Related topics: nasa

Mars has belts of glaciers consisting of frozen water

Mars has distinct polar ice caps, but Mars also has belts of glaciers at its central latitudes in both the southern and northern hemispheres. A thick layer of dust covers the glaciers, so they appear as surface of the ground, ...

Dark, massive asteroid to fly by Earth on May 31

It's 1.7 miles long. Its surface is covered in a sticky black substance similar to the gunk at the bottom of a barbecue. If it impacted Earth it would probably result in global extinction. Good thing it is just making a flyby.

Scientists demonstrate quantum radar prototype

Physicists at the Institute of Science and Technology Austria (IST Austria) have invented a new radar prototype that uses quantum entanglement as a method of object detection. This successful integration of quantum mechanics ...

'Lakes' under Mars' south pole: A muddy picture?

Two research teams, using data from the European Space Agency's Mars Express orbiter, have recently published results suggesting that what were thought to be subsurface lakes on Mars may not really be lakes at all.

Scientists set new speed record for big data

( —IBM today announced that it has achieved a new technological advancement that will help improve Internet speeds to 200 - 400 Gigabits per second (Gb/s) at extremely low power.

Massive asteroid with moon to pass Earth today

An asteroid nearly two miles (three kilometers) wide is set to pass by Earth Friday with no risk of impact, offering scientists a rare chance to study a massive flying object with its own moon.

New NASA radar technique finds lost lunar spacecraft

Finding derelict spacecraft and space debris in Earth's orbit can be a technological challenge. Detecting these objects in orbit around Earth's moon is even more difficult. Optical telescopes are unable to search for small ...

page 1 from 40


Radar is an object detection system that uses electromagnetic waves to identify the range, altitude, direction, or speed of both moving and fixed objects such as aircraft, ships, motor vehicles, weather formations, and terrain. The term RADAR was coined in 1941 as an acronym for radio detection and ranging. The term has since entered the English language as a standard word, radar, losing the capitalization. Radar was originally called RDF (Radio Direction Finder, now used as a totally different device) in the United Kingdom.

A radar system has a transmitter that emits microwaves or radio waves. These waves are in phase when emitted, and when they come into contact with an object are scattered in all directions. The signal is thus partly reflected back and it has a slight change of wavelength (and thus frequency) if the target is moving. The receiver is usually, but not always, in the same location as the transmitter. Although the signal returned is usually very weak, the signal can be amplified through use of electronic techniques in the receiver and in the antenna configuration. This enables radar to detect objects at ranges where other emissions, such as sound or visible light, would be too weak to detect. Radar is used in meteorological detection of precipitation, measuring ocean surface waves, air traffic control, police detection of speeding traffic, and by the military.

This text uses material from Wikipedia, licensed under CC BY-SA