Miniature low-power submillimeter-wave spectrometer for remote sensing in the solar system

Mass and power for the next generation of NASA's heterodyne spectrometers m ust be greatly reduced to satisfy the constraints of future small-spacecraf t missions. In this paper, we present a new receiver concept for remote sen sing in the solar system, with greatly reduced mass, power, and size compar ed to instruments implemented in current missions. This spectrometer was or iginally proposed for operation in the vicinity of the 557-GHz emission fro m the H2O ground-state transition. With the 557-GHz mixer and associated mu ltiplier chain still under development, we prototyped a 220-GHz version of the instrument to verify the receiver concept, and experimentally demonstra ted its functionality. The 220-GHz prototype Schottky-diode receiver requir es less than 4.8 W, and has a mass of less than 1.1 kg-more than a factor o f ten in mass and power reduction compared to current instruments, This sig nificant savings, achieved through minimizing the number of receiver compon ents, does not compromise the functionality necessary, e,g,, for a surface- based Mars atmospheric sounding instrument. For the 557-GHz version, we ant icipate that the total mass would be about the same as that of the millimet er-wave prototype, while required power would be reduced by about 1.5 W wit h the use of InP MMIC amplifiers.