Cassini Orbital Insertion
Credit: NASA, JPL, CIT
The Cassini-Huygens spacecraft was the fourth mission to observe Saturn. Previously, Saturn was visited by Pioneer 11 in September 1979, Voyager 1 in November 1980 and Voyager 2 in August 1981.
Cassini has seven primary objectives:
- Determine the three-dimensional structure and dynamic behavior of the rings of Saturn
- Determine the composition of the satellite surfaces and the geological history of each object
- Determine the nature and origin of the dark material on Iapetus’s leading hemisphere
- Measure the three-dimensional structure and dynamic behavior of the magnetosphere
- Study the dynamic behavior of Saturn’s atmosphere at cloud level
- Study the time variability of Titan’s clouds and hazes
- Characterize Titan’s surface on a regional scale
- The Composite Infrared Spectrometer (CIRS) searches for heat and is capable of discerning an object’s composition. “What’s cool is that CIRS can tell us how hot something is and what’s in it — like finding out that there’s a hot bowl of soup over there and that it’s chicken noodle, not tomato” explains Dr. Glenn Orton, a senior research scientist and CIRS co-investigator.
- the Imaging Science Subsystem (ISS) consists of a wide-angle camera and a narrow-angle camera. The narrow-angle camera provides high-resolution images of targets of interest, while the wide-angle camera allows more extended spatial coverage at lower resolution.
- Ultraviolet Imaging Spectrograph (UVIS) is a box of four telescopes that can see ultraviolet light. Ultraviolet (UV) light, known as the cause of sunburn on Earth, is invisible to the human eye.
- The Visible and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft is made up of two cameras in one: one is used to measure visible wavelengths, the other infrared. Combined, the two cameras gather a lot of information on the composition of moon surfaces, the rings, and the atmospheres of Saturn and Titan.
- The Cassini Plasma Spectrometer (CAPS) measures the energy and electrical charge of particles such as electrons and protons, and studies the composition, density, flow, velocity, and temperature of ions and electrons in Saturn’s magnetosphere.
- The Cosmic Dust Analyzer (CDA) is capable of detecting the impact of tiny particles — 1/1,000 of a millimeter wide. Giovanni Cassini was the first astronomer to recognize this dust in interplanetary space, and its presence around the sun, through telescopic observations in the 17th century. Revealing the origins of this cosmic dust, its composition and how it may affect life on Earth has been an ongoing focus of research and exploration ever since.
- The Ion and Neutral Mass Spectrometer (INMS) is collecting data to determine the composition and structure of positive ions and neutral particles in the upper atmosphere of Titan and the magnetosphere of Saturn.
- The Magnetometer (MAG) measures the strength and direction of Saturn’s magnetic field near the spacecraft. “The coolest thing about the magnetometer is that it allows you to ‘see’ inside planets such as Saturn and moons such as Enceladus,” says Marcia Burton, investigation scientist for the Cassini magnetometer and the Cassini Magnetospheric Discipline Scientist. “By measuring the magnetic field very accurately we can determine the size of Saturn’s core.”
- The Magnetospheric Imaging Instrument (MIMI) is designed to measure the composition, charge state and energy distribution of energetic ions and electrons; detect fast neutral particles; and conduct remote imaging of Saturn’s magnetosphere. The information gathered is used to study the overall configuration and dynamics of the magnetosphere and its interactions with the solar wind, Saturn’s atmosphere, rings, and icy moons, and Titan.
- The Radio and Plasma Wave Science (RPWS) instrument receives and measures the radio signals coming from Saturn, including the radio waves given off by the interaction of the solar wind with Saturn and Titan.
- Radar (RADAR) takes pictures like a camera but it “sees” using microwaves instead of light. It measures how objects reflect microwaves, which tells scientists something about how rough they are, or how they would conduct electricity.
- The Radio Science (RSS) instrument is designed to take measurements using radio waves beamed to Earth. “Our instrument can measure exactly how well you could hear somebody talking, and the quality of the sound traveling through whatever is between you and the speaker,” explains Sami Asmar, RSS task leader. “By studying the changes in your voice as it goes through various materials, we’d learn information on the composition and characteristics of the door or the curtain behind which you’d be talking. For us, the materials are the rings of Saturn or the planet’s atmosphere.”
Credit: NASA, JPL
Cassini-Huygens Spacecraft Animation
Credit: NASA, JPL
(UVIS) Ultraviolet Image of Saturn’s
A Ring From the Inside Out
Credit: NASA, JPL
(MAG) Saturn’s Magnetic Field Lines
Credit: NASA, JPL
The international Cassini spacecraft mission left Earth bound for Saturn atop an Air Force Titan IV/B Centaur rocket on October 15, 1997 at 4:43 a.m. EDT (1:43 a.m. PDT) from Cape Canaveral, FL.
The first major milestone for the Cassini program was accomplished successfully on 9 November 1997 when Cassini spacecraft controllers performed the spacecraft’s first planned trajectory correction maneuver. The maneuver required an adjustment of only 2.7 meters per second (about 8 feet per second) to fine-tune the spacecraft’s flightpath.
Mission analysts designed a unique trajectory which involved gravity-assists from Venus, Earth, and Jupiter. The spacecraft arrived at Saturn in July 2004. On 26 October 2004, Cassini made its first close pass by Titan.
On 24 December 2004, the European Space Agency’s Huygens probe successfully detached from NASA’s Cassini orbiter today to begin a three-week journey to Saturn’s moon Titan. Huygens successfully landed on Titan on January 14, 2005.
Current information on the Cassini mission and its exploration of Saturn and its moons can be found here.
Look here for the primary events for Cassini in 2010.