November 7, 2014

Instruments

Rosetta is an interplanetary spacecraft whose main objective is to rendezvous with Comet 67P/Churyumov-Gerasimenko. In order to investigate the comet nucleus and the gas and dust ejected from the nucleus as the comet approaches the Sun, Rosetta carries a suite of eleven instruments on the comet orbiter and Philae, a lander equipped with a further ten instruments which perform surface measurements.

The orbiter instruments combine remote sensing techniques, such as cameras and radio science measurements, with direct sensing systems such as dust and particle analysers.

The instruments are provided by collaborative efforts between scientific institutes in ESA member states and the USA. Principal investigators in different European countries and America lead the nationally funded collaborations:

Orbiter instruments

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Rosetta orbiter Instruments © ESA
  • ALICE: Ultraviolet Imaging Spectrometer. ALICE will characterize the composition of the nucleus and coma, and the nucleus/coma coupling of the comet. This will be accomplished through the observation of spectral features in the extreme and far ultraviolet (EUV/FUV) spectral regions from 70 to 205 nm.
    ALICE will make measurements of noble gas abundances in the coma, the atomic budget in the coma, and major ion abundances in the tail and in the region where solar wind particles interact with the ionosphere of the comet. ALICE will determine the production rates, variability, and structure of H2O and CO, and CO2 gas surrounding the nucleus and the far-UV properties of solid grains in the coma.
     
  • CONSERT: Comet Nucleus Sounding Experiment by Radio wave Transmission. CONSERT will perform tomography of the comet nucleus. CONSERT operates as a time domain transponder between Philae once landed on the comet surface and the orbiter that will orbit the comet. A radio signal passes from the orbiting component of the instrument to the component on the comet surface and is then immediately transmitted back to its source. The varying propagation delay as the radio waves pass through different parts of the cometary nucleus will be used to determine the dielectric properties of the nuclear material and the internal structure of the nucleus.
     
  • COSIMA: Cometary Secondary Ion Mass Analyser. COSIMA is a secondary ion mass spectrometer equipped with a dust collector, a primary ion gun, and an optical microscope for target characterization. Dust from the near comet environment is collected on a target. The target is then moved under a microscope where the positions of any dust particles are determined. The cometary dust particles are then bombarded with pulses of indium ions from the primary ion gun. The resulting secondary ions are extracted into the time-of-flight mass spectrometer. They will give the elemental and isotopic composition of the cometary grains.
     
  • GIADA: Grain Impact Analyser and Dust Accumulator. GIADA will measure the scalar velocity, size and momentum of dust particles larger than 15 µm and heavier than 10-10 g collected in the coma of the comet thanks to an optical grain detection system and received by a mechanical grain impact sensor. Five microbalances will measure the amount of dust collected as the spacecraft escorts the comet.
     
  • MIDAS: Micro-Imaging Dust Analysis System. MIDAS is intended for the microtextural and statistical analysis of cometary dust particles. The instrument is based on the technique of Atomic Force Microscopy. This technique, under the conditions prevailing at the Rosetta orbiter permits textural (small structures in 3 dimensions down to a spatial resolution of 4 nm) and dust particles population statistics (shape, size and flux).
     
  • MIRO: Microwave Instrument for the Rosetta Orbiter. MIRO is composed of a millimetre wave mixer receiver (1.6 µm) and a submillimetre heterodyne receiver (0.5 µm). The submillimetre wave receiver provides both broad band continuum and high resolution spectroscopic data, whereas the millimetre wave receiver provides continuum data only.
    MIRO will measure the near surface temperature of the comet, allowing estimation of the thermal and electrical properties of the surface. In addition, the spectrometer portion of MIRO will allow measurements of water, carbon monoxide, ammonia, and methanol in the comet coma.
     
  • OSIRIS: Optical, Spectroscopic, and Infrared Remote Imaging System. OSIRIS is a dual camera imaging system operating in the visible, near infrared and near ultraviolet wavelength ranges (250 - 1000 µm) to characterize the shape, volume and rotational state of the nucleus. 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.
     
  • ROSINA: Rosetta Orbiter Spectrometer for Ion and Neutral Analysis. ROSINA consists of the double focusing mass spectrometer, a reflectron-type time of flight mass spectrometer and two pressure gauges. ROSINA will determine the molecular, elemental and isotopic composition of the volatile material of the coma as well as the density, velocity and temperature of the cometary gas.
     
  • RPC: Rosetta Plasma Consortium. RPC is a set of five instruments sharing a common electrical and data interface with the Rosetta orbiter. The RPC instruments are designed to make complementary measurements of the plasma environment of ions and electrons around comet 67P/Churyumov-Gerasimenko.
    • ICA: Ion Composition Analyser
    • IES: Ion and Electron Sensor
    • LAP: Langmuir Probe
    • MAG: Fluxgate Magnetometer
    • MIP: Mutual Impedance Probe
    • PUI: Plasma Interface Unit

  • RSI: Radio Science Investigation. RSI makes use of the communication system that the Rosetta spacecraft uses to communicate with the ground stations on Earth. Either one-way or two-way radio links can be used for the investigations. In the one-way case, a signal generated by an ultra-stable oscillator on the spacecraft is received on Earth for analysis. In the two way case, a signal transmitted from the ground station is transmitted back to Earth by the spacecraft. In either case, the downlink may be performed in either X-band or both X-band and S-band.
    RSI will investigate the nondispersive frequency shifts (classical Doppler) and dispersive frequency shifts (due to the ionised propagation medium), the signal power and the polarization of the radio carrier waves. Variations in these parameters will yield information on the motion of the spacecraft, the perturbing forces acting on the spacecraft and the propagation medium.
     
  • VIRTIS: Visible and Infrared Thermal Imaging Spectrometer. VIRTIS is an imaging spectrometer that combines three data channels in one instrument. Two of the data channels are designed to perform spectral mapping (220 - 5060 µm). The third channel is devoted to spectroscopy (2 - 5 µm). VIRTIS will detect, characterize and map the typical spectral bands of minerals and molecules from nucleus surface components and from materials dispersed in the coma.
     

Lander instruments

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Rosetta Lander Instruments © ESA
    • APXS: Alpha Proton X-ray Spectrometer. APXS goal is the determination of the chemical composition of the landing site and its potential alteration during the comet's approach to the Sun. The data obtained will be used to characterize the surface of the comet, to determine the chemical composition of the dust component, and to compare the dust with known meteorite types. APXS consists of an alpha-mode for alpha spectroscopy and an X-ray mode for alpha-particle and X-ray spectroscopy.
       
    • ÇIVA: Comet Infrared and Visible Analyser. ÇIVA-P is composed of seven identical miniaturized cameras to take panoramic pictures of the surface and reconstruct the local 3-dimension structure of the surface. ÇIVA-M is constituted of a visible microscope and a near infrared hyperspectral imager to study the molecular and mineralogical composition, texture and albedo (reflectivity) of samples collected from the surface.
       
    • CONSERT: Comet Nucleus Sounding Experiment by Radio wave Transmission. CONSERT will perform tomography of the comet nucleus. CONSERT operates as a time domain transponder between Philae once landed on the comet surface and the orbiter that will orbit the comet. A radio signal passes from the orbiting component of the instrument to the component on the comet surface and is then immediately transmitted back to its source. The varying propagation delay as the radio waves pass through different parts of the cometary nucleus will be used to determine the dielectric properties of the nuclear material and the internal structure of the nucleus.
       
    • COSAC: COmetary SAmpling and Composition experiment. COSAC is a multi-column gas chromatograph coupled to a linear reflectron time-of-flight mass spectrometer. COSAC will identify and quantify volatile cometary compounds including large organic molecules obtained from sub-surface samples heated in medium-temperature (180°) ovens or high-temperature (600°) ovens.
       
    • MUPUS: MUlti-PUrpose Sensors for Surface and Sub-Surface Science. MUPUS scientific objectives are to understand the properties and layering of the near-surface matter as these evolve with time as the comet rotates and approaches the Sun; to understand the energy balance at the surface and its variation with time and depth; to understand the mass balance at the surface and its evolution with time. MUPUS is mainly composed of a penetrator that is deployed by an arm, of temperature sensors and accelerators in harpoons, of depth and temperature sensors in the penetrator, of a surface thermal mapper.
       
    • PTOLEMY: Ptolemy is is an evolved gas analyser, which is composed of three gas chromatograph columns whose injected gases are provided by medium-temperature (180°) ovens or high-temperature (800°) ovens, and of a mass spectrometer. The scientific goal of PTOLEMY is to understand the geochemistry of light elements, such as hydrogen, carbon, nitrogen and oxygen, by determining their nature, distribution and stable isotopic compositions.
       
    • ROLIS: ROsetta Lander Imaging System. This descent & down-looking camera will deliver the first close-ups of the environment of the landing site during the descent.
      After landing ROLIS will make high-resolved investigations to study the structure (morphology) and mineralogy of the surface. ROLIS is a miniaturized CCD camera allowing multi-spectral imaging in 4 spectral bands (470, 530, 640 and 870 nm) provided by an illumination device.
       
    • ROMAP: Rosetta Lander Magnetometer and Plasma Monitor. ROMAP is a multi-sensor experiment. The magnetic field is measured with a fluxgate magnetometer. An electrostatic analyzer with integrated Faraday cup measures ions and electrons. The local pressure is measured with Pirani and Penning sensors. The sensors are situated on a short boom. The scientific goals are to study magnetic field and plasma waves emitted by the surface as a function of the heliocentric distance.
       
    • SD2: Sampling, Drilling and Distribution. SD2 is in charge to collect comet soil samples at different depths below the surface of the comet and distribute them to three different instruments for analysis (Çiva, Cosac, Ptolemy). Specifically SD2 can bore up to 250 mm into the surface of the comet. It then transports each sample to a carousel which feeds samples to different instrument stations: a spectrometer, a volume check plug, ovens for high and medium temperatures and a cleaning station. SD2 is accommodated on the flat ground-plate of Philae, where it is exposed to the cometary environment.
       
    • SESAME: Surface Electric Sounding and Acoustic Monitoring Experiment. SESAME is composed of three instruments. Two measure mechanical and electrical properties of the comet's outer layers that are indicators of the cometary evolution history, one studies velocity and mass distribution of dust particles emitted by the comet surface. Most of the sensors are mounted in the 6 soles of the landing gear.
      • CASSE: Comet Acoustic Surface Sounding Experiment. CASSE measures the way in which sound travels through the surface
      • DIM: Dust Impact Monitor. DIM measures dust falling back to the surface.
      • PP: Permittivity Probe. PP investigates its electrical characteristics.
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