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SPACE WEATHER EFFECTS ON SATELLITE DRAG

6 January 2006

Cheryl Huang, Frank A. Marcos and William Burke

Space Vehicles Directorate

Air Force Research Laboratory

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Marcos et al., 1997

AFRL Atmospheric Calibration Technique Results

Operational data

Drag model corrected

Historic Errors in Empirical Models

Model errors reduced from 15% to 5%

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• AF Space Battlelab Initiative

• Objective: Near real time corrections to J70 model, enhanced spatial resolution

- Drag from ~75 LEO calibration satellites

- Range of altitudes (200-800 km) and inclinations

- Enhanced Tracking

• Error reduced to 8%

• Operational: Sept 2004

High Accuracy Satellite Drag Model (HASDM)

• AFRL Support:

- Technical consultation

- Extend operational model below 90 km

- Evaluate candidate solar proxies

- Evaluate spatial resolution

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Sapphire Dragon (HASDM-2)

• AF Space Battlelab Initiative to upgrade current HASDM

• Objective: 3-day forecast with improved resolution and accuracy (TBD); 180 - 800 km

– Track 240 satellites

– Improve model parameterizations for semiannual, latitude, local time, solar and geomagnetic variations

• Model complete April 2006

– AFRL will provide model operational algorithms for local time vs latitude, altitude and solar flux

• Validation complete August 2006

– AFRL will present results at Aug 06 Astrodynamics Conference

• Operational in 2008

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Predicted Position

Actual Position

Superstorm Impacts: • Changed scale heights and wind patterns

• Degraded ability to track space objects

Electromagnetic Energy Flow

Undetected on the ground, hundreds to thousands of TeraJoules enter I/T

Interplanetary

MediumMagnetosphere Ionosphere/Thermosphere

Poynting vector measure of net

electromagnetic energy transfer

M-I-T Coupling and Satellite Drag

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M-I-T Coupling and Satellite Drag During Magnetic Storms

GRACE densities compared with model and PC predictions during November 7-10, 2004 magnetic storm

• MSIS and J 70 underestimate storm effects by 300%

• Fail to predict GRACE fine structure

• Predicted increases arrive 4 to 6 hours late

• ACE data from L1 give 4-hour forecast

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M-I-T Coupling and Satellite Drag

• During super storms, intense field-aligned currents impact upper ionosphere

• Storms introduce large quantities of stealth power (up to 3 TW) in the form of net Poynting flux into the upper ionosphere

• Modeled neutral densities underestimate observed increases

• Discrepancies significantly degrade predicted drag estimates

• PC estimates from ACE give several hour density predictions

Summary