Lunar Exploration Transportation
System (LETS)
Customer Briefing
12-17-2007
LETS go to the Moon!
Agenda
• IPT Class
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Overall objectives
Class Flow/Schedule
Requirement Process
Review Board Membership
Technical Mentors
Level 1 Requirements
Proposed FOMs
Surface Objectives
Concept Design Constraints
“Efficiency” Design Thoughts
– Previous Landers/Rovers
– Alternative Mobility Concepts
• Final Report Requirements
Integrated Product Team Class
• Develop a system-level
perspective for translating
requirements into feasible
solutions
• Develop oral, written, and
information technologybased communication skills
• Practice the critical thinking
skills required for success in
a changing environment
• Acquire basic character
qualities that enable
individuals and teams to
function effectively
Class Flow
Baseline Review (1/31/08)
• Evaluate baseline per CDD
• Understand CDD from
customer
• Demonstrate your ability to
review board
Alternatives Review (2/28/08)
• Develop alternatives to accomplish
mission
• Select a concept to continue detailed
design
Detailed Design Review (4/29/08)
• Develop detailed design of selected
concept
• Provide prototype model to review board
Process of Requirements
• Requirements…
Review Board Membership
• Board of 6-10 government/industry/academic
officials
• Review board chair selected by customer
– Coordinates input from members to faculty personnel
• Review board ranks teams, does not provide
input to final grades
• Time commitment
– 3 reviews, 2-3 hrs. each
Technical Mentors
• Officials that provide guidance to student teams in a
technical discipline
• ARE NOT members of the review board
• Disciplines needed
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GN&C
Thermal
Power
Structures
Payload
Systems Engineering
Operations
• Time commitment
– On-call basis
Level 1 Requirements
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Landed Mass 1450 kg + 100 kg
1st mission landing site is polar region
Design must be capable of landing at other lunar locations
Minimize cost across design
Launch Date NLT September 30th 2012
Mobility is required to meet objectives
Survivability ≥ 1 year
Lander/Rover must survive conops.
The mission shall be capable of meeting both SMD and ESMD
objectives.
• The lander must land to a precision of ± 100m 3 sigma of the
predicted location.
• The lander must be capable of landing at a slope of 12 degrees
(slope between highest elevated leg of landing gear and lowest
elevated leg)
• The lander shall be designed for g-loads during lunar landing not to
exceed the worst case design loads for any other phase of the
mission (launch to terminal descent).
Proposed FOMs
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Surface exploration
Maximized Payload Mass (% of total mass)
Objectives Validation: Ratio of SMD to ESMD: 2 to 1.
Conops: Efficiency of getting data in stakeholders hands
vs. capability of mission.
• Mass of Power System: % of total mass.
• Ratio of off-the-shelf to new Development
– Minimize cost
Surface Objectives
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Single site goals:
– Geologic context
• Determine lighting conditions every 2 hours over the course of one year
• Determine micrometeorite flux
• Assess electrostatic dust levitation and its correlation with lighting conditions
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Mobility goals:
– Independent measurement of 15 samples in permanent dark and 5 samples in lighted
terrain
• Each sampling site must be separated by at least 500 m from every other site
– Minimum: determine the composition, geotechnical properties and volatile content of the
regolith
• Value added: collect geologic context information for all or selected sites
• Value added: determine the vertical variation in volatile content at one or more sites
– Assume each sample site takes 1 earth day to acquire minimal data and generates 300
MB of data
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Instrument package baselines:
– Minimal volatile composition and geotechnical properties package, suitable for a
penetrometer, surface-only, or down-bore package: 3 kg
– Enhanced volatile species and elemental composition (e.g. GC-MS): add 5 kg
– Enhanced geologic characterization (multispectral imager + remote sensing instrument
such as Mini-TES or Raman): add 5 kg
Concept Design Constraints
• Surviving Launch
– EELV Interface (Atlas 431)
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Mass
Volume
Power
Communications
Environments
– Guaranteed launch window
• Survive Cruise
– Survive Environment
• Radiation
• Thermal
• Micrometeoroids
Concept Design Constraints
• Lunar Environment (@ poles and equator)
– Radiation
– Micrometeoroid
– Temperature
– Dust
– Lighting
• Maximize use of OTS Technology (TRL 9)
• Mission duration of 1 year
• Surface Objectives
Reference: Dr. Cohen
Efficiency Design Thoughts
• Previous Landers
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Surveyor
Apollo Lunar Lander
Viking
Pathfinder
• Rover concepts
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Apollo Lunar Rover
Sojourner
Spirit & Opportunity
MSL
• Alternative mobility concepts
Previous Landers - Surveyor
• Atlas-Centaur Launch
Vehicle
• Useful Mass was 292 kg
• Mission Duration was 65
hours
• Science Instruments
included: A TV camera,
and strain gauges
mounted on each leg
shock absorber.
Previous Landers – Apollo
• Designed to transport
astronauts to and from
the moon
• Mass 14,696 kg
• Volume 6.65m2
• Height 6.37m
• Diameter 4.27m
• Endurance 72 hrs
• Provides life support for
2 crew
Previous Landers - Viking
• Two Viking Landers
were the first spacecraft
to conduct prolonged
scientific studies on the
surface of another planet
• Dry Mass 576kg
• Dimensions 3m by 3m
by 2m
• One Lander survived 6.5
yrs
Previous Landers - Pathfinder
• Flight System Launch
Mass (890kg)
• Payload (25kg)
• X Band Antenna
• Solar Arrays
• Deploys airbags which
reduce impact by as much
as 40 g
• Designed to survive 30
sols with an extended
mission lifetime of up to 1
year
Previous Rovers - LRV
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Lunar Roving Vehicle
Total range 35.89km
Rover mass 210kg
Useful Payload mass
490kg
• Each wheel 0.25 hp DC
motor
• Two 36v silver-zinc
potassium hydroxide nonrechargeable batteries
with a capacity of 121 A·h.
Previous Rovers - Sojourner
• Rover Mass (10.5 kg)
• Solar Powered generating 16
Watts during peak operation
• Non-Rechargeable Battery which
generates approximately 300
Watts/hour
• Contains a Six Wheel Drive
Rocker Bogie Design (made
rover very versatile)
• Can carry approximately 1.5 kg
of payload at a time
Previous Rovers – Spirit and
Opportunity
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Delta II Launch Vehicle
Lander mass: 348 kg
Rover mass: 185 kg
Mission duration was 90
days
• Scientific Instruments
included: Several
cameras, spectrometer,
alpha particle x-ray,
microscopic imager, RAT,
and several other tools
Previous Rovers - MSL
• Mass 800kg
• Max Speed 90m per
hr
• Average Speed 30m
per hr
• Expected to traverse
a minimum of 6km
over its two year
mission duration
Alternative Mobility Concepts
LETS
Lander(s)
Rover(s)
Penetrators
Other?
Alternative Mobility Concepts
Landing
Mobility
Single Lander
1 Rover
Multiple Rovers
Penetrators
1 Rover + Penetrators
Multiple Rovers + Penetrators
Land on Wheels
1 Rover
Multiple Rovers
Penetrators
1 Rover + Penetrators
Multiple Rovers + Penetrators
Multiple Lander
1 Rover
Multiple Rovers
Penetrators
1 Rover + Penetrators
Multiple Rovers + Penetrators
Alternative Mobility Concepts
Single Lander +
Mobility
Advantages
Disadvantages
Single Rover
•Proven technology
•More OTS
•Minimum ground support
•Single point of failure
•Increased chances of Con-Ops (Mission)
failure
Multiple Rovers
•Maximize data return
•Increased range/area
•Increased comm area w/ networking
•Faster mission completion
•Increased ground support
•More complex comm
•Increased dry mass
•Individual science payload limited (no single
large device)
Penetrators
•Maximize data return
•Less weight
•No moving parts
•“Random” spread (penetrator not accurate)
•Complex comm
•Nonwired: batt & comm req
•Wired: limited range
•Propulsion (?)
•Unproven
Single Rover +
Penetrators
•Good light/dark solution
•“Intelligent” data analysis/gathering
•Maximize data return
•Sacrifice mass for penetrators
Multiple Rovers +
Penetrators
•Maximize data return
•Increased range/area
•Faster mission completion
•Increased comm area w/ networking
•Dry mass penalty
•Complex comm
•Complex power
•Limited individual science payload
Alternative Mobility Concepts
Land On Wheels (LOW) +
Mobility
Advantages
Disadvantages
Single Rover
(same vehicle)
•Mass savings
•Less ground support
•Lower probability of mission completion and
data return
•Unproven technology
•Rover might be damaged by landing
•Rover moves with prop system
Multiple Rovers
(same vehicles)
•Maximize data return
•Increased range/area
•Increased comm area w/ networking
•Faster mission completion
•Increased ground support
•More complex comm
•Increased dry mass
•Science payload limited (no single large
device)
Penetrators
•Maximize data return
•Less weight
•No moving parts (penetrators)
•Good light/dark solution
•“Intelligent” data analysis/gathering
•“Random” spread (penetrator not accurate)
•Complex comm
•Penetrators require comm/pwr (?)
•Propulsion (?)
•Unproven technologies
Single Rover +
Penetrators
•(same as above)
•(same as above)
Multiple Rovers +
Penetrators
•Maximize data return
•Increased range/area
•Faster mission completion
•Increased comm area w/ networking
•Dry mass penalty
•Complex comm
•Complex power
•Limited individual science payload
Alternative Mobility Concepts
Multiple Landers +
Mobility
Advantages
Disadvantages
Single Rover
•Comm relay stations
•Maximize data return (no single point
failure)
•Mass penalty
•Volumetric penalty
Multiple Rovers
•Wide range/area
•Comm relay
•Increased data return
•Dry mass penalty
•Volumetric penalty
•Science individual payload limited
•Complex comm
Penetrators
•Wide range/area
•Fast mission completion time
•No moving parts
•Multiple data sites (possible linking for
seismic analysis)
•Dry mass penalty
•Complex comm
•Comm/pwr required for each
lander/penetrator
Single Rover +
Penetrators
•Comm relay stations
•Maximize data return
•“Intelligent” data analysis/gathering
•Dry mass penalty
•Complex comm
•Comm/pwr required for each
lander/pen/rover
Multiple Rovers +
Penetrators
•Maximize data return
•Increased range/area
•Faster mission completion
•Increased comm area w/ networking
•Dry mass penalty
•Complex comm
•Limited individual science payload
•Comm/pwr required for each
lander/pen/rover
Final Report Requirements
• Lander development schedule
– By subsystems
• Configuration drawing
– Lander
– Rover concepts (Southern)
– Sample return vehicle (ESTACA)
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Concept of operations
Level 2 Requirements
CDD
Design Analysis Package
Parts List/ Vendor List