Subject: LCROSS Trajectory Plots
From: adamod <[email-masked]>
Date: Sat, 20 Jun 2009 10:31:46 -0500

ATIG Members-

Although NASA posts all kinds of detailed as-tracked trajectory data for
Shuttle and ISS (I used to help do that job in my former FDO life), there's
the usual dearth of this information available following Thursday's
LRO/LCROSS launch.  All I could find was a planned LCROSS trajectory posted
on JPL Horizons.  Although these planned data assume an on-time Thursday
launch 20-min earlier than the actual event, the attached plots should be
reasonably accurate for purposes of gross situational awareness.

In the LCROSSgeo Earth-centered plot, lunar encounter is evident from the
trajectory's S-turn as the nearly stationary LCROSS and attached Centaur
upper stage are overrun by the Moon at a geocentric speed 5 times greater.
The resulting lunar gravity assist flings LCROSS/Centaur into a longer
period Earth orbit at greater ecliptic inclination from which lunar impact
will be targeted for 2009 October 9.

The LCROSS lunar gravity assist is plotted at greater detail in the
LCROSSsel attachment.  Perspective for this plot is orthogonal to the
Moon-centered trajectory's plane from a direction very close to Earth's.  As
indicated by the Moon's shading, its geocentric phase is just past new.
According to the USNO, new Moon is 2009 June 22 @ 19:35 UTC.  If LCROSS is
able to operate its visible and IR cameras during closest approach to the
Moon, some spectacular imagery of rugged terrain at low solar elevation
directly below the spacecraft would be obtained.  These images might include
the eventual impact site near the Moon's south pole.

-Dan