Radar astronomy

From Academic Kids

Radar astronomy is a technique of imaging nearby astronomical objects. It is reflecting microwaves off objects in the Solar system with reception and analysis of the echoes. This research has been conducted for four decades. Radar astronomy differs from radio astronomy in that the latter is a passive observation and this technique is active one. Radar systems have been used for a wide range of solar system studies. It works by sending extremely powerful pulses of radio waves in the microwaves spectrum from ground based generators, and then detecting the return signal with large arrays of radio dishes. A difference exists between pulse and continuous wave radar astronomy.

First age of radar astronomy was from 1960 to 1975. Relatively low sensitivity observation occurred and limited observations to terrestrial planets and near terresterial objects. The second age has been from 1975 to the present.

The strength of the radar return signal is proportional to the fourth root of the distance to the object. Upgraded facilities, increase in transceiver power, and improved apparatus will lead to increased observational opportunities.

Radar techniques provide unavailable information from other means. Radar astronomy provided tests of general relativity. Radar astronomy has provided a refinement in the value of the astronomical unit. Radar images provide information about the shapes and surface properties of solid bodies. Radar can determine distances and planetary features within the solar system.

Contents

1 Planetary
2 Asteroids and comets
3 External links

Advantages

  • Control of attributes of the signal [i.e., the waveform's time/frequency modulation and polarization];
  • Resolve objects spatially;
  • Delay-Doppler measurement precision;
  • Optically opaque penetration;
  • Sensitive to high concentrations of metal or ice.

Planetary

The following are a list of planetary bodies that have been observed by this means:

Mars
Mercury - Improved value for the distance from the earth observed. Rotational periods and gross surface properties recorded to a greater accuarcy.
Venus - first made in 1960. Rotation period first determined. First by Earth-based radar and then by probes. Improved value for the distance from the earth to the moon observed. Rotational periods and gross surface properties recorded to a greater accuarcy. Surface mapped by unmanned probes [by radar altimeters].
Moon - first made in 1945. Rotation period first determined. First by Earth-based radar and then by probes. Improved value for the distance from the earth to the moon observed [within centimeters]. Special reflectors were installed [Apollo Mission]. Falloff of a few seconds cased by libration recorded and faraday rotation.
Jupiter System
Saturn System

Mars is planned on being scanned for water.

Asteroids and comets

The techniques of radar astronomy have been applied to non-planetary solar system bodies. Radar provides the ability to study the position, shape, size and spin state of the asteroids. The observation of asteroids with reflectivity allows remote sensing of the surface composition of the surfaces. Radar return reception, and its interferometric data, have produced sharp images. With more such data, the range of size, shape, spin and radar albedo of asteroids and comets will be explored.

Comets have not been studied as yet, due to technical deficiencies and the range of many comets. Upgraded telescopes will enable detections of asteroids.

External links

See also: Radio astronomy; Deep Space Networkde:Radarastronomie

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