Spacecraft standardization has been a topic of great debate within the space community. This paper intends to be a provocative thought piece asking one fundamental question: “is there a ‘right size’ for small satellites?” In order to answer this question, we propose three top-down design factors for the space systems engineering process: spacecraft utility, mission utility, and optimum cost. Spacecraft utility quantitatively measures the capability of a spacecraft, derived from its volume and power properties. Mission utility then measures the aggregate value of a constellation. Optimum cost, which is a function of spacecraft mass and quantity, can be determined by assessing the break-even point. Data from the small satellite community, including USAF Academy FalconSAT and Surrey Satellite Technology Ltd. (SSTL) missions, is presented in support of this discussion, constrained to systems with a mass less than 200 kg. These design factors inform the mission developer in determining the appropriate system architecture. Using these design factors, a notional standardized spacecraft configuration is presented, with a mass of 30 kg and 50 cm cubed volume that optimizes spacecraft utility, mission utility, and cost

Barnhart, David

Sweeting, Martin

DigitalCommons@USU

David J Barnhart, USAF AcademyMartin N Sweeting, Surrey Space CentreRight-sizing Small SatellitesSSC14-V-4DISTRIBUTION STATEMENT A: Approved for Public Release.DISTRIBUTION STATEMENT A: Approved for Public Release.Introduction Fundamental question: “what is the right size for a small satellite?” ( < 200 kg) Three proposed design factors: Spacecraft Utility (ScU) Mission Utility (MU) Optimum Cost Motivation Provoke thought, not discredit prior work Develop comparison metrics for decision-makersDISTRIBUTION STATEMENT A: Approved for Public Release.SmallSat Momentum First satellites were SmallSats! Re-birth in 1980s CubeSats/containerization early 2000s US Government CubeSat interest late 2000s Recent major findings/publications NASA Ames “Small Satellite Technology State of the Art” ( < 180 kg) USAF SAB “Microsatellite Mission Applications” (< 300 kg)DISTRIBUTION STATEMENT A: Approved for Public Release.SmallSat Community Focus Lowering launch costs through containerization NASA’s Payload Ejection System (PES) Orbiting Picosat Activated Launcher (OPAL) P-POD Standardized bus designs STP-SIV – 180 kg ESPA configuration 3U CubeSats – 4.5 kg – such as NRO’s Colony Plug-and-play architecture Little work in quantitative assessmentsDISTRIBUTION STATEMENT A: Approved for Public Release.Theoretically Perfect Satellite Firstly, we must define the “perfect” satellite Payload consumes 100% of resources Power Volume Infinite power available Volume is unconstrained (infinite) Mass is zero Impossible to approach, but helps us modelDISTRIBUTION STATEMENT A: Approved for Public Release.Spacecraft Utility (ScU) Proposed mathematical model:  = aggregate payload volume & power efficiency  P = OAP in Watts ( = ideal) V = spacecraft volume in m3 ( = ideal) Initial weighting factors: 100 Watts  1 m3 1100 VVPPScU DISTRIBUTION STATEMENT A: Approved for Public Release.ScU ExamplesMission Bus Cost($K)Mass(kg) OAP (W)Volume(cm3)ScUSpaceChip 2.7 0.01 0.01 0.001 220.3 1.210-13MCMSat 24 0.170 0.1 0.88 10101 8.410-8PCBSat 13 0.25 0.05 0.88 10102.5 1.210-7$50Sat 0.25 0.22 0.3 0.55 557.5 3.110-71U CubeSat 75 1 0.1 1.6 101010 1.610-6Colony I 250 3 0.4 8 101030 8.910-5Colony II 250 3 0.4 10 101030 0.0001FS-2 1,500 19.5 0.2 10 323232 0.0006FS-3 2,100 54.3 0.21 18.9 454563 0.004DMC - 88 0.5 30 646468 0.025FS-5 2,400 137.7 0.51 38 617297 0.043DMC-2 15,000 96 0.5 50 636684 0.043SIV - 181 0.35 225 617297 0.07FS-6 2,600 164.3 0.48 102 617297 0.07DISTRIBUTION STATEMENT A: Approved for Public Release.Mission Utility (MU) Proposed mathematical model: Similar to parallel reliability equation n = number of spacecraft in mission architecture MU, like ScU, approaches unity (1) nScUMU  11DISTRIBUTION STATEMENT A: Approved for Public Release.MU Examples (apples to oranges) Disaster Monitoring Constellation (DMC) 88 kg bus mass, 646468 cm bus volume  = 0.50, OAP of 30 W; results in an ScU of 0.025 Five satellites in architecture yields MU of 0.12  Space Weather 1 kg 1U CubeSat, 101010 cm bus volume  = 0.1, OAP of 1.6 W; yields ScU of 1.610-6 Ten satellites in architecture yields MU of 1.610-5 100 satellites yields MU of 1.610-4DISTRIBUTION STATEMENT A: Approved for Public Release.Optimum Cost Bus cost (drives ScU) Invest in raising ScU LVI costs (drives MU) CubeSat mass overhead 40-55% ESPA mass overhead 13% Launch opportunity cost not yet considered Potential revenue A commercial issue in general Academic programs typically not concernedProposed Objective Design 505050 cm  = 70% OAP = 100 W Target cost of $1M Mass of 30 kg Non-containerizedFalconSAT-1 was about this sizeDISTRIBUTION STATEMENT A: Approved for Public Release.ScU Component Analysis00.10.20.30.40.50.60.70.8PayloadVolumePower 1100 VVPPScU DISTRIBUTION STATEMENT A: Approved for Public Release.ScU/Cost1E-171E-161E-151E-141E-131E-121E-111E-101E-091E-080.00000010.0000011E-131E-121E-111E-101E-091E-080.00000010.0000010.000010.00010.0010.010.11SpaceChipMCMSatPCBSat$50Sat1U CSColony IColony IIFS-2FS-3DMCFS-5DMC-2SIVFS-6ObjectiveScUScU/CostScUKnee of curve unknown, need more data!DISTRIBUTION STATEMENT A: Approved for Public Release.Conclusions Theoretically perfect satellite proposed First step in quantifying the “utility” of spacecraft and mission capabilities Much more work to be done Need more data, extend to all satellite classes Develop ScU and MU standard reference points Career lessons learned in the community Miniaturizing payloads to fit is costly Overselling SmallSats reduces credibility Decision-makers need metrics for comparison SmallSat potential barely tapped…DISTRIBUTION STATEMENT A: Approved for Public Release.Questions?Feedback welcomed at:david.j.barnhart@outlook.comdavid.barnhart.1@us.af.milVisit us at:USAF Academy University Exhibit 15USurrey Satellite Technology-USSurrey Satellite Technology, Ltd.

Right-sizing Small Satellites

Barnhart, D

Surrey Research Insight

Barnhart, D

Sweeting, Martin

University of Surrey

David J Barnhart, USAF AcademyMartin N Sweeting, Surrey Space CentreRight-sizing Small SatellitesSSC14-V-4DISTRIBUTION STATEMENT A: Approved for Public Release.DISTRIBUTION STATEMENT A: Approved for Public Release.Introduction Fundamental question: “what is the right size for a small satellite?” ( < 200 kg) Three proposed design factors: Spacecraft Utility (ScU) Mission Utility (MU) Optimum Cost Motivation Provoke thought, not discredit prior work Develop comparison metrics for decision-makersDISTRIBUTION STATEMENT A: Approved for Public Release.SmallSat Momentum First satellites were SmallSats! Re-birth in 1980s CubeSats/containerization early 2000s US Government CubeSat interest late 2000s Recent major findings/publications NASA Ames “Small Satellite Technology State of the Art” ( < 180 kg) USAF SAB “Microsatellite Mission Applications” (< 300 kg)DISTRIBUTION STATEMENT A: Approved for Public Release.SmallSat Community Focus Lowering launch costs through containerization NASA’s Payload Ejection System (PES) Orbiting Picosat Activated Launcher (OPAL) P-POD Standardized bus designs STP-SIV – 180 kg ESPA configuration 3U CubeSats – 4.5 kg – such as NRO’s Colony Plug-and-play architecture Little work in quantitative assessmentsDISTRIBUTION STATEMENT A: Approved for Public Release.Theoretically Perfect Satellite Firstly, we must define the “perfect” satellite Payload consumes 100% of resources Power Volume Infinite power available Volume is unconstrained (infinite) Mass is zero Impossible to approach, but helps us modelDISTRIBUTION STATEMENT A: Approved for Public Release.Spacecraft Utility (ScU) Proposed mathematical model:  = aggregate payload volume & power efficiency  P = OAP in Watts ( = ideal) V = spacecraft volume in m3 ( = ideal) Initial weighting factors: 100 Watts  1 m31100 VVPPScU DISTRIBUTION STATEMENT A: Approved for Public Release.ScU ExamplesMission Bus Cost($K)Mass(kg) OAP (W)Volume(cm3)ScUSpaceChip 2.7 0.01 0.01 0.001 220.3 1.210-13MCMSat 24 0.170 0.1 0.88 10101 8.410-8PCBSat 13 0.25 0.05 0.88 10102.5 1.210-7$50Sat 0.25 0.22 0.3 0.55 557.5 3.110-71U CubeSat 75 1 0.1 1.6 101010 1.610-6Colony I 250 3 0.4 8 101030 8.910-5Colony II 250 3 0.4 10 101030 0.0001FS-2 1,500 19.5 0.2 10 323232 0.0006FS-3 2,100 54.3 0.21 18.9 454563 0.004DMC - 88 0.5 30 646468 0.025FS-5 2,400 137.7 0.51 38 617297 0.043DMC-2 15,000 96 0.5 50 636684 0.043SIV - 181 0.35 225 617297 0.07FS-6 2,600 164.3 0.48 102 617297 0.07DISTRIBUTION STATEMENT A: Approved for Public Release.Mission Utility (MU) Proposed mathematical model: Similar to parallel reliability equation n = number of spacecraft in mission architecture MU, like ScU, approaches unity (1) nScUMU  11DISTRIBUTION STATEMENT A: Approved for Public Release.MU Examples (apples to oranges) Disaster Monitoring Constellation (DMC) 88 kg bus mass, 646468 cm bus volume  = 0.50, OAP of 30 W; results in an ScU of 0.025 Five satellites in architecture yields MU of 0.12  Space Weather 1 kg 1U CubeSat, 101010 cm bus volume  = 0.1, OAP of 1.6 W; yields ScU of 1.610-6 Ten satellites in architecture yields MU of 1.610-5 100 satellites yields MU of 1.610-4DISTRIBUTION STATEMENT A: Approved for Public Release.Optimum Cost Bus cost (drives ScU) Invest in raising ScU LVI costs (drives MU) CubeSat mass overhead 40-55% ESPA mass overhead 13% Launch opportunity cost not yet considered Potential revenue A commercial issue in general Academic programs typically not concernedProposed Objective Design 505050 cm  = 70% OAP = 100 W Target cost of $1M Mass of 30 kg Non-containerizedFalconSAT-1 was about this sizeDISTRIBUTION STATEMENT A: Approved for Public Release.ScU Component Analysis00.10.20.30.40.50.60.70.8PayloadVolumePower1100 VVPPScU DISTRIBUTION STATEMENT A: Approved for Public Release.ScU/Cost1E-171E-161E-151E-141E-131E-121E-111E-101E-091E-080.00000010.0000011E-131E-121E-111E-101E-091E-080.00000010.0000010.000010.00010.0010.010.11SpaceChipMCMSatPCBSat$50Sat1U CSColony IColony IIFS-2FS-3DMCFS-5DMC-2SIVFS-6ObjectiveScUScU/CostScUKnee of curve unknown, need more data!DISTRIBUTION STATEMENT A: Approved for Public Release.Conclusions Theoretically perfect satellite proposed First step in quantifying the “utility” of spacecraft and mission capabilities Much more work to be done Need more data, extend to all satellite classes Develop ScU and MU standard reference points Career lessons learned in the community Miniaturizing payloads to fit is costly Overselling SmallSats reduces credibility Decision-makers need metrics for comparison SmallSat potential barely tapped…DISTRIBUTION STATEMENT A: Approved for Public Release.Questions?Feedback welcomed at:david.j.barnhart@outlook.comdavid.barnhart.1@us.af.milVisit us at:USAF Academy University Exhibit 15USurrey Satellite Technology-USSurrey Satellite Technology, Ltd.

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https://digitalcommons.usu.edu/cgi/viewcontent.cgi?filename=0&article=3046&context=smallsat&type=additional

Right-sizing Small Satellites

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