T-101: Bouncing Radio Waves off Titan’s Lakes
For Cassini’s Radio Science team, the May 17 flyby of Titan was one of the most scientifically valuable encounters of the spacecraft’s current extended mission. The focus of this flyby, designated T-101, was on enabling the Radio Science (RSS) team to bounce signals off the surface of Titan, toward Earth, where they would be received by the stations of NASA Deep Space Network. This sort of observation is known as a bistatic scattering experiment; its results can be used to reveal details about the nature and composition of the smoggy moon’s surface and how those characteristics vary from place to place. A successful bistatic experiment can yield clues to help answer a variety of questions about large areas of Titan’s surface: Are they solid, slushy, or liquid? Are they reflective? What are they made of?
During the T-101 encounter, the RSS experiments beamed radio waves over the two largest bodies of liquid on Titan, Ligeia Mare and Kraken Mare. In addition, the RSS team conducted an Earth occultation that included a limb track maneuver.
Prior to the RSS observation, Cassini’s Ultraviolet Imaging Spectrograph (UVIS) probed Titan’s atmosphere with a stellar occultation – that is, by watching how a bright star is dimmed as it passes behind the moon’s hazy envelope. The UVIS observations are expected to provide a high-resolution vertical profile of hydrocarbons, haze and temperatures in the atmosphere.