Venus Orbiting Imaging Radar (VOIR; also called Venus Orbital Imaging Radar) was a planned 1983 U.S. spacecraft mission to

Venus Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never f ...

that was primarily intended to use a

microwave imaging Microwave imaging is a science which has been evolved from older detecting/locating techniques (e.g., radar) in order to evaluate hidden or embedded objects in a structure (or media) using electromagnetic (EM) waves in microwave regime (i.e., ~300&n ...

radar to perform mapping of the Venusian surface. The goal was to map up to 50% of the planet's surface down to a resolution of 2 km with the eventual goal of targeting landers and atmospheric probes. A 1978 study evaluated the potential use of

synthetic aperture radar Synthetic-aperture radar (SAR) is a form of radar that is used to create two-dimensional images or three-dimensional reconstructions of objects, such as landscapes. SAR uses the motion of the radar antenna over a target region to provide fine ...

to achieve 200 meter resolution. The spacecraft was to be launched from the

Space Shuttle The Space Shuttle is a retired, partially reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program. Its official program ...

using a twin stage IUS in December 1984, and arrive in orbit May 1985. The mission was expected to last until November 1985. By 1981, the plan was for the spacecraft to launch in 1987 and to use

aerobraking Aerobraking is a spaceflight maneuver that reduces the high point of an elliptical orbit ( apoapsis) by flying the vehicle through the atmosphere at the low point of the orbit ( periapsis). The resulting drag slows the spacecraft. Aerobraking ...

to circularize its orbit, whereupon it would be able to generate radar coverage of the entire planet over a period of 126 days. Data transmission rates were 1 Mbit per second, matching the imaging and recording speed. It would have two resolutions: mapping mode of 600 m per line-pair, then a high-resolution mode at 150 m per line-pair. The mission was cancelled in 1982 when it exceeded its budget limit. In 1983, it was replaced by a less ambitious mission called the Venus Radar Mapper, which was later renamed

Magellan Ferdinand Magellan ( or ; pt, Fernão de Magalhães, ; es, link=no, Fernando de Magallanes, ; 4 February 1480 – 27 April 1521) was a Portuguese explorer. He is best known for having planned and led the 1519 Spanish expedition to the East ...

References

{{Venus spacecraft Missions to Venus Cancelled spacecraft Projects disestablished in 1982