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VLBI Radio Tracking

NSSDCA ID: 1984-128F-03

Mission Name: Vega 2 Balloon
Principal Investigators:Prof. Jacques E. Blamont
Principal Investigators:Dr. Roald Z. Sagdeev
Principal Investigators:Mr. Robert Preston


The Vega balloon's traverse through the atmosphere was tracked from Earth stations using differential Very Long Baseline Interferometry (VLBI) radio tracking between the balloon and its associated flyby spacecraft. The balloon was equipped with a 4.5 W transmitter which sent signals to a network of 20 radio telescopes on Earth (6 Soviet, 14 other (French, DSN)). The long baselines (5000-10000 km) between the Earth tracking stations allowed resolution of the balloon location.

In coordinated measurement (KI) mode, the transmitter sent two sideband tones separated by 3.25 MHz on either side of the 1667.9 MHz carrier signal along with a 20-dB suppressed carrier. These transmissions lasted 330 seconds, with 30-second pure carrier signals also transmitted on each side of the data in telemetry mode. Three transmissions were made every two hours for the first 10 hours and also between roughly hours 22-34 and one every two hours at other times. The effective power transmitted to Earth varied from 4.5-2 W. The 20 radio telescopes recorded about 1,200 individual sessions over the four day lifetime of the Vega 1 and Vega 2 battery power.

Alternate Names

  • Vega2Balloon/VLBIRadioTracking

Funding Agency

  • Unknown (U.S.S.R)


  • Planetary Science: Atmospheres

Additional Information

Questions and comments about this experiment can be directed to: Dr. David R. Williams



NameRoleOriginal AffiliationE-mail
Prof. Jacques E. BlamontTeam LeaderCentre National d'Etudes Spatiales
Dr. Roald Z. SagdeevTeam LeaderRussian Academy of
Mr. Robert PrestonTeam LeaderNASA Jet Propulsion

Selected References

  • Sagdeyev, R. Z., et al., Differential VLBI measurements of the Venus atmosphere dynamics by balloons - VEGA project, Astron. Astrophys., 254, 387-392, Feb. 1992.
  • Preston, R. A., et al., The VEGA balloon experiment: Initial results from the global radio tracking, Sov. Astron. Lett., 12, No. 1, 10, Jan.-Feb. 1986.
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