Assessing the Impacts of Fractionation on Pointing

Assessing the Impacts of Fractionation on Pointing-Intensive Spacecraft

American Institute of Aeronautics and Astronautics Space 2009 Conference and Exposition

September 14-17, 2009

M. Gregory O’NeillGraduate Research Assistant

[email protected]

Annalisa Weigel, PhDAssistant [email protected]

Department of Aeronautics and AstronauticsMassachusetts Institute of Technology

Cambridge, Massachusetts

• Problem Formulation

• Methodology & Analysis

• Synthesis

• Conclusion

Agenda

• Conclusion

© 2009 Massachusetts Institute of Technology Slide 2

Enablers

S3

Enablers

Module 1 Module 2

Concepts & Terminology

Fractionated Spacecraft(O’Neill, 2009)

Problem Formulation

S2

S3

S4

S4

S5

Shared Resource Enablers

Subsystem Payload

S1

S1 S2

Representative

EnablerComm_CS_C&DH ADS_G�S Power

Application antenna IMU (receiving) solar array

Developmenttasking, schedule, &

control

(autonomous) relative

navigationlaser diode array

Domain

Enablers

Module 3Shared Subsystem Resources(O’Neill 2009)

PL PL

S4S5


Concepts & Terminology

Fractionated Spacecraft(O’Neill, 2009)

Problem Formulation

S2

S3

S4

S2

S3

S4

S/C-to-Ground

Directional AntennaSubsystem Payload

S1S1

Source Recipient

S3S4

S5

S1 S2

Representative

EnablerComm_CS_C&DH ADS_G�S Power

Application antenna IMU (receiving) solar array

Developmenttasking, schedule, &

control

(autonomous) relative

navigationlaser diode array

DomainShared Subsystem Resources(O’Neill 2009)

PLPL

S4S5

S4

S5

Omni-antenna

or

Directional Antenna


Recipient

PL

Monolithic Spacecraft

Fractionated Spacecraft

Mission Type Spacecraft Type

Context

Motivation: Critical QuestionProblem Formulation

Remote Sensing Mission

Launch, Technical, Environmental, Operational

Pointing-Intensive~36 mas pointing tolerance

Lifecycle Uncertainties(O’Neill, 2009)

GEOEye-1Source: GEOEye

A Fractionated SpacecraftSource: DARPA

Value Proposition

Value Proposition

- Performance - Lifecycle Cost- Mission Lifetime - Mass- Propellant Usage

Given the context, how do monolithic and fractionated spacecraft value propositions compare?




• Synthesis

• Conclusion

Agenda

• Conclusion


� Market Supply & Demand

� National Security

� Technical

� Environmental

� Funding

� Operational

� Launch

� Programmatic

Methodology: Spacecraft Evaluation ToolMethodology &

Analysis

Lifecycle Uncertainties

Physics-based Model Cost ModelSpacecraft Architecture

Models and Model Processes

Operationalize

via a

Monte Carlo Analysis

Lifecycle & Design Input Group

Component-Level Outputs

Physics-based Model Cost ModelArchitecture Input Group Payload

Size/Volume

Power

Launch Vehicle

COCOMO II

Parametric CERs

Mass

Subsystems

Launch Vehicle Input Group

Dynamic Model

Subsystem-Level Outputs

Module-Level Outputs

System-Level Outputs


Case Study InputsMethodology &

Analysis

No Shared Resources

Shared Resources1. Comm_CS_C&DH 2. ADS_GNS

Shared Resources1. Comm_CS_C&DH 2. ADS_GNS

Lifecycle & Design

Spacecraft Architecture

Category Input Value Units

Altitude 700 km

Inclination 98 °

Mission Lifetime 7 years

MCA no. of Trials 2,500 -

PoIM 1.5 %

Payload Resolution 0.5 m

Variable CONOPS Separation Distance 20, 1000, 5000 m

Orbit

Dynamic

Constant

Nu

mb

er

of

Mo

du

les

2. ADS_GNS 2. ADS_GNS 3. Power

1 Module

2 Modules

Arch 1

Arch 4Arch 7

Arch 2Arch 27

3 Modules Arch 10Arch 13

Arch 8Arch 26

4 Modules Arch 22Arch 25

Arch 20Arch 29

Monolithic S/C

Use of Shared Subsystem Resources


900

1,000

1,100

1,200

1,300

1,400

1,500

1,600

1,700

1,800M

ed

ian

Sy

ste

m D

yn

am

ic L

ife

cycl

e C

ost

(FY

20

08

$M

)

Results: Inter-module Separation DistanceMethodology &

Analysis

300

400

500

600

700

800

900

1,600 2,000 2,400 2,800 3,200 3,600 4,000 4,400 4,800

Me

dia

n S

yst

em

Dy

na

mic

Lif

ecy

cle

Co

st (F

Y2

00

8$

M)

System Mass (kg)

Arch 1 Arch 2 Arch 4




Arch 25


900

1,000

1,100

1,200

1,300

1,400

1,500

1,600

1,700

1,800M

ed

ian

Sy

ste

m D

yn

am

ic L

ife

cycl

e C

ost

(FY

20

08

$M

)


Analysis

Dynamic Lifecycle Cost1. Nonrecurring

- Manufacture and IA&T2. Initial deployment/launch3. Recurring

- Manufacture and IA&T- Operations support

300

400

500

600

700

800

900

1,600 2,000 2,400 2,800 3,200 3,600 4,000 4,400 4,800

Me

dia

n S

yst

em

Dy

na

mic

Lif

ecy

cle

Co

st (F

Y2

00

8$

M)

System Mass (kg)





Arch 25


- Operations support- Wrapper (e.g., human labor)- Ground station facilities

4. Lifecycle replenishments- Recurring (manufacture and IA&T)- Launch

900

1,000

1,100

1,200

1,300

1,400

1,500

1,600

1,700

1,800M

ed

ian

Sy

ste

m D

yn

am

ic L

ife

cycl

e C

ost

(FY

20

08

$M

)

always less massive Monolithic spacecraft are always less massive

than fractionated spacecraft +2,871 kg

+159 kg


Analysis

+2,115 kg

Monolithic spacecraft are not necessarily less expensive than fractionated spacecraft

300

400

500

600

700

800

900

1,600 2,000 2,400 2,800 3,200 3,600 4,000 4,400 4,800

Me

dia

n S

yst

em

Dy

na

mic

Lif

ecy

cle

Co

st (F

Y2

00

8$

M)

System Mass (kg)





Arch 25


900

1,000

1,100

1,200

1,300

1,400

1,500

1,600

1,700

1,800M

ed

ian

Sy

ste

m D

yn

am

ic L

ife

cycl

e C

ost

(FY

20

08

$M

) The Dynamic Lifecycle Cost of fractionated spacecraft

increases with thenumber of modules

The Mass of fractionated spacecraft increases with the use of shared resources

The Dynamic Lifecycle Cost of fractionated spacecraft

may or may not increase with the use of shared resources

+627 kg

+333 $M


Analysis

300

400

500

600

700

800

900

1,600 2,000 2,400 2,800 3,200 3,600 4,000 4,400 4,800

Me

dia

n S

yst

em

Dy

na

mic

Lif

ecy

cle

Co

st (F

Y2

00

8$

M)

System Mass (kg)





Arch 25

+6 $M+20 kg

-136 $M-87 $M+53 kg


+284 kg

900

1,000

1,100

1,200

1,300

1,400

1,500

1,600

1,700

1,800M

ed

ian

Sy

ste

m D

yn

am

ic L

ife

cycl

e C

ost

(FY

20

08

$M

) The Dynamic Lifecycle Cost of fractionated spacecraft

increases with thenumber of modules

The Mass of fractionated spacecraft increases with the number of modules

+171 $M

+140 kg

+357 $M


Analysis

+280 kg

300

400

500

600

700

800

900

1,600 2,000 2,400 2,800 3,200 3,600 4,000 4,400 4,800

Me

dia

n S

yst

em

Dy

na

mic

Lif

ecy

cle

Co

st (F

Y2

00

8$

M)

System Mass (kg)





Arch 25


MMD - (1) number of modes, (2) number of dominant modes,

Multimodal Distribution (MMD)

Normal Distribution (ND)

Results: Confidence in Dynamic LCCMethodology &

Analysis

Spacecraft Cost Modeling

Spacecraft Dynamic Lifecycle Cost Distribution

ND - Mean

MMD – Median, Mean, or Mode

Measure of Variability (due to distribution)

ND - Variance

Dynamic Lifecycle

Value

Measure of Central Tendency

(2) number of dominant modes, (3) skewness, (4) kurtosis, and (5) order statistic, five-number summary (aka box-and-whisker plot)

Measure of Variability (due to CERs)

Value

Percentage confidence levels


(5) order statistic, five-number summary (aka box-and-whisker plot)


Analysis

Spacecraft Cost Modeling

MMD – Median

Measure of Variability (due to distribution)

Measure of Variability (due to CERs)

Measure of Central Tendency

Percentage confidence levels


1,100

1,200

1,300

1,400

1,500

1,600

1,700

1,800

1,900

Dy

na

mic

Lif

ecy

cle

Co

st (

FY

20

08

$M

)

6.36 8.06 8.22 8.30 8.96


Analysis

300

400

500

600

700

800

900

1,000

1 2 3 4 5

Dy

na

mic

Lif

ecy

cle

Co

st (

FY

20

08

$M

)

Spaceraft Architecture

Arch 1 Arch 2 Arch 4 Arch 27 Arch 10

+44.91-90.73 -41.71

+168.95

Two-Module

Monolithic

Spacecraft

Three-

Module© 2009 Massachusetts Institute of Technology Slide 16

1,100

1,200

1,300

1,400

1,500

1,600

1,700

1,800

1,900

Dy

na

mic

Lif

ecy

cle

Co

st (

FY

20

08

$M

)

6.36 8.06 8.22 8.30 8.96

Fractionated spacecraft can have inter-quartile ranges encapsulated by monolithic

inter-quartile ranges


Analysis

300

400

500

600

700

800

900

1,000

1 2 3 4 5

Dy

na

mic

Lif

ecy

cle

Co

st (

FY

20

08

$M

)



+44.91-90.73 -41.71

+168.95

Two-Module

Monolithic

Spacecraft

Three-


1,100

1,200

1,300

1,400

1,500

1,600

1,700

1,800

1,900

Dy

na

mic

Lif

ecy

cle

Co

st (

FY

20

08

$M

)

6.36 8.06 8.22 8.30 8.96


Analysis

Certain fractionated spacecraft demonstrate to have less cost “risk” than comparable monolithic spacecraft

300

400

500

600

700

800

900

1,000

1 2 3 4 5

Dy

na

mic

Lif

ecy

cle

Co

st (

FY

20

08

$M

)



+44.91-90.73 -41.71

+168.95

Two-Module

Monolithic

Spacecraft

Three-


1,100

1,200

1,300

1,400

1,500

1,600

1,700

1,800

1,900

Dy

na

mic

Lif

ecy

cle

Co

st (

FY

20

08

$M

)

6.36 8.06 8.22 8.30 8.96


Analysis

but fractionated spacecraft can be 950 $M more

expensive than monolithic spacecraft

Fractionated spacecraft can be up to 104 $M less than comparable monolithic spacecraft...

300

400

500

600

700

800

900

1,000

1 2 3 4 5

Dy

na

mic

Lif

ecy

cle

Co

st (

FY

20

08

$M

)



+44.91-90.73 -41.71

+168.95

Two-Module

Monolithic

Spacecraft

Three-




• Synthesis

• Conclusion

Agenda

• Conclusion


System (Aggregate) Mass and Shared Subsystem Resources• System mass increases

• With increase in the use of shared resources• With increase in the number of modules via system-wide redundancy

NRE and RE Costs• Dynamic Lifecycle Cost is dependent on NRE and RE costs

• NRE and RE costs correlate positively with mass

Number and Cost of Replenishments

Key Lessons LearnedSynthesis

Number and Cost of Replenishments• Aggregate number of replenishments increases with number of modules

• Aggregate cost of replenishments increases

Launch Vehicle Usage and Costs• Fractionation decouples subsystems and payloads into modules

• New spacecraft deployment strategies• Fractionated spacecraft may fit into a smaller launch vehicle orset of smaller launch vehicles• Reduces the launch costs (significantly)


Mass: monolithic spacecraft are less massive than fractionated spacecraft• Number of modules and shared resource usage

Dynamic Lifecycle Cost: monolithic spacecraft are less expensive than fractionated spacecraft. Fractionated spacecraft have higher...

• Number of modules and shared resource usage• System mass (and size)

• NRE and RE costs• Launch costs

• Aggregate number of replenishments

Fundamental Reason for Selected TrendsSynthesis

• Aggregate number of replenishments• Aggregate cost of replenishments (launch + RE costs)

Dynamic Lifecycle Cost: monolithic spacecraft are more expensive than fractionated spacecraft. Fractionated spacecraft have higher...

• Number of modules and shared resource usage• System mass (and size)

• NRE and RE costs• Aggregate number of replenishments

Fractionated spacecraft have lower...• Aggregate cost of replenishments (due to launch costs)




• Synthesis

• Conclusion

Agenda

• Conclusion


Are Fractionated Spacecraft Viable?Conclusion

Are fractionated spacecraft a suitable, if not “better”, alternative to monolithic spacecraft in the current spacecraft paradigm?

Monolithic Fractionated


Context





Mass


LifecycleCost

LifecycleCost

Value Proposition

Value Proposition









Context





Mass

+159 kg+2,871 kg A Fractionated Spacecraft

Source: DARPA

LifecycleCostValue

PropositionMass









Context





-104 $M+950 $M

Mass


LifecycleCost

LifecycleCost





O'Neill, M. G. (2009). Assessing the Impacts of Fractionation on Pointing-Intensive Spacecraft. SM Thesis, Aeronautics and Astronautics, Massachusetts Institute of

Technology. www.seari.mit.edu

AddressedInclude other cardinal measures of effectiveness in the Value Proposition

What about the benefits of fractionation?• Analysis of the mission lifetime benefits of fractionation

Further Exploration of the Value Proposition

DiscussedInvestigate alternative wireless power distribution systems

• Radically change the value proposition• Radio and microwave power transmission(O’Neill, 2009; Kerslake, 2008)

• Laser power beaming(O’Neill, 2009; Kerslake, 2008)

• Concentrated, reflected sunlight(Turner, 2006)

• Electromagnetic formation flight (EMFF) (MIT Space Systems Lab)

What about other benefits of fractionation?• Remote sensing mission, fractionated spacecraft interferometers


ReferencesO'Neill, M. G. (2009). Assessing the Impacts of Fractionation on Pointing-Intensive Spacecraft. SM Thesis,

Aeronautics and Astronautics, Massachusetts Institute of Technology.

Kerslake, T. W. (2008). Lunar Surface-to-Surface Power Transfer. In University of New Mexico's Institute for Space and Nuclear Power Studies: Space Technology and Applications International Forum. Albuquerque, New Mexico.

Turner, A. E. (2006). Power Transfer for Formation Flying Spacecraft. In American Institute of Astronautics and Astronautics: Space 2006 Conference and Exposition. San Jose, California.


Documents

Assessing the Impacts of Fractionation on Pointing