Entry, Descent, and Landing Operations Analysis for the
Genesis Entry Capsule
Prasun N. Desai*
NASA Langley Research Center, Hampton, VA, 23681-2199
Daniel T. Lyons†
Jet Propulsion Laboratory, Pasadena, CA, 91109-8099
On September 8, 2004, the Genesis spacecraft returned to Earth after spending 29
months about the sun-Earth libration point (L1) collecting solar wind particles. Four hours
prior to Earth arrival, the sample return capsule containing the samples was released for
entry and subsequent landing at the Utah Test and Training Range. This paper provides an
overview of the entry, descent, and landing trajectory analysis that was performed during
the mission operations phase leading up to final approach to Earth. The final orbit
determination solution produced an inertial entry flight-path angle of -8.002 deg (which was
the desired nominal value) with a 3-σ error of ±0.0274 deg (a third of the requirement). The
operations effort accurately delivered the entry capsule to the desired landing site. The final
landing location was 8.3 km from the target, and was well within the allowable landing area.
Overall, the Earth approach operation procedures worked well and there were no issues
(logistically or performance based) that arose. As a result, the process of targeting a capsule
from deep space and accurately landing it on Earth was successfully demonstrated.
I.
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Introduction
ENESIS, the fifth of NASA’s Discovery class missions, was launched on August 8, 2001. It was the first
mission to return samples from beyond the Earth-moon system. Genesis was inserted into a halo orbit about the sun-
Earth libration point (L1), where it collected solar wind particles over a period of approximately 29 months. The
solar wind particles were collected in collector arrays, which were exposed by opening the capsule (Fig. 1). The
arrays faced the sun, and the particles were trapped in a silica-based material. The collector arrays were retracted at
the end of the collection period, and the capsule was cl