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GLOBAL CONSTELLATION OF STRATOSPHERIC SCIENTIFIC PLATFORMS Presentation to the NASA Institute of Advanced Concepts (NIAC) by Kerry T. Nock Global Aerospace Corporation November 9, 1999 Global Aerospace Corporation

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Page 1: Nock nov99

GLOBAL CONSTELLATION OFSTRATOSPHERIC SCIENTIFIC

PLATFORMSPresentation to the NASA Institute of

Advanced Concepts (NIAC)

byKerry T. Nock

Global Aerospace Corporation

November 9, 1999

GlobalAerospace

Corporation

Page 2: Nock nov99

Global Stratospheric Constellation

Global Aerospace Corporation 2 KTN - November 9, 1999

GlobalAerospace

Corporation

TOPICS• CONCEPT OVERVIEW• EARTH SCIENCE OVERVIEW• CONSTELLATION MANAGEMENT• TRAJECTORY CONTROL• BALLOON• GONDOLA• INTERNATIONAL CONSIDERATIONS• PHASE 2 PLAN• SUMMARY

Page 3: Nock nov99

CONCEPT OVERVIEW

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Global Stratospheric Constellation

Global Aerospace Corporation 4 KTN - November 9, 1999

GlobalAerospace

Corporation BENEFITS OFSTRATOSPHERIC CONSTELLATIONS

TO NASA

• Provide low-cost, continuous, simultaneous,global Earth observations options

• Provides in situ and remote sensing from verylow Earth “orbit”

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Global Stratospheric Constellation

Global Aerospace Corporation 5 KTN - November 9, 1999

GlobalAerospace

Corporation

CONCEPT DESCRIPTION

• Tens to Hundreds of Small, Long-life StratosphericBalloons or StratoSats

• Uniform Global Constellation Maintained by TrajectoryControl Systems (TCS)

• Flight Altitudes of 30-35 km Achievable With Advanced,Lightweight, Superpressure Balloon Technology

• Gondola and TCS Mass of 235 kg at 35 km Altitude• Goal of ~50% Science Instrument Payload of Gondola

Page 6: Nock nov99

Global Stratospheric Constellation

Global Aerospace Corporation 6 KTN - November 9, 1999

GlobalAerospace

Corporation CONCEPT SCHEMATICStratoSat Flight SystemGlobal Constellation

Gondola

10-15 km

StratoSail™Trajectory Control

System (TCS)

~40-50 m dia.Super-pressure

Balloon

PossibleScienceSensors

~50-100 kg

Rel. Wind0.3-10 m/s

Rel. Wind5-50 m/s

30-35 kmFlight Altitude

Dropsonde

Page 7: Nock nov99

Global Stratospheric Constellation

Global Aerospace Corporation 7 KTN - November 9, 1999

GlobalAerospace

Corporation RATIONALE FOR STRATOSATS• High Cost of Space Operations (Spacecraft and

Launchers) Relative to Balloon Platforms• Advanced Balloons Are Capable and Desirable High

Altitude Science Platforms• In Situ Measurement Costs Are Reducing With the

Advance of Technology (Electronics Miniaturization,Sensor Advances)

• There is an Emerging and Widely Accessible GlobalCommunications Infrastructure

• Balloons Fly Close to the Earth and Are Slow, BothPositive Characteristics for Making Remote SensingMeasurements

• A Constellation of Balloon Platforms May Be More CostEffective Than Satellites for Some Measurements

Page 8: Nock nov99

Global Stratospheric Constellation

Global Aerospace Corporation 8 KTN - November 9, 1999

GlobalAerospace

Corporation

KEYS TO THE CONCEPT

Affordable, Long-duration StratosphericBalloon and Payload Systems

Lightweight, Low Power Balloon TrajectoryControl Technology

Global Communications Infrastructure

Page 9: Nock nov99

EARTH SCIENCE OVERVIEW

Page 10: Nock nov99

ESE STRATEGIC PLAN GOALS

• Understand the causes and consequences of land-cover/land-usechange

• Predict seasonal-to-interannual climate variations• Identify natural hazards, processes, and mitigation strategies• Detect long-term climate change, causes, and impacts• Understand the causes of variation in atmospheric ozone

concentration and distribution

• Understand the causes and consequences of land-cover/land-usechange

• Predict seasonal-to-interannual climate variations• Identify natural hazards, processes, and mitigation strategies• Detect long-term climate change, causes, and impacts• Understand the causes of variation in atmospheric ozone

concentration and distribution

Expand scientific knowledgeof the Earth system . . . fromthe vantage points of space,aircraft, and in situ platforms

Expand scientific knowledgeof the Earth system . . . fromthe vantage points of space,aircraft, and in situ platforms

Page 11: Nock nov99

Global Stratospheric Constellation

Global Aerospace Corporation 11 KTN - November 9, 1999

GlobalAerospace

Corporation PROMISING EARTHSCIENCE THEMES– Climate Change Studies

• Water Vapor and Global Circulation in the Tropics*• Radiative Studies in the Tropics:• Global Radiation Balance*

– Ozone Studies• Mid-latitude Ozone Loss• Arctic Ozone Loss*• Global Distribution of Ozone*

– Weather Forecasting• Hurricane Forecasting and Tracking• Forecasting Weather from Ocean Basins & Remote Areas

– Global Circulation and Age of Air– Global Ocean Productivity– Hazard Detection and Monitoring– Communications for Low Cost, Remote Surface Science

* Discussed further in later charts

Page 12: Nock nov99

CLIMATE CHANGE: GLOBALRADIATION BALANCE

Equator 30 60 90-30-60-900

20

30

40

10

Tropopause

Stratosphere

Troposphere

km

© Global Aerospace Corporation

Rotatable

Detector&

Filter

Data Acquisition

Pyronometer

Cloud LIDAR

DetectorSystem

LaserSystem

Page 13: Nock nov99

CLIMATE CHANGE: DYNAMICALPROCESSES IN TROPICS

Equator 30 60 90-30-60-900

20

30

40

10

Tropopause

Stratosphere

Troposphere

Subsidence

Large-scaleAscent

in situ TDL Water, Ozone & CO2

Absorption Measurement Cell

AirFlow

Source Beam

Detector

MicrowaveTemperature

Profiler

Mixer Detector

LOCal TargetScanning

Mirror

µwave

Ozone &WaterVaporLIDAR

DetectorSystem

LaserSystem

km

© Global Aerospace Corporation

Page 14: Nock nov99

OZONE STUDIES: GLOBALDISTRIBUTION OF OZONE

Equator 30 60 90-30-60-900

20

30

40

10

Stratosphere

Tropopause

Troposphere

km

© Global Aerospace Corporation

DropsondesH2O, O3, CH4, N2O and T, PMeteorology

Science PodsEvery 2-3 km, T, P

CrossTropopauseExchange

Page 15: Nock nov99

OZONE STUDIES: POLAR OZONE LOSS

Pole 80 708070

20

30

40

10

Stratosphere

TroposphereMixingRegion

km

Polar Vortex4445 km

Scattered Light Partical DetectorMeasures: Aerosols

AirFlow

Source Beam

Detector

Multipass Absorption CellMeasures: HCl, CH4, N2O, O3

AirFlow

Source Beam

Detector

VortexEdge

LimbFTIRMid-latitude Air

Polar StratosphericClouds (PSCs)

FTIRInterferometer

Camera

SunTracker

ForeOptics

FXSTOptics

T, P

FTIR / SLS Limb Scan GeometrySubmillimeterEmission

LimbScanner

(SLS)HarmonicMixer

GunnOscillator

318.5 GHz

Data Handling

LimbRadiation640 GHz

IF SpectralAnalysis

StreerableReflector

Plate

SLS

© Global Aerospace Corporation

665 km

35 km

Page 16: Nock nov99

Global Stratospheric Constellation

Global Aerospace Corporation 16 KTN - November 9, 1999

GlobalAerospace

Corporation SURFACE REMOTE SENSING

30-45 km

1000 km

7200 m/s

<50 m/s

• At 30 km a StratoSat Platform Is >30 times Closerto the Earth’s Surface Than Sun-synchronous LEOSatellites

• The Ground Speed of a 30 km StratoSat Is a Factorof >140 times Slower Than LEO Satellites (angularrates over nadir are >2 times less)

• A Constellation of Stratospheric Balloons CanObserve the Entire Earth at the Same Time

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CONSTELLATION MANAGEMENT

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ASSUMPTIONS• 100 StratoSats @ 35 km• Simulation Start: 1992-11-10• UK Met Office Assimilation• 4 hrs per frame• 4 month duration

STATISTICS

0

200

400

600

800

1000

0 2 0 4 0 6 0 8 0 100 120

σ NN

SD [

km]

Time from start [days]

Start Date: 1992-11-10T00:00:0035 km constant altitude flights

100 balloons, UKMO Environment

GLOBAL CONSTELLATION WITHOUTTRAJECTORY CONTROL

Page 19: Nock nov99

Global Stratospheric Constellation

Global Aerospace Corporation 19 KTN - November 9, 1999

GlobalAerospace

Corporation CONSTELLATIONGEOMETRY MAINTENANCE

• Balloons Drift in the Typical and Pervasive ZonalStratospheric Flow Pattern

• Trajectory Control System Applies a Small, ContinuousForce to Nudge the Balloon in Desired Direction

• Balloons Are in Constant Communications With a CentralOperations Facility

• Stratospheric Wind Assimilations and Forecasts AreCombined With Balloon Models to Predict BalloonTrajectories

• Balloon TCS Are Periodically Commanded to AdjustTrajectory Control Steering to Maintain OverallConstellation Geometry

Page 20: Nock nov99

ILLUSTRATION OF CONTROLEFFECTIVENESS

5 m/s Toward Equator 5 m/s Toward Poles

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Global Stratospheric Constellation

Global Aerospace Corporation 21 KTN - November 9, 1999

GlobalAerospace

CorporationMAINTENANCE STRATEGIES

• Environment Information Used– Successive Correction Data (Interpolated Measurements)– Assimilations (Atmospheric Model Tuned by Actual Measurements)– Forecasts (Can Be Used for “Look-ahead” Decision-making)

• Level of TCS Model Fidelity1. Omni-directional Delta-v of Fixed Amount Applied at StratoSat2. Delta-v Proportional to True Relative Wind at TCS3. Actual TCS Aerodynamic Model and Sophisticated TCS Control

Algorithms

• Network Control Algorithms– Randomization: Move StratoSats North or South Randomly– “Molecular” Control: Each Balloon Responds Only To Its Neighbor– Macro Control: Entire Network Is Managed, Balloons Are Moved

Between Zones

• Cyclone Scale Coordinates for Control Algorithms

Page 22: Nock nov99

GLOBAL CONSTELLATION WITHSIMPLE, INTELLIGENT CONTROL

ASSUMPTIONS• 100 StratoSats @ 35 km• Simulation Start: 1992-11-10• UK Met Office Assimilation• 4 hrs per frame• 4 month duration• 5 m/s control when separation

is < 2000 km• Same initial conditions

0

200

400

600

800

1000

0 2 0 4 0 6 0 8 0 100 120

σ NN

SD [

km]

Time from start [days]

Start Date: 1992-11-10T00:00:0035 km altitude flights

100 balloons, UKMO Environment

Free-floating

Paired NS andZonal Control

STATISTICS

Page 23: Nock nov99

TRAJECTORY CONTROL

Page 24: Nock nov99

Global Stratospheric Constellation

Global Aerospace Corporation 24 KTN - November 9, 1999

GlobalAerospace

Corporation FEATURES OFSTRATOSAIL™ TCS

• Passively Exploits Natural Wind Conditions• Operates Day and Night• Offers a Wide Range of Control Directions Regardless of

Wind Conditions• Can Be Made of Lightweight Materials, Mass <100 kg• Does Not Require Consumables• Requires Very Little Electrical Power• Relative Wind at Gondola Sweeps Away Contaminants

Page 25: Nock nov99

Global Stratospheric Constellation

Global Aerospace Corporation 25 KTN - November 9, 1999

GlobalAerospace

Corporation ADVANCED TRAJECTORYCONTROL SYSTEM

Advanced Design Features– Lift force can be greater than weight– Will stay down in dense air– Less roll response in gusts– Employs high lift cambered airfoil– Greater operational flexibility

ULDB Dynamically-scaledModel Flight Test

ULDB Dynamically-scaledULDB Dynamically-scaledModel Flight TestModel Flight Test

Page 26: Nock nov99

BALLOON

Page 27: Nock nov99

Global Stratospheric Constellation

Global Aerospace Corporation 27 KTN - November 9, 1999

GlobalAerospace

Corporation BALLOON DESIGN OPTIONSSpherical Envelope• Spherical Structural Design• High Envelope Stress• High Strength, Lightweight Laminate Made of Gas Barrier Films

and Imbedded High Strength Scrims• Multi-gore, Load / Seam Tapes

Pumpkin Envelope• Euler Elastica Design• Medium Envelope Stress• Lightweight, Medium Strength Films• Lobbed Gores With Very High Strength PBO Load-bearing

Tendons Along Seams

Page 28: Nock nov99

Global Stratospheric Constellation

Global Aerospace Corporation 28 KTN - November 9, 1999

GlobalAerospace

Corporation BALLOON VEHICLEDESIGN

Baseline Balloon Design• Euler Elastica Pumpkin Design• 68,765 m3, 59/35 m Eq/Pole Dia.,

Equivalent to 51 m dia. Sphere• Advanced Composite Film, 15 µm

thick, 15 g/m2 Areal Density• 140 gores each 1.34 m Max Width• Polybenzoxazole (PBO) Load

Tendons At Gore Seams• Balloon Mass of 236 kg

Page 29: Nock nov99

SOLAR ARRAY / BALLOONINTEGRATION

Seam/LoadTape as

Solar Array

Seam/LoadTape as

Solar Array

Gore CenterAs

Solar Array

Gore CenterAs

Solar Array

Seam/Load Tape / Solar Cells(~ 3 cm wide)

Envelope FilmEnvelope Film

Thin Film Amorphous SiSolar Array Cells

(~30 cm wide)

Example Power • 48 m dia Spherical Design• 100 Gores/Seams• 3 cm Wide Solar Array• 10 % Efficiency• 4.7 kW

Sphere Pumpkin

Page 30: Nock nov99

GONDOLA

Page 31: Nock nov99

Global Stratospheric Constellation

Global Aerospace Corporation 31 KTN - November 9, 1999

GlobalAerospace

Corporation

STRATOSAT GONDOLA

StratoSat Gondola• Example Climate Change

Science Payload• 2x1x0.5 m warm electronic

box (WEB) with louvers fordaytime cooling

• Electronics attached tosingle vertical plate

• LIDAR telescopesexternally attached to WEB

• TCS wing assembly (TWA)stowed below gondola atlaunch before winch-down

• Science pods on tether

Stowed Gondola

Page 32: Nock nov99

INTERNATIONAL OVERFLIGHTCONSIDERATIONS

Page 33: Nock nov99

Global Stratospheric Constellation

Global Aerospace Corporation 33 KTN - November 9, 1999

GlobalAerospace

Corporation INTERNATIONAL OVERFLIGHT• Current Scientific Balloon Program

– Overflight Often Allowed Especially If No Imaging and If Scientistsof Concerned Countries Are Involved

– Not All Countries Allow Overflight and This List ChangesDepending on World Political Conditions

• Treaty on Open Skies - Signed By 25 Nations in 1992 – Establishes a Regime of Unarmed Military Observation Flights Over

the Entire Territory of Its Signatory Nations– First Step of Confidence Building Security Measures (CBSM)

• Future Political Climate– Global Networks Can Build on World Meteorological Cooperation– World Pollution Is a Global Problem Which Will Demand Global

Monitoring Capability– First Steps Need to Be Important Global Science That Does Not

Require Surface Imaging

Page 34: Nock nov99

PHASE II PLAN

Page 35: Nock nov99

Global Stratospheric Constellation

Global Aerospace Corporation 35 KTN - November 9, 1999

GlobalAerospace

Corporation PHASE II PLAN• Constellation Management

– Control of Distributed Systems in Chaotic Environments Research– Develop Advanced Constellation Geometry Control Algorithms– Integrate Balloon Model, Environment and Advanced TCS Models

and Control Algorithms in Constellation Simulations and Analysis

• Advanced Trajectory Control– Develop Control Models and Design Concepts

• Advanced Balloon Design– Materials Research– Structural and Thermal Design– Envelope Design and Fabrication Technology

• Science Applications Development– Proof-of-Concept Flight Definition - A Logical Next Step– Broaden Search for New Earth Science Concepts

Page 36: Nock nov99

SUMMARY

Page 37: Nock nov99

Global Stratospheric Constellation

Global Aerospace Corporation 37 KTN - November 9, 1999

GlobalAerospace

Corporation SUMMARY• The StratoSat Is a New Class of in Situ Platform Providing:

– Low-cost, Continuous, Simultaneous, Global Observations Options

– In Situ and Remote Sensing From Very Low Earth “Orbit”

• Global Stratospheric Constellations Will Expand ScientificKnowledge of the Earth System

• Broader Involvement of the Earth Science Community IsEncouraged and Sought in the Definition of ConstellationMission and Instrument Concepts

• A Proof-of Concept Science Mission Is One Essential FirstStep on the Path Toward Global StratosphericConstellations

Page 38: Nock nov99

APPENDIX

Page 39: Nock nov99

Global Stratospheric Constellation

Global Aerospace Corporation 39 KTN - November 9, 1999

GlobalAerospace

Corporation STEPS TO GLOBAL STRATO-SPHERIC CONSTELLATIONS

Constellation Types / Locale– Regional

• South Polar• Tropics• North Polar

– Southern Hemisphere– Global

• Sparse Networks for Widerepresentative Coverage

• Dense Networks for GlobalSurface Accessibility

Measurements Types– In Situ & Remote Sensing of

Atmospheric Trace Gases– Atmospheric Circulation– Remote Sensing of Clouds– Atmospheric State (T, P, U, Winds)– Radiation Flux– Low Resolution Visible & IR

Surface and Ocean Monitoring– High Resolution Surface Imaging

and Monitoring

A First Step Is a Proof-of-concept Science ExperimentUsing Soon to Be Available ULDB Technology

Page 40: Nock nov99

Global Stratospheric Constellation

Global Aerospace Corporation 40 KTN - November 9, 1999

GlobalAerospace

Corporation STRATOSAT FLIGHTSYSTEM DESCRIPTION

Flight System Design Features• Sample Payload for Climate Change

Studies in Tropics• 68,800 m3 Pumpkin balloon• 5 kW capable integrated solar array• Telecom capable of 6 Mb/s• Advanced TCS• Tethered science pods

Mass SummarySubsystem Mass, kgBalloon 236Helium 87Power 19Telecomm 5Mechanical 30Guidance & Control 1Robotic Controller 1Trajectory Control 81Science 56Science Reserve 44Total 560

Page 41: Nock nov99

Global Stratospheric Constellation

Global Aerospace Corporation 41 KTN - November 9, 1999

GlobalAerospace

Corporation HOW THE TCS WORKS

• Winds vary with altitude– Balloon at 30 km– Wing at 20 km– Relative wind velocity

~15 m/s

• Wing generates lift force– “Lift” force is horizontal– force is transmitted by tether to balloon– balloon drifts relative to local air mass– balloon drag ≈ wing lift

• Wing is in much denser air than balloon– 25km : 35km (5x); 20km : 35km (10x)– equivalent wing area increased relative to balloon

-40 -30 -20 -10 0 10 200

10

20

30

40

Mean Zonal Wind, m/s

Altitude,km

Alice Springs,January, 24¡ S

Fairbanks,July, 65¡ N

Source: Randel, W.J.,Global Atmospheric CirculationStatistics, 1000-1 mb,NCAR/TN-366+STR, Feb. 1992

15 m/s

Page 42: Nock nov99

Global Stratospheric Constellation

Global Aerospace Corporation 42 KTN - November 9, 1999

GlobalAerospace

Corporation HOW THE TCS WORKS,CONTINUED

TCSLIFT mode

TCSSTALL mode

TOP VIEW OF TCS

LIFT / DRAG FORCE POLAR

0

0.5

1.0

1.5

0 10 20 30 40 50 60 70 80 90

Alpha

CL

LIFT vs ANGLE OF ATTACK

Lift/Drag Polar: Contours of Feasible Aerodynamic Forces

θ

Stall Point

Fh

Fh

Vrel

θ

Fh

Vrel

α α Fhθ

Page 43: Nock nov99

Global Stratospheric Constellation

Global Aerospace Corporation 43 KTN - November 9, 1999

GlobalAerospace

CorporationHOW THE TCS WORKS,

CONTINUEDV

cross

Vdrift

Vrel

V b

Vtrue

VTCS

Vrel

LD

Fh

Balloon

TCS

Fdrift ~ Fh

Vdrift =2 * Fdrift

ρ ∗ Ab ∗ CD

( )1/2

β = φ - tan-1(D/L)

Vcross

=Vdrift * Cos β

Tether

φ

β

Expanded Vector Diagram}

Top View

Page 44: Nock nov99

Global Stratospheric Constellation

Global Aerospace Corporation 44 KTN - November 9, 1999

GlobalAerospace

Corporation

ANGLES EXAGGERATED & FORCES NOT TO SCALE

FB

θB ~ 0.25¡

FBV ~ 16,000 N

FBH ~ 70 N

FT

θG ~ 0.4¡

WG ~ 15,000 N

l 1

l 2

θT ~ 4¡

FT

L ~ 70 N

LV ~ 5 N

WTCS ~ 1000 N

L + W = - FT

SYMBOLS T -> TETHER G -> GONDOLA B -> BALLOON H -> HORIZONTALV -> VERTICAL W -> WEIGHT F -> FORCE L -> LIFT

θT ~ 4¡

GONDOLA AT 35 km

TCS AT 20 km

BALLOON

ASSUMPTIONS ¥ BALLOON DRIFT ~ 2 m/s ¥Ê0.6 million m3 BALLOON ¥ GONDOLA ~ 1500 kg ¥ TCS ~ 100 kg

l 1 = 2 l 2

LIFT OF ~ 70 N REQUIRES TCP WING

AREA OF ~ 16 m2 ASSUMING CL of 1.0

ULDB TCSFORCE

DIAGRAM