... Instruments on Rosetta start comet science . ... Three NASA science instruments aboard the European Space Agency s (ESA) Rosetta spacecraft, which is set to become the first to orbit a comet and land a probe on its nucleus, are beginning observations and sending science data back to Earth. ... The instrument will measure the charged particles in the Sun s outer atmosphere, or solar wind, as they interact with the gas flowing out from the comet while Rosetta is drawing nearer to the comet s nucleus. ...