385 research outputs found
An assessment of the measurement of the Lense-Thirring effect in the Earth gravity field, in reply to: ``On the measurement of the Lense-Thirring effect using the nodes of the LAGEOS satellites, in reply to ``On the reliability of the so far performed tests for measuring the Lense-Thirring effect with the LAGEOS satellites'' by L. Iorio,'' by I. Ciufolini and E. Pavlis
In this paper we reply to recent claims by Ciufolini and Pavlis about certain
aspects of the measurement of the general relativistic Lense-Thirring effect in
the gravitational field of the Earth. I) The proposal by such authors of using
the existing satellites endowed with some active mechanism of compensation of
the non-gravitational perturbations as an alternative strategy to improve the
currently ongoing Lense-Thirring tests is unfeasible because of the impact of
the uncancelled even zonal harmonics of the geopotential and of some
time-dependent tidal perturbations. II) It is shown that their criticisms about
the possibility of using the existing altimeter Jason-1 and laser-ranged Ajisai
satellites are groundless.III) Ciufolini and Pavlis also claimed that we would
have explicitly proposed to use the mean anomaly of the LAGEOS satellites in
order to improve the accuracy of the Lense-Thirrring tests. We prove that it is
false. In regard to the mean anomaly of the LAGEOS satellites, Ciufolini
himself did use such an orbital element in some previously published tests.
About the latest test performed with the LAGEOS satellites, IV) we discuss the
cross-coupling between the inclination errors and the first even zonal harmonic
as another possible source of systematic error affecting it with an additional
9% bias. V) Finally, we stress the weak points of the claims about the origin
of the two-nodes LAGEOS-LAGEOS II combination used in that test.Comment: LaTex2e, 22 pages, no figures, no tables. To appear in Planetary and
Space Science. Reference Ries et al. 2003a added and properly cite
The impact of the new Earth gravity model EIGEN-CG03C on the measurement of the Lense-Thirring effect with some existing Earth satellites
The impact of the latest combined CHAMP/GRACE/terrestrial measurements Earth
gravity model EIGEN-CG03C on the measurement of the Lense-Thirring effect with
some linear combinations of the nodes of some of the existing Earth's
artificial satellites is presented. The 1-sigma upper bound of the systematic
error in the node-node LAGEOS-LAGEOS II combination is 3.9% (4% with
EIGEN-GRACE02S, \sim 6% with EIGEN-CG01C and \sim 9% with GGM02S), while it is
1$% for the node-only LAGEOS-LAGEOS II-Ajisai-Jason-1 combination (2% with
EIGEN-GRACE02S, 1.6% with EIGEN-CG01C and 2.7% with GGM02S).Comment: LaTex2e, 7 pages, 16 references, 1 table. It is an update of the
impact of the even zonal harmonics of the geopotential on the Lense-Thirring
effect with the EIGEN-GGM03C Earth gravity model publicly released on May 11
2005. Typos corrected. Reference added. To appear in General Relativity and
Gravitation, March 200
Testing General Relativity with Satellite Laser Ranging: Recent Developments
In this paper the most recent developments in testing General Relativity in
the gravitational field of the Earth with the technique of Satellite Laser
Ranging are presented. In particular, we concentrate our attention on some
gravitoelectric and gravitomagnetic post--Newtonian orbital effects on the
motion of a test body in the external field of a central mass.Comment: Latex2e, 10 pages, no figures, no tables. Paper presented at
COSPAR2002 conference held in Houston, TX, from 10 October 2002 to 19 October
2002. To appear in Advance in Space Research. References added and update
On a new observable for measuring the Lense-Thirring effect with Satellite Laser Ranging
In this paper we present a rather extensive error budget for the difference
of the perigees of a pair of supplementary SLR satellites aimed to the
detection of the Lense-Thirring effect.Comment: LaTex2e, 14 pages, 1 table, no figures. Some changes and additions to
the abstract, Introduction and Conclusions. References updated, typos
corrected. Equation corrected. To appear in General Relativity and
Gravitatio
The impact of the new CHAMP and GRACE Earth gravity models on the measurement of the general relativistic Lense--Thirring effect with the LAGEOS and LAGEOS II satellites
Among the effects predicted by the General Theory of Relativity for the
orbital motion of a test particle, the post-Newtonian gravitomagnetic
Lense-Thirring effect is very interesting and, up to now, there is not yet an
undisputable experimental direct test of it. To date, the data analysis of the
orbits of the existing geodetic LAGEOS and LAGEOS II satellites has yielded a
test of the Lense-Thirring effect with a claimed accuracy of 20%-30%. According
to some scientists such estimates could be optimistic. Here we wish to discuss
the improvements obtainable in this measurement, in terms of reliability of the
evaluation of the systematic error and reduction of its magnitude, due to the
new CHAMP and GRACE Earth gravity models.Comment: LaTex2e, 6 pages, no figures, no tables. Paper presented at 2nd CHAMP
science meeting, Potsdam, 1-4 September 200
Is it possible to measure the Lense-Thirring effect on the orbits of the planets in the gravitational field of the Sun?
Here we explore a novel approach in order to try to measure the
post-Newtonian 1/c^2 Lense-Thirring secular effect induced by the
gravitomagnetic field of the Sun on the planetary orbital motion. Due to the
relative smallness of the solar angular momentum J and the large values of the
planetary semimajor axes a, the gravitomagnetic precessions, which affect the
nodes Omega and the perihelia omega and are proportional to J/a^3, are of the
order of 10^-3 arcseconds per century only for, e.g., Mercury. This value lies
just at the edge of the present-day observational sensitivity in reconstructing
the planetary orbits, although future missions to Mercury like Messenger and
BepiColombo could allow to increase it. The major problems come from the main
sources of systematic errors. They are the aliasing classical precessions
induced by the multipolar expansion of the Sun's gravitational potential and
the classical secular N-body precessions which are of the same order of
magnitude or much larger than the Lense-Thirring precessions of interest. This
definitely rules out the possibility of analyzing only one orbital element of,
e.g., Mercury. In order to circumvent these problems, we propose a suitable
linear combination of the orbital residuals of the nodes of Mercury, Venus and
Mars which is, by construction, independent of such classical secular
precessions. A 1-sigma reasonable estimate of the obtainable accuracy yields a
36% error. Since the major role in the proposed combination is played by the
Mercury's node, it could happen that the new, more accurate ephemerides
available in future thanks to the Messenger and BepiColombo missions will offer
an opportunity to improve the present unfavorable situation.Comment: LaTex2e, A&A macros, 6 pages, no figure, 3 tables. Substantial
revision. More realistic conclusions. Estimations of the impact of
BepiColombo presente
A critical approach to the concept of a polar, low-altitude LARES satellite
According to very recent developments of the LARES mission, which would be
devoted to the measurement of the general relativistic Lense--Thirring effect
in the gravitational field of the Earth with Satellite Laser Ranging, it seems
that the LARES satellite might be finally launched in a polar, low--altitude
orbit by means of a relatively low--cost rocket. The observable would be the
node only. In this letter we critically analyze this scenario.Comment: LaTex2e, 11 pages, 4 figures, 1 table. Accepted for publication in
Classical and Quantum Gravit
Measuring the relativistic perigee advance with Satellite Laser Ranging
One of the most famous classical tests of General Relativity is the
gravitoelectric secular advance of the pericenter of a test body in the
gravitational field of a central mass. In this paper we explore the possibility
of performing a measurement of the gravitoelectric pericenter advance in the
gravitational field of the Earth by analyzing the laser-ranged data to some
existing, or proposed, laser-ranged geodetic satellites. At the present level
of knowledge of various error sources, the relative precision obtainable with
the data from LAGEOS and LAGEOS II, suitably combined, is of the order of
. Nevertheless, these accuracies could sensibly be improved in the
near future when the new data on the terrestrial gravitational field from the
CHAMP and GRACE missions will be available. The use of the perigee of LARES
(LAser RElativity Satellite), in the context of a suitable combination of
orbital residuals including also LAGEOS II, should further raise the precision
of the measurement. As a secondary outcome of the proposed experiment, with the
so obtained value of \ppn and with \et=4\beta-\gamma-3 from Lunar Laser
Ranging it could be possible to obtain an estimate of the PPN parameters
and at the level.Comment: LaTex2e, 14 pages, no figures, 2 tables. To appear in Classical and
Quantum Gravit
On the possibility of measuring the solar oblateness and some relativistic effects from planetary ranging
In this paper we first calculate the post-Newtonian gravitoelectric secular
rate of the mean anomaly of a test particle freely orbiting a spherically
symmetric central mass. Then, we propose a novel approach to suitably combine
the presently available planetary ranging data to Mercury, Venus and Mars in
order to determine, simultaneously and independently of each other, the Sun's
quadrupole mass moment J_2 and the secular advances of the perihelion and the
mean anomaly. This would also allow to obtain the PPN parameters gamma and beta
independently. We propose to analyze the time series of three linear
combinations of the experimental residuals of the rates of the nodes, the
longitudes of perihelia and mean anomalies of Mercury, Venus and Mars built up
in order to absorb the secular precessions induced by the solar oblateness and
the post-Newtonian gravitoelectric forces. The values of the three investigated
parameters can be obtained by fitting the expected linear trends with straight
lines, determining their slopes in arcseconds per century and suitably
normalizing them. According to the present-day EPM2000 ephemerides accuracy,
the obtainable precision would be of the order of 10^-4-10^-5 for the PPN
parameters and, more interestingly, of 10^-9 for J_2. The future BepiColombo
mission should improve the Mercury's orbit by one order of magnitude.Comment: LaTex2e, 11 pages, no figures, 3 tables. Extensively rewritten
version. The role of the classical N-body secular precessions has been
discussed. New observable found for J2. Improved accuracy in it: 10^-9. The
role of BepiColombo discusse
How to reach a few percent level in determining the Lense-Thirring effect?
In this paper we discuss and compare a node-only LAGEOS-LAGEOS II combination
and a node-only LAGEOS-LAGEOS II-Ajisai-Jason1 combination for the
determination of the Lense-Thirring effect. The new combined EIGEN-CG01C Earth
gravity model has been adopted. The second combination cancels the first three
even zonal harmonics along with their secular variations but introduces the
non-gravitational perturbations of Jason1. The first combination is less
sensitive to the non-conservative forces but is sensitive to the secular
variations of the uncancelled even zonal harmonics of low degree J4 and J6
whose impact grows linearly in time.Comment: Latex2e, 22 pag. 1 table, 2 figures, 45 references. Changes in the
Abstract, Introduction and Conclusions. Discussion on the non-gravitational
perturbations on Ajisai and on the impact of the secular rates of the even
zonal harmonics added. EIGEN-CG01C CHAMP+GRACE+terrestrial
gravimetry/altimetry Earth gravity model used. Reference adde
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