"Early next year (Feb-Mar 2007) the default Mars Express ground station (New Norcia) will be used by Rosetta for the preparation and execution of its Mars flyby. With Cebreros being used by Venus Express and DSN availability uncertain, this will probably mean two months with lower science return for Mars Express."

http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=40362

I've certainly not read that the ESA network is not at full capacity - what leads you to believe this? It is, after all, only two large dishes... one in Spain at Cebreros ( i.e. mirroring the spacecraft visibility of Madrid ) and one in Australia at New Norcia(i.e. mirroring the spacecraft visibility of Canberra ) - those are the only DSN-analogous dishes ( 35m ). The other assets are 15m or smaller - not of much use for deep space communications and used for things such as XMM-Newton, Eumetsat, Envisat, Integral etc... Near Earth stuff.

I agree, I would be very happy for the ESA network to start repaying the favour of DSN useage but there's a lot of IF's involved I would imagine... IF there is spare capacity on the ESA network (which may be true but I've not read anywhere that it is) and IF NASA would be prepared to let its spacecraft talk thru the European network ( which isn't certain ) - then bring it on.

Take the total number of active missions, divide by the total number of dishes...and I doubt that the DSN or ESTRACK are very different in terms of utilisation.

I would be very very happy to see ESTRACK capacity used for NASA missions (and Mars Express do some MER relay as well) , but above anything else - I wouldn't be at all suprised to see ITAR get in the way of it even being legal to do so, particularly given that ITAR is so broad reaching it doesn't even allow the Canadian MET team access to the commands to turn their instrument on with the Phoenix spacecraft.

Doug