Venera 15 (russian: Венера-15 meaning ''Venus 15'') was a

spacecraft A spacecraft is a vehicle or machine designed to fly in outer space. A type of artificial satellite, spacecraft are used for a variety of purposes, including communications, Earth observation, meteorology, navigation, space colonization, ...

sent 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 ...

by the

Soviet Union The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nationa ...

. This uncrewed orbiter was to map the surface of Venus using high resolution imaging systems. The spacecraft was identical to Venera 16 and based on modifications to the earlier

Venera The Venera (, , which means "Venus" in Russian) program was the name given to a series of space probes developed by the Soviet Union between 1961 and 1984 to gather information about the planet Venus. Ten probes successfully landed on the s ...

space probes.

Mission profile

Venera 15 was launched on June 2, 1983, at 02:38:39 UTC and reached Venus' orbit on October 10, 1983. The spacecraft was inserted into Venus orbit a day apart from Venera 16, with its orbital plane shifted by an angle of approximately 4° relative to the other probe. This made it possible to reimage an area if necessary. The spacecraft was in a nearly polar orbit with a

periapsis An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any elli ...

~1000 km, at 62°N latitude, and

apoapsis An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any elli ...

~65000 km, with an

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Ea ...

~90°, the orbital period being ~24 hours. Together with Venera 16, the spacecraft imaged the area from the north pole down to about 30°N latitude (i.e. approx. 25% of Venus surface) over the 8 months of mapping operations.

Spacecraft structure

The Venera 15 and 16 spacecraft were identical and were based on modifications to the

Venera 9 Venera 9 (russian: Венера-9, lit=Venus-9), manufacturer's designation: 4V-1 No. 660, was a Soviet uncrewed space mission to Venus. It consisted of an orbiter and a lander. It was launched on June 8, 1975, at 02:38:00 UTC and had a m ...

orbiter and the Venera 14 carrier spacecraft. Each spacecraft consisted of a long cylinder with a diameter, tall parabolic dish antenna for the

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 ...

(SAR) at one end. A 1-meter diameter parabolic dish antenna for the radio altimeter was also located at this end. The electrical axis of the radio altimeter antenna was lined up with the axis of the cylinder. The electrical axis of the SAR deviated from the spacecraft axis by 10 degrees. During imaging, the radio altimeter would be lined up with the center of the planet (local vertical) and the SAR would be looking off to the side at 10 degrees. A bulge at the opposite end of the cylinder held fuel tanks and propulsion units. Two square solar arrays extended like wings from the sides of the cylinder. A radio dish antenna for communications was also attached to the side of the cylinder. The spacecraft each massed . Both Venera 15 and 16 were equipped with a

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 fin ...

(SAR). A

radar Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, Marine radar, ships, spacecraft, guided missiles, motor v ...

was necessary in this mission because nothing else would be able to penetrate the dense clouds of Venus. The probes were equipped with on board computers that saved the images until the entire image was complete. This radar system replaced the normal landers that previous Venera probes brought to Venus. List of spacecraft instruments and experiments: * Polyus-V Synthetic Aperture Radar * Omega

Radar altimeter A radar altimeter (RA), also called a radio altimeter (RALT), electronic altimeter, reflection altimeter, or low-range radio altimeter (LRRA), measures altitude above the terrain presently beneath an aircraft or spacecraft by timing how long it t ...

* Infrared Fourier Spectrometer * Cosmic-Ray Detectors (6 sensors) * Solar-Plasma Detectors To get to Venus, Venera 15 was placed in a

heliocentric orbit A heliocentric orbit (also called circumsolar orbit) is an orbit around the barycenter of the Solar System, which is usually located within or very near the surface of the Sun. All planets, comets, and asteroids in the Solar System, and the Sun ...

with

perihelion An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any elli ...

of 0.71 AU, apohelion of 1.01 AU, eccentricity of 0.17,

orbital inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Ea ...

of 2.3 degrees and

orbital period The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting pla ...

of 293 days.

References

External links

The Soviet Exploration of Venus
{{Orbital launches in 1983 Venera program Derelict space probes 1983 in the Soviet Union Space synthetic aperture radar Non Earth orbiting satellites of the Soviet Union Spacecraft launched by Proton rockets Spacecraft launched in 1983

Mission profile

Spacecraft structure

See also

References

External links