OSIRIS: The Scientific Camera System Onboard Rosetta

Abstract

Abstract. The Optical, Spectroscopic, and Infrared Remote Imaging System OSIRIS is the scientific camera system onboard the Rosetta spacecraft (Figure 1). The advanced high performance imaging system will be pivotal for the success of the Rosetta mission. OSIRIS will detect 67P/Churyumov-Gerasimenko from a distance of more than 10 6 km, characterise the comet shape and volume, its rotational state and find a suitable landing spot for Philae, the Rosetta lander. OSIRIS will observe the nucleus, its activity and surroundings down to a scale of ~2cmpx~1. The observations will begin well before the onset of cometary activity and will extend over months until the comet reaches perihelion. During the rendezvous episode of the Rosetta mission, OSIRIS will provide key information about the nature of cometary nuclei and reveal the physics of cometary activity that leads to the gas and dust coma.OSIRIS comprises a high resolution Narrow Angle Camera (NAC) unit and a Wide Angle Camera (WAC) unit accompanied by three electronics boxes. The NAC is designed to obtain high resolution images of the surface of comet 67P/Churyumov-Gerasimenko through 12 discrete filters over the wavelength range 250-1000 nm at an angular resolution of 18.6 /xradpx -1 . The WAC is optimised to provide images of the near-nucleus environment in 14 discrete filters at an angular resolution of 101 ¡xrad px~1. The two units use identical shutter, filter wheel, front door, and detector systems. They are operated by a common Data Processing Unit. The OSIRIS instrument has a total mass of 35 kg and is provided by institutes from six European countries.

Distance determination method of dust particles using Rosetta OSIRIS NAC and WAC data

“…It can be seen that most analyzed particles have produced only weak signals. Table 1 The filter numbers and names, which the NAC and WAC use, whereas all data the WAC collected is taken utilizing F21, the "Green Empty" filter (Keller et al 2007). The second orange filter (F32) was added to the sequences in an attempt to use the different focus distances of the Far Focus Plate (FFP) and the Near Focus Plate (NFP) to determine the distance via defocusing.…”

“…The scientific camera system onboard Rosetta is the Optical, Spectroscopic, and Infrared Remote Imaging System, OSI-RIS (Keller et al 2007). It consists of two cameras, a Narrow Angle Camera (NAC), with a field of view (FOV) of 2.20° x 2.22°, and a Wide Angle Camera (WAC), which has a FOV of 11.35° x 12.11°.…”

“…It consists of two cameras, a Narrow Angle Camera (NAC), with a field of view (FOV) of 2.20° x 2.22°, and a Wide Angle Camera (WAC), which has a FOV of 11.35° x 12.11°. Both cameras are equipped with a 2048 x 2048 pixel CCD detector (Keller et al 2007). …”

“…Overall, the WAC enables observations of the whole nucleus over a long period when Rosetta is close to the nucleus and the NAC studies it in a more detailed way. This is explained in more detail in Keller et al (2007).…”

“…It hosts the OSIRIS instruments: the Optical, Spectroscopic, and Infrared Remote Imaging System composed of two cameras, see e.g. Keller et al (2007). In some imaging sequences dedicated to observe dust particles in the comet's coma, the two cameras took images at the same time.…”