Change in Venus Express's pericentre altitude with time
This plot shows the change in Venus Express's pericentre altitude (Y-axis) as the mission progresses, from medium term plan 75 to 77 (MTP075 - MTP077), from 8 January to 31 March 2012. The X-axis shows the orbit number; each orbit lasts 24 hours.
The pericentre altitude decreases due to predicted forces experienced by the spacecraft. For the purposes of the Atmospheric Drag Experiment campaign in MTP075 (8 January to 4 February 2012), the pericentre altitude was allowed to decrease beyond nominal, down to 175 kilometres.