A unique signature of the modified Newtonian dynamics (MOND) paradigm is its peculiar behavior in the vicinity of the points where the total Newtonian acceleration exactly cancels. In the Solar System, these are the saddle points of the gravitational potential near the planets. Typically, such points are embedded into low-acceleration bubbles where modified gravity theories à la MOND predict significant deviations from Newton’s laws. As it has been pointed out recently, the Earth-Sun bubble may be visited by the LISA Pathfinder spacecraft in the near future, providing a unique occasion to put these theories to a direct test. In this work, we present a high-precision model of the Solar System’s gravitational potential to determine accurate positions and motions of these saddle points and study the predicted dynamical anomalies within the framework of quasilinear MOND. Considering the expected sensitivity of the LISA Pathfinder probe, we argue that interpolation functions which exhibit a “faster” transition between the two dynamical regimes have a good chance of surviving a null result. An example of such a function is the QMOND analog of the so-called simple interpolating function which agrees well with much of the extragalactic phenomenology. We have also discovered that several of Saturn’s outermost satellites periodically intersect the Saturn-Sun bubble, providing the first example of Solar System objects that regularly undergo the MOND regime.

• Received 29 November 2011

DOI:https://doi.org/10.1103/PhysRevD.86.044002