Prospects of dynamical determination of General Relativity parameter beta and solar quadrupole moment J2 with asteroid radar astronomy

TL;DR

This study explores how asteroid radar observations can precisely measure the general relativity parameter beta and the solar quadrupole moment J2, potentially rivaling helioseismology in accuracy.

Contribution

It demonstrates the feasibility of using asteroid radar astronomy to independently determine beta and J2 with high precision, using covariance analysis and Monte Carlo simulations.

Findings

Estimated precision of beta as 6×10⁻⁴, likely closer to 2×10⁻⁴

Estimated precision of J2 as 3×10⁻⁸, likely closer to 10⁻⁸

Potential to rival helioseismology in measuring solar oblateness

Abstract

We evaluated the prospects of quantifying the parameterized post-Newtonian parameter beta and solar quadrupole moment J2 with observations of near-Earth asteroids with large orbital precession rates (9 to 27 arcsec century$^{-1}$). We considered existing optical and radar astrometry, as well as radar astrometry that can realistically be obtained with the Arecibo planetary radar in the next five years. Our sensitivity calculations relied on a traditional covariance analysis and Monte Carlo simulations. We found that independent estimates of beta and J2 can be obtained with precisions of $6\times10^{-4}$ and $3\times10^{-8}$, respectively. Because we assumed rather conservative observational uncertainties, as is the usual practice when reporting radar astrometry, it is likely that the actual precision will be closer to $2\times10^{-4}$ and $10^{-8}$, respectively. A purely dynamical determination of solar oblateness with asteroid radar astronomy may therefore rival the helioseismology determination.