Space Research

The Ion Beam Spectrometer (IBS) for the NASA Spacecraft Cassini

The Ion Beam Spectrometer is a particle detector for Cassini Plasma Spectrometer.

The Ion Beam Spectrometer measures the kinetic energy of electrically charged particles and their direction of arrival in space. IBS sensor has been installed on NASA spacecraft Cassini, which was launched in 1997 and arrived at Saturn in 2004. VTT developed the IBS sensor jointly with University of Oulu, Los Alamos National Laboratory, and Southwest Research Institute in the USA. VTT was responsible for the design, fabrication, assembly and alignment of the mechanical structures of the sensor.

The mechanical structure of IBS consists of two hemispherical analyzer shells, detectors and particle entrance apertures on a front plate. An electric field is generated to the 2.5 mm gap between the hemispheres, and it functions as a band pass filter for the particles with desired energy.

Diameters of the hemispheres are in the range of 200 mm, and their thickness varies from 0.7 to 0.8 mm. Hemispheres were machined to the spherity of 0.05 mm. To ensure the function of the sensor, the hemispheres were positioned with an accuracy of 20 m relative to each other with a 3D coordinate measuring machine.

The mass of the mechanical parts of the sensor is 700 grams, while the total mass is 1200 grams. Power consumption of the sensor is about 0.8 Watts.