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
Global Aerospace
Global Stratospheric Constellation
Corporation
• • • • • • • • •
TOPICS
CONCEPT OVERVIEW EARTH SCIENCE OVERVIEW CONSTELLATION MANAGEMENT TRAJECTORY CONTROL BALLOON GONDOLA INTERNATIONAL CONSIDERATIONS PHASE 2 PLAN SUMMARY
Global Aerospace Corporation
2
KTN - November 9, 1999
CONCEPT OVERVIEW
Global Aerospace
Global Stratospheric Constellation
BENEFITS OF STRATOSPHERIC CONSTELLATIONS TO NASA Corporation
• Provide low-cost, continuous, simultaneous, global Earth observations options • Provides in situ and remote sensing from very low Earth “orbit”
Global Aerospace Corporation
4
KTN - November 9, 1999
Global Aerospace
Global Stratospheric Constellation
Corporation
CONCEPT DESCRIPTION • Tens to Hundreds of Small, Long-life Stratospheric Balloons or StratoSats • Uniform Global Constellation Maintained by Trajectory Control 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 Aerospace Corporation
5
KTN - November 9, 1999
Global Aerospace Corporation
Global Stratospheric Constellation
CONCEPT SCHEMATIC StratoSat Flight System
Global Constellation
~40-50 m dia. Super-pressure Balloon
Gondola
30-35 km Flight Altitude Rel. Wind 0.3-10 m/s
Dropsonde
10-15 km
StratoSail™ Trajectory Control System (TCS)
Global Aerospace Corporation
6
Possible Science Sensors ~50-100 kg
Rel. Wind 5-50 m/s
KTN - November 9, 1999
Global Stratospheric Constellation Global AerospaceRATIONALE FOR STRATOSATS Corporation
• 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 Global Communications Infrastructure • Balloons Fly Close to the Earth and Are Slow, Both Positive Characteristics for Making Remote Sensing Measurements • A Constellation of Balloon Platforms May Be More Cost Effective Than Satellites for Some Measurements Global Aerospace Corporation
7
KTN - November 9, 1999
Global Aerospace Corporation
Global Stratospheric Constellation
KEYS TO THE CONCEPT
Affordable, Long-duration Stratospheric Balloon and Payload Systems Lightweight, Low Power Balloon Trajectory Control Technology Global Communications Infrastructure
Global Aerospace Corporation
8
KTN - November 9, 1999
EARTH SCIENCE OVERVIEW
ESE STRATEGIC PLAN GOALS
Expand scientific knowledge of the Earth system . . . from the vantage points of space, aircraft, and in situ platforms • Understand the causes and consequences of land-cover/land-use change • 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
Global Aerospace
Global Stratospheric Constellation
Corporation
– Climate Change Studies
PROMISING EARTH SCIENCE THEMES
• 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
Global Aerospace Corporation
11
KTN - November 9, 1999
40
CLIMATE CHANGE: GLOBAL RADIATION BALANCE Stratosphere
Cloud LIDAR Detector System
Detector & Filter Data Acquisition
30
Pyronometer
Laser System
km
Rotatable
20
o Tr
e s u pa o p
10 Troposphere 0 -90
-60
-30
Š Global Aerospace Corporation
Equator
30
60
90
CLIMATE CHANGE: DYNAMICAL PROCESSES IN TROPICS 40
Detector System
in situ TDL Water, Ozone & CO 2 Absorption Measurement Cell
30
Ozone & Water Vapor LIDAR Laser System
Source Beam
Air Flow
Detector
Microwave Temperature Profiler
km Stratosphere 20 Subsidence
Large-scale Ascent
Cal Target
Scanning Mirror
LO Mixer
e s u pa o op r T
Detector
µwave
10 Troposphere 0 -90
-60
-30
© Global Aerospace Corporation
Equator
30
60
90
40
OZONE STUDIES: GLOBAL DISTRIBUTION OF OZONE
30 Stratosphere km 20
Meteorology Science Pods Every 2-3 km, T, P
e s u pa o op r T Cross Tropopause Exchange
10
Troposphere 0 -90
Dropsondes H2O, O3, CH4, N2O and T, P
-60
-30
Š Global Aerospace Corporation
Equator
30
60
90
OZONE STUDIES: POLAR OZONE LOSS FTIR Fore Optics FXST Optics
Submillimeter Emission Limb Radiation Limb 640 GHz Scanner Harmonic (SLS) Mixer
FTIR / SLS Limb Scan Geometry
Streerable Reflector Plate
Interferometer
Sun Tracker
IF Spectral Analysis
318.5 GHz
35 km
Camera Data Handling
40
665 km
Gunn Oscillator
Mid-latitude Air
FTIR SLS
km 30
Vortex Edge
Multipass Absorption Cell Measures: HCl, CH 4 , N2 O, O3
T, P
Stratosphere
Source Beam
Air Flow
Detector
Limb
Scattered Light Partical Detector Measures: Aerosols
Polar Vortex
Source Beam
Air Flow
Detector
20
4445 km
Polar Stratospheric Clouds (PSCs)
Mixing Region
10
Troposphere
Š Global Aerospace Corporation
70
80
Pole
80
70
Global Aerospace Corporation
Global Stratospheric Constellation
SURFACE REMOTE SENSING 7200 m/s
• At 30 km a StratoSat Platform Is >30 times Closer to the Earth’s Surface Than Sun-synchronous LEO Satellites • The Ground Speed of a 30 km StratoSat Is a Factor of >140 times Slower Than LEO Satellites (angular 1000 km rates over nadir are >2 times less) • A Constellation of Stratospheric Balloons Can Observe the Entire Earth at the Same Time <50 m/s 30-45 km
Global Aerospace Corporation
16
KTN - November 9, 1999
CONSTELLATION MANAGEMENT
GLOBAL CONSTELLATION WITHOUT TRAJECTORY CONTROL ASSUMPTIONS • 100 StratoSats @ 35 km • Simulation Start: 1992-11-10 • UK Met Office Assimilation • 4 hrs per frame • 4 month duration
STATISTICS 1000
σ
NNSD
[km]
800 600 400
Start Date: 1992-11-10T00:00:00 35 km constant altitude flights 100 balloons, UKMO Environment
200 0 0
20
40 60 80 Time from start [days]
100
120
Global Aerospace Corporation
Global Stratospheric Constellation
CONSTELLATION GEOMETRY MAINTENANCE
• Balloons Drift in the Typical and Pervasive Zonal Stratospheric Flow Pattern • Trajectory Control System Applies a Small, Continuous Force to Nudge the Balloon in Desired Direction • Balloons Are in Constant Communications With a Central Operations Facility • Stratospheric Wind Assimilations and Forecasts Are Combined With Balloon Models to Predict Balloon Trajectories • Balloon TCS Are Periodically Commanded to Adjust Trajectory Control Steering to Maintain Overall Constellation Geometry Global Aerospace Corporation
19
KTN - November 9, 1999
ILLUSTRATION OF CONTROL EFFECTIVENESS
5 m/s Toward Equator
5 m/s Toward Poles
Global Aerospace Corporation
Global Stratospheric Constellation
MAINTENANCE 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 Fidelity 1. Omni-directional Delta-v of Fixed Amount Applied at StratoSat 2. Delta-v Proportional to True Relative Wind at TCS 3. 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 Aerospace Corporation
21
KTN - November 9, 1999
GLOBAL CONSTELLATION WITH SIMPLE, 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
STATISTICS 1000
σ
NNSD
[km]
800
Free-floating
600 400 Paired NS and Zonal Control
200
Start Date: 1992-11-10T00:00:00 35 km altitude flights 100 balloons, UKMO Environment
0 0
20
40 60 80 Time from start [days]
100
120
TRAJECTORY CONTROL
Global Aerospace Corporation
Global Stratospheric Constellation
FEATURES OF STRATOSAIL™ 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 Aerospace Corporation
24
KTN - November 9, 1999
Global Aerospace Corporation
Global Stratospheric Constellation
ADVANCED TRAJECTORY CONTROL 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 ULDB Dynamically-scaled Dynamically-scaled Model Model Flight Flight Test Test
Global Aerospace Corporation
25
KTN - November 9, 1999
BALLOON
Global Aerospace Corporation
Global Stratospheric Constellation
BALLOON DESIGN OPTIONS
Spherical 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 Aerospace Corporation
27
KTN - November 9, 1999
Global Aerospace Corporation
Global Stratospheric Constellation
BALLOON VEHICLE DESIGN
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
Global Aerospace Corporation
28
KTN - November 9, 1999
SOLAR ARRAY / BALLOON INTEGRATION Sphere Pumpkin Seam/Load Tape as Solar Array
Gore Center As Solar Array
Envelope Film
Envelope Film
Example Power • • Seam/Load Tape / Solar Cells • (~ 3 cm wide) • •
48 m dia Spherical Design 100 Gores/Seams 3 cm Wide Solar Array 10 % Efficiency 4.7 kW
Thin Film Amorphous Si Solar Array Cells (~30 cm wide)
GONDOLA
Global Aerospace Corporation
Global Stratospheric Constellation
STRATOSAT GONDOLA
StratoSat Gondola • •
• • •
•
Stowed Gondola
Example Climate Change Science Payload 2x1x0.5 m warm electronic box (WEB) with louvers for daytime cooling Electronics attached to single vertical plate LIDAR telescopes externally attached to WEB TCS wing assembly (TWA) stowed below gondola at launch before winch-down Science pods on tether
Global Aerospace Corporation
31
KTN - November 9, 1999
INTERNATIONAL OVERFLIGHT CONSIDERATIONS
Global Aerospace Corporation
Global Stratospheric Constellation
INTERNATIONAL OVERFLIGHT
• Current Scientific Balloon Program – Overflight Often Allowed Especially If No Imaging and If Scientists of Concerned Countries Are Involved – Not All Countries Allow Overflight and This List Changes Depending 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 Global Aerospace Corporation
33
KTN - November 9, 1999
PHASE II PLAN
Global Aerospace Corporation
Global Stratospheric Constellation
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 Global Aerospace Corporation
35
KTN - November 9, 1999
SUMMARY
Global Aerospace Corporation
Global Stratospheric Constellation
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 Scientific Knowledge of the Earth System • Broader Involvement of the Earth Science Community Is Encouraged and Sought in the Definition of Constellation Mission and Instrument Concepts • A Proof-of Concept Science Mission Is One Essential First Step on the Path Toward Global Stratospheric Constellations Global Aerospace Corporation
37
KTN - November 9, 1999
APPENDIX
Global Aerospace Corporation
Global Stratospheric Constellation
STEPS TO GLOBAL STRATOSPHERIC CONSTELLATIONS
Constellation Types / Locale – Regional • South Polar • Tropics • North Polar
– Southern Hemisphere – Global • Sparse Networks for Wide representative Coverage • Dense Networks for Global Surface 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 Experiment Using Soon to Be Available ULDB Technology Global Aerospace Corporation
39
KTN - November 9, 1999
Global Aerospace Corporation
Global Stratospheric Constellation
STRATOSAT FLIGHT SYSTEM DESCRIPTION Mass Summary
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
Global Aerospace Corporation
40
Subsystem Mass, kg Balloon 236 Helium 87 Power 19 Telecomm 5 Mechanical 30 Guidance & Control 1 Robotic Controller 1 Trajectory Control 81 Science 56 Science Reserve 44 Total 560
KTN - November 9, 1999
Global Aerospace Corporation
Global Stratospheric Constellation
HOW THE TCS WORKS 15 m/s
• Winds vary with altitude
40
– Balloon at 30 km – Wing at 20 km – Relative wind velocity ~15 m/s
30
Alice Springs, January, 24¡ S
20 Altitude, km 10
• Wing generates lift force – – – –
Fairbanks, July, 65¡ N
“Lift” force is horizontal force is transmitted by tether to balloon balloon drifts relative to local air mass balloon drag ≈ wing lift
Source: Randel, W.J., Global Atmospheric Circulation Statistics, 1000-1 mb, NCAR/TN-366+STR, Feb. 1992
0 -40
-30
-20 -10 0 10 Mean Zonal Wind, m/s
20
• Wing is in much denser air than balloon – 25km : 35km (5x); 20km : 35km (10x) – equivalent wing area increased relative to balloon Global Aerospace Corporation
41
KTN - November 9, 1999
Global Stratospheric Constellation
Global Aerospace
HOW THE TCS WORKS, CONTINUED
Corporation
TOP VIEW OF TCS
Fh TCS LIFT mode
TCS STALL mode
θ
α
α
θ
Fh
Vrel Stall Point 1.5
Fh
1.0
Vrel
CL
θ
Fh
0.5
0 0
10
20
30
40
50
60
70
80
Lift/Drag Polar: Contours of Feasible Aerodynamic Forces
90
Alpha
LIFT / DRAG FORCE POLAR
LIFT vs ANGLE OF ATTACK
Global Aerospace Corporation
42
KTN - November 9, 1999
Global Stratospheric Constellation
Global Aerospace
HOW THE TCS WORKS, CONTINUED }
Corporation
Vdrift
Vcross
Expanded Vector Diagram
Vrel Vtrue
φ Vrel
D
Vb
L VTCS
Fh
Tether
TCS
β Fdrift ~ Fh Balloon
Top View Global Aerospace Corporation
Vdrift =
(
2 * Fdrift ρ ∗ Ab ∗ CD
1/2
)
β = φ - tan-1(D/L) Vcross=Vdrift * Cos β 43
KTN - November 9, 1999
Global Stratospheric Constellation
Global Aerospace
ANGLES EXAGGERATED & FORCES NOT TO SCALE
Corporation
θB ~ 0.25¡ FB
BALLOON
FBV ~ 16,000 N F BH ~ 70 N
GONDOLA AT 35 km l 2
ASSUMPTIONS
¥ BALLOON DRIFT ~ 2 m/s ¥Ê0.6 million m3 BALLOON ¥ GONDOLA ~ 1500 kg ¥ TCS ~ 100 kg θ G ~ 0.4¡
θT ~ 4¡
FT
l1 = 2 l2
l1
WG ~ 15,000 N
SYMBOLS
T -> TETHER G -> GONDOLA B -> BALLOON H -> HORIZONTAL V -> VERTICAL W -> WEIGHT F -> FORCE L -> LIFT
θT ~ 4¡
TCS AT 20 km
FT
L ~ 70 N
ULDB TCS FORCE DIAGRAM
LIFT OF ~ 70 N REQUIRES TCP WING AREA OF ~ 16 m2 ASSUMING CL of 1.0
LV ~ 5 N
WTCS ~ 1000 N
Global Aerospace Corporation
L + W = - FT
44
KTN - November 9, 1999