ALICE

ALICE, an Ultraviolet Imaging Spectrometer, will characterize the composition of the nucleus and coma, and the nucleus/coma coupling of comet 67 P/Churyumov-Gerasimenko. 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.

ALICE will also map the cometary nucleus in the FUV, and study Mars and the Rosetta asteroid flyby targets while en route to to comet 67P/Churyumov-Gerasimenko.

CONSERT

CONSERT (Comet Nucleus Sounding Experiment by Radio wave Transmission) will perform tomography of the comet nucleus. CONSERT operates as a time domain transponder between one module which will land on the comet surface and another 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.

COSIMA

COSIMA (Cometary Secondary Ion Mass Analyser) 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.

GIADA

GIADA (Grain Impact Analyser and Dust Accumulator) will measure the scalar velocity, size and momentum of dust particles in the coma of the comet using an optical grain detection system and a mechanical grain impact sensor. Five microbalances will measure the amount of dust collected as the spacecraft orbits the comet.

MIDAS

MIDAS (Micro-Imaging Dust Analysis System) 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 and other analysis of dust particles to be performed down to a spatial resolution of 4 nm.

MIRO

MIRO (Microwave Instrument for the Rosetta Orbiter) is composed of a millimetre wave mixer receiver and a submillimetre heterodyne receiver. 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

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.

ROSINA

ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) consists of two mass spectrometers, since no one technique is able to achieve the resolution and accuracy required to fulfil the Rosetta mission goals over the range of molecular masses under analysis. In addition, two pressure gauges provide density and velocity data for the cometary gas.

The two mass analysers are:

• A double focusing magnetic mass spectrometer with a mass range of 1 - 100 amu and a mass resolution of 3000 at 1 % peak height, optimised for very high mass resolution and large dynamic range
• A reflectron type time-of-flight mass spectrometer with a mass range of 1 - 300 amu and a mass resolution better than 500 at 1 % peak height, optimised for high sensitivity over a very broad mass range
  

RPC

RPC (Rosetta Plasma Consortium) 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 around comet 67P/Churyumov-Gerasimenko.

The RPC instruments are:

• an Ion Composition Analyser (ICA)
  to measure the three-dimensional velocity distribution and mass distribution of positive ions
• an Ion and Electron Sensor (IES)
  to simultaneously measure the flux of electrons and ions in the plasma surrounding the comet
• a Langmuir Probe (LAP)
  to measure the density, temperature and flow velocity of the cometary plasma
• a Fluxgate Magnetometer (MAG)
  to measure the magnetic field in the region where the solar wind plasma interacts with the comet
• a Mutual Impedance Probe (MIP)
  to derive the electron gas density, temperature, and drift velocity in the inner coma of the comet

All five instruments are controlled by the common Plasma Interface Unit (PIU) which also provides the interface to the Rosetta spacecraft and distributes power from the spacecraft to the five RPC instruments at the required secondary voltages.

RSI

RSI (Radio Science Investigation) 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

VIRTIS (Visible and Infrared Thermal Imaging Spectrometer) is an imaging spectrometer that combines three data channels in one instrument. Two of the data channels are designed to perform spectral mapping. The third channel is devoted to spectroscopy.

	Introduction
	ALICE: Ultraviolet Imaging Spectrometer