LARES orbital configuration, were an orders-of-magnitude improvement of the current limits in the equivalence principle
and a measurement of the multidimensional braneworld DGP model
. It was later shown that such goals would have been unattainable. Anyway, the LARES satellite may be used for measurements in the fields of geodynamic and space geodesy.
Italian Space Agency
The Italian Space Agency is a government agency established in 1988 to fund, regulate and coordinate space exploration activities in Italy...
scientific satellite
Satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....
to be launched with the new European launch vehicle Vega.
LARES will be launched by Vega's maiden flight, scheduled for 2011.
The mission
The satellite, completely passive, is made of tungsten alloy and houses 92 cube corner retroreflectors that will be used to track the satellite via laser from stations on Earth. LARES body will have a diameter of about 36.4 centimetres (14 in) and weights about 400 kilograms (882 lb). LARES will be inserted in an orbitOrbit
In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System...
with 1400 kilometres (870 mi) of perigee
Perigee
Perigee is the point at which an object makes its closest approach to the Earth.. Often the term is used in a broader sense to define the point in an orbit where the orbiting body is closest to the body it orbits. The opposite is the apogee, the farthest or highest point.The Greek prefix "peri"...
, an inclination from 60 to 86 degrees and reduced eccentricity. The satellite should be tracked by the International Laser Ranging Service stations. but, at present, it does not result in the list of the approved future missions with retroreflectors.
Scientific goals
The main scientific target of the LARES mission is the measurement of the Lense-Thirring effect, also known as frame-draggingFrame-dragging
Einstein's general theory of relativity predicts that non-static, stationary mass-energy distributions affect spacetime in a peculiar way giving rise to a phenomenon usually known as frame-dragging...
, with an accuracy of about 1%, according to its proponent. In fact, doubts have been raised concerning the reliability of such an estimate: the realistic total accuracy may be orders of magnitude larger. This would be due to the fact that LARES will be launched in a lower orbit with respect to the existing LAGEOS satellites, being, thus, more sensitive to a larger number of even zonal harmonic coefficients of the multipolar expansion of the Newtonian part of the terrestrial gravitational potential which account for the non-sphericity of the Earth because of its diurnal rotation. The proponent of the LARES mission, I. Ciufolini, does not agree with such criticisms. Other goals of the mission, which were later dismissed because of a change in the LARES orbital configuration, were an orders-of-magnitude improvement of the current limits in the equivalence principle
Equivalence principle
In the physics of general relativity, the equivalence principle is any of several related concepts dealing with the equivalence of gravitational and inertial mass, and to Albert Einstein's assertion that the gravitational "force" as experienced locally while standing on a massive body is actually...
and a measurement of the multidimensional braneworld DGP model
DGP model
The DGP model is a model of gravity proposed by Gia Dvali, Gregory Gabadadze, and Massimo Porrati in 2000. The model is popular among some model builders, but has resisted being embedded into string theory....
. It was later shown that such goals would have been unattainable. Anyway, the LARES satellite may be used for measurements in the fields of geodynamic and space geodesy.
External links
- LARES - Testing of General Relativity on ASI's page