Space Topics: Cassini-Huygens
Cassini's Science Instruments
The Cassini orbiter has a dozen science instruments that can examine Saturn
from a distance across a vast range of the electromagnetic spectrum and that
can sample directly the energetic particles and magnetic fields in Saturn's
space environment. The instruments fall into three categories: Optical remote
sensing, microwave remote sensing, and in-situ studies. Although each
instrument was built for a specific set of science investigations of its own,
additional investigations will be accomplished by scientists using several
of the instruments in concert.
Optical Remote Sensing Experiments
Remote sensing instruments are used to study the Saturn system from a distance
using electromagnetic waves (ultraviolet, visible light, infrared, and radio)
that are reflected from or emitted by the planet, its rings, and moons. All
of the optical remote sensing instruments are located together on Cassini's
Optical Remote Sensing Pallet, which means that they always point at the same
target at the same time.
Imaging Science Subsystem (ISS)
The ISS is Cassini's main camera system. It is performing multispectral
imaging of Saturn, its rings, Titan, and the other moons to observe their
properties. Camera images also provide context for other remote sensing investigations
and help navigators keep the spacecraft on course.
Team Leader: Carolyn Porco, Space Science Institute
Visual and Infrared Mapping Spectrometer
(VIMS)
VIMS creates maps of the color properties of the atmospheres of Saturn
and Titan, the surfaces of the moons, and the rings in order to study their
composition and structure.
Team Leader: Robert Brown, University of Arizona Lunar and Planetary Laboratory
Composite Infrared Spectrometer (CIRS)
The CIRS instrument senses longer wavelengths than ISS or VIMS. Like VIMS,
it is used to map the color properties of the atmospheres of Saturn and
Titan, the surfaces of the moons, and the rings in order to study their
composition and temperature.
Principal Investigator: Virgil Kunde, NASA Goddard Space Flight Center
Ultraviolet Imaging Spectrograph (UVIS)
UVIS senses shorter wavelengths than any other instrument. It actually
consists of four instruments that take spot measurements and low resolution
images of the Saturn and Titan atmospheres in order to study their structure,
chemistry, and composition.
Principal Investigator: Larry Esposito, University of Colorado
Microwave Remote Sensing Experiments
Both of these experiments are performed using Cassini's 4-meter (13-foot)
high-gain antenna, the big dish on one end of the spacecraft. Unlike the optical
remote sensing experiments, which passively receive radiation from their targets,
most of the radio experiment activities require Cassini to broadcast a radio
signal and for either Cassini or Earth-based radio antennas to listen for
the echo.
Cassini Radar (RADAR)
Cassini's microwave radio broadcasts are able to penetrate Titan's atmosphere.
The instrument is producing images, topographic maps, and compositional
maps of the surface of Titan, as well as the other moons. It can also
penetrate to deeper levels within Saturn’s atmosphere than any other
instrument.
Team Leader: Charles Elachi, Jet Propulsion Laboratory
Radio Science Subsystem (RSS)
Radio broadcasts from Cassini through the rings and the atmospheres of
Saturn and Titan to Earth can explore finer structures than can be exposed
by any other instrument. In addition, Doppler tracking of the spacecraft
constrains the masses and gravity fields of Saturn’s moons.
Team Leader: Arvydas Kliore, Jet Propulsion Laboratory
In-Situ Investigations
"In Situ" means "in place." These instruments measure
the particles, ions, and magnetic fields at the position of the spacecraft
in the Saturn system. For maximum effectiveness of these experiments, Cassini
needs to visit as many different positions within the Saturn system as possible:
close in, far out, near the ring plane, and above and below the ring plane.
Each instrument is sensitive to particles with different mass, electrical
charge, and speed, although the instruments overlap in their detection capabilities.
Cosmic Dust Analyzer (CDA)
The CDA has two sensors, one that counts the number of tiny particles impacting
it every second--up to 10,000--and another that determines the flight direction,
impact speed, mass, and chemical composition of some ice and dust particles.
Principal Investigator: Eberhard Grün, Max Planck Institut für Kernphysik
Ion and Neutral Mass Spectrometer (INMS)
INMS can detect neutral (uncharged) atoms as well as positively charged
ions. It scoops up material and determines the compositions and isotopic
abundances of chemicals and elements in the upper reaches of Saturn's and
Titan's atmospheres and throughout the tenuous E ring.
Team Leader: Hunter Waite, Southwest Research Institute
Cassini Plasma Spectrometer (CAPS)
Saturn's magnetic field strips the electrons from atoms, creating plasma.
CAPS scoops up plasma and measures its composition, density, speed, and
temperature throughout Saturn's three-dimensional magnetic field. CAPS can
detect higher-energy particles than INMS can.
Principal Investigator: David Young, Southwest Research Institute
Radio and Plasma Wave Science (RPWS)
RPWS measures the electric and magnetic fields and electron density and
temperature in the interplanetary medium and within the Saturn magnetosphere.
Principal Investigator: Donald Gurnett, University of Iowa
Magnetospheric Imaging Instrument (MIMI)
MIMI consists of three instruments. Two measure the composition, charge,
and energy of energetic ions and electrons and detect fast neutral particles.
The third is actually a remote sensing instrument that can produce an image
of the distribution of charge and composition of the ions in Saturn's magnetosphere
in order to study the structure of the magnetosphere and its interaction
with the solar wind.
Principal Investigator: Stamatios Krimigis, Johns Hopkins University Applied
Physics Laboratory
Dual Technique Magnetometer (MAG)
The magnetometer experiment will map the strength and direction of Saturn's
magnetic field and interactions with the solar wind
Principal Investigator: Michele Dougherty, Imperial College, London
Interdisciplinary Investigations
There are six teams of Interdisciplinary Scientists who will coordinate the
activities of the individual instrument teams. Workshops run by the Interdisciplinary
Scientists will allow the science team to turn conjectures based on one instrument’s
results into conclusions based on many separate lines of evidence.
Satellites
Mapping of the surfaces of Saturn's moons and study of their morphology,
structure, composition, and geologic history
Interdisciplinary Scientist: Larry Soderblom, United States Geological
Survey
Rings and Dust
Study of the structure, composition, sources, motion, and evolution of
rings and dust particles
Interdisciplinary Scientist: Jeffrey Cuzzi, NASA Ames Research Center
Atmospheres
Study of the structure, composition, circulation, and climate of the atmospheres
of Titan and Saturn
Interdisciplinary Scientist: Tobias Owen, University of Hawaii
Aeronomy and Solar Wind Interaction
Interdisciplinary study of the composition and structure of the upper atmospheres
of Titan and Saturn and their interaction with the solar wind
Interdisciplinary Scientist: Darrell Strobel, Johns Hopkins University
Magnetosphere and Plasma
Study of the motion of plasma near Saturn to determine how the magnetosphere
and ionosphere are connected
Interdisciplinary Scientist: Michel Blanc, Observatoire Midi-Pyrénées
Magnetosphere and Plasma
Understanding the plasma environment in Saturn's magnetosphere
Interdisciplinary Scientist: Tamas Gombosi, University of Michigan
|
[ what is this? ]