What do the orbital motions of the outer planets of the Solar System tell us about the Pioneer anomaly?

In this paper we investigate the effects that an anomalous acceleration as that experienced by the Pioneer spacecraft after they passed the 20 AU threshold would induce on the orbital motions of the Solar System planets placed at heliocentric distances of 20 AU or larger as Uranus, Neptune and Pluto. It turns out that such an acceleration, with a magnitude of 8.74\times 10^-10 m s^-2, would affect their orbits with secular and short-period signals large enough to be detected according to the latest published results by E.V. Pitjeva, even by considering errors up to 30 times larger than those released. The absence of such anomalous signatures in the latest data rules out the possibility that in the region 20-40 AU of the Solar System an anomalous force field inducing a constant and radial acceleration with those characteristics affects the motion of the major planets.Comment: Latex2e, 19 pages, 3 tables, 10 figures, 18 references. Authorship changed; new figures added for a direct comparison with the observable quantities. Accepted for publication in New Astronom

Constraints to a Yukawa gravitational potential from laser data to LAGEOS satellites

In this paper we investigate the possibility of constraining the hypothesis of a fifth force at the length scale of two Earth's radii by investigating the effects of a Yukawa gravitational potential on the orbits of the laser--ranged LAGEOS satellites. The existing constraints on the Yukawa coupling $\alpha$, obtained by fitting the LAGEOS orbit, are of the order of | \alpha | < 10^{-5}-10^{-8} for distances of the order of 10^9 cm. Here we show that with a suitable combination of the orbital residuals of the perigee \omega of LAGEOS II and the nodes \Omega of LAGEOS II and LAGEOS it should be possible to constrain \alpha at a level of 4 X 10^{-12} or less. Various sources of systematic errors are accounted for, as well. Their total impact amounts to 1 X 10^{-11} during an observational time span of 5 years. In the near future, when the new data on the terrestrial gravitational field will be available from the CHAMP and GRACE missions, these limits will be further improved. The use of the proposed LARES laser--ranged satellite would yield an experimental accuracy in constraining \alpha of the order of 1 X 10^{-12}.Comment: LaTex, no figures, no tables. To appear in Physics Letters

Lasing properties and nonlinearities of dyes under high power pumping

AbstractNitrogen lasers have been used for many years to make dye solutions lase. A nitrogen laser, which transverse electrical discharge in gas at atmospheric pressure has been built in our laboratory. It has been characterized and applied to pump different dyes: Rhodamine 6G, Coumarin 440, DOTCI, and pyranine in simple "on axis" geometric configuration. It has been shown that pyranine can lase in the absence of any optical external mirror cavity, this happens at very low threshold, and in different solvents. Dyes under consideration can be grouped into two major classes according to their lasing behavior independently on their concentration in the solvent: Rhodamine 6G and DOTCI can lase both axially or transversally and Coumarin 440 and pyranine can lase only axially. Other intriguing features have been observed that span from simultaneous multiple beam generation, to super fluorescence and to distribute axial pumping of dye solutions. A preliminary basis for understanding and controlling such processes is the spatial energy distribution and the energy density of the beam

The impact of the Kuiper Belt Objects and of the asteroid ring on future high-precision relativistic Solar System tests

We preliminarily investigate the impact of the Kuiper Belt Objects (KBOs) and of the asteroid ring on some proposed high-precision tests of Newtonian and post-Newtonian gravity to be performed in the Solar System by means of spacecraft in heliocentric \approx 1 AU orbits and accurate orbit determination of some of the inner planets. It turns out that the Classical KBOSs (CKBOS), which amount to \approx 70% of the observed population of Trans-Neptunian bodies, induce a systematic secular error of about 1 m after one year in the transverse direction T of the orbit of a test particle orbiting at 1 AU from the Sun. For Mercury the ratios of the secular perihelion precessions induced by CKBOs to the ones induced by the general relativity and the solar oblateness J_2 amount to 6 10^-7 and 8 10^-4, respectively. The secular transverse perturbation induced on a \approx 1 AU orbit by the asteroid ring, which globally accounts for the action of the minor asteroids whose mass is about 5 10^-10 solar masses, is 10 m yr^-1; the bias on the relativistic and J_2 Mercury perihelion precessions is 6.1 10^-6 and 1 10^-2, respectively. Given the very ambitious goals of many expensive and complex missions aimed to testing gravitational theories to unprecedented levels of accuracy, these notes may suggest further and more accurate investigations of such sources of potentially insidious systematic bias.Comment: Latex2e, Elsevier macros, 5 pages, no figures, 1 table. To appear in Planetary Space Science. Small change in table's captio

Perspectives in measuring the PPN parameters beta and gamma in the Earth's gravitational fields with the CHAMP/GRACE models

The current bounds on the PPN parameters gamma and beta are of the order of 10^-4-10^-5. Various missions aimed at improving such limits by several orders of magnitude have more or less recently been proposed like LATOR, ASTROD, BepiColombo and GAIA. They involve the use of various spacecraft, to be launched along interplanetary trajectories, for measuring the effects of the solar gravity on the propagation of electromagnetic waves. In this paper we investigate what is needed to measure the combination nu=(2+2gamma-beta)/3 of the post-Newtonian gravitoelectric Einstein perigee precession of a test particle to an accuracy of about 10^-5 with a pair of drag-free spacecraft in the Earth's gravitational field. It turns out that the latest gravity models from the dedicated CHAMP and GRACE missions would allow to reduce the systematic error of gravitational origin just to this demanding level of accuracy. In regard to the non-gravitational errors, the spectral noise density of the drag-free sensors required to reach such level of accuracy would amounts to 10^-8-10^-9 cm s^-2 Hz^-1/2 over very low frequencies. Although not yet obtainable with the present technologies, such level of compensation is much less demanding than those required for, e.g., LISA. As a by-product, an independent measurement of the post-Newtonian gravitomagnetic Lense-Thirring effect with a 0.9% accuracy would be possible as well. The forthcoming Earth gravity models from CHAMP and GRACE will further reduce the systematic gravitational errors in both of such tests.Comment: LaTex2e, 14 pages, 3 tables, no figures, 75 references. To appear in Int. J. Mod. Phys.

Gravitomagnetism and the Earth-Mercury range

We numerically work out the impact of the general relativistic Lense-Thirring effect on the Earth-Mercury range caused by the gravitomagnetic field of the rotating Sun. The peak-to peak nominal amplitude of the resulting time-varying signal amounts to 1.75 10^1 m over a temporal interval 2 yr. Future interplanetary laser ranging facilities should reach a cm-level in ranging to Mercury over comparable timescales; for example, the BepiColombo mission, to be launched in 2014, should reach a 4.5 - 10 cm level over 1 - 8 yr. We looked also at other Newtonian (solar quadrupole mass moment, ring of the minor asteroids, Ceres, Pallas, Vesta, Trans-Neptunian Objects) and post-Newtonian (gravitoelectric Schwarzschild solar field) dynamical effects on the Earth-Mercury range. They act as sources of systematic errors for the Lense-Thirring signal which, in turn, if not properly modeled, may bias the recovery of some key parameters of such other dynamical features of motion. Their nominal peak-to-peak amplitudes are as large as 4 10^5 m (Schwarzschild), 3 10^2 m (Sun's quadrupole), 8 10^1 m (Ceres, Pallas, Vesta), 4 m (ring of minor asteroids), 8 10^-1 m (Trans-Neptunian Objects). Their temporal patterns are different with respect to that of the gravitomagnetic signal.Comment: LaTex2e, 19 pages, 2 tables, 6 figures. Small typo in pag. 1406 of the published version fixe