As we wait for Rosetta to (carefully) manuver back closer to 67P/CG (diving close to a boiling comet is riskier than expected), and also hope to hear from plucky little Philae, 67P/CG is swinging closer to the Sun and s coming in range of Earth-based instruments, which will join the party, adding as much data as possible to the richest understanding ever achieved for a comet.
The ground-based observations will be able to make multiple records of various wavelengths from 67P/CG, which can be correlated with the high resolution (but limited scope) space observations. The multiple observations will give an opportunity to cross validate and calibrate all the data.
(It is an interesting philosophical question as to which observations should be considered the more “ground truthy”. Are the multiple, highly reliable but quite distant Earth based instruments the “gold standard”, or are the in situ but very remote and singleton space-based instruments on Rosetta the “best data”.)
In addition to the relatively few large, professional observations, ESA and many other collaborators are organizing a “citizen science” campaign: “Rosetta ground based campaign: calling all amateur astronomers”.
This isn’t a mere publicity campaign. There are only so many big telescopes and professional astronomers (and fewer every year with slashed science budgets), and “amateurs” have pretty darn good equipment these days. This will add a third layer, with many additional measurements to further strengthen the data set.
This should result in a massive (and probably messy) data set, which will take some work to get the most out of it.
Perhaps there will be another call for participation, a “data wranglers challenge”, to whip this collection into order and squeeze every last drop of insight from it.