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1
Lunar Lava Tube Survey Mission
4/5/2016
Rohan Deshmukh
Swapnil Pujari
Giovanny Guecha
Advisor: Professor David Spencer
2
About Us
Rohan Deshmukh Swapnil Pujari Giovanny Guecha
School Georgia Institute of
Technology
Georgia Institute of
Technology
Georgia Institute of
Technology
Major Aerospace Engineering Aerospace Engineering Aerospace Engineering
Hometown Fairfax, VA Alpharetta, GA Kennesaw, GA
Year 4th Year 4th Year 3rd Year
2
3
Presentation Outline
•Concept Motivation
•Mission Overview
•Flight System Overview
•Technical Resource Budgets
•Summary
3
44
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Global Exploration Roadmap (GER)
•A vision for globally coordinated human and robotic space exploration
focused on the solar system destinations where humans may someday
live and work
•Calls for sustainable human exploration of the Moon, near-Earth
asteroids, and Mars.
5
Image Source: The Global Exploration Roadmap, 2011
Option 1: Asteroid Next
Option 2: Moon Next
6
Detection of Buried Empty Lava Tubes Using
GRAIL Gravity Data
•Gravity Recovery and Interior Laboratory (GRAIL) provided high-
resolution lunar gravity data through NASA’s Discovery Program
•Analysis of the GRAIL data has provided insight into the presence and
extent of empty subsurface lava tubes
–Ref: Chappaz, Melosh, Howell, and Milbury, “Detection of Buried Empty Lava Tubes
Using GRAIL Gravity Data,” 47th Lunar and Planetary Science Conference, Abstract No.
1509, 2016.
6
nus Iridum. The pit itself is approximately 20 m deep
with central hole of 70 m x 33Dde m and an outer fun-
nel of 110 x 125 m. The maps overlay local topogra-
phy, and the color represents the signed magnitude
corresponding to the largest eigenvalue of the Hessian
derived from the gravitational potential. Both free-air
and
Figure 2: Local gradiometry (top), cross-correlation
(bottom) maps for free-air (left), Bouguer (center), and
free-air/Bouguer correlation (right) for Sinus Iridum
pit.
Bouguer eigenvalue maps show gravity low in the vi-
cinity of the lunar pit. The correlation map distinctively
marks the region near the pit as a region of mass deficit
with a potential access to an underground buried empty
lava tube. The cross-correlation technique applied is
shown in the second row of Figure 2. The schematic
shows that for both free-air and Bouguer cross-
correlation maps, the anomaly is detected in the same
region as via the gradiometry technique. Both tech-
niques provide evidence for a subsurface anomaly in
the vicinity of the newly found lunar pit.
Free-air and Bouguer Gravity Anomaly: Contin-
uing the validation of the subsurface anomaly, regional
free-air and Bouguer gravity maps are generated. Fig-
ure 3 illustrates local maps for the free-air gravity on
the left and Bouguer gravity on the right. On closer in-
Figure 3: Local free-air (left) and Bouguer (right) grav-
ity map for Marius Hills skylight with overlay of to-
pography.
spection, the two gravity maps demonstrate a gravity
low surrounding the rille along which the Marius Hills
skylight lies. The Bouguer low adds to the evidence
suggesting a potential buried empty lava tube along the
rille with an access through the Marius Hills skylight.
Similar free-air and Bouguer gravity analysis is car-
ried out for the newly found pit in Sinus Iridum as
shown in Figure 4. The color bar is adjusted to visually
Figure 4: Local free-air (left) and Bouguer (right) grav-
ity map for the newly found lunar pit in Sinus Iridum
with overlay of topography.
distinguish the region in proximity to the lunar pit in
Sinus Iridum. The gravity low shown in both the free-
air and Bouguer gravity suggest an underground mass
deficit in the vicinity of the pit. Although the pit itself
is relatively small, it can potentially be an access to a
larger underground structure as evident from the gravi-
ty maps and the two detection strategies. Additional
maps have also been studied to identify a possible con-
nection of this anomaly to a buried empty lava tube
structure.
Conclusions: Two strategies are employed to de-
tect small scale lunar features: one based on gradiome-
try and a second one that relies on cross-correlation of
individual tracks. The two methods have previously
been validated with a known surface rille, Schröter’s
Valley. Then, a signal suggesting an unknown buried
structure is observed in the vicinity of Marius Hills
skylight that is robust enough to persist on a map creat-
ed from an average of several hundred simulations. A
similar signal is also observed in the vicinity of the
Sinus Iridum pit suggesting a possible subsurface mass
deficit.
The technique has been extended to cover the vast
mare regions. Multiple new candidates for buried emp-
ty lava tube structures have been discovered as a part
of this study. Some of the candidates bear no surface
expression but similar signals are observed from both
the detection strategies as observed for candidates with
surface expressions, i.e., skylights/pits.
References:
[1] Zuber et al. (2013) SSR 178, 1.
[2] Chappaz et al. (2014) AIAA 2014-4371.
[3] Haruyama et al. (2009), GRL 36, L21206.
1509.pdf47th Lunar and Planetary Science Conference (2016)
7
Applications to Human Exploration
• Empty lava tubes represent
potential sites for human
habitation, providing natural
protection from:
– Cosmic radiation
– Micrometeorite impacts
– Diurnal temperature
extremes
• Lunar lava tubes may be stable
up to about 5 km wide
7
Image Source: Building a Lunar Base with 3D Printing, ESA 2013
8
Sinuous Rilles & Skylights
•Surface features associated with
lunar lava flow include sinuous rilles
and skylights
•Sinuous rilles are channel-like
depressions formed when lava tubes
collapse
–Lunar rilles can be 30-50 times
larger than terrestrial analogs
•Skylights are collapsed openings into
empty caverns
–Potential access points to empty lava
tubes
8
Schroeter Vallis sinuous rille captured from
orbit during Apollo 15 mission
Image Source: Buried Empty Lava
Tube Detection with GRAIL Data,
2014
Marius Hills Skylight
99
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Mission Objectives
•Survey the depth, volume, and extent of subsurface empty lunar lava
tubes
•Provide high resolution surface topography of regions containing
sinuous rilles associated with subsurface lava tubes
–Direct measurements of skylights and depth of lava tubes below skylights
10
Image Source: Lava tubes safe enough for Moon base, 2015
11
Mission Concept
•Orbiter/lander combination
–Orbiter equipped with visible camera, ground penetrating radar
(GPR) and LIDAR
–Lander equipped with GPR and visible camera
–Telecom relay from lander through orbiter
•Spaceflight, Inc. SHERPA 2200 (derived from ESPA Grande) is
utilized as a carrier vehicle, hosting
–Orbiter & payload
–Lunar tensegrity lander & payload
–Lunar Orbit Insertion (LOI) module
–Deorbit module
•Targeted launch on NASA EM-2
11
12
Trans-Lunar Orbit Lunar Orbit Insertion Lunar Parking Orbit
12
1) Launch
from EM-2
4) LOI
Burn
5) Orbit Trim
Maneuvers:
2 Days
2) Deployment from L/V
Duration to Lunar Orbit: 5 Days
6) Elliptical Lunar
Parking Orbit
hp: 5 km
ha: 50 km
inc: 15.4°
3) Trajectory Correction
Maneuver (TCM)
13
1. Disposal State
Trajectory
2. LOI: ΔV = 493 m/s
3. Post-LOI Orbit Propagated to
Apoapsis (10,000 km)
4. Trajectory Propagated
to Periapsis
5. PLM-1: Periapsis
Anti-Velocity Burn
ΔV = 500 m/s
7. PLM-2: Periapsis Anti-
Velocity Burn ΔV = 242 m/s
6. PLM-1 Orbit with 250 km
periapsis altitude
8. PLM-2 Orbit with
50 km periapsis altitude9. PLM-3: Periapsis
Anti-Velocity Burn
ΔV = 69 m/s
10. 5 x 50 km
Science Orbit
Elliptical Capture Maneuvers – STK Analysis
13
14
Tensegrity Lander Entry, Descent, and Landing
Altitude: 5 km
1. Orbiter & Lander
Separation
∆𝑉 = −1190 𝑚/𝑠
Altitude: 10 m
2. De-orbit Burn
4. Powered Descent
7. Backshell Flyaway
3. Backshell
Reorientation
𝑉𝐿 = 0𝑚/𝑠
5. Tensegrity Deployment
14
Altitude: 3 km
∆𝑉 = −637 𝑚/𝑠
∆𝑉 = −100 𝑚/𝑠
6. Tensegrity TDZ
1515
16
Orbiter Overview
Payload•GPR•LIDAR•Visible Camera
S/C Bus•X-Band Antenna•X-Band Transceiver•UHF Antenna•UHF Transceiver•3-axis attitude control•Solar Panels•Cold Gas Thruster
16
LIDAR
Visible
Camera
GPR
** CAD Model used for Visual Representation Only **Image Source: Prox-1 CAD
17
Tensegrity Lander Overview
Top Plate:
•GPR Electronics
•Visible Camera
•UHF Antenna
•UHF Transceiver
•Gimbal System
•C&DH
•Battery, PDM
• IMU
•Thermal Control
Bottom Plate:
•GPR Antenna
Mass Ratio of Tensegrity to
Payload vs Impact Landing Velocity
17*CAD Model used for Visual Representations*
Image Source: Julian Rimoli
18
Tensegrity Structure
•Light weight, mechanically stable, and
loadbearing structure under extreme
deformation
•Alternative to Airbag EDL system
•Reduces complexity, weight, costs, and
form factor for launch
•Currently researched/developed by Dr.
Julian Rimoli – Georgia Tech
18
19
Ground Penetrating Radar
Orbiter GPR (Analogous to SHARAD-MRO/KAGUYA)
• Send electromagnetic waves into the ground and
detect the reflected signals to reveal subsurface
structure and composition
• Uses an FM/CW radar technique in High
Frequency range
• Survey the lunar crust up to kilometers of depth
Lander GPR (Analogous to RIMFAX-Mars 2020 Rover)
• Successfully used by Apollo 17 (1972) and the
Chinese lunar rover Yuto (2014)
• RIMFAX (Mars 2020) will image the subsurface
stratigraphy to maximum depths of 10 to 500
meters, with vertical resolutions of 5 to 20 cm
19
** Images used for Visual Representations **
20
SHERPA Tug - Overview
•Developed by Spaceflight, Inc.
•Built upon existing Spaceflight
Secondary Payload System
(SSPS)
–Tested on Falcon 9 in 2013
•Customized ESPA Grande Ring
–Payload Capacity: 1,500 kg
–ΔV capability: > 2.2 km/s
–Integrated ADCS, Power, Comms,
and Avionics
•Future testing in 2016/2017
20
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SHERPA Tug – Propulsion Performance
Sherpa ΔV Performance vs. Payload Mass
SHERPA 2200
• Bi-propellant propulsion system
• NTO/MMH Propellant
• Four 90N thrusters
734 kg
21
22
SHERPA Tug – Payload Capabilities
• Five 24” Ports available on ESPA
Grande:
– 1 Port LOI Module
– 1 Port Deorbit Module
– 1 Port for Orbiter
– 1 Port for Tensegrity System
• Payload Constraints:
– 39” X 45” X 49” volume
constraint
– 300 kg mass constraint per port
22
Orbiter
LOI
Module
Tensegrity
Lander System
Deorbit
Module
ESPA Grande Ring
2323
24
Delta-V Budget
Maneuver # Description ΔV (km/s)Propulsion
System
6 De-orbit 1.190De-orbit
Module
7Rocket Assisted
Deceleration Burn0.637 SHERPA 2200
8 Backshell Fly-away 0.100 SHERPA 2200
CBE Total (km/s) 1.927 -
Segment ΔV (km/s)
TCM, Lunar Orbit
Insertion
& Orbit Trim
1.324
Deorbit & Descent 1.927
System Margin (%) 25
MEV Total (km/s) 4.064
Maneuver # Description ΔV (km/s)Propulsion
System
1 TCM 0.020 SHERPA 2200
2 LOI 0.493 LOI Module
3 PLM-1 0.500 SHERPA 2200
4 PLM-2 0.242 SHERPA 2200
5 PLM-3 0.069 SHERPA 2200
CBE Total (km/s) 1.324 -
24
Propulsion System ΔV (km/s)
SHERPA 2200 1.568
LOI Module 0.493
Deorbit Module 1.190
25
Mass Equipment List
25
Sherpa PayloadsUnit CBE Mass (kg)
QTYCBE Mass
(kg)Notes
Orbiter 75 1 75 ~Prox-1 Mass
LOI Module 263 1 263 Orbital ATK Star 26C (SRM)
De-orbit Module 218 1 218 Orbital ATK Star 24 (SRM)
Tensegrity 1.2 1 1.2 0.04 Payload/Tensegrity Ratio
Lander Payload 30 1 30 ~24U mass
CBE Total Mass (kg) 587
System Contingency 25%
MEV Payload Mass (kg) 734
Margin (kg) 766
MPV Sherpa Payload Mass (kg) 1500
Orbital ATK Star 24 (SRM)
Orbital ATK Star 26C (SRM)
2626
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Summary
•The Lunar Lava Tube Survey mission will provide direct observations
to confirm the analytical finding of empty subsurface lava tubes, and
will characterize their depth, volume, and extent.
–Empty lava tubes provide natural protection from radiation,
micrometeorites, and diurnal temperature extremes, and represent
potential “safe zones” for future human habitation
•Through utilization of the SHERPA 2200 as a carrier vehicle for small
spacecraft and solid rocket propulsion modules, a highly capable
orbiter/lander combination can be delivered to the Moon at low cost
•Tensegrity lander concept offers robust landing capability for small
lunar payloads
27
2828
Image Source: Diversity of Basaltic Lunar Volcanism, Lunar Reconnaissance Orbiter, ASU
2929
30
Proposed Organizational Roles
•NASA Marshall Spaceflight Center–Project management, project system engineering, mission assurance, integration & testing,
mission operations
–SHERPA 2200 interface
–LOI & Deorbit modules
•Purdue University (Jay Melosh, Kathie Howell, Dave Spencer)–Mission design, flight system engineering, payload system engineering
–Orbiter, orbiter payload
–Lander payload
–UHF comm system (lander/orbiter)
•Georgia Tech (Julian Rimoli, Brian Gunter, Grady Tuell)–Tensegrity Lander
–LIDAR
30
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GER - Moon
31
Image Source: The Global Exploration Roadmap, 2011
32
Space Exploration Key Supporting Objectives
32
Source: The Global Exploration Roadmap, 2011
33
References
1. https://www.nasa.gov/pdf/284273main_Radiation_HS_Mod1.pdf
2. http://www.lpi.usra.edu/publications/books/lunar_sourcebook/pdf/Luna
rSourceBook.pdf
3. http://www.kinetics.nsc.ru/chichinin/books/spectroscopy/Stuart04.pdf
4. http://pds-smallbodies.astro.umd.edu/holdings/di-c-hrii_hriv_mri_its-6-
doc-set-
5. http://www.planetary.brown.edu/pdfs/4309.pdf
6. http://onlinelibrary.wiley.com/doi/10.1029/93JE02604/pdf
7. http://spaceflightnow.com/news/n1212/13grail/#.Vv6X0U8rJD8
8. http://www.bbc.com/news/science-environment-31953052
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