Title:
Trajectory Trade-space Design for Robotic
Entry at Titan
Trajectory Trade-space Design for Robotic
Entry at Titan
Author(s)
Roelke, Evan
Advisor(s)
Braun, Robert D.
Editor(s)
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Abstract
In recent years, scientific focus has emphasized other ocean worlds such as Europa,
Enceladus, and Titan, due to their potential for harboring life. The only spacecraft ever to
land on these moons was the Huygens Probe in 2005; however, this probe’s main purpose was
to study the atmosphere and surface of Titan, with no real landing target. Future missions
to other ocean worlds would likely require a science target and thus add several constraints
to the mission such as arrival time, entry state, and aeroshell geometry, among others. Of
the three ocean worlds previously mentioned, Titan is an optimal target for initial mission
concepts for several reasons. The atmospheric composition, winds, and surface features
are well studied by Cassini and the Huygens Probe. Additionally, of the aforementioned
moons, Titan does not have a thick ice sheet to penetrate in order to sample the surface
and/or liquid seas, enabling such mission to double as a stepping stone for missions to other
ocean worlds. Finally, Titan exhibits a myriad of interesting planetary features that, if
studied, could further the understanding of both Titan’s and the solar system’s geologic
history. In this paper we analyze the trade-spaces of various important parameters involved
in Entry, Descent, and Landing (EDL) as it pertains to robotic missions for Titan in order
to provide a guideline for optimizing a mission’s system parameters while minimizing both
system complexity and the landing footprint. It is found that the ideal geometry is a
ballistic spherecone body entering from orbit to allow flexibility in the entry state vector.
The aerothermodynamic environment is most affected by the entry velocity and the vehicle
bluntness ratio, while the peak deceleration is most influenced by the entry velocity and
entry flight path angle. In addition, multiple parachutes decrease the landing footprint,
impact speed, and descent time compared to single parachute systems, at the expense of
being more complex. Larger ballistic coefficients decrease the landing footprint and descent
time while increasing the impact speed. Finally, it is discovered that the uncertainty in the
entry altitude and flight path angle have the most impact on the final state vector.
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Date Issued
2017-05-01
Extent
Resource Type
Text
Resource Subtype
Masters Project
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