Info

Fiyby trajectory Flywheel

Focus, of an ellipse

Force, Units and conversion factors

Forced attitude solutions

Forced response, of a linear system

Forcing function, of( jifferentiai equation

Fourier series, use to solve linear differential equations Fourier transform Frame, of data Frame synchronization signal Framing of telemetry data Fredbolm equation Free response, of a linear system Freon, as gas jet fuel Fresnel reflection

Friction modeling, for reaction wheels Fuel-

Budget for gas jets Loss due to engine misalignments Tanks, torques in Used for gas jets

Gain matrix, in sequential estimators 461

Gal (unit of acceleration) 809

Galactic coordinates 28

Gamma (unit of magnetic induction) 811

Gas Jets-

Attitude control systems using 503, 506 Attitude maneuver analysis for 649-654 Disturbance torques due to propellant slosh 577-578

Effects of thrusting on flexible spacecraft 551-552 Example of use in attitude control 14-16 Hardware description 206-210 List of spacecraft using 796 Mathematical models 272-275 Nutation damping with 630-631 Use for attitude control 19 Use for attitude stabilization 622-625 Ganss (unit of magnetic induction) 811 Gauss, Karl 113,779 Gauss' Equation 45 Gauss-Newton least-squares procedure 448,455 Gaussian coefficients, Geomagnetic field 117 Table of 779 Gaussian measurement errors 430-431 Probabilities associated with 381 Sample computation 434 GC1 (See Geocentric Inertial Coordinates) Gemini program, use of horizon sensors

167, 168, 180 General perturbations, method of (orbit analysis) 139

Geocentric coordinates, conversions with geodetic 820-822

820-822 8,99.125 99 125

Geocentric Inertia] Coordinates Geodetic coordinates, on the Earth's surface Geold

Geoid height Map of

Geomagnetic field (See also Magnetic, magnetometers, etc.) 113-123,779-786

Accuracy of models 118-119

Analytic approximations for 782-785 As attitude determination reference source 17

Dipole model 782-785

—For Earth-referenced spacecraft 613

—Rectangular components 784

—Spherical components 783

Diurnal variation 122-123

General description 113-120

Index of geomagnetic activity 122

Magnetic storms 121

Mathematical models 779-785

Models 117-123

Perturbations of 120-123

Secular drift 113

Solar perturbations :20-123

Spherical harmonic model 779-782

Subroutine for (MAGFLD) 693.

Geometric albedo 79 Geometric method of three-axis attitude determination 421-424

Geometrical axes of spacecraft 487 Geometrical limitations of attitude accuracy 389-402

Applications 397-402 Geometry—

Attitude 22-35 Effect of changes on information content of measurements 478-482 Spherical (See Global geometry plots; Spherical geometry), GEOS (Geodynamics Experimental Ocean Satellite)— Attitude acquisition 662,666,672-677

Attitude system of 790-791

Control system description 612-617

Data records 304 Data sample 312,313,314

Deadbeat boom deployment 669

Fitting magnetometer data 321

Libration damping 632

Magnetic stabilization 672

Momentum wheel 202-203

Spacecraft 672

Stabilization method 503

State vector for bias determination 441

Sun sensor 157

—Data correction 330

Use of open-loop control 663 GESS (See Graphics Executive Support System)

GETHDR (subroutine) 693

Use of 133

GETTY (subroutine) 693

Gibbous (illumination phase) 331

Glbbs vector 416,763

Kinematic equations of motion for SI2-513 Glbbs, J. Wlllard 416

Gimbal (gyroscope support) 196

Gtmbal rotation axb (gyroscope) 196

Glmbaled star traders 186,187-189

List of spacecraft using 797

Global geometry plots Construction of 737-743

Explanation of 22-26

For attitude determination 397-399

Spacecraft orbit on 398

Subroutines for (SPHGRD, SPHCNV,

SPHPLT) 694-695

Global Positioning System 8-10

GMT (See Vnioersal Time) Goddard Space Flight Center-Attitude Data Link 292

Computer environment 682

Information Processing Division

292,299-303

Network Operations Control Center 284 Role in CTS mission 7

Role in receiving & relaying data 284

SCAMA (Switching, Conferencing, etc.) 291 Goddard Trajectory Determination

System (GTDS) 133-134

subroutines for 693

GOBS (Geostationary Operational _ Environmental Satellite)— Application of block averaging to attitude solutions 371

Attitude acquisition 661

Attitude determination accuracy 397

Attitude software structure 698

Attitude system of 790-791

Correlation among measurement types 480-484

Data collection for bias determination 474 Determination of sensor mounting angle bias 483

Fitting attitude solutions 322-323

Orbit generator accuracy 138

Spin rate change due to orbit maneuvers 582 Sun sensor analysis 717-718

Telemetiy data errors 311

Use of carbon dioxide band horizon sensor 92

Use of open-loop control 663

Use of tody-mounted horizon sensor 173 Goodness-of-flt function 318

GPS (See Global Positioning System) Gradient, of a scalar function 756

Gradient operator 756

Gradient search, "method of differential correction 455

GRAPH (subroutine) 694

Graphic software systems 686-690

Graphic Subroutine Package (GSP) 687

Graphic support systems 686-690 Graphics (See also Interact ice graphics) Graphics Executive Support System

(GESS) 688-690

Graphing subroutines 694-695 Gravitation, Newton's development of laws 36-38

Gravitational constant, accuracy of 41 Gravitational constants. Earth, Moon, and

Sun 827

Gravitational field models 123-129

Gravitational potential 123-129

Gravity assist trajectory 60

Gravity-gradient attitude control 614-617

Gravity-gradient capture sequence 672-677 Gravity-gradient stabilization 19, 503,505-506

Conditions for 611-612

List of spacecraft using 787

Gravity-gradient tensor 128-129

Gravity-gradient torque 17

Effect on flexible spacecraft 549, 551 For dual-spin spacecraft, math.

model 568-570

For Earth-referenced spacecraft 609

Mathematical model 566-570 Gray Code—

' ■ Algorithm for conversion to binary 306-307

Conversion table 164 Output vs. Sun angle for sensors using 165

Reason for use 163-164

Reticle pattern for 164

Great circle 22 Construction of on global geometry plot 742

Equations for 728-729

Properties of 32

Greatest elongation 50

Greenwich Hour Angle 802-803 Greenwich Mean Time (GMT) (See also

Universal Time) 19, 801

Greenwich meridian 801 Subroutine for right ascension of

(RAGREN) 692

Greenwich Sidereal Time (GST) 802-804

Gregorian calendar century 809

GRO, use of MMS spacecraft 720 GSFC (See Goddard Space night Center) GTDS (See Goddard Trajectory

Determination System) Gyroscopes— Accuracy of attitude propagation with for HEAO-1 708-709

-As attitude determination reference 17 Attitude propagation with 564-566,558-559

Biases 198,200 Effect of misalignments on slew maneuvers 660

Hardware description 196-201 Mathematical models 266-270, 558,559 Measurements from (rate and rate integrating) 266-270

Modeling noise effects 268-270

Solution of differential equation 771-773 Spacecraft using 797

Gyrotorquer (See Control moment gyroscope)

Half-angle formulas, for spherical triangles 732 Hamming Code 296-297

Harmonic oscillator— Equation for forced 614

Solution for forced 771-773

Haversines 735-736

Advantages over normal trig functions 735 HCMM (Heat Capacity Mapping Mission) (See also AEM)— Attitude acquisition 662, 672

Attitude system 720, 790-791

Control system description 612-613. 617-621 Momentum wheel 202

Nutation damping 630

Scanwheels horizon sensor 176-178

Use of carbon dioxide band horizon

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