NASA's Planetary Decadal Survey Vision and Voyages has concluded that measurements of isotopic cometary water vapor, and in particular the deuterium-to-hydrogen ratio (D/H) ratio, are an important tool for unraveling the mysteries involving the origin of Earth's water, and the evolution of our solar system. To support this goal, we have developed, through an internal Jet Propulsion Laboratory research program, quantum-limited superconductor insulator superconductor (SIS) receivers covering the important 500-600 GHz submillimeter frequency band. These instruments can detect the (1 10 -1 01 ) HDO rotational transition, and the (1 10 -1 01 ) ground state (rotational) transitions of Ortho H 2 16 O, H 2 17 O, and H 2 18 O with exquisite sensitivity. However, given the extremely weak HDO emission and the time-variability of the outgassing processes in comets, expeditious low noise D/H ratio measurements of these sources remain extremely challenging. To address this issue, we investigate the possibility of acquiring HDO, H 2 17 O, and H 2 18 O simultaneously by means of a novel dual local oscillator (2LO) down-conversion process, as an alternative to ultra-broadband IF bandwidth systems.

中文翻译：

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用于同时观测太阳系中水同位素体的双本振 SIS 接收器


NASA 的行星年代际调查愿景与航程得出的结论是，同位素彗星水蒸气的测量，特别是氘氢比 (D/H) 的比率，是解开涉及地球水起源之谜的重要工具，并且我们太阳系的演化。为了支持这一目标，我们通过内部喷气推进实验室研究计划开发了覆盖重要的 500-600 GHz 亚毫米频段的量子限制超导绝缘体超导 (SIS) 接收器。这些仪器可以精确地检测（1 10 -1 01 ）HDO旋转跃迁，以及Ortho H 2 16 O、H 2 17 O和H 2 18 O的（1 10 -1 01 ）基态（旋转）跃迁。敏感性。然而，考虑到彗星中 HDO 发射极弱和除气过程的时间变化，对这些源进行快速低噪声 D/H 比测量仍然极具挑战性。为了解决这个问题，我们研究了通过新型双本振 (2LO) 下变频过程同时采集 HDO、H 2 17 O 和 H 2 18 O 的可能性，作为超宽带 IF 带宽系统的替代方案。