The spacecraft Cassini will make a second pass today through the jets spraying from the south pole of Enceladus, one of Saturn’s moons. Less than three weeks ago, Cassini made a similar pass through the jets (27 March). Combined with a previous pass on 1 October, these three passes should allow the ion and neutral mass spectrometer to determine the three dimensional structure of the jets and how they change over time.
This flyby will occur at an altitude of 74 kilometers (46 miles), the same as the March flyby. The plumes are composed of jets of water ice and vapor, and organic compounds emanating from the south polar region. Other measurements of the plumes include the plasma spectrometer and composite infrared spectrometer.