OEM Day 2

Question 1

Reference frame

Answer 1

consists of an abstract coordinate system and the set of physical reference points that uniquely fix (locate and orient) the coordinate system and standardize measurements within that frame

Question 2

Equatorial plane

Answer 2

Passes through Earth’s equator

Question 3

Ecliptic plane

Answer 3

Plane of Earth’s orbit around the sun (separated from Equatorial plane by 23.5º due to the tilt of Earth’s axis)

Question 4

Orbital plane

Answer 4

The plane on which a satellite orbits

Question 5

Earth Centered Inertial Frame (ECI)

Answer 5

• Describe orbits and define the Classical Orbital Elements (COEs)
• Non-rotating
• Origin: Earth
• Fundamental Plane: Equatorial
• Principal Direction: Vernal Equinox (Spring)

Question 6

First Point of Aries

Answer 6

Points from Earth through Sun when planes intersect

Question 7

Earth Centered Earth Fixed Frame (ECEF)

Answer 7

• describe ground tracks, the path a satellite travels relative to the Earth’s surface.
• Rotating
• Origin: Earth
• Fundamental Plane: Equatorial
• Principal Direction: 0° Latitude, 0° Longitude (Prime Meridian)

Question 8

Perifocal Frame

Answer 8

• top-down view/birds eye view of the orbit
• Origin: Earth
• Fundamental Plane: Orbital
• Principal Direction: Eccentricity Vector (Points towards Periapsis)

Question 9

Radial In-Track Cross-Track Frame (RIC)

Answer 9

• describes motion from an individual satellite’s perspective, - Origin: Satellite
• Fundamental Plane: Orbital
• Principal Direction: Radial (Points directly away from the Earth)

Question 10

Sidereal Day

Answer 10

• angle between the principal axes of the Earth-Inertial and Earth-Fixed frames
• determine when to do a launch, in order to launch at a specific RAAN.
• 23h56m04.09s
• Earth rotates exactly 360°

Question 11

Mean Solar Day

Answer 11

• 24 h
• Earth rotates past 360° to face the Sun