Subject: InSight's VAFB Departure For Mars
From: Daniel Adamo <[email-masked]>
To: Daniel Adamo <[email-masked]>
Date: Fri, 25 May 2018 09:27:37 -0700

ATIG Members-

With regard to InSight, NASA's most recently launched robotic Mars probe, I
had several requests to write a paper on how a high inclination launch from
Vandenberg AFB can access interplanetary destinations.  The short answer is:
thanks to an Earth gravity assist in the parking orbit arc between LEO
insertion and the trans-Mars injection (TMI) burn.  The Russians have been
coping with this geometry for years, their biggest problem lately being
executing TMI (ref. the Phobos-Grunt ATIG_032 upload archived at
http://www.aiaahouston.org/adamo_astrodynamics/).  In fact, only higher
Earth parking orbit inclinations can access all Mars departure opportunities
without occasional performance-robbing "dogleg" TMIs or dedicated plane
change impulses post-TMI.

The attached white paper on InSight's Earth departure for Mars on 5 May 2018
documents two trajectories.  First, an approximate patched conic design with
a purely prograde TMI impulse is developed.  An as-flown trajectory is then
reconstructed (with its own set of approximations in lieu of proprietary
data unavailable for public release) leading to some interesting insights on
InSight's departure, particularly when compared with the patched conic
design.  Feel free to be in touch with further insights, questions, or
comments on this upload.

-Dan