Cassini CDA: Cosmic Dust Analyzer - CERTIFIED

The Cosmic Dust Analyzer (CDA) consisted of two instruments that detect incoming particles: the High Rate Detector (HRD) and the Dust Analyzer (DA). These co-aligned instruments were mounted on a turntable that allowed them to articulate. The HRD was designed, built and tested at the University of Chicago. The DA was developed and built as a joint project by the Institute of Planetary Research at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) in Berlin Adlershof and the Max Planck Institute for Nuclear Physics (MPI-K). It contained components that were developed at the University of Kent in Canterbury, UK.

Scientific objectives for the CDA include the following:

• Extend studies of interplanetary dust out to the orbit of Saturn
• Map the size distribution and analyzing the chemical composition of ring material in and near the known rings
• Study the dynamical processes (erosional and electromagnetic) responsible for E ring structure, study the interactions between the E ring and Saturn's magnetosphere, search for electromagnetic resonances
• Determine the role that dust plays as a source and sink of magnetospheric charged particles
• Study the chemical composition of icy satellites from studies of ejecta particles
• Study the effect of Titan on the Saturn dust complex

The HRD detected up to 10,000 particles per second, while the DA detected 1 particle per second. The HRD was capable of detecting particles at a higher rate and therefore returned only particle count and mass for particles with a known speed. Assuming a particle velocity of 15 km/s, the HRD detected particles within a range of 8x10^-16 to x10^-11 kg for differential and cumulative flux measurements and >8x10^-11 kg for cumulative flux measurements. The DA used four grids spanning its aperture to determine the electric charge, impact direction, impact speed, mass and chemical composition of the particles it detected. The DA accomplished these goals through the use of three subsystems: the charger detector, the impact ionization detector and the chemical analyser. Particles impacting at 10 km/s, and larger than 5.9x10^-17 kg (corresponding to a spherical grain with a radius of 0.25 µm and density of 930 kg/m³) should have been detected by the DA.

The engineering details of the CDA instrument and the science objectives it was built to address are described in further detail in the Space Science Reviews paper by Srama et al. (2004). Additionally, Kempf (2008) includes an example of analysis and dead-time correction.

• The Event Calendar is an interactive event finding-tool that can be used to search for data associated with particular events.
• The Master Schedule is a time-ordered listing of observations by all instruments. This can be used to find data based on particular events.

Browse Raw Data Products

• CDA Data Products can be found on the PDS Dust subnode.
• The High Rate Detector (HRD) Data is in a separate archive, and measures the dust flux and particle mass distribution of dust particles hitting HRD detectors.

Derived Data Products

• An extensive set of Mass Spectra (Temporarily unavailable)

Analyzing CDA Data

Once data products have been selected and retrieved, users will need to read, manipulate and display that data. Resources that will enable users to make use of CDA data are listed below.
• Kempf, S. Interpretation of High Rate Dust Measurements with the Cassini Dust Detector CDA, Planetary and Space Science, 2008 (378-385). Includes process for dead-time correction.
• SPICE WebGeocalc allows users to search for observation computations by geometry. Be aware that since CDA was able to articulate its pointing relative to the spacecraft, SPICE will display this information as well.
• IDL Package Spectra

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For questions and comments, visit the PDS Cassini Contact Page