Analysis and Optimization of Thermal Protection
System Design for a Manned Martian Entry
Vehicle
HP390
Andrew Bingham
04/05/06
Introduction
On January 14th, 2004, President George W. Bush gave a historic speech at the
headquarters of the National Aeronautics and Space Administration in Washington, D.C.
President Bush unveiled a new Vision for Space Exploration, and in doing so gave
NASA its first clear direction for future exploration beyond Low Earth Orbit since the
Apollo lunar program ended in 1974. The Vision directs NASA to finish the
International Space Station and retire the Space Shuttle by 2010, and to begin developing
the new spacecraft required to enable further human exploration of the Moon and
eventually Mars.
Central to achieving the goals of the Vision is the new manned spacecraft, which
is currently referred to as the Crew Exploration Vehicle (CEV). The CEV reference
design currently consists of a five meter diameter blunt capsule with a shape similar to
that of the Apollo capsule. Crew capacity is expected to be four astronauts for missions
to the International Space Station and the Moon, and six for potential future missions to
Mars. The CEV will be launched on a Crew Launch Vehicle derived from the Shuttle
Solid Rocket Booster and the J-2S engine from the Apollo program.
The current CEV is being designed as a base upon which future improvements
can be made to enable longer durations missions to destinations beyond the Earth-Moon
system, including Mars and possible the Asteroid Belt. While the CEV is designed
specifically to carry astronauts into space and return them to Earth’s surface, a vehicle
will eventually be required which is able to safely deliver a crew to the surface on Mars.
This Mars Entry Vehicle (MEV) will undoubtedly draw heavily on the technology
developed as part of the CEV program.
Previous missions to re-enter the Martian atmosphere have included the Viking 1
& 2 Landers, Mars Polar Lander, Mars Pathfinder, and the twin Mars Exploration
Rovers. All of these missions have utilized ablative heat shields designed based on the
best current knowledge of the Martian atmosphere. These unmanned missions, while
successful, were not necessarily held to the same safety standards as a manned MEV.
Thermal protection is critical to maintaining the safety of the crew and the
integrity of the vehicle during a re-entry mission. Even when a Thermal Protection
System operates properly, thermal loading can cause changes in the way that a
spacecraft’s structure responds to the atmospheric forces which are also generated during
re-entry. The objective of this thesis is to investigate potential thermal protection system
designs for a manned Mars Entry Vehicle, taking into account the entire range of thermal
protection systems which are currently available and those may be available when
manned exploration of Mars begins in the 2030 timeframe.
Methods
This project will make use of several NASA resources, as well as knowledge
gained from heat transfer, aerodynamics, gas dynamics, and structures classes at Clarkson
University. Analysis of TPS performance will be conducted with increasing levels of
accuracy, culminating in an analysis of the aerothermal effect on the spacecraft structure
during re-entry. A representative ‘best’ design for the MEV TPS will be identified based
on the overall results.
Based on the mass of previous manned and unmanned spacecraft design and the
geometry of the Fast Opposition trajectory which current Mars Reference Missions make
use of, the entry mass, velocity, and trajectory of the MEV will be estimated. These
parameters will be combined with a Mars Atmospheric Model from NASA Glenn to
provide information on atmospheric heating of the MAV during atmospheric entry.
One-dimensional analysis of TPS performance for specific TPS configurations
will be performed using techniques outlined in Heat and Mass Transfer, 5th Ed. Twodimensional analysis of the blunt body in the atmospheric flow will be conducted using a
program such as MARC or ANSYS, combined with the Mars Atmospheric Model.
Based on these analyses, an optimum TPS configuration will be selected for
implementation on the 3-D model of the MEV.
A 3-D model of the MEV will be generated, with sufficient fidelity for
atmospheric and structural calculations. Available NASA hypersonic re-entry codes will
be used to perform aerodynamic analysis of the entry profile. Once the thermal loading
of the structure is known, this information will be used to determine aerothermal effects
on the structure of the vehicle and its performance.
Wherever possible, results will be compared to results for previous unmanned
Mars entry vehicles, as well as other blunt body capsules such as the Apollo capsule.
Work will be coordinated with applicable NASA centers where possible to ensure that a
measurable contribution is being made to the engineering community’s understanding of
entering the Martian atmosphere.
Plan
The research outlined above will be performed on the following timeline:
Spring 2006 – Continue Background Research
Spring 2006 – Request NASA Mars Atmospheric Model
Early Summer 2006 – Select Representative TPS Systems
Early Summer 2006 - Perform 1-D Thermal Analysis
Late Summer 2006 – Perform 2-D Thermal Analysis
Late Summer 2006 – Develop 3D MEV Model
Fall 2006– Perform 3-D Thermal Analysis
Fall 2006 – Perform Analysis of Aerothermal Structural Effects
This will allow for completion of the project and presentation of a paper at the AIAA
Region I-Northeast Student Conference at the Massachusetts Institute of Technology in
March of 2007, as well as completion of the Honors Thesis requirements well before the
end of the Spring 2007 semester.