This letter presents experimental investigations conducted on the Matanuska Glacier in Alaska to evaluate radio frequency (RF) attenuation for through-ice communications. Software-defined radio-based transceivers employing Frequency Shift Keying (FSK) modulation were utilized for measurements on both a frozen lake and directly on the glacier at 169 MHz. Received signal levels and bit error rates were measured at 1 kbit/s with and without Forward Error Correction (FEC) codes. Additionally, a through-ice link budget analysis is presented to provide insights for future wireless communication between moon landers and cryobots exploring extraterrestrial oceans beneath ice surfaces. These findings are relevant for potential deep space missions to icy moons, such as Jupiter's moon Europa, which may harbor conditions conducive to life.

Many studies have found that volatile cues from damaged plants can induce resistance to herbivores in undamaged neighbors. However, fewer studies have examined the effects of soilborne cues. Furthermore, there are few studies that have considered the effects of plant-plant communication on plant reproduction. We conducted experiments with tomato seedlings exposing them to airborne and soilborne cues from experimentally damaged neighbors. These plants were then transplanted to the field and the level of damage by chewing and sucking herbivores was observed in the field. We also recorded the time before flowering was initiated by these plants. We found that both airborne and soilborne cues trend to reduce the proportion of leaves that were damaged for plants exposed to cues relative to controls that were near undamaged neighbors. Furthermore, these two cues were found to interact synergistically. Plants that had been exposed to soilborne cues flowered sooner than controls, those exposed to airborne cues, and both cues. These results suggested that soilborne and airborne cues induce different responses in plants.

The rapid advancement toward smart cities has accelerated the adoption of various Internet of Things (IoT) devices for underground applications, including agriculture, which aims to enhance sustainability by reducing the use of vital resources such as water and maximizing production. On-farm IoT devices with above-ground wireless nodes are vulnerable to damage and data loss due to heavy machinery movement, animal grazing, and pests. To mitigate these risks, wireless Underground Sensor Networks (WUSNs) are proposed, where devices are buried underground. However, implementing WUSNs faces challenges due to soil heterogeneity and the need for low-power, small-size, and long-range communication technology. While existing radio frequency (RF)-based solutions are impeded by substantial signal attenuation and low coverage, acoustic wave-based WUSNs have the potential to overcome these impediments. This paper is the first attempt to review acoustic propagation models to discern a suitable model for the advancement of acoustic WUSNs tailored to the agricultural context. Our findings indicate the Kelvin-Voigt model as a suitable framework for estimating signal attenuation, which has been verified through alignment with documented outcomes from experimental studies conducted in agricultural settings. By leveraging data from various soil types, this research underscores the feasibility of acoustic signal-based WUSNs.

Subsurface exploration of ice-covered planets and moons presents communications challenges because of the need to communicate through kilometers of ice. The objective of this task is to develop the capability to wirelessly communicate through kilometers of ice and thus complement the potentially failure-prone tethers deployed behind an ice-penetrating probe on Ocean Worlds. In this paper, the preliminary work on the development of wireless deep-ice communication is presented and discussed. The communication test and acoustic attenuation measurements in ice have been made by embedding acoustic transceivers in glacial ice at the Matanuska Glacier, Anchorage, Alaska. Field test results show that acoustic communication is viable through ice, demonstrating the transmission of data and image files in the 13-18 kHz band over 100 m. The results suggest that communication over many kilometers of ice thickness could be feasible by employing reduced transmitting frequencies around 1 kHz, though future work is needed to better constrain the likely acoustic attenuation properties through a refrozen borehole.

In recent years, there has been an increasing necessity for monitoring facilities like gas or water pipelines to ensure high security and adequate infrastructure maintenance. The pipeline network is very large, and the main problem is its continuous monitoring. In particular, there is the necessity to monitor the cathodic protection (CP) voltage, which ensures maintaining the pipeline under a state of protection from corrosion and avoids considerable damage to the infrastructure. A communication channel is necessary to monitor the pipeline network continuously. Most of the pipeline monitoring systems make use of wireless communication, like global system for mobile communications (GSM) or general packet radio service (GPRS) technology and even Wi-Fi, to transmit the measurements. By their nature, the implementation of these systems is often expensive and furthermore, not all the pipeline is covered by the signals of the mobile operators. In this article, the communication approach is presented, and, in particular, the pipeline is used as a communication channel. Due to the challenges of pipelined transmission, an identification of the characteristic impedance of the medium must be conducted to obtain the best possible performance. This value is used to design a circuit that can match the function generator output to the impedance of the communication channel. The circuit to be made must allow bidirectional communication of the half-duplex type. Given the low frequencies that can be used for communication on the pipe, a low-frequency circulator must be created. Given the frequencies involved, the bidirectional circuit will be composed of operational amplifiers. The presented circulator allows matching the signal generator output impedance with the pipeline input impedance, to obtain an improvement in the transmission distance achievable using the pipeline as a communication channel.

One of NASA priorities is the in-situ exploration of ocean worlds in the solar system where potentially there might be life under the ice shell. This requires reaching the ocean below extremely cold through significant deep ice. Jupiter's moon, Europa, is such a challenging body, where it is estimated to have a 40 km thick ice shell. An approach for reaching the ocean has been conceived using a melting probe Cryobot concept that has been studied for a potential future mission. A lander is assumed to be the platform from which the Cryobot would be deployed. The ice penetrating vehicle concept consists of a cylindrical, narrow-body probe that encases a radioisotope heat/power source that would be used to do the penetration by melting through the icy crust. The baseline design of the probe includes a suite of science instruments to analyze the ice during descent and the liquid ocean underneath. For communication, a set of fiber optic wire as well as wireless RF in the very cold porous top layer is assumed, and then acoustic modules would be used for the communication in warmer denser ice over distance of 25 km between the modules. In addition to the acoustic communication modules, a sonar is part of the concept, for obstacle avoidance. The focus of this paper is on the use of elastic waves in the 1kHz range.