PC 1 Study Guide Flashcards by Gray Nguyen

How long is the Period of a satellite in Low Earth Orbit (LEO)?

90-120 minutes

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What is the inclination and eccentricity of Geo-stationary GEO orbit?

𝑖 = 0 and 𝑒 = 0

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The same sun angle or shadow every orbit is a characteristic of what orbit?

Sun-Synchronous Orbit
(SSO)

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What orbit creates long dwell times, normally over the northern latitudes, for mission requirements?

Highly-Elliptical Orbit
(HEO)

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What operational consideration describes the portion of Earth’s surface that is geometrically visible from the satellite’s position in space?

Field of regard

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What operational consideration describes the instantaneous coverage area capable of being seen by the payload?

Field of view

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What operational consideration describes the length of time a satellite has line of sight to a point on Earth?

Dwell time

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Principal Direction of:

Earth Centered Inertial
(ECI)

Vernal Equinox

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Principal Direction of:

Earth Centered Earth Fixed
(ECEF)

0° Latitude, 0° Longitude

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Principal Direction of:

Perifocal

Eccentricity Vector

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Principal Direction of:

Radial In-track Cross-track
(RIC)

Radial

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Use case of:

Earth Centered Inertial
(ECI)

A non-rotating view

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Use case of:

Earth Centered Earth Fixed
(ECEF)

Show a satellite’s ground track

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Use case of:

Perifocal

A frame centered at the focus of the orbit

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Use case of:

Radial In-track Cross-track
(RIC)

Relative motion and maneuvers

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What orbital element is used to find size of orbit?

Semi major axis, 𝑎

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What orbital element is used to find shape of orbit?

Eccentricity, 𝑒

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What orbital element is used to find tilt of orbit?

Inclination, 𝑖

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What orbital element is used to find twist of orbit?

Right Ascension of the Ascending Node
(RAAN), Ω

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What orbital element is used to find orbit rotation/orientation?

Argument of Perigee, 𝜔

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What orbital element is used to find satellite location?

True Anomaly, 𝜈

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What 3 orbital elements have a range of 0 to 360°?

RAAN, Ω
Argument of Perigee, 𝜔
True Anomaly, 𝜈

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What is the range of the Semi Major Axis, 𝑎?

0 to ∞

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What is range of Eccentricity, 𝑒?

0 to 1+

The chart in the packet says 0 to 1 but remember that an eccentricity of over 1 is hyperbolic.

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What is the range of Inclination, 𝑖?

0 to 180°

The ECI and ECEF reference frames utilize what as their fundamental plane?

Equatorial Plane

Which reference frame uses a satellite as its origin?

Radial In-track Cross-track (RIC)

Newton's 3rd Law

To every action there is always an opposed and equal reaction

# Define: Newton's 1st Law

An object either remains at rest or continues to move at a constant velocity, unless acted upon by an external force

# Define: Universal Gravitation

Any two bodies attract one another with a force proportional to the product of their masses and inversely proportional to the square of the distance between them

# Define: Newton's 2nd Law

The rate of change of momentum is proportional to the force impressed and is in the same direction as that force

# Define: Kepler's 2nd Law

The orbiting body must be moving faster when it is closer and slower when it is farther away

Kepler's 2nd Law is also known as what?

Law of Equal Areas

Kepler's 1st Law

The planets orbit the sun in elliptical orbits, with the Sun at one focus of the ellipse

Kepler's 1st Law is also known as what?

Law of Ellipses

Kepler's 3rd Law

The period of the orbit squared is proportional to the semi-major axis cubed

Kepler's 3rd Law is also known as what?

Law of Harmonies

How long is a sidereal day?

23H 56M 04.09S

Low Earth Orbit (LEO) has a period of?

90 to 120 minutes

Low Earth Orbit (LEO) has an altitude of?

2000 km or less

Medium Earth Orbit (MEO) has a period of?

Greater than 120 minutes and less than 24 hours

Medium Earth Orbit (MEO) supports what mission(s)?

* Position, Navigation, & Timing (PNT) * SATCOM * Persistent Earth Observation

MEO Semi-Synchronous Orbit is a MEO orbit with a period of?

~12 hours

Geo-Synchronous Orbit (GEO) orbits have a period of?

~24 hours

Geo-Synchronous Orbit (GEO) orbits have an altitude of?

35,786 km

How can you get global coverage with the exception of the polar regions?

Three satellites in Geo-Synchronous Orbit (GEO)

# Define: Geo-Stationary Orbit

A GEO orbit where inclination and eccentricity both equal 0

# Define: Sun-Synchronous Orbit (SSO)

Special, near-polar inclination, LEO orbit with a retrograde motion

Highly Elliptical Orbit (HEO) orbits allow max coverage at higher latitudes. Why is this needed?

There are gaps left by GEO orbits

Geo-Synchronous Orbit (GEO) supports what mission(s)?

* SATCOM * Missile Warning

# Define: Field of Regard

The portion of Earth's surface that is geometrically visible from the satellite's position in space

# Define: Field of View

The instantaneous coverage area capable of being seen by the payload

# Define: Dwell Time

The length of time a satellite has line of sight to a point on the Earth

What is the semi-major axis of Geo-Synchronous Orbit (GEO)?

42,164 km

ECI reference frame is used to do what?

* Describe orbits * Define classical orbital elements

What is a non-rotating reference frame?

Earth Centered Inertial (ECI)

What reference frame is "rotating" with the Earth?

Earth Centered Earth Fixed (ECEF)

The ECEF reference frame used to do what?

Describe ground tracks and the path a satellite travels relative to the Earth's surface

What reference frame is best used to describe motion from an individual satellite's perspective?

Radial In-track Cross-track (RIC)

What is the shape of 𝑒 = 0? ## Footnote Eccentricity

Circular

What is the shape of 0 < 𝑒 < 1? ## Footnote Eccentricity

Elliptical

What is the shape of 𝑒 = 1? ## Footnote Eccentricity

Parabolic

What is the shape of 𝑒 > 1? ## Footnote Eccentricity

Hyperbolic

What type of orbit is 𝑖 = 0°, 180°?

Equatorial

What type of orbit is 𝑖 = 90°?

Polar Orbit

What type of orbit is 0° > 𝑖 > 90°?

Prograde Orbit

What type of orbit is 90° < 𝑖 < 180°?

Retrograde Orbit

How is Right Ascension of the Ascending Node (RAAN)(Ω) measured?

From Vernal Equinox (First Point of Aries) to Ascending Node

How is Argument of Perigee (𝜔) measured?

From Ascending Node to Perigee

How is True Anomaly (𝜈) measured?

From perigee to the satellite location

What do Sidereal Angles determine?

Determine when to do a launch, in order to launch at a specific RAAN, Ω

What is the most commonly used orbital regime?

Low Earth Orbit (LEO)

What is the inclination of a satellite orbiting Earth measured off of?

Equatorial Plane

The greater the energy of an orbit, the larger the what?

Orbit/Size

PC 1 Study Guide Flashcards

Assignment 1 + Study Guide: Physics Intro, Two Body Problem, Kepler's Laws, Reference Frames, Classic Orbital Elements, Kepler's Problems, Orbit Types (74 cards)