The Venus Express spacecraft has completed an 'aerodrag' exercise, using its solar wings to catch and measure faint wisps of atmosphere just 180km above the planet.
During five measurements last week, Venus Express' solar arrays and control systems were used as a single massive flying sensor, with the solar arrays tilted at various angles to the direction of flight.
This exposed them to the faint wisps of atmosphere around Venus, generating a tiny but measurable aerodynamic torque.
The solar array on Venus Express consists of two symmetrical wings supporting gallium-arsenide solar cells. Their combined 5.7 square meters can generate up to 1,400W of power in Venus orbit.
Starting Monday, the solar panels rotated through five daily-changing sets of orientations. While one panel remained perpendicular to the direction of flight, the other rotated in steps, gradually increasing the torque to be counter-balanced by the reaction wheels.
On the last day, the solar arrays were rotated at plus and minus 45° to the atmospheric flow like the vanes of a windmill, in order to gather additional information on the behaviour of the molecules of the atmosphere bouncing off the solar wings.
"The aerodrag campaign went without problem, and conclusively demonstrated that Venus Express can be securely and accurately used to sense the density of the planet's atmosphere. Venus Express has shown once again that it is a very capable satellite," said ESA Spacecraft Operations Manager Octavio Camino.
The mission operations team will now study the results to develop an optimised configuration for aerodrag campaigns in October and next year.