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At least 577 records · Page 32
All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

Parameterizing Gravity Waves and Understanding Their Impacts on Venus' Upper Atmosphere

The complexity of Venus’ upper atmospheric circulation is still being investigated. Simulations of Venus’ upper atmosphere largely depend on the utility of Rayleigh Friction (RF) as a driver and necessary process to reproduce observations (i.e. temperature, density, nightglow emission). Currently, there are additional observations which provide more constraints to help characterize the driver(s) of the circulation. This work will largely focus on the impact parameterized gravity waves have on Venus’ upper atmosphere circulation within a three dimensional hydrodynamic model (Venus Thermospheric General Circulation Model).

Brecht, A. S.↗
NASA NTRS2018

Studies in Support of Venus Aerocapture Utilizing Drag Modulation

Aerocapture has been extensively studied and these studies have shown the benefit for planetary exploration missions. While the traditional approach to aerocapture with lifting configurations and lift-guided modulations have been assessed to be technologically feasible, aerocapture using purely drag modulation was proposed and studied by Prof. Braun and his students. These studies show that if one can assess the feasibility of aerocapture using drag modulation at Venus, and develop tall pole technologies needed at Venus, then this concept is much easier to execute at all other relevant destinations. Based on the above finding, partnered proposals were submitted by Adam Nelessen at JPL and Ethiraj Venkatapathy at Ames in collaboration with Prof. Braun at the University of Colorado, Boulder (UCB). Under this partnership, Ames Research Center (ARC) is working to address some of the key entry technology challenges associated with drag modulation aerocapture at Venus. Drag modulation aerocapture is a simple, scalable, and likely cost-effective way to enhance planetary science missions. The approach envisioned is to design a small spacecraft, that would most likely be a secondary payload, with a removable drag skirt. The vehicle would enter the atmosphere at Venus with a low ballistic coefficient, decelerate rapidly, drop the skirt resulting in a smaller vehicle with a higher ballistic coefficient which would skip out of the atmosphere and enter into a desired orbit. ARC's role in this collaboration is multifold. First of which is to perform design studies on various pre- and post-jettison geometries utilizing a 3-DOF trajectory code to determine the aerodynamics and aerothermodynamics of the vehicles and evaluate viable thermal protection material system designs. Once these design studies are complete, Ames will then perform higher fidelity CFD and TPS sizing to further design the vehicles. Second, the multi-body separation dynamics of the drag modulation event will be explored using both CFD simulations (CART3-D and US3D) as well as possible ballistic range testing. ARC's tools and expertise have been used to assess and advise on the selection of the separating configuration. In addition to the preliminary evaluation, ARC will provide tools and expertise to UCB team members to further assess aerodynamic interactions between the separating bodies and provide guidance as to the feasibility of stable transition.

Beck, Robin↗
NASA NTRS2018

High Temperature Photovoltaics Silicone Adhesives for Venus Surface

The harsh environment at the surface of Venus, with a low solar intensity, red-rich solar spectrum, high temperatures, and a corrosive acid environment, makes it a challenging location to use photovoltaics. For the design of photovoltaic power generation for future missions to Venus, solar arrays that can function at high temperatures under low light intensity must be developed, and a significant difficulty in this is achieving a long lifetime without degradation under Venus conditions. One issue that must be addressed is the encapsulation to protect the solar cells from the environment, and most particularly the transparent adhesive affixing the coverglass to the cells. In this paper the factors affecting the reliability and degradation of transparent silicone adhesives under Venus conditions are discussed.

Katampe, Ibrahim↗
NASA NTRS2019

Long Duration Venus Probes and Landers

Planetary probes have long been a tool used by scientists to gain early clues on environments and systems of new planetary targets. This not only fueled the scientific process but also helped prepare for future missions, such as landers, and helped ensure their success. Venus, Earth's sister planet, has been the target of more probes and landers than any other body in our solar system except for Earth and yet many fundamental questions are unanswered. Challenge for Venus Surface Science: This lack of knowledge is a result of the challenging Venus environments. Remote sensing of the surface and portions of the atmosphere is difficult at best due to the thick layers of sulfuric acid clouds and the high pressure supercritical CO2 atmosphere below those clouds. This has hampered the ability of orbiting missions to provide us insight into surface features and processes and thus hides potential clues on interior process from our view. Surface probes and landers face an even more daunting challenge, which is the extreme temperature, pressure and unfriendly chemical composition of the near surface atmosphere. Over 10 assets have landed on the surface yet the longest surviving asset Venera-13 lasted only 127 minutes before succumbing to the extreme temperature. While this and other landers provided valuable new data, the short life impacted ability to understand any temporal processes, for example meteorology, seismic active, and therefore very little is known about the interior and surface atmosphere interactions. New Capability Offering Potential Solutions: Re-cent developments by NASA are offering hope of overcoming the technical challenges of surface operations and life with the use of high temperature electronics and systems. Wide band gap, SiC based electronics have been demonstrated to function successfully for extended periods of time both at 500C, Venus surface temperatures as well as when temperature is combined with the reactive chemistry of the surface atmosphere and the high pressures (over 90 bar pressure at the surface). In addition to electronics a number of other subsystems are in development including power in the form of high temperature batteries and power management devices, communications including antennas, transmitters and other components, materials, and structures and mechanisms. These are all activities under NASA's Long Lived In situ Solar System Exploration (LLISSE) project. Other activities are also funded under NASA's HOTTech program.

Kremic, T.↗
NASA NTRS2017

Kepler-1649b: An Exo-Venus in the Solar Neighborhood

The Kepler mission has revealed that Earth-sized planets are common, and dozens have been discovered to orbit in or near their host star’s habitable zone. A major focus in astronomy is to determine which of these exoplanets are likely to have Earth-like properties that are amenable to follow-up with both ground- and future space-based surveys, with an ultimate goal of probing their atmospheres to look for signs of life. Venus-like atmospheres will be of particular interest in these surveys. While Earth and Venus evolved to have similar sizes and densities, it remains unclear what factors led to the dramatic divergence of their atmospheres. Studying analogs to both Earth and Venus can thus shed light on the limits of habitability and the potential for life on known exoplanets. Here, we present the discovery and confirmation of Kepler-1649b, an Earth-sized planet orbiting a nearby M5V star that receives incident flux at a level similar to that of Venus. We present our methods for characterizing the star, using a combination of point-spread function photometry, ground-based spectroscopy, and imaging, to confirm the planetary nature of Kepler-1649b. Planets like Kepler-1649b will be prime candidates for atmospheric and habitability studies in the next generation of space missions.

Terrestrial planets↗
NASA NTRSDate not supplied

Settling Venus: A City in the Clouds?

Although the surface of Venus is an extremely hostile environment, at about 50 kilometers above the surface the atmosphere of Venus is the most earthlike environment (other than Earth itself) in the solar system, and the atmospheric pressure is similar to the Earth surface atmospheric pressure of 1 Bar, there is abundant solar energy, and the temperature is in the habitable "liquid water" range of 0-50C. Although humans cannot breathe the atmosphere, pressure vessels are not required to maintain one atmosphere of habitat pressure, and pressure suits are not required for humans outside the habitat. In the near term, human exploration of Venus could take place from aerostat vehicles in the atmosphere, and in the long term, permanent settlements could be made in the form of cities designed to float at about fifty kilometer altitude in the atmosphere of Venus.

Geoffrey A. Landis↗
NASA NTRS2019

Leveraging Mars aerobraking experience for the Venus environment

Aerobraking was first demonstrated at Venus during the Magellan extended mission in 1993 and on every Mars orbiter since, from the Mars Global Surveyor (MGS) in 1997 to ESA’s Trace Gas Orbiter (TGO) in 2017. This paper illustrates the differences between aerobraking at Venus and at Mars from both the astrodynamics and thermal perspectives. It shows how the periapsis velocity hammers the drag versus aerothermal heating relationship with comparable aerothermal heating limits and initial conditions at Mars and at Venus. Even though there are noticeable differences in the aerobraking environment between these two planets, the Mars heritage operations, processes, tactics, and strategy remain the same while addressing these differences in mission design and environment. Additionally, the spacecraft design requirements, capabilities, and thermal guards are retained across projects and planets. The operations processes and procedures developed over the 20 years of Mars experience can be equally applied back to the birthplace of aerobraking: Venus.

Wallace, Mark S.↗
NASA NTRS2021

Spin State and Moment of Inertia of Venus

Fundamental properties of the planet Venus, such as its internal mass dis-tribution and variations in length of day, have remained unknown. We usedEarth-based observations of radar speckles tied to the rotation of Venus ob-tained in 2006–2020 to measure its spin axis orientation, spin precession rate,moment of inertia, and length-of-day variations. Venus is tilted by 2.6392±0.0008 degrees (1σ) with respect to its orbital plane. The spin axis precessesat a rate of 44.58±3.3 arcseconds per year (1σ), which gives a normalized mo-ment of inertia of 0.337±0.024 and yields a rough estimate of the size of thecore. The average sidereal day on Venus in the 2006–2020 interval is 243.0226±0.0013 Earth days (1σ). The spin period of the solid planet exhibits variationsof 61 ppm (∼20 minutes) with a possible diurnal or semidiurnal forcing. Thelength-of-day variations imply that changes in atmospheric angular momentumof at least∼4% are transferred to the solid planet.

Jean-Luc Margot↗
NASA NTRS2022

Non-Volatile, Low Power, and High Density SiC Memory For Future Venus Missions

Long lived memory would transform Venus landers & missions. Venus durable memory demonstrated in earlier HOTTech with impractically high power and low bit capacity. This project seeks to develop and demonstrate the world’s first Venus-durable low power memory device (Non-Volatile Random Access Memory (NVRAM) to enhance extended Venus surface missions.

silicon carbide↗
NASA NTRSDate not supplied

VfOx in GEER: Functional Test of a Venus Oxygen Fugacity Sensor

VfOx, which stands for “Venus Oxygen Fugacity” is the DAVINCI mission’s Student Collaboration Experiment (SCE); a small single- objective sensor used to measure the partial pressure of molecular oxygen in Venus’ lower atmosphere. Through the mission timeline, VƒOx will be designed, fabricated, tested, operated, and results analyzed by undergraduate and graduate students mentored by the DAVINCI team in partnership with Johns Hopkins University and other institutions. The simple principal of VƒOx is a ceramic O 2 sensor derived from common applications, utilizing diffusion of O -2 ions between a standard (PdO) inside the sensor and the target atmosphere measured by a mW level voltage that depends directly on the standard/sample fO 2 ratio. A 60-day environmental test of a prototype design of the sensor was conducted at the Glenn Extreme Environment Rig (GEER) from August to October of 2022, in which VƒOx (Fig. 1) was placed inside the experimental chamber (Fig. 2) and brought to Venus surface temperature (460 °C) and pressure (92 bar) conditions, in a Venus like atmosphere (96.5% CO 2 , 3.5% N 2 ) that included trace gases like SO 2 , maintained by occasional “boosts” of extra gas during the experimental run.

Noam R. Izenberg↗
NASA NTRS2022

A Deep and Wide Twilight Survey for Asteroids Interior to Earth and Venus

We are conducting a survey using twilight time on the Dark Energy Camera with the Blanco 4 m telescope in Chile to look for objects interior to Earth's and Venus' orbits. To date we have discovered two rare Atira/Apohele asteroids, 2021 LJ4 and 2021 PH27, which have orbits completely interior to Earth's orbit. We also discovered one new Apollo-type Near Earth Object (NEO) that crosses Earth's orbit, 2022 AP7. Two of the discoveries have diameters ≳1 km. 2022 AP7 is likely the largest Potentially Hazardous Asteroid (PHA) discovered in about eight years. To date we have covered 624 square degrees of sky near to and interior to the orbit of Venus. The average images go to 21.3 mag in the *r* band, with the best images near 22nd mag. Our new discovery 2021 PH27 has the smallest semimajor axis known for an asteroid, 0.4617 au, and the largest general relativistic effects (53 arcsec/century) known for any body in the solar system. The survey has detected ∼15% of all known Atira NEOs. We put strong constraints on any stable population of Venus co-orbital resonance objects existing, as well as the Atira and Vatira asteroid classes. These interior asteroid populations are important to complete the census of asteroids near Earth, including some of the most likely Earth impactors that cannot easily be discovered in other surveys. Comparing the actual population of asteroids found interior to Earth and Venus with those predicted to exist by extrapolating from the known population exterior to Earth is important to better understand the origin, composition, and structure of the NEO population.

Scott S. Sheppard↗
NASA NTRSDate not supplied

Magnetohydrodynamic and Aerodynamic Assessment of Ballistic Entry of a 70deg Spherecone at Mars and Venus

An electrical conductivity database for continuum flow in a CO2 atmosphere over a 70 deg spherecone was created using the Data Parallel Line Relaxation Code computational fluid dynamics software to inform development of future magnetohydrodynamic subsystems at Venus and Mars. Sixteen freestream conditions were considered at Mars with atmospheric relative velocities from 5 to 8 km/s and altitudes between 20 and 80 km. Sixteen freestream conditions were considered at Venus with atmospheric relative velocities from 9 to 12 km/s and altitudes between 85 and 115 km. Results indicate that the total electrical conductivity in the flow volume always increases as velocity increases. At low velocities, the electrical conductivity is higher at high altitudes, while at high velocities, the electrical conductivity is higher at low altitudes. Three of the 80 km altitude computational fluid dynamics solutions show good agreement with Direct Simulation Monte Carlo results. In general, computational fluid dynamics predicts thinner shocks, higher electron number density, and similar vibrational temperatures as direct simulation Monte Carlo. The magnetohydrodynamic force was calculated at both Mars and Venus. Results indicate there may not be sufficient control authority to use magnetohydrodynamics as a trajectory control mechanism at Mars without artificially increasing the electrical conductivity of the flow, but there may be appreciable control authority for a drag-modulated aerocapture at Venus.

Destiny M Fawley↗
NASA NTRS2024

Effects of Water on the Density and Elevation of Tesserae on Venus

While the current conditions on Venus are inhospitable, with surface temperatures of ~ 470 °C, pressures of 92 bars, and a CO 2 dominated atmosphere, early Venus may have had a more temperate climate with water on the surface. Water is not only crucial to understanding the habitability potential of Venus, but also has major implications for the tectonic regime and thermal evolution of a planet. Tesserae are believed to be the oldest exposed features on the surface of Venus and may have formed during a period with higher water content. Some of this water might have been preserved as hydrous minerals in the Venusian subsurface. The presence of these minerals has an effect on the density profiles and isostatic behaviour of the tesserae and therefore requires a more detailed investigation. Here we will present results of phase equilibria and isostasy modelling on a range of Tesserae-analogue rock compositions with varying water content and along a range of potential thermal gradients. We compare our results to anhydrous models performed previously under similar thermal regime to constrain the conditions (rock composition, thermal gradient, and water content) needed for tesserae stability.

A R Baker↗
NASA NTRS1996

A 360-Degree and -Order Model of Venus Topography

This report presents the most recent spherical harmonic topography model of Venus developed at Jet Propulsion Laboratory. It was produced by a spherical harmonic analysis of the most complete set of Magellan altimetry data, augmented by Pioneer Venus and Venera data. The harmonic coefficients of the topography were computed to degree and order 360. Compared to previous topography models, this one has the highest correlation with the gravity field of Venus.

Venus venus topgraphy harmonic analysis spherical ↗
DOE OSTI2020

Chemically distinct regions of Venus’s atmosphere revealed by measured N 2 concentrations

A defining characteristic of the planet Venus is its thick, CO 2 -dominated atmosphere. Despite over 50 years of robotic exploration of Venus, including thirteen successful atmospheric probes and landers, our knowledge of N 2 , the second most abundant compound in the atmosphere, is highly uncertain. We report the first measurement of the nitrogen content of Venus’s atmosphere at altitudes between 60 and 100 km. Our result, 5.0 ± 0.4 v% N 2 , is 40% higher than the value of 3.5 v% N 2 reported for the lower atmosphere (<50 km altitude). Our discovery of altitude-dependent variations in the N 2 content of the atmosphere defies early expectations of homogeneous composition below 100 km (for example, see ref. 1), and necessitates complete chemical modelling to investigate chemical versus physical explanations for the enhanced N 2 in the upper atmosphere. Furthermore, the existence of chemically distinct lower and upper atmosphere regions complicates the use of remote sensing measurements of the upper atmosphere to infer the properties of the lower atmosphere and surface, an important lesson that also extends to the growing field of exoplanet astronomy.

99 GENERAL AND MISCELLANEOUS↗
NASA NTRS1961

Objectives of the Mariner Venus Microwave Radiometer Experiment

At present, there are several models involving the surface, atmosphere (and ionosphere), and cloud conditions of the planet Venus which attempt to account for the observed high brightness temperature of 600 degrees Kelvin in the microwave temperature region. None of these models can be definitely accepted or rejected on the basis of presently available data, and it is the goal of the microwave radiometer experiment planned for the Mariner Venus mission to determine which of the proposed models most nearly approximates Venusian conditions. The disc of the planet will be scanned at 4 wavelengths - 4, 8, 13.5 and 19 millimeters - to measure the temperature distribution across the planet. Measurement accuracy is expected to be to within 2 percent. In addition to the study of gross thermal characteristics of surface and atmosphere (or ionosphere), some information regarding the fine-scale thermal variations will be obtained. Since Venus appears to be continuously covered by clouds, it is obvious that only in the microwave region can one be sure of penetrating clear to the solid surface. Because of the absorbing characteristics of the Earth's atmosphere, and because of the relatively poor resolution obtainable in this region of the spectrum, one is forced to utilize the platform afforded by a planetary flyby or orbiter in order to conduct a reliable high resolution study of the planet. To do so from Earth (neglecting terrestrial atmospheric attenuation ) would require colossal radio telescopes.

RADIO ASTRONOMY↗
NASA NTRS1967

Manned Venus Orbiting Mission

Manned orbiting stopover round trips to Venus are studied for departure dates between 1975 and 1986 over a range of trip times and stay times. The use of highly elliptic parking orbits at Venus leads to low initial weights in Earth orbit compared with circular orbits. For the elliptic parking orbit, the effect of constraints on the low altitude observation time on the initial weight is shown. The mission can be accomplished with the Apollo level of chemical propulsion, but advanced chemical or nuclear propulsion can give large weight reductions. The Venus orbiting mission weights than the corresponding Mars mission.

LAUNCH DATE↗
NASA NTRS1996

The 825-1110 angstroms EUV spectrum of Venus

On 15 August 1994 we launched the EUVS sounding rocket payload to observe the 825-1110 angstrom region of Venus's far ultraviolet airglow spectrum. The EUVS telescope/spectrograph obtained good data at five times higher spectral resolution than was previously available in the far ultraviolet. We present these data and compare our results to those obtained by the Galileo UVS and Venera 11/12 UV spectrophotometers. We identify several new spectral emission features, including both singly ionized nitrogen and molecular nitrogen in Venus's spectrum. We also see evidence for electron-impact-induced emission from CO. Finally, the EUVS data indicate that the "Ar" emissions detected in Venus's far ultraviolet spectrum by Venera 11/12 spectrophotometers are in fact not due to argon, thus eliminating the discrepancy between in situ and remote sensing measurements.

Flight Experiment↗