During the 18-day long coordinated campaign, the apparent size of Venus increases from 19.7" to 23.5" and its phase lies between 80° and 90°. The ground-based observations are an important supplement to the data gathered by the Venus Express spacecraft which is currently orbiting Venus, and provide additional information on Venus's atmospheric characteristics.

The coordinated period also encompasses the second of two flybys of Venus by the MESSENGER spacecraft, which occurs on 5 June, at 23:10 UTC. NASA's MESSENGER mission is on its way to Mercury and uses several planetary gravity assists to reach the innermost planet. During the Venus flyby, it will perform science observations of the planet allowing for simultaneous measurements to be made with Venus Express.

Science Goals

During the coordinated ground-based campaign, observations by the different teams will focus on the atmosphere above Venus's cloud layer and will include:

• Wind measurements at different altitudes
   - cloud top level: visible spectroscopy
   - mesosphere (90-105 km): mm/submm spectroscopy
   - thermosphere (120 km): 10 μm observations
• Morphology of the mesosphere airglow emission (O, O₂)
• Mesospheric composition (H₂O, SO, SO₂, HCl)
• Deep atmosphere nightside composition

An overview of the participating teams and their observation goals is given below, sorted by wavelength region and by observation date. Some of the proposals for observing time are still pending approval, also indicated in the overview.

Participating Teams

* HST = Hawaiian Standard Time

Telescopes

Venus Amateur Observing Project

Started already in early 2006, the Venus Amateur Observing Project (VAOP) for ground-based observations by amateur astronomers is running throughout the Venus Express mission. During the coordinated campaign by the professional astronomer teams (23 May-9 June), it will run in parallel. For details on how to participate in the VAOP project follow the link in the right-hand side navigation.