(c)2001 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)' Sponsoring Organization.

At A A A0116155

AIAA 2001-0242Neutral Atmosphere Variability and Implicationsfor Spacecraft Design and OperationsJerry K. OwensNASA Marshall Space Flight CenterHuntsville, AL

Frank MarcosSpace Weather Center of ExcellenceHanscom AFB, MA

W. Kent TobiskaFDC/Jet Propulsion LaboratoryPasadena, CA

William W. VaughanUniversity of Alabama in HuntsvilleHuntsville, AL

39th AIAA Aerospace SciencesMeeting & Exhibit

8-11 January 2001 / Reno, NVFor permission to copy or republish, contact the American Institute of Aeronautics and Astronautics1801 Alexander Bell Drive, Suite 500, Reston, VA 20191

BackgroundOO

Density Calibration Technique f- Observed drag for calibration satellite used to correct model estimates for |

other spacecraft |o

- Short-term (< 2 weeks) accuracy of 5% - 7% achieved |8'

- Studies of correlations with solar and geomagnetic variations in progress %CT

Fidelity of Thermospheric Model Inputs |- Comparison of accuracies of various future estimation techniques for solar I

activity |ID

- Comparison of accuracies of various future estimation techniques for |geomagnetic activity

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Parameterization of operation solar EUV data to replacesolar activity indices- How well can it be made to perform?- What are the associated problems?

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Background (continued)OO

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SOLAR2000 Model Objectives- Provide the world's premier empirical solar irradiance specification

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- Link with other space physics models for a space weather nowcasting and Jforecasting capability f

- Provide daily historical, nowcast, and forecast irradiances |TI

SOLAR2000 heritage and characteristics 1O CD

- heritage from SERF2 (1989), EUV91 (1991), EUV97 (1998) solar models Iand UARS, ASTM I

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- S2K is the first self-consistent empirical full solar spectrum I>

- irradiances from the X-rays to the IR at 1 nm spectral resolution; temporal |resolution from minutes to solar cycles I

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- ISO draft solar standard compliant |o

- S2K is modular (packaged, autonomously web-served) and is coupled with Jother models and visualization software to produce improved ionospheric |and thermospheric densities z

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Drag Derived Atmospheric Density8CD

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GFZ Orbital Drag vs F10.7

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-F10.7

GFZ Drag

1E-16

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1&17

28-Oct-95 15-May-96 1-Dec-96 19-Jun-97 5-Jan-98 24-Jul-98 9-Feb-991E-18

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ATMOSPHERIC CALIBRATION CD

Local correction to density model based on tracking a "calibrationsatellite is applied globally.

Calibrationsatellite

Orbit

SSN Tracking Data

Operational

Drag Errors

Precision orbitdetermination

with newglobal density

Effective solarEUV heating for

improvedpredictions

Local

operational

density model

correction

Globaloperational

density modelcorrection

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Long Duration Exposure FacilityBallistic Coefficient Values

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Temperatures Derived fromLDEF Ballistic Factors

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Improvement Achievable ThroughExospheric Temperature Adjustment

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ERROR REDUCTION USINGATMOSPHERIC CALIBRATION

INITIAL DATA — CALIBRATED DATA

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Application of Calibration From LowInclination Satellite (LDEF)

H Initialll LDEF Cal

28.5 28.5 65.9

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Thermosphere ModelOO

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Development Data Sets - satellite drag and incoherent scatter radar dataModel Formulation

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- Static diffusive equilibrium *£

- Regression fits to determine empirical coefficients IModel Dependencies- Solar flux (daily and average)- Geomagnetic activity (3 hourly)- Local Time- Latitude and Longitude- Season

Model Outputs- Neutral Temperature- Total density- Number density of major species |

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Spacecraft Orbital Lifetime PredictionTechnique Block Diagram

SPACECRAFTORBITAL STTATE

VECTORESTIMATEDFUTURE

SOLAR FLUXBEHAVIOR

ESTTIMATEDATMOSPHERIC

DENSITY

ORBITALLIFETIME

MODELATMOSPHERE

MODELESTIMATED

GEOMAGNETIC

PREDICTEDSPACECRAFT

ATTITUDET1MELINE

PREDICTEDBALLISTIC

FACTOR ANDTIMELINE

SPACECRAFTCHARACTERISmCS

PREDICTEDSPACECRAFT

ORBITALLIFETIME

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SOLAR2000 Formatsfor Spectra and Solar Indices

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Satellite use of the E10.7 Proxy CD

Satellite Drag:E10.7 and F10.7 daily values

are compared via theLOP orbit propagatorusing a J71 modelatmosphere.

El0.7 provides the solarcomponent ofatmospheric heating andis an improvementcompared with F10.7.Non-solar effects are notincluded in this modeledcomparison with theSME actual altitudes.

300

f- 250E

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150__go 100

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I 525DDcr

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Com pans o n of da i ly EmT d nd F10,-10,7

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E10;> ——————

^10,7— — —

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1OD 20O 30Q 4OODays (01 Apr 1992 - 09 Aug 1993}

Comparison of daily SME altitudes •from LOP

1OD 20O 300 4OODays (01 Apr 1992 — 09 Aug 1993)

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Summary and Outlook >CD

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Satellite tracking data provides extensive neutraldensity information for the data-sparsethermosphereNeutral density model errors can now be reliablyreduced to the 5 % levelA significant component of the density model errorsis related to errors in the solar EUV proxy (F10.7)Time-dependent corrections to F10.7 yield accuratesolar EUV data for space weather applications inthe thermosphere and ionosphereE10.7 characterizes the physical solar irradiancethat deposits energy in the upper atmosphere.

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