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GLOBAL CONSTELLATION OFSTRATOSPHERIC SCIENTIFIC
PLATFORMSPresentation to the NASA Institute of
Advanced Concepts (NIAC)
byKerry T. Nock
Global Aerospace Corporation
November 9, 1999
GlobalAerospace
Corporation
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
CONCEPT OVERVIEW
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”
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
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
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
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
EARTH SCIENCE OVERVIEW
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
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
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
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
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
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
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
CONSTELLATION MANAGEMENT
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
Global Stratospheric Constellation
Global Aerospace Corporation 19 KTN - November 9, 1999
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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
ILLUSTRATION OF CONTROLEFFECTIVENESS
5 m/s Toward Equator 5 m/s Toward Poles
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
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
TRAJECTORY CONTROL
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
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
BALLOON
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
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
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
GONDOLA
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
INTERNATIONAL OVERFLIGHTCONSIDERATIONS
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
PHASE II PLAN
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
SUMMARY
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
APPENDIX
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
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
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
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
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
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