GLOSSARY

Acquisition
When a satellite in space takes a picture of the Earth.

Astrobleme
An eroded remnant of a large crater made by the impact of a meteorite or comet.

Classification
The computational process of assigning individual pixels in a digital image into different groups.

Change detection
The process of monitoring an event and observing its changes over time.

Digital Elevation Model (DEM)
An image representing the Earth’s altitude from sea level.

Dome
A circular feature consisting of symmetrically dipping anticlines.

Earth observation
A process of looking down at the Earth and capturing images of the Earth using an elevated platform such as an aircraft or satellites of various sensors.

Electromagnetic radiation
Energy propagated from the sun or through material media in the form of an advancing interaction between electrical and magnetic fields.

Electromagnetic spectrum
The range of energy in the visible, infrared, ultraviolet, microwave, gamma ray, x-ray and radio, which travels at the speed of light.

False colour composite
An image colour combination not representing a true colour.

Geostationary orbit
The circular path around the Earth equator at a distance of 36 000km following the movement of the Earth.

Gravity field
A model used to explain the influence that a massive body extents into space around itself, producing a force on another massive body.

High-resolution camera
See Spatial Resolution.

Launch vehicle
A rocket used to carry a payload from the Earth’s surface into outer space.

Low Earth Orbit (LEO) Satellite
A satellite that circumnavigate Earth at a distance of between 160km and 2 000km.

Minitrack station
See Receiving Station.

Multispectral cameras
A section of cameras that captures image data at specific frequencies across the electromagnetic spectrum.

Meteorite
A meteorite is a solid piece made up of fragments, from asteroids or comets, that originates in outer space and survives its impact with the Earth's surface Before impact it is called a meteoroid.

Orbit
The gravitational curved path traced by a satellite as it passes around a planet.

Panchromatic band
A higher-resolution image of a satellite.

Rocket
An aircraft or a vehicle that is used to propel satellites to orbit.

Spatial (geometric) resolution
The distance each image pixel covers on the ground.

Sensor
A scanner and/or camera that records a remote-sensing image.

Spectral band
Satellite image captured at a specific wavelength of the electromagnetic spectrum.

Swath width
The linear ground distance in the across-track direction that is covered by a sensor on a single overpass.

Satellite
The platform that carries imaging sensors in space orbiting the Earth.

Subset
A section cut off from a larger satellite image or a scene.

Temporal resolution
The length of time it takes for a satellite to complete an entire orbit cycle or the period it takes a satellite sensor to capture the same area.

Telecommunications
Communication at a distance by technological means, particularly through electrical signals or electromagnetic waves.

Tracking Telemetry and Command
Provides the monitoring of the health and status of the satellite through the collection, processing and transmission of data from the various satellites.

Transmitting
To send signals or commands to a satellite in space or from space to ground receiving stations.

True Colour Composite
An image colour combination representing a true colour.

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© Copyright: South African National Space Agency 2015. All rights are reserved.