Here we present a preliminary design for a dielectrically embedded mesh lens, with the intended purpose of being deployed on a 6-unit CubeSat to observe the 556GHz water emission line. A CubeSat offers a cost-effective potential solution for observing these emissions, which cannot be observed from the ground, given it has a lens which can offer a significant effective collecting area at that frequency. To this end, we investigate designs for a lens by using transmission line theory to model a flat, lightweight, dielectrically embedded mesh lens which can be fabricated using layers of photolithographically etched material. We demonstrate that, using commercially available material, transmittances of over 95% may be achieved.
While great strides have been made in far-infrared astrophysics with the NASA Spitzer and ESA Herschel missions, subarcsecond spatial resolution from space is still beyond the reach of current technologies. The Atacama Large Millimeter Array has produced stunning images from the ground of planetary systems in the process of formation but cannot observe the key molecules of water or O<sub>2</sub>, due to the presence of Earth’s atmosphere. The concept presented here will enable interferometric imaging with sub-arcsecond resolution of water and other key far infrared molecular species from space at a cost far lower than the flagship class interferometric missions previously proposed (i.e. ESA’s ESPRIT). We present a concept for a far infrared interferometer based on a constellation of CubeSat antenna elements with a central ESPA-class correlator satellite optimized for the imaging of water in protoplanetary systems. Such a mission would produce groundbreaking images of newly forming planetary systems in a key astrophysical and astrobiological tracer, the 557 GHz ground state line of water. By leveraging recent developments in CubeSat technology, inflatable reflectors, miniaturized receiver systems and low power CMOS digital electronics, such a mission could be implemented at an Explorer level budget. In addition to the proposed astrophysics application, the developments proposed here could also find application in planetary science (FIR spectroscopy of comets and small bodies) and Earth observing (high resolution imaging of Earth from geostationary orbit).
Here we present the characterization of the performance of a novel design for a digital spectrometer that could be used for high resolution cm/mm/submm spectroscopy. The CMOS ASIC spectrometer design, developed at JPL and UCLA, has dramatically lower power consumption than current approaches that generally employ Field Programmable Gate Arrays (FPGAs). Particularly for space missions and for small satellites, power consumption is a major issue. The order of magnitude lower power consumption of the ASIC approach is thus critical for future missions employing large-format focal plane arrays. Our task was to evaluate this 1024 channel, 1.3-GHz bandwidth CMOS spectrometer in terms of stability and filter shape. The chip was to be tested largely at half-maximum speed to allow for use of the polyphase filter bank. The results of this testing show that the ASIC spectrometer can be made to perform largely as expected based on its design parameters, however, they suggest that more testing of the spectrometer chip could be beneficial. Follow-up tests and newer versions of the chip are discussed at the end of the proceeding.