A propellant (or propellent) is a mass that is expelled or expanded in such a way as to create a thrust or other motive force in accordance with Newton's third law of motion, and "propel" a vehicle, projectile, or fluid payload. In vehicles, the engine that expels the propellant is called a reaction engine.
In the aerospace context, 'ocean' refers to the use of satellites, aircrafts and unmanned aerial vehicles (UAVs) to monitor, survey, and study the oceans, their characteristics, and the life forms that inhabit them. This is known as oceanography and it is a branch of Earth science.
Examples of applications of aerospace technology in oceanography include:
- Satellite remote sensing, which uses satellites to measure ocean temperature, color, and roughness to track ocean currents and monitor phytoplankton blooms
- Aerial remote sensing, which uses aircrafts and UAVs to measure ocean parameters such as temperature, salinity, and chlorophyll
- Oceanographic research, which involves using aircrafts, UAVs and satellites to study the ocean's physical and biological processes
- Marine pollution monitoring, which uses satellite data to detect and track oil spills and other forms of marine pollution
- Fisheries management, which uses satellite data to track fish populations and monitor fishing activity
Some examples of organizations that are involved in the aerospace and oceanography field are NASA, European Space Agency (ESA), National Oceanic and Atmospheric Administration (NOAA) and European Centre for Medium-Range Weather Forecasts (ECMWF).