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At least 1,153 records · Page 64
All sourcesNASA NTRSDOE OSTI
NASA NTRS2012

Analysis of the Touch-And-Go Surface Sampling Concept for Comet Sample Return Missions

This paper studies the Touch-and-Go (TAG) concept for enabling a spacecraft to take a sample from the surface of a small primitive body, such as an asteroid or comet. The idea behind the TAG concept is to let the spacecraft descend to the surface, make contact with the surface for several seconds, and then ascend to a safe location. Sampling would be accomplished by an end-effector that is active during the few seconds of surface contact. The TAG event is one of the most critical events in a primitive body sample-return mission. The purpose of this study is to evaluate the dynamic behavior of a representative spacecraft during the TAG event, i.e., immediately prior, during, and after surface contact of the sampler. The study evaluates the sample-collection performance of the proposed sampling end-effector, in this case a brushwheel sampler, while acquiring material from the surface during the contact. A main result of the study is a guidance and control (G&C) validation of the overall TAG concept, in addition to specific contributions to demonstrating the effectiveness of using nonlinear clutch mechanisms in the sampling arm joints, and increasing the length of the sampling arms to improve robustness.

Touch-and-Go (TAG)↗
NASA NTRS2014

Minerology and Crystallography of Some Itokawa Particles Returned by the Hayabusa Mission

JAXA Hayabusa mission success-fully returned particles of the asteroid Itokawa to the earth in 2010. The recovered particles were carefully studied by the preliminary examination (PE) team and the obtained results are providing significant and unique information about the formation and evolution of meteorite parent bodies [1-6]. These particles further revealed that their mineral compositions and oxygen isotopes are close to those of equilibrated LL chon-drites [1,2], which matches with the observation at the orbit [7]. After the PE, JAXA distributed the samples as international AO study and we received 4 new and 3 PE particles. The new samples may contain some exot-ic components that have not been found by the PE study, and are of special interest. We have performed a detailed mineralogical and crystallographic study on these particles and here report the results.

Mikouchi, T.↗
NASA NTRS2014

Analysis of Particulate and Fiber Debris Samples Returned from the International Space Station

During the period of International Space Station (ISS) Increments 30 and 31, crewmember reports cited differences in the cabin environment relating to particulate matter and fiber debris compared to earlier experience as well as allergic responses to the cabin environment. It was hypothesized that a change in the cabin atmosphere's suspended particulate matter load may be responsible for the reported situation. Samples were collected and returned to ground-based laboratories for assessment. Assessments included physical classification, optical microscopy and photographic analysis, and scanning electron microscopy (SEM) evaluation using energy dispersive X-ray spectrometry (EDS) methods. Particular points of interest for assessing the samples were for the presence of allergens, carbon dioxide removal assembly (CDRA) zeolite dust, and FGB panel fibers. The results from the physical classification, optical microscopy and photographic analysis, and SEM EDS analysis are presented and discussed.

Perry, Jay L.↗
NASA NTRS2014

Mars Sample Return and Flight Test of a Small Bimodal Nuclear Rocket and ISRU Plant

A combined Nuclear Thermal Rocket (NTR) flight test and Mars Sample Return mission (MSR) is explored as a means of "jump-starting" NTR development. Development of a small-scale engine with relevant fuel and performance could more affordably and quickly "pathfind" the way to larger scale engines. A flight test with subsequent inflight postirradiation evaluation may also be more affordable and expedient compared to ground testing and associated facilities and approvals. Mission trades and a reference scenario based upon a single expendable launch vehicle (ELV) are discussed. A novel "single stack" spacecraft/lander/ascent vehicle concept is described configured around a "top-mounted" downward firing NTR, reusable common tank, and "bottom-mount" bus, payload and landing gear. Requirements for a hypothetical NTR engine are described that would be capable of direct thermal propulsion with either hydrogen or methane propellant, and modest electrical power generation during cruise and Mars surface insitu resource utilization (ISRU) propellant production.

George, Jeffrey A.↗
NASA NTRS2014

The Benefits of Sample Return: Connecting Apollo Soils and Diviner Lunar Radiometer Remote Sensing Data

The Diviner Lunar Radiometer, onboard NASA's Lunar Reconnaissance Orbiter, has produced the first global, high resolution, thermal infrared observations of an airless body. The Moon, which is the most accessible member of this most abundant class of solar system objects, is also the only body for which we have extraterrestrial samples with known spatial context. Here we present the results of a comprehensive study to reproduce an accurate simulated lunar environment, evaluate the most appropriate sample and measurement conditions, collect thermal infrared spectra of a representative suite of Apollo soils, and correlate them with Diviner observations of the lunar surface. We find that analyses of Diviner observations of individual sampling stations and SLE measurements of returned Apollo soils show good agreement, while comparisons to thermal infrared reflectance under terrestrial conditions do not agree well, which underscores the need for SLE measurements and validates the Diviner compositional dataset. Future work includes measurement of additional soils in SLE and cross comparisons with measurements in JPL Simulated Airless Body Emission Laboratory (SABEL).

Greenhagen, B. T.↗
NASA NTRS2014

A Framework for Land Cover Classification Using Discrete Return LiDAR Data: Adopting Pseudo-Waveform and Hierarchical Segmentation

Acquiring current, accurate land-use information is critical for monitoring and understanding the impact of anthropogenic activities on natural environments.Remote sensing technologies are of increasing importance because of their capability to acquire information for large areas in a timely manner, enabling decision makers to be more effective in complex environments. Although optical imagery has demonstrated to be successful for land cover classification, active sensors, such as light detection and ranging (LiDAR), have distinct capabilities that can be exploited to improve classification results. However, utilization of LiDAR data for land cover classification has not been fully exploited. Moreover, spatial-spectral classification has recently gained significant attention since classification accuracy can be improved by extracting additional information from the neighboring pixels. Although spatial information has been widely used for spectral data, less attention has been given to LiDARdata. In this work, a new framework for land cover classification using discrete return LiDAR data is proposed. Pseudo-waveforms are generated from the LiDAR data and processed by hierarchical segmentation. Spatial featuresare extracted in a region-based way using a new unsupervised strategy for multiple pruning of the segmentation hierarchy. The proposed framework is validated experimentally on a real dataset acquired in an urban area. Better classification results are exhibited by the proposed framework compared to the cases in which basic LiDAR products such as digital surface model and intensity image are used. Moreover, the proposed region-based feature extraction strategy results in improved classification accuracies in comparison with a more traditional window-based approach.

Light Detection & Ranging (LIDAR)↗
NASA NTRS2014

ROPEC - ROtary PErcussive Coring Drill for Mars Sample Return

The ROtary Percussive Coring Drill is a light weight, flight-like, five-actuator drilling system prototype designed to acquire core material from rock targets for the purposes of Mars Sample Return. In addition to producing rock cores for sample caching, the ROPEC drill can be integrated with a number of end effectors to perform functions such as rock surface abrasion, dust and debris removal, powder and regolith acquisition, and viewing of potential cores prior to caching. The ROPEC drill and its suite of end effectors have been demonstrated with a five degree of freedom Robotic Arm mounted to a mobility system with a prototype sample cache and bit storage station.

Chu, Philip↗
NASA NTRS2010

Earth Return Navigation Analysis for Manned Spacecraft Using Optical and Radiometric Measurements

Future manned space missions will travel beyond low Earth orbit with more stringent navigation requirements and fewer navigation resources than used for the Apollo Program of the 1960s. A study has been performed to assess radiometric and optical tracking capabilities necessary to meet nominal and contingency Earth entry flight path angle requirements. Results indicate that 3 tracking stations will be insufficient for meeting nominal entry requirements, while the performance of a 6 station architecture is dependent on the entry geometry. Optical tracking results indicate that a narrow-angle camera is required for satisfying contingency Earth return requirements.

GN&C↗
NASA NTRS2015

A Free-Return Earth-Moon Cycler Orbit for an Interplanetary Cruise Ship

A periodic circumlunar orbit is presented that can be used by an interplanetary cruise ship for regular travel between Earth and the Moon. This Earth-Moon cycler orbit was revealed by introducing solar gravity and modest phasing maneuvers (average of 39 m/s per month) which yields close-Earth encounters every 7 or 10 days. Lunar encounters occur every 26 days and offer the chance for a smaller craft to depart the cycler and enter lunar orbit, or head for a Lagrange point (e.g., EM-L2 halo orbit), distant retrograde orbit (DRO), or interplanetary destination such as a near-Earth object (NEO) or Mars. Additionally, return-to-Earth abort options are available from many points along the cycling trajectory.

Interplanetary cruise ship↗
NASA NTRS1961

Scatter Theories and Their Application to Lunar Radar Return

The research work being done under this NASA grant is divided into the following three categories: (1) An estimate of the radar return for the NASA Aerobee rocket shot at White Sands Missile Range. (WSMR) (2) Development of new scatter theories, modification and correlation of existing scatter theories, and application of the theories to moon-echo data for estimation of the surface features of the moon. (3) Acoustic modeling of the lunar surface and correlation of the theoretical with both full scale and acoustical experimental results.

Hayre, H. S.↗
NASA NTRS2016

Larch Forests of Middle Siberia: Long-Term Trends in Fire Return Intervals

Fire history within the northern larch forests of Central Siberia was studied (65+degN). Fires within this area are predominantly caused by lightning strikes rather than human activity. Mean fire return intervals (FRIs) were found to be 112 +/- 49 years (based on firescars) and 106 +/- 36 years (based on firescars and tree natality dates). FRIs were increased with latitude increase and observed to be about 80 years at 64N, about 200 years near the Arctic Circle and about 300 years nearby the northern range limit of larch stands (approx.71+degN). Northward FRIs increase correlated with incoming solar radiation (r = -0.95). Post- Little Ice Age (LIA) warming (after 1850) caused approximately a doubling of fire events (in comparison with a similar period during LIA). The data obtained support a hypothesis of climate-induced fire frequency increase. Keywords Fire ecology Fire history Fire frequency Siberian wildfires Larch forests Climate change

Fire ecology↗
NASA NTRS1973

An Approximate Equation For The Multiply Scattered Contribution to A Lidar Return

An approximate equation is developed which describes the contribution of Nth order scattering to a lidar return. This development assumes a homogeneous scattering medium characterized by a scattering function sharply peaked in the forward direction and relatively insensitive to angle near the backscatter direction. The derivation includes the effects of finite divergence of the transmitted laser beam, finite receiver field of view, finite separation between the laser and the receiver and nonparallel system alignment. The derivation presented uses small angle approximations to reduce the time dependent multiple scattering problem to a time independent form which is then solved with techniques previously developed for multiple small angle nuclear scattering.

Eloranta, Edwin W.↗
NASA NTRS2014

Titan Science Return Quantification

Each proposal for a NASA mission concept includes a Science Traceability Matrix (STM), intended to show that what is being proposed would contribute to satisfying one or more of the agency's top-level science goals. But the information traditionally provided cannot be used directly to quantitatively compare anticipated science return. We added numerical elements to NASA's STM and developed a software tool to process the data. We then applied this methodology to evaluate a group of competing concepts for a proposed mission to Saturn's moon, Titan.

Saturn↗
NASA NTRS2016

Filter Efficiency and Leak Testing of Returned ISS Bacterial Filter Elements After 2.5 Years of Continuous Operation

The atmosphere revitalization equipment aboard the International Space Station (ISS) and future deep space exploration vehicles provides the vital functions of maintaining a habitable environment for the crew as well as protecting the hardware from fouling by suspended particulate matter. Providing these functions are challenging in pressurized spacecraft cabins because no outside air ventilation is possible and a larger particulate load is imposed on the filtration system due to lack of sedimentation in reduced gravity conditions. The ISS Environmental Control and Life Support (ECLS) system architecture in the U.S. Segment uses a distributed particulate filtration approach consisting of traditional High-Efficiency Particulate Adsorption (HEPA) filters deployed at multiple locations in each module. These filters are referred to as Bacteria Filter Elements (BFEs). As more experience has been gained with ISS operations, the BFE service life, which was initially one year, has been extended to two to five years, dependent on the location in the U.S. Segment. In previous work we developed a test facility and test protocol for leak testing the ISS BFEs. For this work, we present results of leak testing a sample set of returned BFEs with a service life of 2.5 years, along with particulate removal efficiency and pressure drop measurements. The results can potentially be utilized by the ISS Program to ascertain whether the present replacement interval can be maintained or extended to balance the on-ground filter inventory with extension of the lifetime of ISS to 2024. These results can also provide meaningful guidance for particulate filter designs under consideration for future deep space exploration missions.

ISS Air Quality↗
NASA NTRS2017

Stroboscopic Goggles as a Countermeasure for Dynamic Visual Acuity and Landing Sickness in Crewmembers Returning from Long-Duration Spaceflight

Long-term exposure to microgravity causes sensorimotor adaptations that result in functional deficits upon returning to a gravitational environment. At landing, the vestibular system and the central nervous system, responsible for coordinating head and eye movements via the vestibulo-occular reflex (VOR), are adapted to microgravity and must re-adapt to the Earth's gravitational environment. This re-adaptation causes decrements in gaze control and dynamic visual acuity, with astronauts reporting oscillopsia and blurred vision. These effects are caused by retinal slip, or the inability to keep an image focused on their retina, which is thought to drive motion sickness symptoms experienced upon landing. Retinal slip can be estimated by dynamic visual acuity (DVA); visual acuity while in motion. Peters et al. (2011) find that DVA is worsened in astronauts by an average of 0.75 eye-chart lines one day after landing. Previously, the use of stroboscopic goggles has shown to be effective in minimizing motion sickness symptoms due to retinal slip (Reschke et al. 2007). In this study, we simulated the decrement in DVA caused by sensorimotor re-adaptation by using minifying lenses and then testing the efficacy of stroboscopic goggles in preventing retinal slip and improving DVA. Dynamic visual acuity is assessed using an oscillating chair developed in the Neuroscience Laboratory at JSC. This chair is motor-driven and oscillates vertically at 2 Hz with a vertical displacement of +/- 2 cm to simulate the vertical translations that occur while walking. As the subject is being oscillated, they are asked to discern the direction of Landolt-C optotypes of varying sizes and record their direction using a gamepad. The visual acuity thresholds are determined using an algorithm that alters the size of the optotype based on the previous responses of the subject using a forced-choice best parameter estimation that is able to rapidly converge on the threshold value. Visual acuity thresholds were determined both for static (seated) and dynamic (oscillating) conditions. Dynamic visual acuity is defined as the difference between the dynamic and static conditions. We found that healthy subjects (n=20) have a significantly impaired DVA while wearing the minifying lenses, demonstrating that the VOR is in an adaptive state and retinal slip is occurring. When subjects' acuity was tested wearing the stroboscopic goggles with the minifying lenses, there was no significant difference in their DVA compared to their baseline DVA. This suggests that stroboscopic goggles are preventing retinal slip and would function as an efficient countermeasure for VOR adaptations and thus help mitigate landing sickness symptoms experienced by long-duration crewmembers. These goggles might also be used to counter blurred vision (caused by retinal slip) experienced by crewmembers during launch where the vehicle vibrations are greatest. The stroboscopic effect could be built into a section of their head mounted displays on the visor of their helmets to be used in these high vibration situation if a mission critical task is necessary.

Rosenberg, M. J. F.↗
NASA NTRS2017

A Multi-Decadal Sample Return Campaign Will Advance Lunar and Solar System Science and Exploration by 2050

There have been 11 missions to the Moon this century, 10 of which have been orbital, from 5 different space agencies. China became the third country to successfully soft-land on the Moon in 2013, and the second to successfully remotely operate a rover on the lunar surface. We now have significant global datasets that, coupled with the 1990s Clementine and Lunar Prospector missions, show that the sample collection is not representative of the lithologies present on the Moon. The M3 data from the Indian Chandrayaan-1 mission have identified lithologies that are not present/under-represented in the sample collection. LRO datasets show that volcanism could be as young as 100 Ma and that significant felsic complexes exist within the lunar crust. A multi-decadal sample return campaign is the next logical step in advancing our understanding of lunar origin and evolution and Solar System processes.

Neal, C. R.↗