ABSTRACT
Leonardo has been involved in the realization of several infrared payloads for Earth observation since 1990. Among the currently in-orbit operative instruments are the two Sea and Land Surface Temperature Radiometers (SLSTRs) and PRISMA (PRecursore IperSpettrale della Missione Applicativa, meaning Hyperspectral Italian Pre-cursor of Operational mission). The SLSTRs are high-accuracy radiometers that provide sea surface temperature data continuity with respect to previous (A)ATSRs in order to serve climatology over the next 20 years, and exist within the framework of the European Space Agency Sentinel-3 mission, which is part of the Copernicus program. The PRISMA program is the first Agenzia Spaziale Italiana optical hyperspectral mission for Earth observation. It is based on a high spectral resolution spectrometer operating in the visible-short wave infrared channels optically integrated with a panchromatic camera.
ABSTRACT
Critical measurements for understanding accretion and the dust/gas ratio in the solar nebula, where planets were forming 4.5 billion years ago, are being obtained by the GIADA (Grain Impact Analyser and Dust Accumulator) experiment on the European Space Agency's Rosetta spacecraft orbiting comet 67P/Churyumov-Gerasimenko. Between 3.6 and 3.4 astronomical units inbound, GIADA and OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) detected 35 outflowing grains of mass 10(-10) to 10(-7) kilograms, and 48 grains of mass 10(-5) to 10(-2) kilograms, respectively. Combined with gas data from the MIRO (Microwave Instrument for the Rosetta Orbiter) and ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) instruments, we find a dust/gas mass ratio of 4 ± 2 averaged over the sunlit nucleus surface. A cloud of larger grains also encircles the nucleus in bound orbits from the previous perihelion. The largest orbiting clumps are meter-sized, confirming the dust/gas ratio of 3 inferred at perihelion from models of dust comae and trails.