Prince William Composite Squadron

Col M. T. McNeely

Presentation for AGI Users Conference

CIVIL AIR PATROL PRESENTS

The CAP-STK Aerospace Education Program

INTRO TO SPACE COURSE

…using AGI’s Satellite Tool Kit

Why is this important?

• Intro to Space will enhance CAP Aerospace Education Program

• Broaden cadet’s knowledge of Space and Satellite operations

• Cadet will gain an understanding of a variety of Space fundamentals

• Orbital Mechanics• Types of Orbits • Placing a Satellite in Orbit• Conducting Satellite Operations

• Stimulate interest in the ‘Final Frontier’: THE FUTURE!!

ORBITAL MECHANICSLesson Plan 1 - Part 1

Origins Physical Laws Requirements for Injection Classifications of Orbits Coordinate Reference Systems Orbital Elements

PHYSICAL LAWSKepler’s 2nd Law: Law of Equal Areas

PHYSICAL LAWSKepler’s 2nd Law: Law of Equal Areas

The line joining the planet to the center of the sun sweeps out equal areas in equal times

T6

T5T4 T3

T2T1A2A3A4A5

A6

A1

PHYSICAL LAWSNewton’s 2nd Law: Law of Momentum

Change in momentum is proportional to and in the direction of the force applied

Momentum equals mass x velocity Change in momentum gives: F = ma

F

F

INJECTION REQUIREMENTSSpeed

100 miles

17,500 mi/hr

ORBITAL ELEMENTSKeplerian Elements

Semi-Major Axis (Size) Eccentricity (Shape) Inclination Right Ascension Argument of Perigee Epoch Time (Location within orbit)

– True Anomaly

(Orientation)

ORBIT CLASSIFICATIONShape (Conic Sections)

CircleEllipse

ORBIT CLASSIFICATIONSEccentricity

Eccentricity = c/a

e = 0.75

e = .45

e = 0

ORBITAL ELEMENTSKeplerian Elements: Inclination

Orbital Plane

Equatorial Plane

Inclination ( i )

ORBITAL ELEMENTSKeplerian Elements: Right Ascension

iLine of N

odes

Right Ascension of the Ascending Node ()

First Point of Aries ()

ORBITAL ELEMENTSKeplerian Elements: Argument of Perigee

iLine of N

odes

Argument of Perigee ()

ORBITAL MECHANICSLesson Plan 1 - Part 2

Ground Tracks Perturbations Launch Considerations Orbital Maneuvers De-orbit/Decay

Ground TracksWestward Regression

- Earth rotates east under a satellite => satellite appears to walk west

- Earth rotates 360 degrees in 24 hours (15 degrees per hour)

Ground TracksWestward Regression

0 30-30-60-90-120

ABC

A - time zeroB - after one orbitC - after two orbits

60

Ground tracks Inclination

60

30

0

30

60

45N

45S

Inclination = 45 degrees Eccentricity ~ 0

Ground TracksEccentricity

Ground Track for Molnyia orbit eccentricity = .7252

PERTURBATIONS

Definition– A disturbance in the regular motion of a

satellite Types

– Gravitational– Atmospheric Drag– Third Body Effects– Solar Wind/Radiation Effects– Electro-magnetic

PERTURBATIONSGravitational: Libration

Ellipticity of the Earth causes gravity wells and hills

Stable points: 75E and 105W-- Himalayas and Rocky Mountains

Unstable points: 165E and 5W-- Marshall Islands and Portugal

Drives the requirement for stationkeeping

PERTURBATIONSElectro-Magnetic

Interaction between the Earth’s magnetic field and the satellite’s electro-magnetic field results in magnetic drag

LAUNCH CONSIDERATIONSLaunch Windows

The period of time during which a satellite can be launched directly into a specific orbital plane from a specific launch site

Window duration driven by safety, fuel requirements, desired injection points, etc.

Window is centered around optimal launch time

DE-ORBIT/DECAY

De-Orbit is the controlled re-entry of a satellite to a specific location– Used for the recovery of payload

Manned missions

Decay is uncontrolled re-entry – Potential impact anywhere along ground

track– Re-entry Assessment (by Cheyenne Mountain)

TYPES OF ORBITSLesson Plan 2

Types of Satellites and Missions

Satellites vs Orbits

Use STK to Evaluate Orbit Type vs Mission Requirement

TYPES OF ORBITS -Uses of Satellites

Daily Uses of Satellites Big Picture Affects of Altitude

TYPES OF ORBITS -Uses of Satellites

GPS Receiver Used in Search and Rescue Missions

TYPES OF ORBITS

LEO MEO HEO GEO

PLACING A SATELLITE IN ORBITLesson Plan 3

How Satellites are Launched

Location Advantages of Two Primary Launch Sites

Purpose of a Hohmann Transfer

Use STK to Demonstrate Concepts

PLACING SATELLITES IN ORBIT

Booster Types

DELTA II

PLACING SATELLITES IN ORBIT

Booster Types

ATLAS 2AS

PLACING SATELLITES IN ORBIT

Booster Types

TITAN IV

PLACING SATELLITES IN ORBIT

Booster Types

TAURUS

PLACING SATELLITES IN ORBIT Booster Types

TheSHUTTLEBOOSTER

PLACING SATELLITES IN ORBIT

Booster Types

PEGASUS

PLACING SATELLITES IN ORBIT Launch Constraints

CONDUCTING SATELLITE OPERATIONSLesson Plan 4

Basic Elements of a Space System

Space System Functions

Access

STK Demonstrations

SATELLITE OPERATIONSFUNCTIONS

GPS Example

EXERCISESLesson Plan 5

Apply Knowledge Concepts to Problems and Formulate Solutions

Demonstrate with STK

INTRO TO SPACESUMMARY

Classroom Presentations

using Powerpoint

Demonstrate with STK

Let’s Demo !!

The world of Space Operations awaits you!!