Space Systems, Policy, and Architecture Research Consortium 1
Hugh McManus
Space Systems, Policy, and Architecture Research Consortium
A joint venture of MIT, Stanford, Caltech & the Naval War College
for the NRO
?2002 Massachusetts Institute of Technology
Space Systems Architecture
Lecture 3
Introduction to
Tradespace Exploration
Metis Design
Space Systems, Policy, and Architecture Research Consortium 2
?
?
Concept
Development
System-Level
Design
Detail
Design
Testing and
Refinement
Production
Ramp-Up
Product Design and
Development, 1995
Phases of
Most relevant to processes
in these phases
?2002 Massachusetts Institute of Technology
Tradespace Exploration
A process for understanding complex solutions to
complex problems
Allows informed “upfront” decisions and planning
From Ulrich & Eppinger, Product Development
1
Space Systems, Policy, and Architecture Research Consortium 3
?
? Ideally, many architectures assessed
? Avoids optimized point solutions that will not support
evolution in environment or user needs
? Provides a basis to explore technical and policy uncertainties
? Provides a way to assess the value of potential capabilities
A process for understanding complex solutions to complex problems
?2002 Massachusetts Institute of Technology
Architecture Trade Space Exploration
Model-based high-level assessment of system capability
Allows informed “upfront” decisions and planning
Space Systems, Policy, and Architecture Research Consortium 4
? State-of-the-art rapid preliminary design method
? Design tools linked both electronically and by co-located
humans
? Design sessions iterate/converge designs in hours
? Requires ready tools, well poised requirements
A process creating preliminary designs very fast
Allows rapid reality check on chosen architectures
Aids transition to detailed design
?2002 Massachusetts Institute of Technology
Integrated Concurrent Engineering
2
Number of Architectures Explored: 50488
Number of Architectures Explored: 50488
Space Systems, Policy, and Architecture Research Consortium 5
User
Needs
Robust
Adaptable
Concepts
Months, not Years
ICE
Conceptual
Design
MATE
Architecture
Evaluation
? Linked method for progressing from vague user needs to
conceptual/preliminary design very quickly
? MANY architectures, several/many designs considered
?
adaptable concepts, consideration of policy, risk.
?2002 Massachusetts Institute of Technology
Emerging Capability
Understanding the trades allows selection of robust and
Space Systems, Policy, and Architecture Research Consortium 6
km
Km
DESIGN VARIABLES: The architectural
trade parameters
? Orbital Parameters
– Apogee altitude (km)
– Perigee altitude (km)
– Orbit inclination
150-1100
150-1100
0, 30, 60, 90
? Physical Spacecraft Parameters
– Antenna gain
– communication architecture
– propulsion type
– power type
– delta_v
Total Lifecycle Cost
($M2002)
a specific
architecture
Assessment of the utility and cost of a large
space of possible system architectures
X-TOS
? Small low-altitude
science mission
?2002 Massachusetts Institute of Technology
What is an Architecture Trade Space?
Each point is
3
Space Systems, Policy, and Architecture Research Consortium 7
? Understand the
Mission
? Create a list of
? Interview the
Customer
? Create Utility Curves
? Develop the design
model
? Evaluate the potential
Architectures
Mission
Concept
Attributes
Calculate
Utility
Develop System
Model
Estimate
Cost
Architecture
Define Design
Vector
?2002 Massachusetts Institute of Technology
“Attributes”
vector and system
Trade Space
Developing A Trade Space
Space Systems, Policy, and Architecture Research Consortium 8
Concept
? Small low-altitude science
mission
? Known instruments
Attributes
? Data Life Span
? Data Collection Altitude(s)
? Diversity of Latitude(s)
? Time Spent at Equator
? Data Latency
? Number of Vehicles and
Mission Design
? Apogee Altitude
? Perigee Altitude
? Orbit Inclination
? Antenna Gain
? Communications Architecture
? Propulsion Type
? Power Type
?
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
150 350 550 750 950
Data Collection Altitude (km)
Utility
?2002 Massachusetts Institute of Technology
XTOS Tradespace Development
Design Vector
Manuever Delta-V Capability
Define Utility
4
Space Systems, Policy, and Architecture Research Consortium 9
Continued
Total Lifecycle Cost
($M2002)
Each point is a
specific architecture
? Orbit Calculations (STK)
? Spacecraft Estimations (SMAD)
? Launch Module
50488 Architectures Explored
? SMAD/NASA mode? Multi-Attribute Utility Theory
architectures
?2002 Massachusetts Institute of Technology
System Model
Estimate Cost Calculate Utility
Pareto front of “best”
Space Systems, Policy, and Architecture Research Consortium 10
?
?
?
? )
? 2002 Massachusetts Institute of Technology
Understanding What Systems Do
Transmit Information
Collect Information
Move Mass (inc. People)
Others (Space Station…
[Beichman et al, 1999]
5
Martin 2000
Space Systems, Policy, and Architecture Research Consortium 11
Stakeholders
?
?
?
Enterprise
Employees
Corporation
End Users ConsumersCustomer
Acquirers
Shareholders
UnionsSociety
Partners
Suppliers
?2002 Massachusetts Institute of Technology
Understanding who cares -
Many interested parties in a complex system
Each “customer” has a set of needs
They are different, and can be contradictory
Space Systems, Policy, and Architecture Research Consortium 12
ATOS:
Multi-vehicle
Ionosphere
Explorer
In Situ
Direct Scintillation Sensing
Topside Sounding
GPS Occultation
GPS
UV Sensing
?2002 Massachusetts Institute of Technology
Concept Selection: Bounding
6
?2002 Massachusetts Institute of Technology 14
Space Systems, Policy, and Architecture Research Consortium 13
Scoping
Spacecraft
Instrument
Control
Center
Physics Model
Instrument -> Local Ionosphere
Current State
Predict Future State
User-Specific
System Integration
User Set
User Set
User Set
User Set
Ionospheric characteristics
Database
Other
Data Sources
(Various assets)
A-TOS
scope
Ionosphere
?2002 Massachusetts Institute of Technology
Global Ionospheric Model
Global Ionospheric Model
Hanscom Model
Raw, commutated, uncalibrated data
Decommutated, calibrated instrument data “Scientist”
“Warfighter”
“Space Weather”
“Knowledgeable”
Go/No-Go “green light”
Space Systems, Policy, and Architecture Research Consortium
Attributes
? “what the decision makers need to
consider”
? ( and/or what the user truly cares about)
? Examples: Billable minutes =
? TPF Pictures =
camera performance metrics
? Rescue/move satellites =
mass moving, grappling capability,
timeliness
– Could have sub-cartoons for above
GINA metrics
[Beichman et al, 1999]
7
DATA
Space Systems, Policy, and Architecture Research Consortium 15
(5)(4)(3)
(2)(1)
1) Data Life Span
2) Data Altitude
3) Maximum Latitude
4) Time Spent at Equator
5) Data Latency
km
Km
2004 2005
?2002 Massachusetts Institute of Technology
XTOS Attributes
Space Systems, Policy, and Architecture Research Consortium 16
Utilities
?
?
?
Single Attribute
Utility function
0
1
Good ->
Attribute
Multi-Attribute
Utility analysis
0
1
Good ->
Expense
?2002 Massachusetts Institute of Technology
“What the attributes are WORTH to the decision
makers”
Single Attribute utility maps attribute to utility
Multi-attribute utility maps an architecture (as
expressed by its attributes) to utility
8
9
Space Systems, Policy, and Architecture Research Consortium ?2002 Massachusetts Institute of Technology 17
Single Attribute Utilities
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
150 350 550 750 950
Data Collection Altitude (km)
Utility
Space Systems, Policy, and Architecture Research Consortium ?2002 Massachusetts Institute of Technology 18
Multi-Attribute Utility
Single Attribute Utility Curve for Data
Point Altitude
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
150 350 550 750 950
Altitude (km)
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
Lifespan Latitude Latency Equator
Time
Altitude
Weight Factors of each Attribute
(k values)
( )
’
=
+=+
N
i
ii
XUKkXKU
1
1)(1)(
Total Lifecycle Cost ($M 2002)
Utility
XTOS Design Vector
? “Parameters of the Trade Space”
Variable: First Order Effect:
Orbital Parameters:
?Apogee altitude (200 to 2000 km) Lifetime, Altitude
?Perigee altitude (150 to 350 km) Lifetime, Altitude
?Orbit inclination (0 to 90 degrees) Lifetime, Altitude
Latitude Range
Time at Equator
Physical Spacecraft Parameters:
?Antenna gain (low/high) Latency
?Comm Architechture (TDRSS/AFSCN) Latency
?Propulsion type (Hall / Chemical) Lifetime
?Power type (fuel / solar) Lifetime
?Total DV capability (200 to 1000 m/s)
Lifetime
Space Systems, Policy, and Architecture Research Consortium ?2002 Massachusetts Institute of Technology 19
Space Systems, Policy, and Architecture Research Consortium 20
?
mothership
?2002 Massachusetts Institute of Technology
ATOS design Vector
Geometry of the Multi-vehicle Swarm
Swarm Orbit Parameters
Mothership/ no
Number of spacecraft in swarm
Geometry of swarm
10
Space Systems, Policy, and Architecture Research Consortium 21
Identify key
interactions
for modeling
that are likely to be (or not be) distinguishers
Design Vars Perigee Apogee Delta-V Propulsion Inclination Comm System Ant. Gain Power system Mission Scenario Total Impact
Attributes
Data Lifespan 9 9 9 6 0 0 0 6 9 48
Sample Altitude 9 9 0 0 0 0 0 0 9 27
Diversity of Latitudes 0 0 0 0 9 0 0 0 9 18
Time at Equator 0 6 0 0 9 0 0 0 9 24
Latency 3 3 0 0 3 9 9 6 3 36
Total 21 27 9 6 21 9 9 12 39
Cost 9 9 3 6 6 3 6 6 9
Total w/Cost 30 36 12 12 27 12 15 18 48
?2002 Massachusetts Institute of Technology
Scoping-QFDs
Sums identify attributes and Design Variables
Space Systems, Policy, and Architecture Research Consortium 22
Scoping-Iteration/evolution
After GINA exercise
module progress
10/20/00 10/31/00 1/15/01 1/21/01
# sats/swarm
# swarms
Instrument type
# instruments/sat
Position control scheme
Concept type
# sats/swarm
Mothership (yes/no)
# sats/swarm
# subplanes/swarm
# suborbits/subplane
# sats/swarm
# subplanes/swarm
# suborbits/subplane
?2002 Massachusetts Institute of Technology
TABLE II. EVOLUTION OF DESIGN VECTOR
First Cut After utility
characterization and
Schedule Crunch
Swarm type
Swarm orbit
Intra-swarm orbit
TT&C scheme
Ground station
Mission lifetime
Processing scheme
Latitude of interest
# swarms per plane
# orbital planes
Swarm altitude
Swarm orientation
Swarm geometry
Separation within swarm
Swarm perigee altitude
Swarm apogee altitude
Yaw angle of subplanes
Max sat separation
Mothership (yes/no)
Swarm perigee altitude
Swarm apogee altitude
Yaw angle of subplanes
Max sat separation
11
Mapping Design Vector to Attributes
and Utilities - Simulation Models
XTOS Simulation Software Flow Chart
All variations
on design
Orbits
Spacecraft
Launch
Satellite
vector
database
Mission
Scenario
Cost (lifecycle)
Utility
Mission scenarios with
Output
acceptable satellites
Space Systems, Policy, and Architecture Research Consortium ?2002 Massachusetts Institute of Technology 23
Space Systems, Policy, and Architecture Research Consortium 24
Availability
Probability of
Detection
# S/C per Cluster
….
….
….
Constellation Altitude
S/C Bus
Launch &
Operations
RadarConstellation
Payload
System
AnalysisAntenna Power
1 2 3 4 5 6 7 8 9 10 0
10
20
30
40
50
60
70
80
90
100
?2002 Massachusetts Institute of Technology
Techsat Models
Inputs (Design Vector)
Key Outputs
Lifecycle Cost
Revisit Rate
Resolution & MDV
# Clusters
Aperture Diameter
MATLAB Models
12
13
Space Systems, Policy, and Architecture Research Consortium ?2002 Massachusetts Institute of Technology 25
Exploring the Tradespace
2300 2400 2500 2600 2700 2800 2900 3000
1150
1200
1250
1300
1350
1400
Zoom in of the TPF System Trade Space
Performance (total # of images)
Lifecycle Cost ($millions)
$0.55M/Image
$0.5M/Image
$0.45M/Image
$0.4M/Image
0 500 1000 1500 2000 2500 3000 3500 4000
800
1000
1200
1400
1600
1800
2000
2200
2400
TPF System Trade Space
Performance (total # of images)
Lifecycle Cost ($millions)
$2M/Image $1M/Image
$0.5M/Image
$0.25M/Image
True Optimal
Solution
Taguchi
Solution
Many good architectures
at c. $0.5M/Image
Each point is an
evaluated architecture
Cadillac
Chevy
TPF: a science
imaging system
Space Systems, Policy, and Architecture Research Consortium ?2002 Massachusetts Institute of Technology 26
The Pareto Front
? Set of “best” solutions
? “Dominated” solutions are more expensive or less
capable
0 500 1000 1500 2000 2500 3000 3500 4000
800
1000
1200
1400
1600
1800
2000
2200
Performance (total # of images)
L
i
f
e
c
y
c
l
e
C
o
s
t
(
$
M
)
TPF System Trade Space Pareto-Optimal Front
Dominated Solutions
Non-Dominated Solutions
$2M/Image
$1M/Image
$0.5M/Image
$0.25M/Image
Utility (images)
Cost ($M)
Multi-Objective SA Exploration of the TPF Trade Space
Performance (total # images
L
i
f
e
c
y
c
l
e
C
o
s
t
(
$
m
i
l
l
i
o
n
s
)
$2M/Image
$1M/Image
$0.5M/Image
$0.25M/Image
Space Systems, Policy, and Architecture Research Consortium 27
?
0 500 1000 1500 2000 2500 3000
700
800
900
1000
1100
1200
1300
1400
1500
1600
Pareto Front
?2002 Massachusetts Institute of Technology
Optimization
Can look for the Pareto front using advanced
optimization techniques
Current Solution Path
Pareto-Optimal Set
Space Systems, Policy, and Architecture Research Consortium 28
Designs from traditional process
TPF
? Terrestrial Planet
Finder - a large
astronomy system
? Design space:
Apertures
separated or
connected, 2-D/3-
D, sizes, orbits
?
?2002 Massachusetts Institute of Technology
Using the Trade Space to Evaluate
Point Designs
From Jilla, 2002
Images vs. cost
[Beichman et al, 1999]
14