3 research outputs found
Is the physics within the Solar system really understood?
A collection is made of presently unexplained phenomena within our Solar
system and in the universe. These phenomena are (i) the Pioneer anomaly, (ii)
the flyby anomaly, (iii) the increase of the Astronomical Unit, (iv) the
quadrupole and octupole anomaly, and (v) Dark Energy and (vi) Dark Matter. A
new data analysis of the complete set of Pioneer data is announced in order to
search for systematic effects or to confirm the unexplained acceleration. We
also review the mysterious flyby anomaly where the velocities of spacecraft
after Earth swing--bys are larger than expected. We emphasize the scientific
aspects of this anomaly and propose systematic and continuous observations and
studies at the occasion of future flybys. Further anomalies within the Solar
system are the increase of the Astronomical Unit and the quadrupole and
octupole anomaly. We briefly mention Dark Matter and Dark Energy since in some
cases a relation between them and the Solar system anomalies have been
speculated.Comment: 22 pages, 3 figures, submitted for the proceedings of the 359th
WE-Heraeus Seminar on "Lasers, Clocks, and Drag-Free: Technologies for Future
Exploration in Space and Tests of Gravity
On Doppler tracking in cosmological spacetimes
We give a rigorous derivation of the general-relativistic formula for the
two-way Doppler tracking of a spacecraft in Friedmann-Lemaitre-Robertson-Walker
and in McVittie spacetimes. The leading order corrections of the so-determined
acceleration to the Newtonian acceleration are due to special-relativistic
effects and cosmological expansion. The latter, although linear in the Hubble
constant, is negligible in typical applications within the Solar System.Comment: 10 pages, 1 figure. Journal versio
Tidal Dynamics in Cosmological Spacetimes
We study the relative motion of nearby free test particles in cosmological
spacetimes, such as the FLRW and LTB models. In particular, the influence of
spatial inhomogeneities on local tidal accelerations is investigated. The
implications of our results for the dynamics of the solar system are briefly
discussed. That is, on the basis of the models studied in this paper, we
estimate the tidal influence of the cosmic gravitational field on the orbit of
the Earth around the Sun and show that the corresponding temporal rate of
variation of the astronomical unit is negligibly small.Comment: 12 pages, no figures, REVTeX 4.0; appendix added, new references, and
minor changes throughout; to appear in Classical and Quantum Gravity; v4:
error in (A24) of Appendix A corrected, results and conclusions unchanged. We
thank L. Iorio for pointing out the erro