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• investigation : VEGA 1
  Mission Overview ================ In the late 1970s it was realised that the return of Halley's comet in 1985/86 would provide a unique opportunity to combine a mission to explore Venus, (which had already been planned) with a mission to Halley by employing a two-element space vehicle consisting of a Venus lander (and balloon) and a Halley flyby probe. The mission was called Vega, a contraction of the Russian words `Venera' (Venus) and `Gallei' (Halley) and was conducted by the USSR with a number of other countries within the framework of Intercosmos. The Vega mission comprised two identical spacecraft, Vega 1 and Vega 2. This was a standard approach in the USSR, aimed primarily at increasing the overall reliability of the mission. In addition, if both flybys were successful there would be a significant increase in the scientific return, which was particularly valuable in the case of the Halley flybys considering the variability of the cometary activity. The Vega project was truly international. While the spacecraft themselves were controlled by Soviet agencies, the scientific programme and payload were coordinated by the International Science and Technical Committee (CIST), representing scientific institutions and space agencies from nine countries. The CIST designed the Vega mission to be complementary to the European Giotto and the Japanese Suisei cometary missions. The two spacecraft were launched by Proton rockets from the cosmoport Baikonur on 15 and 21 December 1984, respectively. On 11 and 15 June 1985, the two spacecraft successfully delivered the first balloons into the Venus atmosphere. After deltaV- Venus gravity assist flybys, Vega 1 and Vega 2 encountered comet Halley on 6 and 9 March 1986, respectively. The interplanetary orbit of Vega 1 from launch to Halley flyby was entirely in the ecliptic. The orbit of Vega 2 was almost identical except for slightly different flyby dates. The plane of Halley's orbit was inclined at 17.8 degrees with respect to the ecliptic. Halley was above the ecliptic from the ascending to the descending node. The flyby speeds were extremely high because Halley's orbit sense was retrograde, that is, directed opposite to that of the Earth and thus of the spacecraft. During the encounter dust particles impacted on the spacecraft at ~ 80 km/s and caused damage to some experiments and the unprotected solar panels. The flight operations centre was located in Evpatoria (Crimea), but during the flybys most investigators were in Moscow at the Space Research Institute, where they were able to obtain all the data in real time. Deep space antennas in Evpatoria (70 m) and Medvezy Ozera (64m), near Moscow, received the telemetry. During the cruise phase the pointing platform was clamped. The clamping mechanism was released on Vega 1 on 14 February 1986 and on Vega 2 on 18 February 1986, and the operation of the TVS and the pointing platform was checked by observing Jupiter and Saturn. The cameras were found to be fully functional. Two days before the Halley encounters the cameras were oriented towards Halley and switched on for two hours. At last, on 6 March 1986, a few minutes before 7:20 UT, for the first time in the history of mankind, the nucleus of comet Halley unveiled itself to the human eye. The second encounter took place almost exactly three days later. (The most important parameters of both flybys are summarised in the Table below.) Key data of the Vega mission----------------------------------------------------------------- Vega 1 Vega 2----------------------------------------------------------------- launch 15.12.1984 21.12.1984time of closest approach (UT) 7:20:06 7:20:00 6.3.1986 9.3.1986closest approach to the nucleus (km) 8.890 8.030encounter velocity (km/s) 79.2 76.8distance of the encounter point from the Sun (AU) 0.7923 0.8341 ----------------------------------------------------------------- Vega mission operations were discontinued a few weeks after the encounters. The general condition of the spacecraft would have allowed further operation. The solar panels were partially damaged by dust impact but could still have provided enough power. The camera performance was tested by observing Jupiter and no essential degradation was registered. Even the amount of fuel onboard was considerable. However, after extensive searches and debates, no interesting object was identified for a possible second encounter. -------------------------------------------------------------- VEGA scientific payload Direct RecordedAcronym Experiment Mass Power telemetry telemetry (kg) (W) (bit/s) (bit/20min) TVS Television 32 50 32768 SystemIKS Infrared l8 18 2048 4320 SpectrometerTKS Three-Channel 14 30 12288 SpectrometerPHOTON Shield Pene- 2 4 108 tration DetectorDUCMA Dust Particle 3 2 100 100 DetectorSP-2 Dust Particle 4 4 1024 2160 DetectorSP-1 Dust Particle 2 l 150 2160 DetectorPUMA Dust Mass 19 31 10240 SpectrometerING Neutral Gas 7 8 1024 1080 Mass Spectro- meterPM-1 Plasma Energy 9 8 2048 15120 AnalyserTN-M Energetic Par- 5 6 512 6480 ticle AnalyzerMISCHA Magnetometer 4 6 512 2160 APV-N Wave and 5 8 2048 28080 Plasma AnalyserAPV-V Wave and 3 2 512 15120 Plasma Analyser----------------------------------------------------------- -------------------------------------------------------------- Collaborating institutes Acronym Experiment Collaborating institutes--------------------------------------------------------------TVS Television LAS, Marseille, France (P. Cruvellier) System Central Research Inst for Physics, Budapest, Hungary (L. Szabo) IKI, Moscow, USSR (G. Avanesov)IKS Infrared Observatoire de Meudon, France(M. Combes) Spectrometer IKI, Moscow, USSRTKS Three-Channel Observatoire de Besancon, France (G. Moreels) Spectrometer IKI, Moscow, USSR (V. Krasnopolskii) Bulgaria (M. Gogoshev)PHOTON Shield Pene- USSR tration DetectorDUCMA Dust Particle University of Chicago, USA (I. Simpson) Detector MPI, Lindau, W. Germany IKI, Moscow, USSR Central Research Institute for Physics, BudapestSP-2 Dust Particle IKI, Leningrad, USSR (E. Mazets) DetectorSP-1 Dust Particle IKI, Moscow, USSR (O. Vaisberg) DetectorPUMA Dust Mass MPI, Heidelberg, W. Germany (J. Kissel) Spectrometer Service d'Aeronomie, Verrieres, France (I.Lertarnsl11(1, Moscow, USSR (R. Sagdeev)ING Neutral Gas MPI, Lindau, W. Germany (E. Keppler) Mass Spectro- Central Research Institute for Physics, meter Budapest, IKI, Moscow, USSR University of Arizona, USAPM-1 Plasma Energy IKI, Moscow, USSR (K. Gringauz) Analyser Central Research Institute for Physics, Budapest, MPI, Lindau, W. Germany ESA Space Science Dept., ESTEC, NetherlandsTN-M Energetic Par- Central Research Institute for Physics, ticle Analyzer Budapest, Hungary (A. Somogyi) IKI, Moscow, USSR MPI, Lindau, W. Germany ESA Space Science Dept., ESTEC, Netherlands Nuclear Research Institute, Moscow, USSRMISCHA Magnetometer Space Research Institute, Graz, Austria (W.Redler) Izmiran, Troitsk, USSRAPV-N Wave and IKI, Moscow, USSR, (S. IClimov) Plasma Analyser Aviation Institute, Warsaw, Poland Geophysical Scientific Institute, PragueAPV-V Wave and ESA Space Science Dept., ESTEC (R. Grard) Plasma Analyser LPCE, Orleans, France Izmiran, Troitsk, USSR---------------------------------------------------------------------
• data set : VEGA1 HALLEY FLYBY MAGNETOMETER DATA
  These are magnetometer data (MISCHA) from the Vega 1 spacecraft flyby of comet Halley, 28 Feb 1986 through 10 Mar 1986.
• data set : VEGA1 TV SYSTEM IMAGES V1.0
  VEGA 1 satellite raw TV system images of 1P/Halley
• data set : VEGA1 PLASMAG-1 PLASMA ENERGY ANALYSER DATA V1.0
  VEGA 1 satellite PLASMAG instrument energy analyzer data from 1P/Halley
• data set : VEGA1 DUST PARTICLE IMPACT DETECTOR DATA V1.0
  VEGA 1 satellite SP2 instrument dust particle impact observations of 1P/Halley
• data set : VEGA1 PUMA DUST MASS SPECTROMETER DATA V1.0
  VEGA 1 satellite PUMA instrument raw dust mass spectrometry of 1P/Halley
• data set : VEGA1 INFRARED SPECTROMETER HIGH RESOLUTION DATA V1.0
  VEGA 1 satellite IKS instrument processed infrared images of 1P/Halley
• data set : VEGA1 ORIGINAL MISCHA DATA SUBMISSION
  Original magnetometer (MISCHA) data delivery from the Vega 1 spacecraft covering 22 Dec 1984 through 31 Dec 1986.
• data set : VEGA2 ORIGINAL MISCHA DATA SUBMISSION
  Original magnetometer (MISCHA) data delivery from the Vega 2 spacecraft covering 28 Dec 1984 through 11 Oct 1986.
• data set : VEGA1 INFRARED SPECTROMETER IMAGING CHANNEL DATA V1.0
  VEGA 1 satellite IKS instrument raw infrared image observaions of 1P/Halley
• data set : VEGA1 DUST PARTICLE IMPACT PLASMA DETECTOR DATA V1.0
  VEGA 1 satellite SP1 instrument dust particle impact plasma detector observations of 1P/Halley
• data set : VEGA1 TV SYSTEM IMAGES PROCESSED BY KFKI V1.0
  VEGA 1 satellite processed TV system images of 1P/Halley
• data set : VEGA1 TUNDE-M ENERGETIC PARTICLE ANALYSER DATA V1.0
  VEGA 1 satellite Tunde-M instrument energetic particle analyser observations of 1P/Halley
• data set : STOOKE SMALL BODY SHAPE MODELS V2.0
  Optical shape models of 12 planetary moons and asteroids, derived from spacecraft imaging by Philip Stooke.
• data set : VEGA1 DUST MASS SPECTROMETER MODAL DATA V1.0
  VEGA 1 satellite PUMA instrument processed dust spectrometry of 1P/Halley
• data set : VEGA1 CRUISE MAGNETOMETER DATA
  These are magnetometer data (MISCHA) from the Vega 1 spacecraft in the cruise phase, 22 Dec 1984 through 31Dec 1986.
• data set : VEGA1 DUST PARTICLE COUNTER MASS ANALYSER DATA V1.0
  VEGA 1 satellite DUCMA instrument dust particle counter and mass analyzer observations of 1P/Halley