Orbiter Instruments
OSIRIS: Optical, Spectroscopic, and Infrared Remote Imaging System
OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) is a dual camera imaging system operating in the visible, near infrared and near ultraviolet wavelength ranges. OSIRIS consists of two independent camera systems sharing common electronics. The narrow angle camera is designed to produce high spatial resolution images of the nucleus of the target comet. The wide angle camera has a wide field of view and high straylight rejection to image the dust and gas directly above the surface of the nucleus of the target comet. Each camera is equipped with filter wheels to allow selection of imaging wavelengths for various purposes. The spectroscopic and wider band infrared imaging capabilities originally proposed and incorporated in the instrument name were descoped during development.
Science Objectives
The OSIRIS science objectives for the comet nucleus, the gases and dust produced by the comet and for the asteroid flybys are: | Nucleus Objectives | | Objective | Method | | Initial detection of nucleus. | Detection of motion of nucleus against background stars from > 1 Mkm with multiple NAC images. | | Initial assessment of rotation period. | Light curve monitoring while nucleus is still unresolved. | | Initial determination of size and shape to an accuracy of 100 m. | Multiple images with narrow angle camera from < 30 000 km at phase angles between 30E and 110E. | | Detailed determination of size, shape, and volume to sufficient accuracy to constrain the density. | In orbit images with both cameras from < 100 km followed by shape deconstruction
on ground. | | Search for residual evidence of formation mechanisms and scale lengths. | High resolution, colour imaging of the surface. | | Investigation of topographic features and associated physical processes. | High resolution, colour imaging of specific surface features and outgassing. | | Mapping the surface variegation. | Global mapping at better than 1 m resolution. | | Investigate the colour and mineralogy of the surface to study the degree of inhomogeneity. | Global mapping in specific mineralogical bands. | | Determine the mass loss rate. | Measurement of the depth eroded by activity with a resolution of 0.2 m or better. | | Determine the effect of non-gravitational forces on the nucleus. | Repeated determination of the angular momentum vector and the instantaneous spin axis through perihelion. | | Characterize the Philae landing site. | High resolution imaging of the target site. | | Analyse short-term variability and outbursts. | Rapid imaging of active regions. | | Dust Objectives | | Objective | Method | | Search for evidence of crustal diffusion. | High signal to noise ratio imaging of weak emission. | | Search for gravitationally-bound material. | High resolution imaging and tracking of bright large dust particles in the coma; Stereo measurements using both cameras. | | Search for evidence of particle fragmentation, acceleration, condensation, and optical effects close to the dust source. | High resolution imaging of the dust emission immediately above the source. | | Determine the near-surface flow-field of dust and its temporal evolution. | Mapping of the dust distribution around the nucleus with a wide field of view. | | Determine the optical and physical properties of the dust and estimate the dust size distribution. | Multi-phase angle and multi-colour imaging. | | Investigate night-side activity. | High signal to noise, low straylight measurements of the night side limb. | | Quantify thermal inertia effects on emission. | Monitoring of active regions as the solar zenith angle varies. | | Gas Objectives | | Objective | Method | | Investigate the chemical inhomogeneity of active region. | Multi-wavelength studies of individual active regions. | | Investigate the changes in volatile emission with heliocentric distances. | Monitoring of an active region from high heliocentric distance through to perihelion. | | Identify scale lengths for dissociation of water molecules. | Measure cometocentric distance dependence of OI and OH emission. | | Determine the onset of emission. | High signal to noise measurements of dust and CN emission. | | investigate the relationship between the dust distribution and the gas distribution in the coma. | Multi-wavelength studies of different species and comparison with the dust distribution using the wide angle camera. | | investigate the distribution of alkali metals in active regions and on emitted dust grains. | Studies of Na and its relationship to the dust distribution. | | To study the nitrogen and sulphur chemistry in the nucleus. | Monitoring of CS, NH and NH2 emission. | | Asteroid Flyby Objectives | | Objective | Method | | Determine the sizes, volumes, and densities of the asteroids. | Resolved imaging over the rotation periods of the targets. | | Derive surface reflectance properties and hence acquire information on the properties of the regolith. | Multiple phase angle observations and absolute calibrated data. | | Study their surface morphologies and estimate their surface ages. | High resolution imaging of surface features and crater statistic measurements. | | Study the mineralogical composition and its homogeneity. | Multi-filter high resolution imaging covering the NIR bands of olivine and pyroxene in detail. | | Search for potential asteroid satellites. | Wide-angle coverage around closest approach. | | Search for evidence of water. | Measurement of the water of hydration feature at 700 nm. | | Mars and Martian Satellites Flyby Objectives | | Objective | Method | | To study the global meteorological conditions on Mars over a two-day period. | Multi-wavelength studies of the disc. | | Investigate the vertical structure of aerosols in the Martian atmosphere. | Multi-wavelength resolved images of the limb. | | Investigate the global chemical heterogeneity on Mars. | Multi-filter images of the surface using the narrow angle camera (concentrating on the near-IR from 650 to 1000 nm). | | Investigate the global chemical heterogeneity on Phobos and Deimos. | High signal to noise resolved multi-wavelength images of the two satellites. | | Search for evidence of the dissociation products of water. | OH and OI measurements. | | Earth/Moon System Flyby Objectives | | Objective | Method | | Study the distribution of atomic oxygen emission in the upper atmosphere of the Earth. | Global OI imaging with the wide angle camera. | | Investigate the global chemical heterogeneity on the Moon. | Multi-wavelength images of the surface using the NAC (concentrating on the near-IR from 650 to 1000 nm). | | Search for evidence of surface sputtering and outgassing from the Moon. | Images of the Na distribution. | | Perform calibration of the imaging system. | Multi-wavelength, multi-phase angle coverage of the Moon. |
Instrument Description
OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) is a dual camera imaging system operating in the visible, near infrared and near ultraviolet wavelength ranges. OSIRIS consists of two independent camera systems sharing common electronics. The narrow angle camera is designed to produce high spatial resolution images of the nucleus of the target comet. The wide angle camera has a wide field of view and high straylight rejection to image the dust and gas directly above the surface of the nucleus of the target comet. Each camera is equipped with filter wheels to allow selection of imaging wavelengths for various purposes. The OSIRIS experiment comprises the two cameras, two sensor readout electronics boxes, the OSIRIS common electronics box and a set of interconnecting harnesses. The cameras are mounted on the outside of the spacecraft and thermally isolated from it. The sensor readout electronics boxes are located inside the spacecraft, each as close as possible to its camera to minimise harness length. The central electronics box is located elsewhere inside the spacecraft with a dedicated cooling louvre on the outside panel surface.
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MIRO: Microwave Instrument for the Rosetta Orbiter |
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ROSINA: Rosetta Orbiter Spectrometer for Ion and Neutral Analysis |
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Last Update: 11 Jan 2010
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