New Horizons Encounter Hazard Update

The New Horizons Project recently completed a 1.5-year study of the potential dust impact hazard from small-satellite-generated debris as the spacecraft flies through the Pluto system in July 2015.

This study concluded that the probability of a mission-ending dust impact is <0.3% if the spacecraft follows the current baseline plan, far below some early, more conservative estimates. Thus, the expectation is that the NH spacecraft will follow this baseline plan, with a close approach of ~12,500 km from the surface of Pluto.

However, two alternative plans (called SHBOTs, for Safe Haven By Other Trajectories) are also being developed to mitigate the (however-unlikely) possibility that new knowledge (e.g., from NH observations during the approach to Pluto, from new dynamical analyses, or from other non-NH observations) indicates the hazard risk is greater than predicted.

One plan, GIS (Generic Inner SHBOT), has essentially the same trajectory as the baseline (i.e., a closest approach distance from Pluto of ~12,500 km), but with the spacecraft turned so that the antenna faces the incoming dust particles (“Antenna-To-Ram”, or ATR), thereby protecting the spacecraft underneath. The other plan, DIS (Deep Inner SHBOT), would also use ATR attitude as protection, but would additionally divert the trajectory to within ~3000 km of Pluto’s surface, where atmospheric drag removes dust on very short timescales.

Further discussion of the impact hazard study and the SHBOTs is provided.

The NH Project presented the results of this impact hazard study, and this mitigation plan, to an independent NASA review panel and to the NASA SMD Program Management Council (PMC). Both of these groups endorsed the plan.

The NH Project is now moving forward to finalize the Encounter plans for 2015.

An in-flight rehearsal of the most critical 9-day portion of the baseline Encounter plan is taking place in early-July 2013.

The NH spacecraft remains on target for a close approach to Pluto in 2015, all subsystems are performing nominally, and the anticipated science observations promise to revolutionize our understanding of dwarf planets and the Kuiper belt.

The NH mission and its planned scientific returns will be presented and discussed, as will pre-encounter scientific predictions, at a scientific conference July 22-26, 2013 at APL in Laurel, MD, where the entire planetary community is invited to share their predictions for what can be expected during this first in situ exploration of the Solar System’s third zone. View registration information.

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