Earth and Space Science Open Archive PosterOpen AccessYou are viewing the latest version by default [v1]Detection of small-magnitude Earthquakesusing balloon-borne infrasound sensorsAuthorsQuentinBrissaudiDSiddharthKrishnamoorthyJenniferJacksonDanielBowmanAttilaKomjathyJamesCuttsJacobIzraelevitzZhongwenZhanYanYangSee all authors Quentin BrissaudiDCorresponding Author• Submitting AuthorNORSARiDhttps://orcid.org/0000-0001-8189-4699view email addressThe email was not providedcopy email addressSiddharth KrishnamoorthyNASA Jet Propulsion Laboratoryview email addressThe email was not providedcopy email addressJennifer JacksonCalifornia Institute of Technologyview email addressThe email was not providedcopy email addressDaniel BowmanSandia National Laboratoriesview email addressThe email was not providedcopy email addressAttila KomjathyNASA Jet Propulsion Laboratoryview email addressThe email was not providedcopy email addressJames CuttsNASA Jet Propulsion Laboratoryview email addressThe email was not providedcopy email addressJacob IzraelevitzNASA Jet Propulsion Laboratoryview email addressThe email was not providedcopy email addressZhongwen ZhanCalifornia Institute of Technologyview email addressThe email was not providedcopy email addressYan YangCalifornia Institute of Technologyview email addressThe email was not providedcopy email address
Very bright meteors, also referred to as fireballs and bolides, are generally produced by objects >10 cm in diameter. While impacts by large asteroids (10s of meters in diameter) are relatively rare, they are not statistically negligible. Such objects carry a destructive potential, as illustrated by the Chelyabinsk event that occurred over a decade ago. Thus, the characterization of these objects is of utmost importance, and helps shed light on why some events might result in more catastrophic outcomes than others. Different sensing modalities can be used in unison to derive various bolide parameters, including its trajectory, entry velocity, and energy deposition, among others. In addition to producing a spectacular display in the sky, bolides are also capable of generating shockwaves. A by-product of shockwaves is a low frequency (< 20 Hz) acoustic wave, or infrasound. Acoustic sensing using infrasound stations installed around the globe has gained momentum over the last decade due to its capability to detect bolides and help estimate their energy deposition irrespective of time of day or cloud coverage. Infrasound is generally used in conjunction with other sensing modalities, such as optical observations, which provide important ground truth information. We present the ground-to-space observations of an energetic bolide that resulted in an airburst over Australia on 20 May 2023. The bolide entered with a speed of 28 km/s over Queensland at 09:22 pm local time, and underwent a catastrophic disintegration at an altitude of 29 km. It deposited energy of ~7.2 kt of TNT equivalent (1 kt = 4.184·1012 J), making it one of the top 20 most energetic bolides detected by the US government sensors and reported in the JPL/NASA CNEOS database since 1988. The bolide was so bright that it was visible at a distance of 600 km. It saturated ground-based cameras, stifling efforts to derive the full trajectory and obtain photometric measurements. We found infrasound signals at four infrasound stations as far as 6000 km away. The energy estimate derived through infrasound signal analysis is ~7 kt of TNT equivalent, which corroborates the value reported by the CNEOS database. We will present observations of this energetic bolide event and discuss implications for planetary defense and characterization of similar events.SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.
The development of an ultrasonic plethysmograph based on the transit time measurement principle is reported, which meets the space-imposed requirements for evaluating cardiovascular deconditioning. It consists of a pulse generator, pulse receiver amplifier, voltage comparator, synchronous pulse generator, elapsed time counter, and transmit and receive piezoelectric crystals resonant at 2 MHz and of 3 mm diameter. The transit time for an ultrasonic pulse to propagate across a limb cross section is computed in a digital fashion using a 32 MHz clock, and resolution is 0.049 mm with the range being approximately 200 mm. Experimental results regarding dynamic system response were found comparable in both accuracy and sensitivity to those of a Whitney strain gage using a 50 torr venous occlusion.
Understanding the determinants of nitrate leaching should improve nitrogen uptake efficiency and reduce ground water contamination. This column lysimeter study examined the effect of root architecture on NO 3 leaching from two genotypes of creeping bentgrass ( Agrostis palustris Huds.) differing in rooting characteristics. Ammonium nitrate was applied (50 kg N ha −1 ) and the columns were irrigated with 1, 2 or 3 cm day −1 (Exp. 1) or irrigation was delayed 1, 3 or 5 d (Exp. 2). In Exp. 1, leachate NO 3 concentrations and total N leached from the shallow‐rooted (SR) genotype were approximately twice those from the deep‐rooted (DR) genotype. An average of 38 and 18% of the applied N leached from the SR and DR genotypes, respectively. Cumulative leaching losses increased with irrigation depth. In Exp. 2, NO 3 leaching was reduced 90% or more by increasing the time period for immobilization from 1 to 5 d. Recovery of applied 15 N in the tissue averaged 87% after 2 mo. Absorption of NO 3 and NH 4 was measured in nutrient solution culture. The SR genotype had significantly higher uptake rates than DR for both forms of N, expressed on a root weight basis. Collectively these data indicate that a deep‐rooted turfgrass absorbs N more efficiently than a shallowrooted turf, reducing the concentration and total amount of NO 3 leached. The effect is apparently not due to differences in N uptake, but rather to rooting patterns. Environmental conditions and management practices that affect rooting depth and density may thus affect N nutrition and NO 3 leaching.
High-altitude balloons carrying infrasound sensor payloads can be leveraged toward monitoring efforts to provide some advantages over other sensing modalities. On 10 July 2020, three sets of controlled surface explosions generated infrasound waves detected by a high-altitude floating sensor. One of the signal arrivals, detected when the balloon was in the acoustic shadow zone, could not be predicted via propagation modeling using a model atmosphere. Considering that the balloon’s horizontal motion showed direct evidence of gravity waves, we examined their role in infrasound propagation. Implementation of gravity wave perturbations to the wind field explained the signal detection and aided in correctly predicting infrasound travel times. Our results show that the impact of gravity waves is negligible below 20 km altitude; however, their effect is important above that height. The results presented here demonstrate the utility of balloon-borne acoustic sensing toward constraining the source region of variability, as well as the relevance of complexities surrounding infrasound wave propagation at short ranges for elevated sensing platforms.
Abstract Infrasound waveforms generated by natural and anthropogenic phenomena contain important clues about the size and nature of the event. We show that sensors on balloons in the lower stratosphere can record faithful representations of the near‐source acoustic wave field at unprecedented range. The acoustic signature of a buried chemical explosion recorded at a range of 56 km and an altitude of 21.8 km was nearly identical to that recorded on the ground 0.5 km from the epicenter, but absent on a ground sensor located 46 km away. Our results demonstrate that balloon‐borne infrasound techniques greatly increase the range at which well‐preserved acoustic representations of near‐source physics can be acquired, and that their propagation is simple to model. Our work has implications for monitoring remote regions of the earth for explosions, volcanic eruptions, and other phenomena. It also supports the prospect of balloon‐based infrasound seismology on Venus.
Abstract Sample return capsules (SRCs) entering Earth’s atmosphere at hypervelocity from interplanetary space are a valuable resource for studying meteor phenomena. The 2023 September 24 arrival of the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer SRC provided an unprecedented chance for geophysical observations of a well-characterized source with known parameters, including timing and trajectory. A collaborative effort involving researchers from 16 institutions executed a carefully planned geophysical observational campaign at strategically chosen locations, deploying over 400 ground-based sensors encompassing infrasound, seismic, distributed acoustic sensing, and Global Positioning System technologies. Additionally, balloons equipped with infrasound sensors were launched to capture signals at higher altitudes. This campaign (the largest of its kind so far) yielded a wealth of invaluable data anticipated to fuel scientific inquiry for years to come. The success of the observational campaign is evidenced by the near-universal detection of signals across instruments, both proximal and distal. This paper presents a comprehensive overview of the collective scientific effort, field deployment, and preliminary findings. The early findings have the potential to inform future space missions and terrestrial campaigns, contributing to our understanding of meteoroid interactions with planetary atmospheres. Furthermore, the data set collected during this campaign will improve entry and propagation models and augment the study of atmospheric dynamics and shock phenomena generated by meteoroids and similar sources.
