View source for Vega 1

{{Use dmy dates|date=May 2020}}
{{short description|Soviet mission to Venus and Halley's Comet (1984–1987)}}
{{Infobox spaceflight
| name                  = Vega 1
| names_list            = Venera-Halley 1

<!--image of the spacecraft/mission-->
| image                 = Vega model - Udvar-Hazy Center.JPG
| image_caption         = A replica of the ''[[Vega program|Vega]]'' spacecraft displayed at the [[Steven F. Udvar-Hazy Center|Udvar-Hazy Center]], Virginia, USA
| image_size            = 300px

<!--Basic details-->
| mission_type          = [[Venus]]/[[Halley's Comet|Halley]] exploration
| operator              = Soviet space program
| COSPAR_ID             = {{COSPAR|1984-125A}}<br>{{COSPAR|1984-125E}}<br>{{COSPAR|1984-125F}}
| SATCAT                = 15432<br>15858<br>15859
| mission_duration      = Balloon: {{time interval|11 Jun 1985|13 Jun 1985}}<br/>Flyby: {{time interval|15 Dec 1984|30 Jan 1987|show=yd|sep=,}}

<!--Spacecraft properties-->
| spacecraft            = 5VK No. 901
| spacecraft_type       = [[5VK]]
| manufacturer          = [[NPO Lavochkin]]
| launch_mass           = {{convert|4,840|kg}}<ref name=beyond/>

<!--Launch details-->
| launch_date           = {{start date|df=yes|1984|12|15}}, 09:16:24 UTC<ref name=beyond/>
| launch_rocket         = [[Proton-K]]/[[Blok D|D]]
| launch_site           = [[Baikonur Cosmodrome|Baikonur]] [[Baikonur Cosmodrome Site 200|200/39]]
| launch_contractor     = [[Khrunichev State Research and Production Space Center|Khrunichev]]

<!--end of mission-->
| last_contact          = 30 January 1987<ref name=beyond/>

<!--orbit parameters-->
| orbit_reference       = [[Heliocentric orbit|Heliocentric]]
| orbit_eccentricity    = 0.1700
| orbit_periapsis       = 0.70 AU
| orbit_apoapsis        = 0.98 AU
| orbit_inclination     = 2.3°
| orbit_period          = 281 days
| apsis                 = helion

|interplanetary         = <!--Infobox spaceflight/IP can be called multiple times for missions with multiple targets or combined orbiter/lander missions, etc-->
 {{Infobox spaceflight/IP
   |type                = flyby
   |object              = [[Venus]]
   |arrival_date        = 11 June 1985
   |distance            = ~{{convert|39000|km|mi}}
 }}

 {{Infobox spaceflight/IP
   |type                = atmospheric
   |object              = [[Venus]]
   |orbits              = <!--number of orbits completed at target body (if applicable and known)-->
   |component           = Vega 1 ''Balloon''
   |arrival_date        = 02:06:10, 11 June 1985
 }}

 {{Infobox spaceflight/IP
   |type                = lander
   |object              = [[Venus]]
   |component           = Vega 1 ''Lander''
   |arrival_date        = 03:02:54, 11 June 1985
   |location            = {{coord|7.5|N|177.7|E|globe:venus|name=Vega 1}} (north of [[Aphrodite Terra]])
 }}

 {{Infobox spaceflight/IP
   |type                = flyby
   |object              = [[Halley's Comet|1P/Halley]]
   |arrival_date        = 6 March 1986
   |distance            = ~{{convert|10000|km|abbr=on}}
 }}

<!--Only use where a spacecraft/mission is part of a clear programme of sequential missions. 
If in doubt, leave it out-->
| programme2            = '''[[Vega program]]'''
| previous_mission      = 
| next_mission          = [[Vega 2]]
| programme             = '''[[Halley Armada]]'''

<!--mission insignia or patch-->
| insignia              = 1986 venera galley nh.jpg
| insignia_size         = 100px
}}

'''Vega 1''' (along with its twin [[Vega 2]]) was a [[Soviet Union|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 [[Khimki]]. The name VeGa (ВеГа) combines the first two letters from the Russian words for [[Venus]] (Венера: "Venera") and [[Halley's Comet|Halley]] (Галлея: "Galleya").

The craft was powered by twin large solar panels and instruments included an antenna dish, cameras, [[spectrometer]], infrared sounder, [[magnetometer]]s (MISCHA), and plasma probes. The {{convert|4,840|kg}} craft was launched by a [[Proton-K]] rocket from [[Baikonur Cosmodrome]], [[Tyuratam]], [[Kazakh SSR]].  Both Vega 1 and 2 were [[Spacecraft attitude control|three-axis stabilized]] spacecraft.  The spacecraft were equipped with a dual [[Whipple shield|bumper shield]]<ref name=Agureikin_1984/> for dust protection from [[Halley's Comet]].

== Venus mission ==
The descent module arrived at Venus on 11 June 1985, two days after being released from the Vega 1 flyby probe. The module, a {{convert|1500|kg}} sphere with a diameter of {{convert|240|cm}}, contained a surface lander and a [[balloon]] explorer. The flyby probe performed a [[gravity assist|gravitational assist]] maneuver using Venus, and continued its mission to intercept the comet.<ref name=nssdc1/>

===Descent craft===
[[File:Vega 1.jpg|thumb|left|220px|Spacecraft Vega 1]]
The surface lander was identical to that of Vega 2 as well as six previous ''[[Venera]]'' missions. The objective of the probe was the study of the atmosphere and the exposed surface of the planet. The scientific payload included an [[ultraviolet]] [[spectrometer]], temperature and pressure sensors, a water concentration meter, a [[Gas-liquid chromatography|gas-phase chromatograph]], an [[X-ray]] [[spectrometer]], a [[mass spectrometer]], and a surface sampling device.  Since the probe made a nighttime landing, no images were taken. 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.<ref name=nssdc1/>

The lander successfully touched down at {{Venus coords and quad cat|7.2|N|177.8|E}} in the [[Surface of Venus|Mermaid Plain]] north of [[Aphrodite Terra]].  Due to excessive turbulence, some surface experiments were inadvertently activated {{convert|20|km}} above the surface. Only the mass spectrometer was able to return data.<ref name=nasa1/>

Tools on the lander include:
* [[Thermometer]]s
* [[Barometer]]s
* [[Ultraviolet ray|UV]] absorption [[spectrometer]]—ISAV-S
* Optical aerosol analyzer, [[Nephelometer]]—ISAV-A
* Aerosol particle-size counter—LSA
* Aerosol [[mass spectrometer]]—MALAKHIT-M 
* Aerosol gas [[chromatograph]]—SIGMA-3
* Aerosol [[X-ray]] fluorescence spectrometer—IFP
* [[Hygrometer]]—VM-4
* Soil [[X-ray]] fluorescence spectrometer—BDRP-AM25 
* [[Gamma-ray]] spectrometer—GS-15STsV
* [[Penetrometer]] / Soil ohmmeter—Prop-V
* Stabilized oscillator / [[Doppler effect|Doppler radio]]

===Balloon===
[[File:Russian "Vega" balloon mission to Venus on display at the Udvar-Hazy museum.jpg|thumb|Vega balloon probe on display at the [[Steven F. Udvar-Hazy Center|Udvar-Hazy Center]] of the Smithsonian Institution]]

The Vega 1 Lander/Balloon capsule entered the Venusian atmosphere ({{convert|125|km|disp=sqbr}} altitude) at 2:06:10 UT (Earth received time; Moscow time 5:06:10&nbsp;a.m.) on 11 June 1985 at roughly {{convert|11|km/s}}. At approximately 2:06:25 UT the parachute attached to the landing craft cap opened at an altitude of {{convert|64|km}}. The cap and parachute were released 15 seconds later at {{convert|63|km}} altitude. The balloon package was pulled out of its compartment by parachute 40 seconds later at {{convert|61|km}} altitude, at 8.1 degrees N, 176.9 degrees east. A second parachute opened at an altitude of {{convert|55|km}}, 200 seconds after entry, extracting the furled balloon. The balloon was inflated 100 seconds later at {{convert|54|km}} and the parachute and inflation system were jettisoned. The ballast was jettisoned when the balloon reached roughly {{convert|50|km}} and the balloon floated back to a stable height between {{convert|53|and|54|km}} some 15 to 25 minutes after entry.

The mean stable height was {{convert|53.6|km}}, with a pressure of {{convert|535|mbar}} and a temperature of {{convert|300|-|310|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 {{convert|69|m/s}} ({{convert|248|km/h|disp=sqbr}}) at nearly constant latitude. The probe crossed the terminator from night to day at 12:20 UT on 12 June after traversing {{convert|8500|km}}. The probe continued to operate in the daytime until the final transmission was received at 00:38 UT on 13 June from 8.1 N, 68.8 E after a total traverse distance of {{convert|11600|km}} or about 30% of the circumference of the planet. It is not known how much farther the balloon traveled after the final communication.<ref name=nasa1/>

== Halley mission ==
After their encounters, the Vegas' motherships used the gravity of Venus, also known as a gravity assist, to intercept [[Halley's Comet]].

Images started to be returned on 4 March 1986, and were used to help pinpoint [[Giotto probe|Giotto]]'s close flyby of the comet. The early images from Vega showed two bright areas on the comet, which were initially interpreted as a double nucleus.  The bright areas would later turn out to be two jets emitting from the comet.   The images also showed the nucleus to be dark, and the infrared spectrometer readings measured a nucleus temperature of {{convert|300|to|400|K}}, much warmer than expected for an ice body.  The conclusion was that the comet had a thin layer on its surface covering an icy body.

Vega 1 made its closest approach on 6 March at around {{convert|8889|km}} (at 07:20:06 UT) of the nucleus. It took more than 500 pictures via different filters as it flew through the gas cloud around the coma. Although the spacecraft was battered by dust, none of the instruments were disabled during the encounter.

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 (cometary)|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.

The Vega images showed the nucleus to be about {{convert|14|km}} long with a rotation period of about 53 hours. The dust mass spectrometer detected material similar to the composition of [[Carbonaceous chondrite|carbonaceous chondrites meteorites]] and also detected [[clathrate]] ice.

After subsequent imaging sessions on 7 and 8 March 1986, Vega 1 headed out to deep space. In total Vega 1 and Vega 2 returned about 1500 images of Comet Halley. Vega 1 ran out of attitude control propellant on 30 January 1987, and contact with Vega 2 continued until 24 March 1987.

Vega 1 is currently in [[heliocentric orbit]], with [[Periapsis|perihelion]] of 0.70 [[Astronomical unit|AU]], [[Apoapsis|aphelion]] of 0.98 AU, [[Orbital eccentricity|eccentricity]] of 0.17, [[Orbital inclination|inclination]] of 2.3 degrees and [[orbital period]] of 281 days. {{citation needed|date=October 2024}}

==See also==
*[[List of missions to Venus]]

== References ==
{{reflist|refs=

<ref name="Agureikin_1984">{{cite journal
| author1= V. A. Agureikin
| author2= S. I. Anisimov
| author3= A. V. Bushman
| author4= G. I. Kanel'
| author5= V. P. Karyagin
| author6= A. B. Konstantinov
| author7= B. P. Kryukov
| author8= V. F. Minin
| author9= S. V. Razorenov
| author10= R. Z. Sagdeev
| author11= S. G. Sugak
| author12= V. E. Fortov
| display-authors= 5
| year= 1984
| title= Thermophysical and Gas-dynamic Studies of the Meteorite Shield for the Vega spacecraft
| url= https://m.mathnet.ru/php/getFT.phtml?jrnid=tvt&paperid=8039&what=fullt&option_lang=eng
| journal= Thermophysics of High Temperatures
| pages= 761–778
| issue= 5
| volume= 22
| language= ru }}.. WoS:[http://ws.isiknowledge.com/cps/openurl/service?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft_id=info:ut/A1984ALC5000020 A1984ALC5000020] Scopus:[http://www.scopus.com/record/display.uri?eid=2-s2.0-0021489019&origin=resultslist 2-s2.0-0021489019]</ref>

<ref name="beyond">{{ cite book
| url= https://www.nasa.gov/sites/default/files/atoms/files/beyond-earth-tagged.pdf
| title= Beyond Earth: A Chronicle of Deep Space Exploration, 1958–2016
| author1= Asif Siddiqi
| publisher= NASA History Program Office
| edition= second
| year= 2018
| isbn= 978-1-626-83043-1 }}
</ref>

<ref name="nasa1">{{Cite web
| url= https://solarsystem.nasa.gov/missions/vega-1/in-depth/
| title= In Depth: Vega 1
| website= solarsystem.nasa.gov
| publisher= [[NASA]]
| access-date= 11 April 2015 }}
</ref>

<ref name="nssdc1">{{cite web
| url= https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1984-125A
| title= Vega 1
| website= nssdc.gsfc.nasa.gov
| publisher= [[NASA]]
| access-date= 21 July 2024 }}
</ref>


}}

==External links==
{{commons category}}
{{Portal|Spaceflight}}
*[https://web.archive.org/web/20061004051408/http://solarsystem.nasa.gov/missions/profile.cfm?MCode=Vega_01 Vega 1 Measuring Mission Profile] by [http://solarsystem.nasa.gov NASA's Solar System Exploration]
*[http://arc.iki.rssi.ru/IPL/vega.html Vega mission images from the Space Research Institute (IKI)]
*[https://web.archive.org/web/20070311040927/http://starbase.jpl.nasa.gov/archive/vega2-c-tvs-5-rdr-halley-transform-v1.0/hal_0026/ Raw data from Vega 1 and Vega 2 on board instruments]
*[http://www.mentallandscape.com/V_Vega.htm Soviet Exploration of Venus]
* [https://pdssbn.astro.umd.edu/data_sb/missions/vega1/index.shtml ''Vega 1'' Mission Comet Halley Data Archive] at the NASA Planetary Data System, Small Bodies Node

{{Venus spacecraft}}
{{Comet spacecraft}}
{{Orbital launches in 1984}}

[[Category:Missions to Halley's Comet]]
[[Category:Vega program]]
[[Category:Derelict satellites in heliocentric orbit]]
[[Category:1984 in spaceflight]]
[[Category:1984 in the Soviet Union]]
[[Category:Derelict space probes]]
[[Category:France–Soviet Union relations]]
[[Category:Extraterrestrial aircraft]]
[[Category:Spacecraft launched in 1984]]
[[Category:Extraterrestrial atmosphere entry]]