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NASA NTRSDate not supplied

Ceres Planetary Mission Concept Study: Exploration of Ceres' Habitability

Dwarf planet Ceres is a compelling target as an evolved ocean world with recent and potentially ongoing geological activity. As the most water-rich body in the inner solar system after Earth (in absolute abundance), it is a representative of the population of planetesimals that brought volatiles and organics to the inner solar system. And, situated in the Main Belt of Asteroids, it is accessible enough to return a sample from within the resources of a typical medium-class (New Frontiers) NASA mission. Habitability is addressed via a combination of geological, geophysical, and compositional investigations. Past and ongoing activity is addressed via high-resolution imaging and gravity measurements from orbit near landforms interpreted as volcanic structures based on the Dawn observations. The depth of deep brines would be probed via electromagnetic sounding. Sample return would enable a vast range of experimental techniques to be applied with sensitivities and accuracies beyond those feasible with in situ instruments and would benefit from future facilities developments. Sample return could be executed with a single flight system with solar electric propulsion. The baseline design of the sample return capsule is inherited from the OSIRIS-REx mission. This concept also relies on the availability of key technologies: an enhanced landing vision system leveraging investments for Mars 2020; retractable/redeployable solar arrays, which have been demonstrated on the International Space Station but not at Ceres’ gravity; and a new design for sample transfer from the pneumatic sampling system to the sample return capsule based off Honeybee Robotics’ design for the MMX mission. The authors acknowledge support from NASA’s Planetary Mission Concept Study program. The information in this abstract is pre-decisional and is provided for planning and discussion purposes only.

K. E. Miller↗
NASA NTRS2018

Juno at Jupiter: The Mission and Its Path to Unveiling Secrets of the History of the Solar System

The Juno mission is described, focusing on its orbits at Jupiter, how the plan evolved, and science return so far. Juno is a NASA New Frontiers spacecraft in a near-polar highly elliptical 53-day orbit at Jupiter. Since arrival in July 2016, it has used 9 science investigations to study the planet’s atmospheric composition and structure, magnetic and gravity fields, and polar and extended magnetosphere. A radiation monitoring investigation contributes to our understanding of Jupiter’s environment. Juno’s primary science goal is to understand the origin and evolution of Jupiter, to shed light on how the Earth and other planets formed. Baseline objectives will be satisfied with 32 science orbits, a spin-stabilized solar powered spacecraft, an electronics vault for radiation shielding, and a robust payload with microwave receivers, X- and Ka-band radio science hardware, vector magnetometers, high- and low-energy charged particle detectors, radio and plasma wave antennas, UV and IR spectroscopic imagers, and a visible light camera for public outreach. Observations are made in a limited number of orientations, including Gravity Science (spin axis and main antenna pointing to Earth), and microwave atmospheric sounding (spin plane passing through Jupiter’s center). Prime science data are collected near closest approach (perijove), plus calibrations, occasional remote sensing, and continued magnetospheric observations in the outer parts of the orbit. Juno’s mission plan has evolved since the 2005 proposal due to design and ops choices, e.g., mission design (cruise or early orbital trajectory), orbit period (11, 14, then 53 days), perijove attitudes (2 or more), and DSN coverage (34- and 70-m stations). Choices were partly motivated by the effect on science return. Selected preliminary science results are summarized, including the benefits of decisions as the plan evolved. Juno has begun to unveil Jupiter – peeling apart its interior by measuring gravity and magnetic fields, using microwaves to probe its atmosphere down to 100s of km, exploring its polar and extended magnetosphere, and imaging the poles for the first time. In doing so, it is revealing secrets of the history of the Earth and solar system.

Stephens, Stuart K.↗
NASA NTRSDate not supplied

Replication of Segments of STS-94 as a Lunar Surface Mission

The Artemis program established the goal to land the first woman and first person of color on the Moon, but that is only the beginning of the program. Artemis plans to move towards a sustainable phase, with four crew living on the lunar surface for roughly 30-day annual missions, operating from a Pressurized Rover (PR) and a Surface Habitat (SH). The crew will split up – two living and operating from the PR and the others in the SH, perhaps swapping places halfway through the surface mission. There is a significant degree of maturity surrounding PR operations due to the NASA Desert Research and Technology Studies field tests from 2007-2011. However, there is a degree of uncertainty surrounding activity in the SH, with anecdotal speculation among some Artemis lunar surface engineers that the SH crew might not be fully utilized. Contrary to this belief, there is evidence in US human spaceflight history that the SH crew may instead be extremely busy. In particular, portions of the STS-94 Microgravity Science Lab mission demonstrate a science-based use case for crew activity in the SH. Fifteen Spacelab missions (not including STS-83, which was terminated early due to a fuel cell problem and reflown as STS-94) and eight Spacehab missions used the previously mentioned modules as science labs to expand the science capability of shuttle orbital missions, most flown prior to the assembly of the International Space Station. STS-94 is selected as an example of these flights. STS-94 was a 15.7-day mission with a 7-person crew. The crew operated in split 12-hour shifts, enabling 24-hour science operations. STS-94 used the space shuttle Columbia with the Spacelab module and Extended Duration Orbiter pallet in the cargo bay. The STS-94 physical science investigations were intended to explore various physical aspects of microgravity. These same investigations can be conducted on the Moon to explore 1/6 gravity. The Spacelab module was outfitted with several key facilities to enable this research: Large Isothermal Furnace, Combustion Module-1, Droplet Combustion Experiment, EXPRESS Rack, TEMPUS, Gravity Measurement Devices, and Middeck Glovebox. The current reference concept for the SH is a hybrid inflatable in a vertical orientation. Fairly typical of hybrid inflatables, the SH has an aluminum core pressurized section and a larger inflatable volume, in this case attaching to the top of the core. Two crew will live in the SH at a time, though four can briefly occupy the habitat, such as for contingency or handover activities. This paper will discuss use of the STS-94 physical science equipment in the SH and options for the architectural layout of a resulting physics laboratory. It will also discuss how this laboratory may accompany other science facilities such as biology, human research, and geology. The person hours used by the STS-94 crew to conduct physical science research will be estimated and then mapped to a two-person SH crew, making it possible to determine how many days are required in the SH to complete the lunar gravity physical science investigations at varying levels of crew availability.

STS-94↗
NASA NTRS2002

Splashing Droplets

Current data on droplet breakup is scarce for the sizes and velocities typical of practical applications such as in spray combustion processes and coating processes. While much more representative of practical applications, the small spatial scales and rapid time-scales prevent detailed measurement of the internal fluid dynamics and liquid property gradients produced by impinging upon surfaces. Realized through the extended spatial and temporal scales afforded by a microgravity environment, an improved understanding of drop breakup dynamics is sought to understand and ultimately control the impingement dynamics of droplets upon surfaces in practical situations. The primary objective of this research will be to mark the onset of different 'splashing modes' and to determine their temperature, pressure and angle dependence for impinging droplets representative of practical fluids. In addition, we are modeling the evolution of droplets that do not initially splash but rather undergo a 'fingering' evolution observed on the spreading fluid front and the transformation of these fingers into splashed products. An example of our experimental data is presented below. These images are of Isopar V impacting a mirror-polished surface. They were acquired using a high-speed camera at 1000 frames per second. They show the spreading of a single droplet after impact and ensuing finger instabilities. Normal gravity experimental data such as this will guide low gravity measurements in the 2.2 second drop tower and KC-135 aircraft as available. Presently we are in the process of comparing the experimental data of droplet shape evolution to numerical models, which can also capture the internal fluid dynamics and liquid property gradients such as produced by impingement upon a heated surface. To-date isothermal numerical data has been modeled using direct numerical simulations of representative splashing droplets. The data obtained so far indicates that the present model describes well the droplet wall interactions to a point in time just before splash. Additional information is included in the original extended abstract.

VanderWal, Randall L.↗
NASA NTRS1972

Physiology of chimpanzees in orbit. Part 2: Interface document

Interface requirements are presented for the design and development of an earth orbiting experiment to be known as POCO, Physiology of Chimpanzees in Orbit. The POCO experiment may be designed to operate within an orbiting space station (provided artificial gravity measures are not employed), a Saturn 4-B workshop, an Apollo command module or service module, a Saturn-1B spacecraft LM adapter, or aboard one of the presently conceived appendages connected by an umbilical to a space station. This document sets forth the experiment definition and requirements and describes the hardware under development to accomplish these objectives.

Firstenberg, A.↗
NASA NTRS1973

Apollo 17 mission. Lunar roving vehicle/traverse gravimeter experiment motion sensitivity

The results of the lunar roving vehicle/traverse gravimeter experiment motion sensitivity test shows that the gravity measurements in both the normal and bypass modes should not be adversely affected by motion induced in the lunar roving vehicle by operation of the television camera position drive device or the operation of the surface electrical properties receiver/recorder. Motion of the traverse gravimeter experiment occurred when a 1.4-hertz resonant mode in pitch of the pallet was excited. Both of these modes were excited by camera elevation changes with the camera axis positioned fore and aft.

Source record↗
NASA NTRS1973

Gravity - Mare Humorum.

Global tracking coverage of the Apollo 15 subsatellite has provided gravity measurements from 50 km altitudes over the entire Humorum basin. An estimate of surface mass points at 2 degree intervals, which best fit the data reveals a mass distribution having a lesser mass excess for the very central area. When two different profiles were fit using a two disk model it was again found for each profile that the smaller central disk decreased the central mass by approximately 30%. The mass distribution per unit area however for the major portion of the mascon is still consistent with the other mascons (Crisium, Nectaris and Serenitatis) of approximately 800-900 kg/sq cm. The surface mass point solution seems to correlate somewhat with the dark areas on Whitaker's IR-UV map.

Sjogren, W. L.↗
NASA NTRS1974

Lunar gravity - Apollo 15 Doppler radio tracking

Analysis and interpretation of the lunar gravity measurements obtained from Apollo 15 Doppler radio tracking data. The extent of surface coverage was limited to the trajectory paths of the command and service module during revolutions 3 through 11, when it was at a relatively low periapsis altitude just prior to undocking with the lunar module. The trajectory was close to the most optimal for study of the details of the Serenitatis and Crisium mascons. The periapsis altitude was about 12 km at the center of Mare Serenitatis, one of the largest mascons, and the one in the most favorable viewing geometry. The results obtained strengthen Booker's (1970) contention that all mascons have approximately the same thickness.

Muller, P. M.↗
NASA NTRS1974

Comment on satellite altimeter data

SKYLAB mission SEASAT-B altimeter observations in combination with surface gravity measurements provide useful data on the marine geoid and expected ocean perturbations from analyses of seamount structures.

Bowin, C.↗
NASA NTRS1977

Gravimetric geoid in the Northwest Pacific Ocean

A total of 3708 1 x 1 deg free-air gravity anomaly averages have been used to construct a new 1 x 1 deg gravimetric geoid of the Northwest Pacific Ocean. The 1 x 1 deg averages are based on a compilation of 147,000 surface ship and pendulum gravity measurements. Difference geoid undulations range from a maximum of +19 m over the Hawaiian ridge to a minimum of -31 m over the junction of the Kuril and Aleutian trenches. The Hawaiian swell is associated with a geoidal high of up to +15 m with wavelengths of about 2200 km and the topographic rises seaward of deep-sea trenches are associated with geoidal highs of up to 4 m with wavelengths of about 220-900 km. The agreement between the gravimetric geoid and Skylab-4 and Geos-3 altimeter data is close for wavelengths greater than about 300 km but poor for shorter wavelengths.

Watts, A. B.↗
NASA NTRS1978

The inverse problem: Ocean tides derived from earth tide observations

Indirect mapping ocean tides by means of land and island-based tidal gravity measurements is presented. The inverse scheme of linear programming is used for indirect mapping of ocean tides. Open ocean tides were measured by the numerical integration of Laplace's tidal equations.

Kuo, J. T.↗
NASA NTRS1980

Gravity anomalies on Venus

Doppler radio tracking of the Pioneer Venus orbiter has provided gravity measures over a significant portion of Venus. Feature resolution is approximately 300-1000 km within an area extending from 10 deg S to 40 deg N latitude and from 70 deg W to 130 deg E longitude (approximately equal to 200 deg). Many anomalies were detected, and there is considerable correlation with radar altimetry topography (Pettengill et al., 1980). The amplitudes of the anomalies are relatively mild and similar to those on earth at this resolution. Calculations for isostatic adjustment reveal that significant compensation has occurred.

Sjogren, W. L.↗
NASA NTRS1981

Role of membrane stresses in the support of planetary topography

The role of membrane stresses and bending stresses in supporting topographic loads on planetary elastic lithospheres is examined. A dimensionless parameter is introduced in order to determine the ability of a spherical shell to support loads through membrane stresses. It is determined that when this parameter is large, membrane stresses can fully support topographic loads with flexure, and when it is small the influence of the membrane stresses can be neglected. Equations governing the behavior of a spherical shell are solved for a topographic load expressed in terms of spherical harmonics, and spherical harmonic expansions of the measured gravity and topography for Mars and the moon are compared with the theory. It is concluded that membrane stresses play an important role in the support of topographic loads on the moon and Mars. The correlation of observed gravitational potential anomalies with the topography on Mars is explained by membrane stresses in the elastic lithosphere.

Turcotte, D. L.↗
NASA NTRS1982

IUE observations of Si and C lines and comparison with non-LTE models

Classical model atmosphere techniques are applied to analyze IUE spectra, and to determine abundances, effective temperatures and gravities. Measurements of the equivalent widths and other properties of the line profiles of 24 photospheric lines of Si II, Si III, Si IV, C II, C III and C IV are presented in the range of 1175-1725 A for seven B and two O stars. Observed line profiles are compared with theoretical profiles computed using non-LTE theory and models, and using line-blanketed model atmospheres. Agreement is reasonably good, although strong lines are calculated to be systematically stronger than those observed, while the reverse occurs for weak lines, and empirical profiles have smaller wings than theoretical profiles. It is concluded that the present theory of line formation when used with solar abundances, represents fairly well observed UV photospheric lines of silicon and carbon ions in the atmospheres of main sequence stars of types B5-O9.

Kamp, L. W.↗
NASA NTRS1984

Pioneer to Venus - The multiprobe and orbiter missions

The missions of the Pioneer multiprobe and orbiter spacecraft to Venus are surveyed and illustrated with drawings, photographs, maps, and diagrams. The general characteristics of Venus and the pre-Pioneer missions are reviewed; the developmental history of the Pioneer project is traced; the spacecraft and their orbits and deployment are described; and the scientific findings on the planet surface, atmosphere, and ionosphere are summarized. The experiments planned for the extended mission of the orbiter (through reentry in 1992) are briefly characterized, includidng solar-wind-interaction studies, comet detection, ionosphere and aeronomy investigations, global lightning survey, optical observations, gamma-ray-burst detection, radar mapping, gravity measurements, and observations of Halley's Comet during February, 1986.

Craig, R. A.↗