Vega 2
Encyclopedia
Vega 2 is a Soviet space probe
part of the Vega program
. The spacecraft was a development of the earlier Venera
craft. They were designed by Babakin Space Center and constructed as 5VK by Lavochkin
at Khimki
. The craft was powered by twin large solar panel
s and instruments included an antenna
dish, camera
s, spectrometer
, infrared
sounder, magnetometer
s (MISCHA), and plasma
probes. The 4,920 kg craft was launched by a Proton 8K82K rocket
from Baikonur Cosmodrome
, Tyuratam
, Kazakh SSR
. Both Vega 1 and 2 were three-axis stabilized spacecraft. The spacecraft were equipped with a dual bumper shield for dust protection from Halley's Comet.
explorer.
. The altitude of the touchdown site was 0.1 km above the planetary mean radius. The measured pressure at the landing site was 91 atm
and the temperature was 736 K
. The surface sample was found to be an anorthosite
-troctolite
rock, rarely found on Earth, but present in the lunar highlands, leading to the conclusion that the area was probably the oldest explored by any Venera vehicle. It transmitted data from the surface for 56 minutes.
The spacecraft initiated its encounter on March 7, 1986 by taking 100 photos of the comet from a distance of 14 million kilometers.
Vega 2 made its closest approach at 07:20 UT on March 9, 1986 at 8,030 km. The data intensive examination of the comet covered only the three hours around closest approach. They were intended to measure the physical parameters of the nucleus, such as dimensions, shape, temperature and surface properties, as well as to study the structure and dynamics of the coma
, the gas composition close to the nucleus, the dust particles' composition and mass distribution as functions of distance to the nucleus and the cometary-solar wind
interaction.
During the encounter, Vega 2 took 700 images of the comet, with better resolution than those from the twin Vega 1
, partly due to the presence of less dust outside of the coma at the time. Yet Vega 2 recorded an 80% power loss during the encounter as compared to Vega 1's 40%.
After further imaging sessions on 10 and 11 March 1986, Vega 2 finished its primary mission. Vega 1 ran out of attitude control propellant on 30 January 1987, and contact with Vega 2 continued until 24 March 1987.
Vega 2 is currently in heliocentric orbit
.
Space probe
A robotic spacecraft is a spacecraft with no humans on board, that is usually under telerobotic control. A robotic spacecraft designed to make scientific research measurements is often called a space probe. Many space missions are more suited to telerobotic rather than crewed operation, due to...
part of the Vega program
Vega program
The Vega program was a series of Venus missions which also took advantage of the appearance of Comet Halley in 1986. Vega 1 and Vega 2 were unmanned spacecraft launched in a cooperative effort among the Soviet Union and Austria, Bulgaria, Hungary, the German Democratic Republic, Poland,...
. The spacecraft was a development of the earlier Venera
Venera
The Venera series probes were developed by the Soviet Union between 1961 and 1984 to gather data from Venus, Venera being the Russian name for Venus...
craft. They were designed by Babakin Space Center and constructed as 5VK by Lavochkin
Lavochkin
NPO Lavochkin is a Russian aerospace company. It is a major player in the Russian space program, being the developer and manufacturer of the Fregat upper stage, as well as interplanetary probes such as Phobos Grunt...
at Khimki
Khimki
Khimki is a city in Moscow Oblast, Russia, situated just northwest of Moscow, at the west bank of the Moscow Canal. Population: 207,125 ; 141,000 ; 106,000 ; 23,000 .-History:...
. The craft was powered by twin large solar panel
Photovoltaic module
A solar panel is a packaged, connected assembly of solar cells, also known as photovoltaic cells...
s and instruments included an antenna
Radio telescope
A radio telescope is a form of directional radio antenna used in radio astronomy. The same types of antennas are also used in tracking and collecting data from satellites and space probes...
dish, camera
Camera
A camera is a device that records and stores images. These images may be still photographs or moving images such as videos or movies. The term camera comes from the camera obscura , an early mechanism for projecting images...
s, spectrometer
Spectrometer
A spectrometer is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials. The variable measured is most often the light's intensity but could also, for instance, be the polarization...
, infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
sounder, magnetometer
Magnetometer
A magnetometer is a measuring instrument used to measure the strength or direction of a magnetic field either produced in the laboratory or existing in nature...
s (MISCHA), and plasma
Plasma (physics)
In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized. Heating a gas may ionize its molecules or atoms , thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions...
probes. The 4,920 kg craft was launched by a Proton 8K82K rocket
Proton rocket
Proton is an expendable launch system used for both commercial and Russian government space launches. The first Proton rocket was launched in 1965 and the launch system is still in use as of 2011, which makes it one of the most successful heavy boosters in the history of spaceflight...
from Baikonur Cosmodrome
Baikonur Cosmodrome
The Baikonur Cosmodrome , also called Tyuratam, is the world's first and largest operational space launch facility. It is located in the desert steppe of Kazakhstan, about east of the Aral Sea, north of the Syr Darya river, near Tyuratam railway station, at 90 meters above sea level...
, Tyuratam
Tyuratam
Tyuratam is a station on the main Moscow to Tashkent railway, located in Kazakhstan. The name is a word in the Kazakh language and means "Töre's grave"; Töre, or more formally, Töre-Baba, was a noble, a descendant of Genghis Khan...
, Kazakh SSR
Kazakh SSR
The Kazakh Soviet Socialist Republic , also known as the Kazakh SSR for short, was one of republics that made up the Soviet Union.At in area, it was the second largest constituent republic in the USSR, after the Russian SFSR. Its capital was Alma-Ata . Today it is the independent state of...
. Both Vega 1 and 2 were three-axis stabilized spacecraft. The spacecraft were equipped with a dual bumper shield for dust protection from Halley's Comet.
The Venus mission
Vega 2 arrived at Venus on June 15, 1985. Its 1500 kg, 240 cm diameter spherical descent unit was released some days before arrival and entered the atmosphere without active inclination changes. It contained a lander and a balloonBalloon
A balloon is an inflatable flexible bag filled with a gas, such as helium, hydrogen, nitrous oxide, oxygen, or air. Modern balloons can be made from materials such as rubber, latex, polychloroprene, or a nylon fabric, while some early balloons were made of dried animal bladders, such as the pig...
explorer.
Descent craft
The Vega 2 lander touched down at 03:00:50 UT on 15 June 1985 at around , in the northern region of Aphrodite TerraAphrodite Terra
Aphrodite Terra is a highland region on Venus, near the equator. It is about the same size as Africa, and much rougher than Ishtar Terra.The surface appears buckled and fractured which suggests large compressive forces. There are also numerous extensive lava flows. Channels cross this terrain and...
. The altitude of the touchdown site was 0.1 km above the planetary mean radius. The measured pressure at the landing site was 91 atm
Atmosphere (unit)
The standard atmosphere is an international reference pressure defined as 101325 Pa and formerly used as unit of pressure. For practical purposes it has been replaced by the bar which is 105 Pa...
and the temperature was 736 K
Kelvin
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...
. The surface sample was found to be an anorthosite
Anorthosite
Anorthosite is a phaneritic, intrusive igneous rock characterized by a predominance of plagioclase feldspar , and a minimal mafic component...
-troctolite
Troctolite
Troctolite is a mafic intrusive rock type. It consists essentially of major but variable amounts of olivine and calcic plagioclase along with variable minor pyroxene. It is an olivine-rich, pyroxene-depleted relative of gabbro. However, unlike gabbro, no troctolite corresponds in composition to a...
rock, rarely found on Earth, but present in the lunar highlands, leading to the conclusion that the area was probably the oldest explored by any Venera vehicle. It transmitted data from the surface for 56 minutes.
Balloon
The Vega 2 Lander/Balloon capsule entered the Venus atmosphere (125 km altitude) at 2:06:04 UT (Earth received time; Moscow time 5:06:04 a.m.) on 15 June 1985 at roughly 11 km/s. At approximately 2:06:19 UT the parachute attached to the landing craft cap opened at an altitude of 64 km. The cap and parachute were released 15 seconds later at 63 km altitude. The balloon package was pulled out of its compartment by parachute 40 seconds later at 61 km altitude, at 7.45 degrees S, 179.8 degrees east. A second parachute opened at an altitude of 55 km, 200 seconds after entry, extracting the furled balloon. The balloon was inflated 100 seconds later at 54 km and the parachute and inflation system were jettisoned. The ballast was jettisoned when the balloon reached roughly 50 km and the balloon floated back to a stable height between 53 and 54 km some 15 to 25 minutes after entry. The mean stable height was 53.6 km, with a pressure of 535 mbar and a temperature of 308-316 K in the middle, most active layer of the Venus three-tiered cloud system. The balloon drifted westward in the zonal wind flow with an average speed of about 66 m/s at nearly constant latitude. The probe crossed the terminator from night to day at 9:10 UT on 16 June after traversing 7400 km. The probe continued to operate in the daytime until the final transmission was received at 00:38 UT on 17 June from 7.5 S, 76.3 E after a total traverse distance of 11,100 km. It is not known how much further the balloon traveled after the final communication.The Halley mission
After their encounters, the Vegas' motherships were redirected by Venus' gravity to intercept Halley's Comet.The spacecraft initiated its encounter on March 7, 1986 by taking 100 photos of the comet from a distance of 14 million kilometers.
Vega 2 made its closest approach at 07:20 UT on March 9, 1986 at 8,030 km. The data intensive examination of the comet covered only the three hours around closest approach. They were intended to measure the physical parameters of the nucleus, such as dimensions, shape, temperature and surface properties, as well as to study the structure and dynamics of the coma
Coma (cometary)
frame|right|The [[153P/Ikeya-Zhang|comet Ikeya-Zhang]] exhibiting a bright, condensed coma In astronomy, a coma is the nebulous envelope around the nucleus of a comet. It is formed when the comet passes close to the Sun on its highly elliptical orbit; as the comet warms, parts of it sublimate...
, the gas composition close to the nucleus, the dust particles' composition and mass distribution as functions of distance to the nucleus and the cometary-solar wind
Solar wind
The solar wind is a stream of charged particles ejected from the upper atmosphere of the Sun. It mostly consists of electrons and protons with energies usually between 1.5 and 10 keV. The stream of particles varies in temperature and speed over time...
interaction.
During the encounter, Vega 2 took 700 images of the comet, with better resolution than those from the twin Vega 1
Vega 1
Vega 1 is a Soviet space probe part of the Vega program. The spacecraft was a development of the earlier Venera craft...
, partly due to the presence of less dust outside of the coma at the time. Yet Vega 2 recorded an 80% power loss during the encounter as compared to Vega 1's 40%.
After further imaging sessions on 10 and 11 March 1986, Vega 2 finished its primary mission. Vega 1 ran out of attitude control propellant on 30 January 1987, and contact with Vega 2 continued until 24 March 1987.
Vega 2 is currently in heliocentric orbit
Heliocentric orbit
A heliocentric orbit is an orbit around the Sun. All planets, comets, and asteroids in our Solar System are in such orbits, as are many artificial probes and pieces of debris. The moons of planets in the Solar System, by contrast, are not in heliocentric orbits as they orbit their respective planet...
.