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NASA NTRS2020

Development of a Venus Surface Wind Sensor Based on a Miniature Drag-Force Anemometer

To better understand the atmospheric structure and dynamics on the Venus surface and provide input to climate models, there is a need to measure the wind velocity and direction on the surface and track changes over extended periods. A wind sensor based on a miniature drag-force anemometer is being developed to meet the challenges for wind measurements and operational requirements on the surface of Venus. The sensor materials are chosen to enhance durability and prevent reactivity with the Venus surface atmosphere. Advantages of this approach include that it is independent on variable heat transfer, has been matured in other harsh environment applications,and has a low mass and power requirement. This report describes demonstration of this miniature drag-force anemometer integrated with high temperature electronics in simulated Venus surface environment. Prototype drag-force anemometers were demonstrated integrated with an operational amplifier recording transient effects in a simulated Venus surface environment. For multidirectional wind monitoring, the sensors are small enough to be deployed orthogonally as a three-dimensional array on a small arm or mast

wind measurement↗
NASA NTRSDate not supplied

Development of a Venus Surface Wind Sensor

To better understand the atmospheric structure and dynamics on the Venus surface and provide input to climate models, there is a need to measure the wind velocity and direction on the surface and track changes over extended periods. A wind sensor based on a miniature drag-force anemometer is being developed to meet the challenges for wind measurements and operational requirements on the surface of Venus. The sensor materials are chosen to enhance durability and prevent reactivity with the Venus surface atmosphere. Advantages of this approach include that it is independent of variable heat transfer, has been matured in other harsh environment applications, and has a low mass and power requirement. Prototype drag-force anemometers were demonstrated, integrated with a high-temperature operational amplifier, recording transient effects in a simulated Venus surface environment. For multidirectional wind monitoring, the sensors are small enough to be deployed orthogonally as a three-dimensional array on a small arm or mast. This presentation describes the development and demonstration of this miniature drag-force anemometer integrated with high temperature electronics in a simulated Venus surface environment.

wind measurement↗
NASA NTRS2022

Geologically Recent Areas as One Key Target for Identifying Active Volcanism on Venus

The recently selected NASA VERITAS and DAVINCI missions, the ESA EnVision, the Roscosmos Venera-D will open a new era in the exploration of Venus. One of the key targets of the future orbiting and in-situ investigations of Venus is the identification of volcanically active areas on the planet. The study of the areas characterized by recent or ongoing volcano-tectonic activity can inform us on how volcanism and tectonism are currently evolving on Venus. Following this key target, the manuscript by Brossier et al. (2022) (https://doi.org/10.1029/2022GL099765) extends the successful approach and methodology used by previous works to Ganis Chasma in Atla Regio. We comment here on the main results of the manuscript published by Brossier et al. (2022) (https://doi.org/10.1029/2022GL099765) and discuss the important implications of their work for the future orbiting and in-situ investigations of Venus. Their results add further lines of evidence indicating possibly recent volcanism on Venus.

Solar system↗
NASA NTRSDate not supplied

A Brief Status Update on Venus Long Lived Lander Technologies

The extreme surface conditions of Venus, including high temperature/pressure and reactive chemistry, have previously limited the lifetime of surface missions to ~2 hours. However, recent advances in high temperature technologies suggest the possibility of extended duration missions on the Venus surface. This presentation gives a brief overview on a range of high temperature technologies to enable a possible extended duration Venus surface mission. This presentation highlights the technology development under the Long-Lived In Situ Solar System Explorer (LLISSE) project and related technologies. The LLISSE project aimed towards developing a full lander system operational for 60 days on the Venus surface and included a power source, electronics, communications, sensors, and the structure, each at a different level of maturity. This presentation briefly describes these and other lander system technologies, their relative level of maturity, and planned future development for Venus surface exploration.

Venus surface exploration high temperature technol↗
NASA NTRS2023

Constraining the Venus Interior Structure With Future VERITAS Measurements of the Gravitational Atmospheric Loading

The complex dynamics of the Venus atmosphere produces a periodic mass redistribution pattern that creates a time-variable modulation of the gravity field of Venus. This gravity signal depends on the net transport of mass across the globe and on the response of the solid body to the normal loading of its crust imparted by the atmosphere. In this work, we explore the possibility of measuring this phenomenon with VERITAS, a NASA Discovery-class mission. By simulating the gravity science experiment, we explore the possibility of measuring the response of Venus to the atmospheric loading, parametrized by the loading Love numbers ( 𝑘 𝑙 ' ), and assess the dependence of these parameters on fundamental interior structure properties. Using the most recent models of Venus' interior, we compute the Venus Love numbers in a compressible viscoelastic setting and compare them with the predicted uncertainty of the VERITAS measurements. We show that VERITAS will measure 𝑘 2 ' at the 4% level and that this measurement could possibly help to distinguish between different equally plausible interior structure models, especially allowing us to distinguish different rheological laws. We also show that a measurement campaign such as the VERITAS gravity science investigation has the potential of measuring 𝑘 2 ' not only at the loading forcing frequency, but also at the tidal frequency, ultimately providing a way to probe the response of the planet at different forcing periods.

Atmospheric tides↗
NASA NTRS2023

Magma Ocean, Water, and the Early Atmosphere of Venus

The current state and surface conditions of the Earth and its twin planet Venus are drastically different. Whether these differences are directly inherited from the earliest stages of planetary evolution, when the interior was molten, or arose later during the long-term evolution is still unclear. Yet, it is clear that water, its abundance, state, and distribution between the different planetary reservoirs, which are intimately related to the solidification and outgassing of the early magma ocean, are key components regarding past and present-day habitability, planetary evolution, and the different pathways leading to various surface conditions. In this chapter we start by reviewing the outcomes of the accretion sequence, with particular emphasis on the sources and timing of water delivery in light of available constraints, and the initial thermal state of Venus at the end of the main accretion. Then, we detail the processes at play during the early thermo-chemical evolution of molten terrestrial planets, and how they can affect the abundance and distribution of water within the different planetary reservoirs. Namely, we focus on the magma ocean cooling, solidification, and concurrent formation of the outgassed atmosphere. Accounting for the possible range of parameters for early Venus and based on the mechanisms and feedbacks described, we provide an overview of the likely evolutionary pathways leading to diverse surface conditions, from a temperate to a hellish early Venus. The implications of the resulting surface conditions and habitability are discussed in the context of the subsequent long-term interior and atmospheric evolution. Future research directions and observations are proposed to constrain the different scenarios in order to reconcile Venus’ early evolution with its current state, while deciphering which path it followed.

Venus↗
NASA NTRSDate not supplied

A Brief Overview of High Temperature Technologies for a Venus Long Lived Lander

The extreme surface conditions of Venus, including high temperature/pressure and reactive chemistry, have previously limited the lifetime of surface missions to ~2 hours. However, recent advances in high temperature technologies suggest the possibility of extended duration missions on the Venus surface. This presentation gives a brief overview on a range of high temperature technologies to enable a possible extended duration Venus surface mission. The technology development under the Long-Lived In Situ Solar System Explorer (LLISSE) project and related technologies will be emphasized as well as that in the High Operating Temperature Technologies (HOTTech) program. The LLISSE project aimed towards developing a full lander system operational for 60 days on the Venus surface and included a power source, electronics, communications, sensors, and the structure, each at a different level of maturity. This presentation briefly describes these and other lander system technologies, their relative level of maturity, and planned future development for Venus surface exploration. It also describes the relevant capabilities and development approach to enable such a mission at NASA Glenn Research Center.

Venus surface↗
NASA NTRSDate not supplied

Venus Sample Return Using In-situ Propellant

This project will pioneer a new approach to return a sample from the surface of Venus. At 450°C and 92 bar pressure, the Venus surface is the most hostile environment in the solar system. This project merges an innovative carbon monoxide rocket concept using propellant made from the Venus atmosphere with innovations in high-temperature technology and solar aircraft. We turn an ambitious mission into a reality. The mission will return a sample from the scorching surface of Venus, using a novel multi-step approach incorporating new technology. The high-temperature solar aircraft collects the sample from the surface and carries it above the main cloud deck to a balloon platform with a launch vehicle & propellant manufacturing plant. The carbon monoxide/oxygen monopropellant is manufactured from the Venus atmosphere.

Venus↗
NASA NTRS2017

Exploration of Venus' Deep Atmosphere and Surface Environment

Venus formed in the same part of our solar system as Earth, apparently from similar materials. Although both planets are about the same size, their differences are profound. Venus and Earth experienced vastly different evolutionary pathways resulting in unexplained differences in atmospheric composition and dynamics, as well as in geophysical processes of the planetary surfaces and interiors. Understanding when and why the evolutionary pathways of Venus and Earth diverged is key to understanding how terrestrial planets form and how their atmospheres and surfaces evolve. Measurements made in situ, within the near-surface or surface environment, are critical to addressing unanswered questions. We have made substantial progress modernizing and maturing pressure vessel technologies to enable science operations in the high temperature and pressure near-surface/surfaceenvironment of Venus.

Venus Atmosphere↗
NASA NTRS1973

System design of the Pioneer Venus spacecraft. Volume 1: Executive summary

The NASA Ames Research Center Pioneer Venus Project objective is to conduct scientific investigations of the planet Venus using spin stabilized spacecraft. The defined approach to accomplish this goal is to implement a multiprobe spacecraft mission and an orbiter spacecraft mission. Candidate launch vehicles for the Pioneer Venus missions were the Thor/Delta and Atlas/Centaur. The multiprobe spacecraft consists of a probe bus, one large probe, and three small probes. The probes are designed to survive to the surface of Venus, and to make in situ measurements of the Venusian atmosphere; the probe bus enters the atmosphere and makes scientific measurements until it burns out. The orbiter mission uses a spacecraft designed to orbit Venus for 225 days with an orbit period of about 24 hours (h). The probe bus and orbiter designs are to use a common spacecraft bus.

Dorfman, S. D.↗
NASA NTRS1977

The Venus bow shock - Detached or attached

Examination of the locations of the bow shock encounters of Mariner 5 and 10 and Venera 4, 6, and 9 suggests that the bow shock of Venus is on the average detached from the ionosphere. However, the standoff distance of the nose of the shock is closer to the planet than the distance that one would obtain by simply scaling the solar wind Venus interaction under the assumption that Venus completely deflects the solar wind. This fact implies that there is a significant influx of solar wind plasma into the Venus ionosphere. If the absorption of the solar wind by Venus is great enough, the shock may become attached to the ionosphere. The Mariner 10 bow shock encounter may have occurred during such a period. A rough estimate of the average fraction of the solar wind incident on the cross section of the planet that is absorbed is 29%.

Russell, C. T.↗
NASA NTRS1977

Earth and Venus - A comparative study

Two hypotheses attempting to account for the anomalously low intrinsic density of Venus in terms of chemical fractionation processes are entertained. Both assume similar relative abundances of major elements (Fe, Si, Mg, Al, Ca) in Venus and earth. One model assigns a larger proportion of the total Fe present in Venus to the planetary mantle, implying a core/mantle ratio lower than that of earth, and more extensive oxidation. The alternate hypothesis projects a Venus more reduced than the earth, with a mantle devoid of oxidized Fe; the difference in intrinsic densities is then attributed to the earth accreting at a lower temperature consonant with its greater distance from the sun. Large amounts of sulfur are presumed accreted on the earth but not on Venus, in the second model. Available chemical evidence tends to favor the first model.

Ringwood, A. E.↗
NASA NTRS1979

Nonresonance rotation of Venus

Radar observations accumulated over the past 14 yr are used to make a precise estimate of the spin vector of Venus. The results obtained show that the spin vector of Venus may be adequately described in the standard 1950.0 coordinate system by a period of 243.01 + or - 0.03 days (retrograde) and a north pole direction corresponding to alpha = 272.8 + or - 0.5 deg and delta = 67.2 + or - 0.3 deg; the quoted errors represent estimates of 70% confidence intervals. The angular separations between the spin vector and those vectors representing the unit normals to the invariable plane of the solar system and the orbital plane of Venus are found to be 0.5 deg and 2.6 deg, respectively. It is concluded that Venus is not rotating with a resonance spin period relative to the orbit of earth and that the spin of Venus may be in a generalized Cassini state.

Shapiro, I. I.↗
NASA NTRS1979

Gravity field of Venus - A preliminary analysis

The gravitational field of Venus obtained by tracking the Pioneer Venus Orbiter is examined. For each spacecraft orbit, two hours of Doppler data centered around periapsis were used to estimate spacecraft position and velocity and the velocity residuals obtained were spline fit and differentiated to produce line of sight gravitational accelerations. Consistent variations in line of sight accelerations from orbit to orbit reveal the presence of gravitational anomalies. A simulation of isostatic compensation for an elevated region on the surface of Venus indicates that the mean depth of compensation is no greater than about 100 km. Gravitational spectra obtained from a Fourier analysis of line of sight accelerations from selected Venus orbits are compared to the earth's gravitational spectrum and spherical harmonic gravitational potential power spectra of the earth, the moon and Mars. The Venus power spectrum is found to be remarkably similar to that of the earth, however systematic variations in the harmonics suggest differences in dynamic processes or lithospheric behavior.

Phillips, R. J.↗
NASA NTRS1981

Comparative aspects of Venus and terrestrial meteorology

The observations and measurements made by Pioneer Venus orbiters are presented in terms of comparison of Venus and terrestrial meteorology. Although the temperature-pressure profiles of the two planets differ at lower altitudes, the temperatures are similar over their common range of pressures except for a much cooler mesosphere on Venus. The additional similarities between the earth and Venus relate to the warm polar stratospheres and the zonally-averaged energy budgets of the two planets. A difference in the mean radiation budgets for Venus is the relative smallness of the upward and downward thermal flux components. It is noted that the observed similarities reflect common mechanisms despite the difference in the dynamical regimes of the two planets.

Taylor, F. W.↗
NASA NTRS1980

On the search for an intrinsic magnetic field at Venus

Magnetic field observations obtained by the Pioneer Venus orbiter at low altitude are now available for two sets of orbits in the Venus wake. Data from these 130 orbits are examined for possible surface correlated features or any intrinsic magnetic moment. No surface correlated magnetic fields are observed, but the threshold for the detectability of such fields at Venus is about an order of magnitude greater than at the moon. A surface feature of 10 deg extent would have to create an anomaly of at least 5 gammas at 200 km to be detected in the Pioneer Venus data. Using measurements averaged in 72 10 x 10 deg bins, a planetary magnetic dipole moment of 0.87 + or - 3.00 x 10 to the 21st gauss-cu cm is obtained. Thus the upper limit of the present day Venus moment is less than 4 x 10 to the -5th of the terrestrial moment.

Russell, C. T.↗
NASA NTRS1982

Deducing the age of the dense Venus atmosphere

It is shown how crater size-density counts may be used to help constrain the history of the Venus atmosphere, based on the predictions of simple but reasonable models for crater production, surface erosion, and the effects of atmospheric drag and breakup on incident meteors in the Venus atmosphere. In particular, if the atmosphere is young, the old (uneroded) surfaces will have crater densities upward of 0.0001/sq km and a ratio of small (4 km) craters to large (128 km) craters near 1000. If the atmosphere is old and the breakup mechanism is dominant, absolute crater densities on Venus surfaces will be diminished by several orders of magnitude relative to the young atmosphere case. If atmospheric drag is dominant, the absolute crater density will be lowered by perhaps an order of magnitude relative to the young atmosphere case, and the ratio of small to large craters will be reduced to a value near 10 to the 1.5 power. Once a large fraction of Venus surface has been imaged at kilometer resolution, as the VOIR project promises to do, it could be possible to make an early determination of the age of the Venus atmosphere.

Kahn, R.↗
NASA NTRS1982

Density constraints on the composition of Venus

It is pointed out that the composition of Venus is constrained most directly by the mean density of the planet because the moment of inertia factor is unknown and seismic data do not yet exist for the interior. Values of mass and mean radius give 5.245 g/cu cm for the mean density of Venus. This value is nearly 5% less than the value for the mean density of earth. Explanations for the density difference between Venus and earth are discussed, taking into consideration five models which have been advocated to account for the difference. On the basis of calculations, it is concluded that none of the models can be excluded solely on the basis of the observed density difference between Venus and earth. Therefore, evaluation of the models for Venus must be based principally on the plausibility or implausibility of their constituent assumptions and on the success of the models in predicting the compositions of other planets for which more data exist.

Goettel, K. A.↗