Subject: The Risk Corridor
From: Daniel Adamo <[email-masked]>
Date: Sun, 04 Mar 2012 15:43:58 -0700

ATIG Members-

Arguably the most compelling reason for space exploration (human or robotic)
is planetary defense from impact by potentially hazardous objects (PHOs),
comprised of near-Earth objects (NEOs) and long-period comets.  The attached
white paper is motivated by NEO 2011 AG5's possible Earth impact in 2040
(reference 
http://www.space.com/14683-big-asteroid-2011-ag5-threat-earth.html), which
if it actually took place, would then be confined to a 15-km-wide locus of
terrestrial locations called the risk corridor.

A non-conventional risk corridor generation method documented by the paper
is inspired by a strategy ATIG members familiar with Shuttle ascent/entry
onboard state vector management will recognize: to correct a down-track
navigation error (the most common type), simply modify the state vector time
tag as appropriate.  In applying this strategy to risk corridor computation,
the time bias is varied to systematically sample a PHO's one-dimensional
uncertainty region for the subset of conditions resulting in Earth impact.

I welcome feedback on this paper and its implications for planetary defense.

-Dan