Orbitals Perturbations
Forces other than Earth's gravitational force that change the orbit of a satellite.
What are Orbital Perturbations?
An orbit with an eccentricity of 0, and an inclination of 0 degrees.
What is a Geostationary Orbit?
The imaginary line which extends straight up from the center of the Earth and intersects the satellite.
What is the Zenith?
The area of the terrain covered by the IFOV of a detector.
What is a Ground Resolution Cell?
An angle measured in the direction of the satellite motion from the ascending node to perigee.
What is the Argument of Perigee?
Shifting of the location of perigee, which changes the argument of perigee.
What is the Rotation of Perigee?
A typical Low Earth Orbit (LEO) takes about this much time to complete one revolution.
What is 90 minutes?
The look angle commonly used to describe NUDET locations with respect to a satellite.
What is the Zenith Angle?
The two angles used to describe relative direction and height above which a satellite is from a ground station.
What is Azimuth and Elevation angle?
An imaginary point on the Earth's surface defined by a line connecting the satellite and the Earth's center. Thought of as the point on Earth directly below the satellite.
What is the Sub-Point?
Molecules without electric charge, along with oxygen ions, which cause perturbing forces on a satellite.
What is Atmospheric Drag?
A specific type of Low Earth Orbit (LEO), it ensures a constant sun angle.
What is a Sun-Synchronous Orbit?
Used to describe the distance between two satellites at approximately the same altitude.
What is a Depression Angle?
The area on the Earth a sensor is capable of seeing.
What is the Field of Regard (FOR)?
1 second increments which are used to keep UTC within 0.9 seconds of the observed solar time.
What is a Leap Second?
The rotation of the orbital about the polar axis, this shift is always opposite of the satellite's rotational direction.
What is Nodal Regression?
Known as a Highly Elliptical Orbit (HEO), has a typical apogee at 38,900 km and perigee near 550 km. Is used to counter the rotation of perigee.
What is a Molniya Orbit?
Region of complete darkness when a satellite sensor would not be looking into the sun.
What is the Umbra?
The three modes of scanning systems.
What is Cross-Track, Along-Track, and Circular Scanners.
Term used to specify the moment in time that all orbital elements are true.
What is the (Orbit) Epoch Time?
Practice of maintaining the orbital position of satellites in their correct orbit.
What is Station Keeping?
Since a Geostationary Orbit cannot provide worldwide coverage, this many satellites can be used in constellation to get that coverage.
What is 3 to 6?
The points in the Earth's orbit that eclipse periods occur for geosynchronous satellites.
What is Vernal and Autumnal Equinoxes?
A set of parameters used to calculate the approximate location of a satellite.
What is Almanac data?
Simply the location where the satellite is launched.
What is the Injection Point?