Stratospheric Satellites Summary of the Concept including Simulations Global Aerospace Corporation...

Stratospheric SatellitesStratospheric SatellitesSummary of the Concept including

Simulations

Global Aerospace Corporation711 West Woodbury Road, Suite H

Altadena, CA 91001-5327626-345-1200

http://www.gaerospace.com/

Global Aerospace

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Global Aerospace

Corporation

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Corporation CONCEPTCONCEPT

• Tens to hundreds of small, long-life (3-10 years) stratospheric balloons or “satellites”

• Uniform global and regional constellations maintained by trajectory control systems (TCS)

• Flight altitudes of 35 km achievable with advanced, lightweight, superpressure balloon technology

• Provide low-cost, continuous, simultaneous, global and regional Earth observations

• Provides in situ and remote sensing from very low earth “orbit”

BENEFITSBENEFITS

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CONCEPT SCHEMATICCONCEPT SCHEMATICStratoSat™ SystemNorthern Hemisphere

Constellation

383 StratoSat™ Platforms2° Elevation Angle

Max Slant Range of 483 kmCoverage Circle Diameter of 960 km

Snap-shot of Controlled Constellation

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BENEFITS AND THEMESBENEFITS AND THEMES

POTENTIAL COVERAGE BENEFITS• Good diurnal coverage

• Low altitude observations improve remote sensing resolution and/or SNR

• Frequent to continuous measurements

• Provide horizontal gradients in addition to vertical profiles

• Long dwell time over science targets

• Targeted dropsonde opportunities

ADAPTIVE SAMPLINGHURRICANE TRACKING

STRING OF PEARLSSTRING OF PEARLSSTRING OF PEARLSSTRING OF PEARLS

• 20 StratoSats, ~$5-10M• Measurements

– Dropsondes– Wind Lidar– Sea-state – Precipitation Radar– Imager

• Economics– Goal to reduce landfall

uncertainty by 50%– Save ~$150M per

landfall

EARTH SCIENCE THEMES• Climate change studies - ERB, Ice shields

• Ozone studies - Distribution, Loss

• Global circulation - Stratosphere/Troposphere

• Global ocean productivity - Biocycles

• Plate Techtonics - Magnetic field anomalies

• Weather and adaptive sampling - Hurricanes and improved prediction

• Hazard detection and monitoring - Early warning & improved communications

Flight Path GuidanceFlight Path Guidance

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CorporationSTRATOSAIL®

TRAJECTORY CONTROL SYSTEMSTRATOSAIL®

TRAJECTORY CONTROL SYSTEM

– Wing hanging vertically on long tether in higher density air below balloon system

– Rudder controls angle of attack

15 kmTether

First GenerationTrajectory Control System (TCS)

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STRATOSAIL® TCS FEATURESSTRATOSAIL® TCS FEATURES

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 Bounded & underactuated control

system

Radio-Controlled Dynamically-scaled Model (1:4) Tested in Natural Winds Suspended From Tethered Blimp,

April 2001

Relative Wind at Wing

Lateral ForceComponent

Drag ForceComponent

ResultantForce

TCSWingAngle of Attack

Wing AssemblyWing Assembly

Winch TestbedWinch Testbed

STRATOSAIL® TCS ROLL OUT

March 16, 2002

STRATOSAIL® TCS ROLL OUT

March 16, 2002

Uncontrolled Trajectory

AliceSpringsLanding

ChristchurchLaunch

• 100-day flight • ~ 60 days at -70° • 35 km Altitude• Launch 11/15/88• Historical Winds• 5 m2 Wing Area• 1st Order Model• Simple Control Strategy

TRAJECTORY CONTROL PERFORMANCE

TRAJECTORY CONTROL PERFORMANCE

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Corporation ADVANCED TCS CONCEPTADVANCED TCS CONCEPT

Advanced StratoSail® TCS Design Features

– Lift force can be greater than weight

– Will stay down in denser air

– Less roll response in gusts

– Employs high lift cambered airfoil

– Greater operational flexibility

– Possible Dynamic Power Generation

BalloonBalloon

ADVANCED SMALL ULTRA LONG DURATION BALLOON (ULDB) DESIGN

ADVANCED SMALL ULTRA LONG DURATION BALLOON (ULDB) DESIGN

• Euler Elastica Pumpkin Design

• Volume ~ 70,000 m3

• Advanced Composite Film, 15 g/m2

• 140 Gores ~1.3 m Wide

• Zylon® Load Tendons

• Balloon Mass ~ 250 kg

• Euler Elastica Pumpkin Design

• Volume ~ 70,000 m3

• Advanced Composite Film, 15 g/m2

• 140 Gores ~1.3 m Wide

• Zylon® Load Tendons

• Balloon Mass ~ 250 kg

NASA ULDBScale Model Tests

NASA ULDBScale Model Tests

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Corporation NASA ULDB FLIGHT TESTNASA ULDB FLIGHT TEST

Stratospheric SatelliteFlight Path Control, Formation Flying

and Constellation Control

Stratospheric SatelliteFlight Path Control, Formation Flying

and Constellation Control

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STRATOSAT™ SYSTEM OVERFLIGHT SIMULATION

STRATOSAT™ SYSTEM OVERFLIGHT SIMULATION

Trajectory Objectives• Achieve overflight of OK ARM site• Avoid overfight of China and Libya

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Corporation HURRICANE TRACKINGHURRICANE TRACKING

• Hurricane Alberto• 20 balloons, Advanced TCS (0.5-5 m/s, reel-up capability)• Actual easterly winds at 35 km• 1-day look-ahead• 4 hrs/frame, 31 days• Latitude control strategy

– >90° track lat

– <90° aim eye

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BEHAVIOR OF NATURAL GROUPS

BEHAVIOR OF NATURAL GROUPS

• Group-level characteristics emerge from individual-level behaviors• Schools/Pods/Flocks

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Corporation ARTIFICIAL POTENTIALS (APs)ARTIFICIAL POTENTIALS (APs)

• Control derived from a gradient of artificial potentials

• Model local "traffic rules"– Attraction– Repulsion

• Potentials and virtual members produce emergent group behavior

– Manipulate group geometry– Direct group motion

• Useful for stability/robustness proofs

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EXAMPLE HEMISPHERICAL CONSTELLATION MANAGEMENT

EXAMPLE HEMISPHERICAL CONSTELLATION MANAGEMENT

• Constellation– 383 StratoSat platforms, >15° latitude– Gondola altitude @ 35 ± 1 km– StratoSail® Trajectory Control System

(TCS) @ 20 km altitude– Artificial Potentials control algorithm

– ~30 days (start 1 June 2000) • Legend

– Red - StratoSat platform locations– Yellow - 2° elevation– Green - overlaps

• 1 hr/frame, 48 frames/sec, 173,000x faster than reality

• UKMO weather data• Control Model

– Bounded and under-actuated control system

– ∆V proportional to relative wind velocity, Vrel, at 20 km

– Feasible, limited control directions with respect to Vrel

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EXAMPLE LINEARNETWORK SIMULATION

EXAMPLE LINEARNETWORK SIMULATION

• Constellation– 100 StratoSat platforms, Overfly 34.5° N

latitude and 69.2° E longitude– Gondola altitude @ 35 ± 1 km– StratoSail® Trajectory Control System

(TCS) @ 20 km altitude– Multiple prioritized objectives: maintain

latitude, equal spacing, overfly target– 15 days (start 15 June 2000)

• Legend– Red - StratoSat platform locations– Yellow - 2° elevation– Green - overlaps

• 4 hr/frame, 12 frames/sec, 173,000x faster than reality

• UKMO weather data

• TCS Model– Bounded and under-actuated control

system– ∆V proportional to relative wind velocity,

Vrel, at 20 km

– Feasible, limited control directions with respect to Vrel

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POSITIONING OVERDISASTER AREAS

POSITIONING OVERDISASTER AREAS

• Constellation Assumptions– 100 StratoSat™ platforms, +/-20° latitude– Gondola altitude @ 35 ± 1 km– StratoSail® Trajectory Control System (TCS) @ 20 km altitude– Biological group control algorithm (like flocks of birds)– 365 days (start 1 January 2000)

• Cost ~ $44 M

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StratoSat™ Gondola and an Operations Strategy

StratoSat™ Gondola and an Operations Strategy

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EXAMPLE STRATOSAT™ GONDOLAEXAMPLE STRATOSAT™ GONDOLA

StratoSat Mass of 221 kg

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EXAMPLE CENTRALIZED STRATOSAT™ OPERATIONS

EXAMPLE CENTRALIZED STRATOSAT™ OPERATIONS

StratosphericForecastCenter

Gondolacalculates

TCS commands

TWA

Observed Strat.Winds &

In-situ DataConstellationOperations

Center ImprovedStratospheric

Forecasts

TCSCommands

ConstellationGeometry &Atm. Param.

Location &Environment

Standard Sat. & In-situ

Observations

ConstellationGeometry &

Environments

Science Mission Cost EstimatesScience Mission Cost Estimates

Global Aerospace

CorporationCOST SUMMARY OF

ATMOSPHERIC DYNAMICS CONSTELLATION

COST SUMMARY OF ATMOSPHERIC DYNAMICS

CONSTELLATION

Operations about $5M/yr.

SummarySummary

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Corporation SUMMARYSUMMARY• Stratospheric satellites can provide:

– Low-cost, continuous, simultaneous, global and regional observations options

– Satellite validation and verification

– In situ and remote sensing from very low earth “orbit”

• Global and regional stratospheric constellations will expand scientific knowledge of the Earth system

• Mission definition has progressed on several demonstration science missions

• A demonstration mission is essential first step toward regional and global measurements from 35 km

• A low-cost demonstration flight could leverage ongoing ULDB technology development (balloons, power generation, flight path control)