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

1
Q

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

A

90-120 minutes

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2
Q

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

A

𝑖 = 0 and 𝑒 = 0

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3
Q

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

A

Sun-Synchronous Orbit
(SSO)

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4
Q

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

A

Highly-Elliptical Orbit
(HEO)

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5
Q

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

A

Field of regard

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6
Q

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

A

Field of view

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7
Q

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

A

Dwell time

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8
Q

Principal Direction of:

Earth Centered Inertial
(ECI)

A

Vernal Equinox

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9
Q

Principal Direction of:

Earth Centered Earth Fixed
(ECEF)

A

0° Latitude, 0° Longitude

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10
Q

Principal Direction of:

Perifocal

A

Eccentricity Vector

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11
Q

Principal Direction of:

Radial In-track Cross-track
(RIC)

A

Radial

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12
Q

Use case of:

Earth Centered Inertial
(ECI)

A

A non-rotating view

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13
Q

Use case of:

Earth Centered Earth Fixed
(ECEF)

A

Show a satellite’s ground track

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14
Q

Use case of:

Perifocal

A

A frame centered at the focus of the orbit

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15
Q

Use case of:

Radial In-track Cross-track
(RIC)

A

Relative motion and maneuvers

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16
Q

What orbital element is used to find size of orbit?

A

Semi major axis, 𝑎

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17
Q

What orbital element is used to find shape of orbit?

A

Eccentricity, 𝑒

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18
Q

What orbital element is used to find tilt of orbit?

A

Inclination, 𝑖

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19
Q

What orbital element is used to find twist of orbit?

A

Right Ascension of the Ascending Node
(RAAN), Ω

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20
Q

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

A

Argument of Perigee, 𝜔

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21
Q

What orbital element is used to find satellite location?

A

True Anomaly, 𝜈

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22
Q

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

A
  1. RAAN, Ω
  2. Argument of Perigee, 𝜔
  3. True Anomaly, 𝜈
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23
Q

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

A

0 to ∞

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24
Q

What is range of Eccentricity, 𝑒?

A

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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25
Q

What is the range of Inclination, 𝑖?

A

0 to 180°

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26
Q

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

A

Equatorial Plane

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27
Q

Which reference frame uses a satellite as its origin?

A

Radial In-track Cross-track (RIC)

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28
Q

Newton’s 3rd Law

A

To every action there is always an opposed and equal reaction

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29
Q

Define:

Newton’s 1st Law

A

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

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30
Q

Define:

Universal Gravitation

A

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

31
Q

Define:

Newton’s 2nd Law

A

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

32
Q

Define:

Kepler’s 2nd Law

A

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

33
Q

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

A

Law of Equal Areas

34
Q

Kepler’s 1st Law

A

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

35
Q

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

A

Law of Ellipses

36
Q

Kepler’s 3rd Law

A

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

37
Q

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

A

Law of Harmonies

38
Q

How long is a sidereal day?

A

23H 56M 04.09S

39
Q

Low Earth Orbit (LEO) has a period of?

A

90 to 120 minutes

40
Q

Low Earth Orbit (LEO) has an altitude of?

A

2000 km or less

41
Q

Medium Earth Orbit (MEO) has a period of?

A

Greater than 120 minutes and less than 24 hours

42
Q

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

A
  • Position, Navigation, & Timing (PNT)
  • SATCOM
  • Persistent Earth Observation
43
Q

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

A

~12 hours

44
Q

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

A

~24 hours

45
Q

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

A

35,786 km

46
Q

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

A

Three satellites in Geo-Synchronous Orbit (GEO)

47
Q

Define:

Geo-Stationary Orbit

A

A GEO orbit where inclination and eccentricity both equal 0

48
Q

Define:

Sun-Synchronous Orbit (SSO)

A

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

49
Q

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

A

There are gaps left by GEO orbits

50
Q

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

A
  • SATCOM
  • Missile Warning
51
Q

Define:

Field of Regard

A

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

52
Q

Define:

Field of View

A

The instantaneous coverage area capable of being seen by the payload

53
Q

Define:

Dwell Time

A

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

54
Q

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

A

42,164 km

55
Q

ECI reference frame is used to do what?

A
  • Describe orbits
  • Define classical orbital elements
56
Q

What is a non-rotating reference frame?

A

Earth Centered Inertial
(ECI)

57
Q

What reference frame is “rotating” with the Earth?

A

Earth Centered Earth Fixed
(ECEF)

58
Q

The ECEF reference frame used to do what?

A

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

59
Q

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

A

Radial In-track Cross-track (RIC)

60
Q

What is the shape of 𝑒 = 0?

Eccentricity

A

Circular

61
Q

What is the shape of 0 < 𝑒 < 1?

Eccentricity

A

Elliptical

62
Q

What is the shape of 𝑒 = 1?

Eccentricity

A

Parabolic

63
Q

What is the shape of 𝑒 > 1?

Eccentricity

A

Hyperbolic

64
Q

What type of orbit is 𝑖 = 0°, 180°?

A

Equatorial

65
Q

What type of orbit is 𝑖 = 90°?

A

Polar Orbit

66
Q

What type of orbit is 0° > 𝑖 > 90°?

A

Prograde Orbit

67
Q

What type of orbit is 90° < 𝑖 < 180°?

A

Retrograde Orbit

68
Q

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

A

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

69
Q

How is Argument of Perigee (𝜔) measured?

A

From Ascending Node to Perigee

70
Q

How is True Anomaly (𝜈) measured?

A

From perigee to the satellite location

71
Q

What do Sidereal Angles determine?

A

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

72
Q

What is the most commonly used orbital regime?

A

Low Earth Orbit (LEO)

73
Q

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

A

Equatorial Plane

74
Q

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

A

Orbit/Size