Launched in 2004, Rosetta is now travelling on a long route around the Sun to rendezvous with Comet Churyumov-Gerasimenko in 2014 and deliver a lander onto its surface.
With Stardust, scientists will have access to information about particles collected from the 'coma', the halo of dust and gas surrounding the comet tail.
"These tiny particles, mostly micrometres in size, will be cut into even finer pieces and will be analysed with the very best instruments and at the highest level of detail for Earth-based labs," continued Schwehm.
"With Rosetta, we will study the comet in situ in all its aspects the tail, the coma and even the surface, the comet 'mantle'. Instead of bringing the comet material to our laboratories, Rosetta will take the 'laboratory' to the comet.
"In particular, our sophisticated suite of instruments will allow us not only to fully characterise the comet's particle content chemical composition and other physical properties but also the volatile content. This means we don't potentially lose any of these properties during a transport back to Earth," he adds.
"However, thanks to Stardust, the analysis of coma particles on Earth will provide the whole scientific community with an unprecedented close-up view. For instance, the analysis of the 'isotopic ratio' of the elements in the dust grains (finding the percentage and the nature of 'decayed' atoms in the dust) gives important information about where and how this material was formed," concluded Schwehm.