Perspectives on effectively constraining the location of a massive trans-Plutonian object with the New Horizons spacecraft: a sensitivity analysis

摘要

The radio tracking apparatus of the New Horizons spacecraft, currentlytraveling to the Pluto system where its arrival is scheduled for July 2015,should be able to reach an accuracy of 10 m (range) and 0.1 mm s^-1(range-rate) over distances up to 50 au. This should allow to effectivelyconstrain the location of a putative trans-Plutonian massive object, dubbedPlanet X (PX) hereafter, whose existence has recently been postulated for avariety of reasons connected with, e.g., the architecture of the Kuiper beltand the cometary flux from the Oort cloud. Traditional scenarios involve arock-ice planetoid with mX = 0.7mE at some 100 - 200 au, or a Jovian body withmX = 5mJ at about 10,000 - 20,000 au; as a result of our preliminarysensitivity analysis, they should be detectable by New Horizons since theywould impact its range at a km level or so over a time span six years long.Conversely, range residuals statistically compatible with zero having anamplitude of 10 m would imply that PX, if it exists, could not be located atless than about 4,500 au (mX = 0.7mE) or 60,000 au (mX = 5mJ), thus making adirect detection quite demanding with the present-day technologies. As aconsequence, it would be appropriate to rename such a remote body as Telisto.Also fundamental physics would benefit from this analysis since certain subtleeffects predicted by MOND for the deep Newtonian regions of our Solar Systemare just equivalent to those of a distant pointlike mass.