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Vega 2 (along with
Vega 1 Vega 1 (along with its twin Vega 2) was 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 Centre and constructed as 5VK by Lavochkin at Khim ...
) was a
Soviet The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, ...
space probe A space probe is an artificial satellite that travels through space to collect scientific data. A space probe may orbit Earth; approach the Moon; travel through interplanetary space; flyby, orbit, or land or fly on other planetary bodies; o ...
part of the
Vega program The Vega program (Cyrillic: ВеГа) was a series of Venus missions that also took advantage of the appearance of comet 1P/Halley in 1986. ''Vega 1'' and '' Vega 2'' were uncrewed spacecraft launched in a cooperative effort among the Soviet ...
to explore
Halley's comet Halley's Comet or Comet Halley, officially designated 1P/Halley, is a short-period comet visible from Earth every 75–79 years. Halley is the only known short-period comet that is regularly visible to the naked eye from Earth, and thus the on ...
and
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 ...
. The spacecraft was a development of the earlier '' Venera'' craft. The name VeGa (ВеГа) combines the first two letters Russian words for Venus (Венера: "Venera") and Halley (Галлея: "Galleya") They were designed by
Babakin Space Centre The Babakin Science and Research Space Centre (russian: Научно-испытательный центр имени Г.Н. Бабакина) is a division of the Lavochkin Design Bureau based in Khimki, Russia. It is managed by them on behalf of ...
and constructed as
5VK The 5VK planetary probe (short for 5th-generation Venus-Comet probe) is a designation for a common design used for Soviet unmanned probes to comet 1P/Halley and Venus. It was an incremental improvement of earlier 4MV probes used for Mars and Venu ...
by
Lavochkin NPO Lavochkin (russian: НПО Лавочкина, OKB-301, also called Lavochkin Research and Production Association or shortly Lavochkin Association, LA) is a Russian aerospace company. It is a major player in the Russian space program, being th ...
at Khimki. The craft was powered by large twin
solar panel A solar cell panel, solar electric panel, photo-voltaic (PV) module, PV panel or solar panel is an assembly of photovoltaic solar cells mounted in a (usually rectangular) frame, and a neatly organised collection of PV panels is called a photo ...
s. Instruments included an
antenna Antenna ( antennas or antennae) may refer to: Science and engineering * Antenna (radio), also known as an aerial, a transducer designed to transmit or receive electromagnetic (e.g., TV or radio) waves * Antennae Galaxies, the name of two collid ...
dish,
camera A camera is an optical instrument that can capture an image. Most cameras can capture 2D images, with some more advanced models being able to capture 3D images. At a basic level, most cameras consist of sealed boxes (the camera body), with ...
s,
spectrometer A spectrometer () is a scientific instrument used to separate and measure spectral components of a physical phenomenon. Spectrometer is a broad term often used to describe instruments that measure a continuous variable of a phenomenon where the ...
,
infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of Light, visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from ...
sounder,
magnetometer A magnetometer is a device that measures magnetic field or magnetic dipole moment. Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A compass is one such device, ...
s (MISCHA) and plasma probes. The craft was launched on top of a Proton 8K82K rocket from
Baikonur Cosmodrome ''Baiqoñyr ğaryş ailağy'' rus, Космодром Байконур''Kosmodrom Baykonur'' , image = Baikonur Cosmodrome Soyuz launch pad.jpg , caption = The Baikonur Cosmodrome's "Gagarin's Start" Soyuz ...
,
Tyuratam Töretam ( kk, link=no, Төретам, Töretam; russian: link=no, Тюратам, Tyuratam) is a station on the main Moscow to Tashkent railway, located in Kazakhstan. The name means "Töre's grave" in the Kazakh language. Töre, or more formal ...
,
Kazakh SSR ; kk, Қазақ Советтік Социалистік Республикасы) *1991: Republic of Kazakhstan (russian: Республика Казахстан; kk, Қазақстан Республикасы) , linking_name = the ...
. Both Vega 1 and 2 were
three-axis stabilized Spacecraft attitude control is the process of controlling the orientation of a spacecraft (vehicle/satellite) with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, et ...
spacecraft. The spacecraft were equipped with a dual bumper shield for dust protection from Halley's Comet.


Venus mission

The descent module arrived at Venus on 15 June 1985, two days after being released from the Vega 2 flyby probe. The module, a , diameter sphere, contained a surface lander and a
balloon A balloon is a flexible bag that can be inflated with a gas, such as helium, hydrogen, nitrous oxide, oxygen, and air. For special tasks, balloons can be filled with smoke, liquid water, granular media (e.g. sand, flour or rice), or lig ...
explorer. The flyby probe performed a gravitational assist maneuver using Venus, and continued its mission to intercept the comet.NASA—NSSDC—Spacecraft—Details
/ref>


Lander

The surface lander was identical to that of Vega 1 as well as the previous six '' Venera'' missions. The objective of the probe was the study of the atmosphere and the exposed surface of the planet. The scientific payload included a UV spectrometer, temperature and pressure sensors, a water concentration meter, a gas-phase chromatograph, an
X-ray An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10  nanometers, corresponding to frequencies in the range 30&nb ...
spectrometer A spectrometer () is a scientific instrument used to separate and measure spectral components of a physical phenomenon. Spectrometer is a broad term often used to describe instruments that measure a continuous variable of a phenomenon where the ...
, a
mass spectrometer Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a '' mass spectrum'', a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is us ...
, and a surface sampling device. Several of these scientific tools (the UV spectrometer, the mass spectrograph, and the devices to measure pressure and temperature) were developed in collaboration with French scientists. Since the probe made a nighttime landing, no images were taken. The Vega 2 lander touched down at 03:00:50 UT on 15 June 1985 at around , in the northern region of
Aphrodite Terra Aphrodite Terra is one of the three continental regions on the planet Venus, the others being Ishtar Terra and Lada Terra. It is named for Aphrodite, the Greek equivalent of the goddess Venus, and is found near the equator of the planet. Aphrod ...
. 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 . The surface sample was found to be an
anorthosite Anorthosite () is a phaneritic, intrusive igneous rock characterized by its composition: mostly plagioclase feldspar (90–100%), with a minimal mafic component (0–10%). Pyroxene, ilmenite, magnetite, and olivine are the mafic minerals most ...
troctolite Troctolite (from Greek τρώκτης 'trout' and λίθος 'stone') is a mafic intrusive rock type. It consists essentially of major but variable amounts of olivine and calcic plagioclase along with minor pyroxene. It is an olivine-rich anort ...
rock, rarely found on Earth, but present in the
lunar highlands The geology of the Moon (sometimes called selenology, although the latter term can refer more generally to " lunar science") is quite different from that of Earth. The Moon lacks a true atmosphere, which eliminates erosion due to weather. It does ...
, 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 Venusian atmosphere (125 km altitude) at 02:06:04 UT (Earth received time; Moscow time 05:06:04) 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 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.


Halley mission

After their encounters, the Vegas' motherships were redirected by Venus' gravity to intercept
Halley's Comet Halley's Comet or Comet Halley, officially designated 1P/Halley, is a short-period comet visible from Earth every 75–79 years. Halley is the only known short-period comet that is regularly visible to the naked eye from Earth, and thus the on ...
. The spacecraft initiated its encounter on March 7, 1986, by taking 100 photos of the comet from a distance of . Vega 2 made its closest approach at 07:20 UT on March 9, 1986, at . 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 A coma is a deep state of prolonged unconsciousness in which a person cannot be awakened, fails to respond normally to painful stimuli, light, or sound, lacks a normal wake-sleep cycle and does not initiate voluntary actions. Coma patients exhi ...
, 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 The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between . The composition of the sol ...
interaction. During the encounter, Vega 2 took 700 images of the comet, with better resolution than those from the twin
Vega 1 Vega 1 (along with its twin Vega 2) was 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 Centre and constructed as 5VK by Lavochkin at Khim ...
, partly due to the presence of less dust outside 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.


Post Halley

A 6 million kilometer distant flyby of
2101 Adonis 2101 Adonis, ''provisional designation'': , is an asteroid on an extremely eccentric orbit, classified as potentially hazardous asteroid and near-Earth object of the Apollo group. ''Adonis'' measures approximately in diameter. Discovered by Eug ...
was considered but it turned out that Vega 2 didn't have enough fuel left to make the necessary orbital changes for the flyby. Instead the Vega probes took the opportunity to measure the dust as they passed through the orbits of 72P/Denning–Fujikawa, Biela's Comet and 289P/Blanpain. Contact with Vega 2 was lost on 24 March 1987. Vega 1 had previously exhausted its
attitude control Attitude control is the process of controlling the orientation of an aerospace vehicle with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, etc. Controlling vehicle ...
propellant on 30 January 1987. Vega 2 is currently in
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 0.70 AU,
aphelion 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 ell ...
of 0.98 AU, eccentricity of 0.17,
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 281 days.


See also

* List of missions to Venus


References


External links


Vega 2 Measuring Mission Profile
b
NASA's Solar System ExplorationRaw data from Vega 1 and Vega 2 on board instruments

''Vega 2'' Mission Comet Halley Data Archive
at the NASA Planetary Data System, Small Bodies Node {{Orbital launches in 1984 Missions to Halley's Comet Vega program Derelict satellites in heliocentric orbit 1984 in spaceflight 1984 in the Soviet Union Derelict space probes France–Soviet Union relations Extraterrestrial aircraft Spacecraft launched in 1984 Extraterrestrial atmosphere entry