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Stratospheric satellitesjun01
This document discusses the concept of global constellations of stratospheric satellites (StratoSats) maintained by trajectory control systems. It proposes maintaining tens to hundreds of small, long-duration balloons at an altitude of 35 km to provide continuous, global earth observations. Key points discussed include StratoSat systems design, promising earth science missions like measuring the Earth's radiation budget, and potential demonstration missions to validate the concept like a hurricane intercept mission or radiometer calibration experiment.
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Stratospheric satellitesjun01
- 1. GLOBAL CONSTELLATIONS OF STRATOSPHERIC SATELLITES Presentation to the NASA Institute for Advanced Concepts (NIAC) 3rd Annual Meeting: Visions of the Future in Aeronautics and Space by Kerry T. Nock Global Aerospace Corporation http://www.gaerospace.com June 5-6, 2001 Global Aerospace Corporation
- 2. Global Constellations ofStratospheric Satellites Global Aerospace Corporation PHASE II STUDY CONTRIBUTORS Global Aerospace Corporation (GAC) Dr. Kim M. Aaron Dale R. Burger Dr. Matthew Heun Brenda Wistor-Linfield Kerry T. Nock, Principal Investigator and NIAC Fellow Dr. Alexey A. Pankine, Project Scientist R. Stephen Schlaifer Princeton University Dr. Naomi Leonard Dr. Edward Belbruno Consultant Dr. Elliot Weinstock, Harvard University Global Aerospace Corporation 2 KTN - NIAC Annual Meeting June 6, 2001
- 3. Global Constellations ofStratospheric Satellites Global Aerospace Corporation TOPICS CONSTELLATION CONCEPT STRATOSAT SYSTEMS EARTH SCIENCE AND OBSERVATIONS DEMONSTRATION MISSIONS SUMMARY Global Aerospace Corporation 3 KTN - NIAC Annual Meeting June 6, 2001
- 4. CONSTELLATIONS OF STRATOSPHERICSATELLITES
- 5. Global Constellations ofStratospheric Satellites Global Aerospace Corporation CONCEPT • Tens to hundreds of small, long-life (3-10 years) stratospheric balloons or StratoSats • Uniform global and regional constellations maintained by trajectory control systems (TCS) • Flight altitudes of 35 km achievable with advanced, lightweight, superpressure balloon technology BENEFITS • Provide low-cost, continuous, simultaneous, global and regional earth observations • Provides in situ and remote sensing from very low earth “orbit” Global Aerospace Corporation 5 KTN - NIAC Annual Meeting June 6, 2001
- 6. Global Constellations ofStratospheric Satellites Global Aerospace Corporation CONCEPT SCHEMATIC Global Constellation StratoSat Flight System Gondola Balloon 35 km Altitude Dropsonde Science Pod StratoSail® TCS 20 km Altitude Global Aerospace Corporation 6 KTN - NIAC Annual Meeting June 6, 2001
- 7. Global Constellations ofStratospheric Satellites Global Aerospace Corporation BENEFITS OF GLOBAL BALLOON PLATFORMS • Good diurnal coverage of entire globe • Low altitude observations that can improve resolution and/or signal-to-noise ratios of measurements • Provide frequent to continuous measurements • Provide horizontal gradients in addition to vertical profiles • Extended duration and low-cost potentially provide a cost-effective method for earth science and/or satellite calibration and validation Global Aerospace Corporation 7 KTN - NIAC Annual Meeting June 6, 2001
- 8. Global Constellations ofStratospheric Satellites Global Aerospace Corporation 7504 m/s REMOTE SENSING StratoSat vs Satellite Remote Sensing Factors • Surface image: R - 20-times closer • Surface emission: R2 - 400-times better • Lidar at 15 km: R2 - 1200-times better • Radar at surface: R4 - 160,000-times better • Integration time at surface: ~8-times more <50 m/s StratoSat 35 km Satellite 700 km Angular Nadir Rate = 11 mrad/s Angular Nadir Rate = 1.4 mrad/s ´© Global Aerospace Corporation 2000 Global Aerospace Corporation 8 KTN - NIAC Annual Meeting June 6, 2001
- 9. Global Constellations ofStratospheric Satellites Global Aerospace SSTTRRCorporAaAtion TTOOSSAATT™ BBAALLLLOOOONN DDEESSIIGGNN • 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 ULDB Scale Model Tests Global Aerospace Corporation 9 KTN - NIAC Annual Meeting June 6, 2001
- 10. Global Constellations ofStratospheric Satellites Global Aerospace Corporation INTEGRATED SOLAR ARRAY & BALLOON ENVELOPE Gore Center As Solar Array Envelope Film Thin Film Amorphous Si Solar Array Cells (~30 cm wide) Example Power • 48 m dia • 100 Gores/Seams • 30 cm Wide Solar Array • 10 % Efficiency • ~45 kW Global Aerospace Corporation 10 KTN - NIAC Annual Meeting June 6, 2001
- 11. THE NEED FORGLOBAL CONSTELLATION MANAGEMENT FREE FLIGHT SIMPLE CONTROL ASSUMPTIONS • 100 StratoSats @ 35 km • 82 day Simulation • 5 m/s Control
- 12. Global Constellations ofStratospheric Satellites Global Aerospace Corporation CONSTELLATION MANAGEMENT • Constellation management is the process of maintaining a desired spatial distribution of balloons in constellation • Constellation management DOF – Environment information used – Fidelity of balloon model – Coordinate system – Constellation control method • Nearest neighbor (molecular) • Biological analogs (flocks, pods, schools, herds) • Weak Stability Boundary (WSB) theory • Constellation management objectives – Uniform global and regional distributions – Targeted overflight Photograph by Norton Wu Global Aerospace Corporation 12 KTN - NIAC Annual Meeting June 6, 2001
- 13. Global Constellations ofStratospheric Satellites Global Aerospace Corporation BALLOON TRAJECTORY CONTROL First Generation System Trajectory Control System (TCS) – Wing hanging vertically on long tether in higher density air below balloon system – Rudder controls angle of attack – Relative wind at StratoSail® TCS generates lift force, which alters balloon trajectory 15 km Tether Global Aerospace Corporation 13 KTN - NIAC Annual Meeting June 6, 2001
- 14. Global Constellations ofStratospheric Satellites Global Aerospace Corporation 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 Radio-Controlled Dynamically-scaled Model (1:4) Tested in Natural Winds Suspended From Tethered Blimp, April 2001 Global Aerospace Corporation 14 KTN - NIAC Annual Meeting June 6, 2001
- 15. TCS Wing Assembly(TWA) Instruments/ Counterweight Wing Control Pod Boom Rudder Tether
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- 17. Global Constellations ofStratospheric Satellites Global Aerospace Corporation ADVANCED 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 Global Aerospace Corporation 17 KTN - NIAC Annual Meeting June 6, 2001
- 18. Global Constellations ofStratospheric Satellites Global Aerospace Corporation CENTRALIZED STRATOSAT OPERATIONS Commands Stratospheric Forecast Center Gondola calculates TCS commands TWA Observed Strat. Location & Environment Constellation Geometry & Atm. Param. Constellation Geometry & Environments Winds & In-situ Data Constellation Operations Center Improved Stratospheric Forecasts TCS Standard Sat. & In-situ Observations Global Aerospace Corporation 18 KTN - NIAC Annual Meeting June 6, 2001
- 19. EXAMPLE Global Constellationsof Stratospheric Satellites Global Aerospace Corporation STRATOSAT GONDOLA StratoSat Mass of 221 kg Global Aerospace Corporation 19 KTN - NIAC Annual Meeting June 6, 2001
- 20. Global Constellations ofStratospheric Satellites Global Aerospace Corporation PROMISING EARTH SCIENCE 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 • Global Circulation and Age of Air • Global Ocean Productivity • Weather and Adaptive Sampling – Hurricane forecasting and tracking – Tropospheric winds – Forecasting weather from ocean basins & remote areas • Hazard Detection and Monitoring Global Aerospace Corporation 20 KTN - NIAC Annual Meeting June 6, 2001
- 21. Global Constellations ofStratospheric Satellites Global Aerospace Corporation ADVANTAGES OF STRATOSATS TO ERB • Radiative flux measured directly at 35 km – Commonly accepted TOA to which ERBE/ERBS products are extrapolated; no extrapolation required from 800 km down to 35 km – High spatial resolution measurements – No angular modeling needed • Complete diurnal coverage (no diurnal model required, the leading source of uncertainty in daily and monthly regional flux averages) • No sun angle bias (Sun synchronous orbits, except ERBE/ERBS and CERES/TRMM) • Global synoptic coverage allows actual dynamics of ERB to be seen (including horizontal fluxes); never before possible Global Aerospace Corporation 21 KTN - NIAC Annual Meeting June 6, 2001
- 22. Global Constellations ofStratospheric Satellites Global Aerospace Corporation ERB COVERAGE Global Aerospace Corporation 22 KTN - NIAC Annual Meeting June 6, 2001
- 23. Global Constellations ofStratospheric Satellites Global Aerospace Corporation HURRICANE PREDICTION • More accurate prediction of a hurricane track and its intensity can avoid economic disruption and save lives • Current data sources – Satellites provide low resolution atmospheric data, – Buoys provide surface wind, pressure, air and ocean temperature, and – Crewed aircraft fly into the storm to supplement the wind, pressure and temperature data around the storm. • While this data and better models have continued to improve hurricane forecasting, more high quality, high resolution in situ data is needed • For example, more accurate wind data is needed – The winds in the vicinity of the hurricane are important for predicting the hurricane’s path – The winds inside the hurricane are important to estimating its eventual intensity Global Aerospace Corporation 23 KTN - NIAC Annual Meeting June 6, 2001
- 24. Global Constellations ofStratospheric Satellites Global Aerospace Corporation ECONOMIC BENEFITS TO IMPROVED PREDICTION • In a 72 hour forecast the current average hurricane landfall error is 200 miles • When a hurricane is predicted to hit a coast, up to 300 miles of a coastal zone is placed under a warning, which is 4-times the area actually seriously effected • The estimated financial impact on US of a hurricane warning is between $1-50 M per mile of coast, depending on economic sectors along that stretch of coast • If landfall prediction could be improved by 50% a potential savings of at least $150 M per hurricane landfall could be achieved Global Aerospace Corporation 24 KTN - NIAC Annual Meeting June 6, 2001
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- 26. Global Constellations ofStratospheric Satellites Global Aerospace Corporation POSSIBLE HURRICANE TRACKING NETWORK • Track a moving target (hurricane) with multiple balloons • As one balloon moves beyond the horizon, new balloon enters the scene for observations • Deploy one or more StratoSat “string-of-pearls” around the World near the latitude of hurricanes • Example constellation management strategy – When > 90° longitude from hurricane, maintain hurricane's latitude – When < 90° longitude from hurricane, aim directly for the eye • After Northern Hemisphere hurricane season the network could move to the Southern Hemisphere Global Aerospace Corporation 26 KTN - NIAC Annual Meeting June 6, 2001
- 27. • Hurricane Alberto • 20 balloons • 1-day look-ahead • 4 hrs/frame • 31 days • Actual easterly winds at 35 km • Advanced TCS (0.5-5 m/s) • Lat control strategy – >90° track lat – <90° aim eye SSSTTTRRRIIINNNGGG OOOFFF PPPEEEAAARRRLLLSSS
- 28.
- 29. Global Constellations ofStratospheric Satellites Global Aerospace Corporation EXAMPLE DEMONSTRATION MISSION OPTIONS • Hurricane Intercept Mission • Satellite Radiometry Calibration and Validation • Wind Lidar Measurements • Demonstration Earth Radiation Budget Experiment (DERBE) • Or a Combination of Mission Objectives Global Aerospace Corporation 29 KTN - NIAC Annual Meeting June 6, 2001
- 30. HURRICANE INTERCEPT MISSION(HIM) • Potential Primary Objectives – Intercept and Possibly Follow Hurricane – Obtain High Resolution Meteorological Measurements – Demonstrate Hurricane Intercept Trajectory Control Capability • Possible Science Experiments – Meteorological Dropsondes – High Resolution Wind Lidar – GPS Reflection Sea-state – Precipitation Radar – Low Resolution Imager • Hurricane Alberto • UKMO winds at 35 & 20 km • Red – Aerodynamic TCS model – ~ 2 m/s control authority – Maintains lat. • Blue – Uncontrolled – Floats with winds • 4 hrs/frame • 4.25 days
- 31. Global Constellations ofStratospheric Satellites Global Aerospace Corporation EXAMPLE DERBE MISSION PROFILE • Radiative flux measurements of the Earth • Float altitude of 35 km • Generally “orbit” Earth at +15° latitude • ~5 overflights of SGP CART at +35° latitude • 100 day mission Global Aerospace Corporation 31 KTN - NIAC Annual Meeting June 6, 2001
- 32. Global Constellations ofStratospheric Satellites Global Aerospace Corporation EXAMPLE DERBE TRAJECTORY SIMULATION Trajectory Objectives • Achieve overflight of SGP CART site • Avoid overfight of China and Libya Global Aerospace Corporation 32 KTN - NIAC Annual Meeting June 6, 2001
- 33. Global Constellations ofStratospheric Satellites Global Aerospace Corporation EXAMPLE DERBE SCIENCE PAYLOAD • Pyranometers – Four instruments of different types – Hemispherical FOV – Short-wave (0.3-3 μm) • Pyrgeometers – Two instruments of different types – Hemispherical FOV – Long-wave (4-40 μm) • Radiometers are modified Earth science instruments • Instruments located on an optical benches • Calibration system Global Aerospace Corporation 33 KTN - NIAC Annual Meeting June 6, 2001
- 34. Global Constellations ofStratospheric Satellites Global Aerospace Corporation CALIBRATION SYSTEM • Pyranometers – Periodically view Sun to provide known input source – Issues • Reflections off balloon will contaminate solar signal • Cosine response of instrument may necessitate corrections • 0.1° pointing knowledge with respect to the Sun required – Collimator tube to eliminate all other signal sources • Pyrgeometers – Rotate to a “black body” to cover field of view of pyrgeometer – Black body temperature must be known to ± TBD (0.1) K – Emissivity of black body must be known to ± TBD (0.5) % Global Aerospace Corporation 34 KTN - NIAC Annual Meeting June 6, 2001
- 35. Global Constellations ofStratospheric Satellites Global Aerospace Corporation EXAMPLE DERBE BALLOON SYSTEM CONCEPT Flight Train (ladder, parachute) ~100 m ~15 km Gondola (<500 kg) TCS Tether (~1 mm dia) Super-pressure ULDB (~60-80 m dia) Instrument Platform StratoSail® TCS (~50 kg) Global Aerospace Corporation 35 KTN - NIAC Annual Meeting June 6, 2001
- 36.
- 37. INTERNATIONAL PATHWAYS TOOVERFLIGHT
- 38. Global Constellations ofStratospheric Satellites Global Aerospace Corporation INTERNATIONAL OVERFLIGHT OPTIONS • Free flight in upper stratosphere • Expand on the 1992 Treaty on Open Skies • Exploit World Meteorological Organization (WMO) cooperation • Seek new treaties – Committee on Space Research (COSPAR) study – World pollution issues – Growing interest in providing method for all countries of the world to participate in global observations Global Aerospace Corporation 38 KTN - NIAC Annual Meeting June 6, 2001
- 39. Global Constellations ofStratospheric Satellites Global Aerospace Corporation COSPAR RESOLUTION • 33rd COSPAR Scientific Assembly in Warsaw, Poland in 2000 • Scientific Balloon Panel formulated a resolution to the COSPAR Executive Council • Resolution requested a task group be formed to study and report to the bureau on the technical aspects of overflight of scientific balloons including: – altitudes, – balloon sizes and payload masses, – characteristics and features of payloads, and – safety requirements) and – possible international actions to enable the geographically-unrestrained and the peaceful free flight of such apparatus over all countries. • This resolution was accepted as COSPAR Internal Decision No. 1/2000. Global Aerospace Corporation 39 KTN - NIAC Annual Meeting June 6, 2001
- 40. Global Constellations ofStratospheric Satellites Global Aerospace Corporation PROPOSED OVERFLIGHT REQUIREMENTS • Airworthiness certificates from appropriate organization, perhaps ICAO, indicating the craft meets equipment and safety requirements • A means of identification • Evidence of liability insurance • Payloads must not compromise any State’s national security • Launch and payload oversight • Any nation free to operate stratospheric platforms if they meet all requirements Global Aerospace Corporation 40 KTN - NIAC Annual Meeting June 6, 2001
- 41.
- 42. Global Constellations ofStratospheric Satellites Global Aerospace Corporation SUMMARY • The StratoSat™ platform is a stratospheric satellite that can provide: – Low-cost, continuous, simultaneous, global and regional observations options – In situ and remote sensing from very low earth “orbit” • Global and regional stratospheric constellations will expand scientific knowledge of the Earth system • A demonstration mission is essential first step toward regional and global measurements from 35 km • Mission definition has progressed on two demonstration missions, – Demonstration Earth Radiation Budget Experiment (DERBE) – Hurricane Intercept Mission (HIM) Global Aerospace Corporation 42 KTN - NIAC Annual Meeting June 6, 2001