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Thumbnail of The Surface of Venus from Venera 14
If you could stand on Venus -- what would you see? Pictured is the view from Venera 14, a robotic Soviet lander which parachuted and air-braked down through the thick Venusian atmosphere in March of 1982. The desolate landscape it saw included flat rocks, vast empty terrain, and a featureless sky above Phoebe Regio near Venus' equator. On the lower left is the spacecraft's penetrometer used to make scientific measurements, while the light piece on the right is part of an ejected lens-cap. Enduring temperatures near 450 degrees Celsius and pressures 75 times that on Earth, the hardened Venera spacecraft lasted only about an hour. Although data from Venera 14 was beamed across the inner Solar System over 40 years ago, digital processing and merging of Venera's unusual images continues even today. Recent analyses of infrared measurements taken by ESA's orbiting Venus Express spacecraft indicate that active volcanoes may currently exist on Venus. Jigsaw Fun: Astronomy Puzzle of the Day
Mount Timpanogos with sky above
Temp:  72 °FN2 Boiling:75.9 K
Humidity: 17%H2O Boiling:   368.3 K
Pressure:85 kPaSunrise6:13 AM
Sunlight:0 W/m²   Sunset8:33 PM
Image for BYU’s Rising Astronomers Take Center Stage at the Winter AAS Conference
In early January 2025, a group of 16 students from Brigham Young University’s Physics & Astronomy Department showcased their research at the prestigious American Astronomical Society (AAS) in National Harbor, Maryland.
Image for Acoustics group studies the roar of SpaceX's Starship
Acoustics faculty and students measure the thunderous noise of the world’s most powerful rocket, exploring its impact on communities and the environment.
Image for Dr. Stephens’ Sabbatical to University of Arizona
Dr. Stephens participated in a research project at the University of Arizona focused on studying brown dwarfs using the James Webb Space Telescope (JWST).
Image for BYU Women Represent at CUWiP 2024
21 women student attend conference at Montana State University, where students engaged in keynote speeches, panels, and research presentations.

Selected Publications

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By Tyce W. Olaveson, Kent L. Gee, Logan T. Mathews, and Hunter J. Pratt (et al.)
Abstract:

This paper presents a comprehensive overview of the operation and spectral performance of a novel lab-scale afterburning jet noise rig at Virginia Tech. The study involved steady-state operation at relevant Total Temperature Ratios (TTR) of approximately 6, typical for afterburning jets. The flow was discharged through a scaled-down GE F-404 supersonic nozzle, and far-field noise measurements were acquired using ground microphones positioned at 27 angular locations on a concrete pad. A key focus of the study is to benchmark the rig's performance by comparing its far-field Overall Sound Pressure Level (OASPL) with that of T-7A and F-35B aircraft operating at afterburner power. The investigation revealed that Nozzle Pressure Ratio (NPR) exerts a significant influence on OASPL at relatively close TTRs. Furthermore, the effects of varying TTR and NPR on OASPL were compared with trends observed in F-35A and F-35B operating at two distinct afterburner power levels. Acoustic efficiency in the presented cases lies in the range 0.41% to 0.51%. Phenomena only observed in full scale afterburning jet engine tests were reproduced for the first time in a laboratory scaled rig. This allowed the identification that engine combustion instabilities can convect downstream through the nozzle and impact the far-field noise spectrum. These instabilities manifest as distinct 'instability streaks' in a spatio-spectral map. The present study highlights the importance of conducting high TTR jet noise experiments in a controlled environment with known operating parameters (total pressure, total temperature, mass flow rate, dynamic pressure, etc.) to enhance the understanding of afterburning jet noise phenomena.

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By Kent L. Gee, Noah L. Pulsipher, Makayle S. Kellison, Grant W. Hart, Logan T. Mathews, and Mark C. Anderson
Abstract:

his Letter analyzes launch noise from Starship Super Heavy's Flights 5 and 6. While Flight-5 data covered 9.7-35.5 km, the stations during Flight 6 spanned 1.0-35.5 km. A comparison of A-weighted and unweighted maximum and exposure levels is made between flights and with an updated environmental assessment (EA). Key findings include: (a) the two flights' noise levels diverge beyond 10 km, (b) EA models overestimate A-weighted metrics, and (c) the acoustic energy from a Starship launch is equivalent to 2.2 Space Launch System launches or ∼11 Falcon 9 launches. These measurements help predict Starship's noise levels around Kennedy Space Center.

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By Samuel D. Bellows, Joseph E. Avila, and Timothy W. Leishman
Abstract:

The directional radiation patterns of musical instruments have long been defining characteristics known to influence their perceived qualities. Technical understanding of musical instrument directivities is essential for applications such as concert hall design, auralizations, and recording microphone placements. Nonetheless, the difficulties in measuring sound radiation from musician-played instruments at numerous locations over a sphere have severely limited their directivity measurement resolutions compared to standardized loudspeaker resolutions. This work illustrates how a carefully implemented multiple-capture transfer-function method adapts well to played musical instrument directivities and achieves compatible resolutions. Comparisons between a musician-played and artificially excited trumpet attached to a mannikin validate the approach’s effectiveness. The results demonstrate the trumpet’s highly directional characteristics at high frequencies and underscore the crucial effects of musician diffraction. Spherical spectral analysis reveals that standardized resolutions may only be sufficient to produce valid complex-valued directivities up to nearly 4 kHz, emphasizing the need for high-resolution, played musical instrumentdirectivity measurements.

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By Scott Bergeson, Matthew Schlitters, Matthew Miller, Ben Farley, and Devin Sieverts (et al.)
Abstract:

Understanding how plasmas thermalize when density gradients are steep remains a fundamental challenge in plasma physics, with direct implications for fusion experiments and astrophysical phenomena. Standard hydrodynamic models break down in these regimes, and kinetic theories make predictions that have never been directly tested. Here, we present the first detailed phase-space measurements of a strongly coupled plasma as it evolves from sharp density gradients to thermal equilibrium. Using laser-induced fluorescence imaging of an ultracold calcium plasma, we track the complete ion distribution function f(x,v,t)⁠. We discover that commonly used kinetic models (Bhatnagar–Gross–Krook and Lenard–Bernstein) overpredict thermalization rates, even while correctly capturing the initial counterstreaming plasma formation. Our measurements reveal that the initial ion acceleration response scales linearly with electron temperature, and that the simulations underpredict the initial ion response. In our geometry we demonstrate the formation of well-controlled counterpropagating plasma beams. This experimental platform enables precision tests of kinetic theories and opens new possibilities for studying plasma stopping power and flow-induced instabilities in strongly coupled systems.

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By Maia A Nelsen, Darin Ragozzine, Benjamin C. N. Proudfoot, and William G. Giforos (et al.)
Abstract:

Dynamically studying trans-Neptunian object (TNO) binaries allows us to measure masses and orbits. Most of the known objects appear to have only two components, except (47171) Lempo, which is the single known hierarchical triple system with three similar-mass components. Though hundreds of TNOs have been imaged with high-resolution telescopes, no other hierarchical triples (or trinaries) have been found among solar system small bodies, even though they are predicted in planetesimal formation models such as gravitational collapse after the streaming instability. By going beyond the point-mass assumption and modeling TNO orbits as non-Keplerian, we open a new window into the shapes and spins of the components, including the possible presence of unresolved "inner" binaries. Here we present evidence for a new hierarchical triple, (148780) Altjira (2001 UQ18), based on non-Keplerian dynamical modeling of the two observed components. We incorporate two recent Hubble Space Telescope observations, leading to a 17 yr observational baseline. We present a new open-source Bayesian point-spread function fitting code called nPSF that provides precise relative astrometry and uncertainties for single images. Our non-Keplerian analysis measures a statistically significant (∼2.5σ) nonspherical shape for Altjira. The measured J2 is best explained as an unresolved inner binary, and an example hierarchical triple model gives the best fit to the observed astrometry. Using an updated non-Keplerian ephemeris (which is significantly different from the Keplerian predictions), we show that the predicted mutual event season for Altjira has already begun, with several excellent opportunities for observations through ∼2030.

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Abstract:

This research describes the changes made to a physics course for preservice elementary teachers during the COVID-19 pandemic and their efforts to engage in constructing scientific explanations in virtual learning. The preservice teachers engaged in three types of virtual labs: simulations, video analysis, and observations. We evaluated the participants’ performance in constructing scientific explanations with a Level of Sophistication rubric scoring engagement from novice to expert levels. We collected data from three cohorts: 2019 (pre-pandemic) and 2020–21 (mid-pandemic), in the form of course documents, interviews, and student lab submissions. We analyzed the data using a-priori and open coding methods as well as applying descriptive statistics and a series of ANOVA tests to the rubric results. We found that the participants (new to science practice) on average engaged at an intermediate level, but were more sophisticated when they used reasoning that included scientific models, theory, or mathematical thinking. Students can successfully engage in constructing explanations in virtual contexts when provided with opportunities to collect their own data through virtual experimentation. This is especially true when scaffolding is in place to prompt sensemaking. The reasoning in their explanations provides a glimpse at the mental models that drive their reasoning and sensemaking.