|Map of Io, centred on the anti-jovian point (180 degrees longitude), showing some of the major volcanic features. The images were compiled here: http://www.britastro.org/jupiter/moonmaps.htm|
The point of these Io observations over the next few nights is to get a new map of Io's SO2 distribution, and to see if the atmosphere has shown signs of deflation after perihelion (March 2011, when presumably SO2 evaporation was at the highest rate). Io goes around Jupiter once every 1.8 days, meaning that a sequence of consecutive nights will allow us to map most of the longitudes to see if the contrasts have changed with time. The hope is that this will differentiate between atmospheric support from volcanic injection, or from frost sublimation.... but the suspicion from Tsang et al. is that there must be at least a little volcanic injection, given that they saw SO2 in the atmosphere still during the aphelion. Con and John were both following along remotely, so I'm sure they'll have their work cut out in analysing this new TEXES Io dataset!