Venus’ atmosphere is composed primarily of CO2 with a surface pressure reaching 93 bars. The planet’s surface is hidden behind multiple global layers of clouds.

The Venus Express spacecraft, in orbit around Venus since April 2006, is the latest spacecraft to explore this fascinating planet, its atmosphere and surface. Previous missions include Pioneer Venus (1978-1992) and Magellan (1990-1994).

The Venus Express Atmospheric Drag Experiment (VExADE) provides the first ever in-situ measurements of atmospheric densities above 150 km near the northern pole of Venus. The experiment consists in accurately tracking the orbit of the spacecraft and determining the effects of atmospheric drag on the spacecraft. During later stages of the Venus Express mission the pericenter altitude will be further lowered, also allowing direct measurement of atmospheric drag with the on-board accelerometers.

VExADE Team members are:

  1. Dr. Ingo Mueller-Wodarg, Imperial College London (Team Leader)

  2. Dr. Sean Bruinsma (CNES Toulouse)

  3. Dr. Pascal Rosenblatt (Royal Observatory of Belgium)

  4. Prof. Jeffrey Forbes (University of Colorago)

  5. Prof. Roger Yelle (University of Arizona)

  6. Dr. Paul Withers (Boston University)

  7. Dr. Miguel Lopez-Valverde (IAA Granada)

  8. Dr. Gerry Keating (George Washington University, Virginia, USA) (deceased)

The following VExADE measurement campaigns have so far occurred:

  1. Campaign 1: July 29-Aug 09, 2008 (pericentre altitude: 185 km)

  2. Campaign 2: Oct 12-17, 2009 (pericentre altitude: 176-179 km)

  3. Campaign 3: Feb 23-28 & April 11-16, 2010 

  4. Campaign 4: Oct 14-25, 2010

  5. Campaign 5: May 23-June 03, 2011

  6. Campaign 6: April 09-15, 2012

This figure shows measurements in the polar atmosphere of Venus from the Venus Express SPICAV-SOIR instrument, ground-based submm measurements and the VExADE experiment. Blue lines denote hydrostatic diffusive equilibrium models that bridge the data gap between around 130 - 175 km.

For more information about VExADE, please contact me.

Image credit: SA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA

NEWS on the Venus Express Atmospheric Drag Experiment: click here and here