The search for extraterrestrial bio-signatures and the origin of Earth’s water remain two of the most compelling questions in planetary science. While no direct evidence of life beyond Earth has been found, water is a key prerequisite for life, and tracing its presence throughout the solar system may provide vital clues. A leading theory suggests that Earth’s water may have originated from comets, supported by limited water isotopic measurements that match Earth’s ocean water. However, more data from a larger sample of comets is needed to validate this theory. Traditional sub-millimeter wave spectrometers, capable of such measurements, are often too large and power-intensive for small spacecraft platforms. To address this, we present WHATSUP—a next-generation, ultra-compact, low-power, room-temperature submillimeter-wave (500-600 GHz) spectrometer—designed primarily for CubeSat and SmallSat platforms, though equally well-suited for a range of other missions. WHATSUP utilizes advances in CMOS system-on-chip electronics, innovative low profile and low mass silicon lens antenna, Micro-electro mechanical system (MEMS)-based THz switching, and a novel programmable calibration load. Together, these innovations deliver a highly integrated system with a total mass of only 2 kg and power consumption under 7 W, which is a substantial improvement over previous submillimeter-wave instruments. This enables affordable, high-frequency spectral observations from multiple low-cost missions, potentially revolutionizing how isotopic studies of cometary water are conducted and opening new pathways for outer solar system exploration. WHATSUP instrument was flown on the NASA Hand Launch Payload (HLP) ballooncraft and performed atmospheric soundings across Texas, USA in July 2023.

Terahertz heterodyne spectrometer instruments have been traditionally limited to a single pixel or a handful of pixels due to integration and assembly constraints and a limited availability of local oscillator (LO) power. As a solution we propose a novel silicon-micromachined planar and modular packaging strategy, that will allow for a dense integration of a large number of pixels. Moreover, the RF- and LO signals will be quasi-optically coupled via two identical but opposite lens arrays, such that a single LO-source can efficiently pump all HEB-mixers of the 2x2 pixel demonstrator array simultaneously. This work reports on an intermediate step, where we validate the lens array performance and LO power coupling efficiency, by slightly modifying the silicon package into a transmit array configuration. In this way, the LO power coupled into the stack is directly reradiated on the other side, which is then measured using a liquid helium cooled bolometer.

A novel transmit lens array is proposed to provide broadband quasi-optical power distribution and beam-steering capabilities for array architectures in future submillimeter-wave heterodyne instruments. The transmit array is composed of a double array layer of lens antenna elements with high aperture efficiency. To enable broadband and low loss quasi-optical (QO) power distribution, the transmit lens array is coupled with a high aperture efficiency single lens antenna. The high aperture efficiency is achieved by using a recently introduced multi-mode leaky wave feed. The top lens array can be used to achieve beam-steering capabilities when fed coherently and mechanically translated using a piezo-motor. In this contribution, we present the development of a prototype based on a transmit lens array of 7 elements at 450-650 GHz with measurements showing a good agreement with simulations. This prototype demonstrates a quasi-optical power coupling efficiency of nearly 60%. Moreover it also shows beam-steering of a 36dBi directivity beam to few discrete angles up to +/-25 degrees with less than 2dB scan loss

In this paper, we will present a novel quasi-optical power distribution technique that will allow achieving an efficient multi-pixel LO power distribution for submillimeter-wave instruments. This method can distribute the power from one antenna to a multi-pixel lens array in a hexagonal configuration with a power coupling efficiency of nearly 60%. We will present a prototype based on a transmit array of 7 pixels at WR1.5.

This article presents the latest developments of our work related to a micro-lens antenna integrated in a heterodyne receiver using silicon micromachining technology at Terahertz frequencies. The antenna is composed of a waveguide feed which uses a leaky wave cavity to enhance the directivity and illuminate a shallow lens efficiently. The receiver is a dual-polarized balanced heterodyne detector using hot-electron bolometers (HEB) as mixers. The front-end receiver, including the antenna, can be fabricated using silicon micromachining processes and has seamless integration, which reduces the overall size and losses.