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Shannen Moira M. Acedillo1, 2, Pascal Lee2,3
1Department of Aerospace Engineering, California State Polytechnic University, Pomona, CA, 2SETI Institute, Mountain View, CA , 3Mars Institute, NASA Ames, CA
Robotic Precursor Measurements For Human Exploration
of Phobos and Deimos
Results
Compared to exploring Near-Earth Asteroids, the exploration of Phobos
and Deimos present us with specific issues and challenges. For instance,
both are relatively large small bodies; both lie in Mars’ gravity well; their
near-surface regolith are among the most porous (and likely under
compacted) of any small body known. The present synthesis study
identifies a total of at least 30 Phobos and Deimos SKG parameters that
need to be determined quantitatively, including geotechnical parameters
such as the adhesion, compressibility, and macro-porosity of the regolith,
and planetary protection parameters such as the toxicity and organics
content of near-surface materials. Some parameters identified are likely
key to any human mission goals at Phobos and Deimos (e.g.,
characterizing in detail the dust environment or the gravity field around
each moon), while others might be needed only in certain mission
scenarios (e.g., assessing resources such as water and loose regolith (for
radiation shielding) that might be present in the subsurface beyond 1 m
depth).
Methods (cont)
An early result is that given our updated list of Phobos and Deimos SKGs,
around only one robotic precursor mission, that will interact actively with
the surface of Phobos and Deimos in several locations on each body (in
addi-ion to doing remote investigations of each), is needed to fill all
Phobos and Deimos SKGs. To begin developing a concept for a SKG-
filling robotic precursor mission for humans to Phobos and Deimos, we
organized the updated list of SKGs in themes and, within each, in
categories and examples as shown on Table 2. Whenever possible, one or
more specific examples of how the SKG may be filled is provided. Each
SKG is then treated as an Investigation Objective. For each Investigation
Objective, we define Measurement Requirements, and identify the specific
Physical Parameters and Observables that need to be measured,
following the classic NASA Science Traceability Matrix (STM) structure.
However, the current STM does not extend to defining specific instrument
or mission functional requirements, which may be better approached as a
broader science and exploration community effort.
Acknowledgements
Special thanks is given to the National Science Foundation and CAMPARE for supporting this research, and to my mentor Dr.
Pascal Lee. Thank you also to the Kellogg Honors College of Cal Poly Pomona and SETI Institute for travel grants. Further
thanks given to Dr. Alex Rudolph and Dr. Jean Chiar for support and advice. This material is supported by the National Science
Foundation for the California-Arizona Minority Partnership for Astronomy Research and Education (CAMPARE). Any opinions,
findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect
the views of the National Science Foundation.
Introduction
We identify a series of specific robotic precursor measurements
required to fill NASA’s Strategic Knowledge Gaps (SKGs) for
planning future human missions to the two moons of Mars, Phobos
and Deimos. NASA is currently developing space exploration
architectures and systems for an Evolvable Mars Campaign that
will enable the human Journey To Mars, similar to that shown in
Figure 1. Reaching Mars orbit is identified as an important early
milestone in achieving human landed missions on Mars itself. This
humans-to-Mars orbit phase creates an opportunity to explore and
use Phobos and Deimos as part of the Evolvable Mars Campaign.
There remain, however, a number of unknowns concerning Phobos
and Deimos that need to be addressed - likely by at least one
robotic precursor mission - before human missions to the surface
of these small bodies may be adequately planned. These
unknowns are Phobos and Deimos-specific SKGs. Phobos and
Deimos SKGs have been identified in previous studies, but they
have been lacking in quantitative specificity. The present study
represents an effort to review NASA latest SKG list for Phobos and
Deimos, and to identify wherever possible the specific
measurements that would be needed to fill the gaps.
.
References
[1] Ben Bussey, Strategic Knowledge Gaps, July 1, 2015 [2] Andrew Rivkin, NEO/Phobos/Deimos Strategic Knowledge Gaps Special Action Team
Final Report, Small Bodies Assessment Group (SBAG) SKG-SAT, November 25, 2012 [3] ISECG, Strategic Knowledge Gaps, August 9, 2013 [4]
Mars Exploration Program Analysis Group (MEPAG) Goals Committee, MEPAG Goals Document, Mars Exploration Program Analysis Group
(MEPAG) Goals Committee, June 18,19 2015 [5] Mike Gernhardt PhD., Human Exploration of Phobos, Nasa JSC [6] Lupisella, M., et al., Low-
Latency Teleoperations for Human Exploration & Evolvable Mars Campaign, 2015 SpaceOps Workshop, June 10-12,2015 [7] Shearer, C. K.,
Neal, C., Strategic Knowledge Gaps for the ‘Moon First’ Human Exploration Scenario, Analysis and Findings of Lunar Exploration Analysis Group,
GAP- Specific Action Team [8] Office of Planetary Protection, Safe on Mars: Precursor Measurements Necessary to Support Human Operations
on the Martian Surface, NASA [9] Dan Mazanek, Considerations for Designing a Human Mission to the Martian Moons, 2013 Space Challenge,
California Institute of Technology, NASA Langley Research Center, NASA HAT, March 25-29,2013, 2013 Space Challenge, California Institute of
Technology, NASA Langley Research Center, NASA HAT, March 25-29,2013
Future Work
To enable humans to reach Mars Orbit and explore Phobos and Deimos by the mid-2030s as
currently considered by NASA, all key Phobos and Deimos SKGs must be filled by the mid-
2020s, which means that identifying the objectives and requirements for a robotic precursor
mission(s) and begin developing mission concepts must begin no later than now.It is ideal to
still continue adding detail to all of the precursor measurements, specifically a measureable
quantity for each qualitative parameter. Reducing the amount of measurements to about 20
should also be aspired to reduce precursor missions and increase efficiency.
Figure 1. Big Picture Graphic Science and Exploration
Objectives (SEO)
Strategic Knowledge Gaps (SKGs)
Themes
Categories
Examples
1.
Determine surface
geology and Minerology
[9]
2.
Sample collection [9]
3.
Determine of origin of
PhD [9]
I. Understand how to
work/interact with the surface of
PhD
IA. Potential hazards for crew, recon,
and operation [1,2,6]
I-
A-1 Geological and natural hazards [1,2]
I-
A-2 Particulate hazards [1,2]
IB. Surface Properties [1,2]
I-
B-1 Geotechnical Measurements of Regolith[1,2]
IC. Overall geological understanding
I-
C-1 Identification of Geological Units
I-
C-2 Geodetic grid and high resolution mapping
[7,9]
ID. Maneuverability and Mobility
[1,2,6]
I-
D-1 Anchoring for tethered activities [1,2]
I-
D-2 Surface Pertubations
II. Understand the PhD
environment and its effects
IIA. Radiation
Environment beyond
surface [1,2]
II-
A-
1 Solar Event Prediction and Flare Activity [1,2]*
II-
A-2 GCR Activity and properties [1,2]
II-
A-3 Secondary Source Activity [1,2]
IIB. Radiation
Environment at surface*
II-
B-1 Charged surface particle environment [5]
II-
B-2 Plasma presence
IIC. Thermal Environment
II-
C-1 Temperature
IID. Atmospheric and Orbital
Environment [1,2,5]
II-
D-1 Orbital Torus Particulate Characteristics [1,2]
II-
D-2 Near-Surface levitating particles [1,2]
IIE. Regolith Environment [1,2,5]
II-
E-1 Regolith composition [1,2,5]
II-
E-2 Disturbed and ejected regolith particulate
properties [1,2]
IIF. Internal Environment
IIF. Internal Composition
III. Understand the PhD resource
potential
IIIA. Solar Resources*
III
-A-1 Solar illumination mapping*
IIIB. In
-
situ Resource Utilization (ISRU)
[1,2]
III
-B-1 Surface Operation techniques for in-situ in
micro
-
g: extraction, collection, storage, refining [1,2]
III
-B-2 Subsurface parameters for operations
IIIC. Surface assets [6]
III
-C-
1 Identification of geological surface utilization
IIID
. Sub-surface and surface resource
potential [3]
III
-D-1 Volatile Properties
III
-D-2 Volatile location
Relevant Measurements (RM)
#
Parameter (characteristic)
Measurement (actual observable)
Description
SKG
fullfilled
RM_1
Mineral content of
regolith [3,4,5]
chemical composition of surface
particles
Determination of inorganic substances
located on the surface; can be
fullfilled through reflectance spectrum
I-
C-1, II-D-1, II-D-2, II-E-
1,
III
-C-1
RM_2
Mineral content of
levitating particles [3,4,5]
chemical composition of levitating
particles in close proximity of surface
Determination of inorganic substances
located below and above surface; can
be
fullfilled through sampling
I-
C-1, II-D-1, II-D-2, II-E-
1,
III
-C-2
RM_3
Regolith property
Grain size distribution of regolith
particles[3,5]
Micrometer to centimeter scale
structure [5]
I-
A-2, I-B-1, I-D-2, I-E-1, II
-
D
-1, II-E-1
RM_4
Regolith property
grain size
- frequency distribution of
regolith [3,5]
Micrometer to centimeter scale
structure [5]
I-
A-2, I-B-1, I-D-2, I-E-1, II
-
D
-1, II-E-2
RM_5
Particulate size range
Grain size of Mars torus solid
particulates (ejecta particles in Mars
orbit) [3,5]
Micrometer to centimeter scale
structure [5]
I-
A-2, I-B-1, I-D-2, I-E-1, II
-
D
-1, II-E-3
RM_6
Particulate Size
distribution
Size
-
frequency distribution of Mars torus
solid particulates (ejecta particles in
Mars orbit) [3,5]
Micrometer to centimeter scale
structure [5]
I-
A-2, I-B-1, I-D-2, I-E-1, II
-
D
-1, II-E-4
RM_7
Toxicity of Particulates
pH and buffer capacity of solid
particulates^
must be <150ppm^
I-
A-2, II-E-1
RM_9
Macro
-proposity;
solubility; compaction of
regolith
Size of macropores in regolith
size around 75microm
I-
B-1, I-D-1, I-E-1, II-E-2,
RM_10
Macro
-proposity;
solubility; compaction of
regolith
Size of macropores in orbital particulates
size around 75microm
I-
B-1, I-D-1, I-E-1, II-E-2,
RM_11
Bearing capacity of soil
Ultimate resistance of soil per unit area
understand sinkage properties of
surface^
I-
B-1, I-D-1, I-D-2, I-E-
1, III-
B-
1 , III-B-2
RM_12
Yield strength of overall
surface^
Stress at which the surface begins to
deform with tested load per unit area
understand sinkage properties of
surface^
I-
B-1, I-D-1, I-D-2, I-E-
1, III-
B-
1 , III-B-2
RM_13
Shear failure occurrence
Internal Friction angle^ of soil
understand sinkage properties of
surface^
I-
B-1, I-D-1, I-D-2, I-E-
1, III-
B-
1 , III-B-2
RM_14
Improved global
topography data sets*
Elevation data
200 m/pixel* accuracy of topography;
possibly done through direct survey or
remote sensing
I-
D-1, III-C-1
Table 1 Table 2
Methods
An initial list of precursor measurements were derived
from analyzing previous NASA studies of SKGs for the
Moon, Small Bodies, and Phobos and Deimos. Data
was also compiled from the Strategic Knowledge Gaps
developed by ISECG [3], a goals document by the Mars
Exploration Program Analysis Group [4], and some
precursor measurements suggested by NASA’s Office of
Planetary Protection [8]. The list was then updated and
quantified wherever possible on the basis of ongoing
discussions within NASA’s Human exploration
Architecture Team (HAT) focusing on Phobos and
Deimos [4]. The list of required SKG measurements was
then structured and formatted to ensure easy
incorporation and use in different mission plans and
scenarios.