19 th International Symposium on Space Terahertz Technology P6-1 Title: Distributed correlator for space applications Authors: A.W. Gunst, A. Bos, L. Venema Affiliation: ASTRON, the Netherl<strong>and</strong>s For radio telescopes on Earth it is quite common to use a centralized correlator. This is used because the data of all the antennas need to be correlated with each other <strong>and</strong> therefore routing all the data to a central place is natural. However, in space the power dissipation <strong>and</strong> size is limited per satellite <strong>and</strong> hence a distributed correlator can be more advantageous. This also spreads the risk of failures. In this paper the proposed architecture for a distributed correlator in space is discussed. Furthermore, the effect of a number of design parameters on the estimated size <strong>and</strong> power consumption is also overviewed. 130
19 th International Symposium on Space Terahertz Technology P6-2 CASIMIR – Caltech Airborne Submillimeter Interstellar Medium Investigations Receiver David Miller, Michael L. Edgar, Alex<strong>and</strong>re Karpov, Sean Lin, Simon J. E. Radford, Frank Rice, Jonas Zmuidzinas (Caltech), Andrew I. Harris (U. Maryl<strong>and</strong>), <strong>and</strong> Neal Erickson (U. Massachusetts) CASIMIR, the Caltech Airborne Submillimeter Interstellar Medium Investigations Receiver, is a multib<strong>and</strong>, far-infared <strong>and</strong> submillimeter, high resolution, heterodyne spectrometer under development for SOFIA. It is a first generation, PI class instrument, designed for detailed, high sensitivity observations of warm (100 K) interstellar gas, both in galactic sources, including molecular clouds, circumstellar envelopes <strong>and</strong> protostellar cores, <strong>and</strong> in external galaxies. Combining the 2.5-meter SOFIA mirror with state of the art superconducting mixers will give CASIMIR unprecedented sensitivity. Initially, CASIMIR will have four b<strong>and</strong>s: 550 GHz, 750 GHz, 1000 GHz, <strong>and</strong> 1250 GHz; with a fifth b<strong>and</strong> under development at 1400 GHz. Any four b<strong>and</strong>s will be available on each flight, contributing to efficient use of observing time. All the CASIMIR b<strong>and</strong>s use advanced Superconductor- Insulator-Superconductor (SIS) mixers fabricated with Nb/AlN/NbTiN junctions in the JPL Micro Devices Lab. These planar mixers are quasi-optically coupled using twin slot antennas, <strong>and</strong> silicon hyperhemisphere lenses with Parylene antireflection coatings. With ongoing development, expectations are for DSB noise temperatures to improve to 3 hv/k at frequencies below 1 THz, <strong>and</strong> 6 hv/k above 1 THz. Each b<strong>and</strong> uses a tunerless solid state local oscillator mounted on the outside of the two cryostats, with injection to the mixers via mylar beamsplitters. The optics box supporting the cryostats is open to the telescope cavity <strong>and</strong> contains the relay optics <strong>and</strong> calibration systems. Besides the cryostat windows, all optics are reflective <strong>and</strong> can accommodate the entire 8’ telescope field of view. Bias electronics <strong>and</strong> warm IF amplifiers are mounted on the cryostats, while electronics racks contain backend spectrometers, control electronics, <strong>and</strong> power supplies. CASIMIR will have two spectrometers available for processing the 4-8 GHz IF b<strong>and</strong>width. The entire instrument is about 1.5 m long, 1 m diameter, <strong>and</strong> weighs about 550 kg. CASIMIR embodies a versatile <strong>and</strong> modular design, able to incorporate future major advances in detector, LO <strong>and</strong> spectrometer technology. CASIMIR will enable the study of fundamental rotational transitions of many astronomically significant hydrides <strong>and</strong> other molecules. Observations of these species can provide critical tests of our underst<strong>and</strong>ing of interstellar chemical networks <strong>and</strong> reactions. The chemistry of oxygen in interstellar clouds is poorly understood, due to the opacity of the atmosphere <strong>and</strong> limited ground observations to many of its key species, such as O, O 2 , H 2 O, H 2 O + , <strong>and</strong> OH. The H 2 D + ion is of particular interest, as it is the deuterated version of H 3 + , which is believed to be responsible for driving much of the chemistry of molecular clouds. Water vapor plays an important role in the energy balance of molecular clouds by mediating radiative heating <strong>and</strong> cooling through its rotational transitions in the far infrared <strong>and</strong> submillimeter. CASIMIR will allow the study of the abundance <strong>and</strong> distribution of interstellar water with exceptional sensitivity <strong>and</strong> spatial <strong>and</strong> spectral resolution. In its initial four b<strong>and</strong>s, CASIMIR can detect nine rotational transitions of the rare H 2 18 O istopomer, including several lines near the ground state. 131
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