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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

The TESS Mission Target Selection Procedure

We describe the target selection procedure by which stars are selected for 2 minute and 20 s observations by TESS. We first list the technical requirements of the TESS instrument and ground systems processing that limit the total number of target slots. We then describe algorithms used by the TESS Payload Operation Center (POC) to merge candidate targets requested by the various TESS mission elements (the Target Selection Working Group, TESS Asteroseismic Science Consortium, and Guest Investigator office). Lastly, we summarize the properties of the observed TESS targets over the two-year primary TESS mission. We find that the POC target selection algorithm results in 2.1–3.4 times as many observed targets as target slots allocated for each mission element. We also find that the sky distribution of observed targets is different from the sky distributions of candidate targets due to technical constraints that require a relatively even distribution of targets across the TESS fields of view. We caution researchers exploring statistical analyses of TESS planet-host stars that the population of observed targets cannot be characterized by any simple set of criteria applied to the properties of the input Candidate Target Lists.

Michael Fausnaugh↗
NASA NTRS2004

Target Selection and Imaging Requirements for JWST Fine Phasing

To achieve and maintain the fine alignment of its segmented primary mirror the James Webb Space Telescope (JWST) plans to use focus-diverse wavefront sensing (WFS) techniques with science camera imagery. The optical requirements for JWST are such that the error contribution from the WFS itself must be limited 10nm rms over all the controllable degrees of freedom of the telescope. In this paper, we will explore the requirements on the target selection and imaging requirements necessary to achieve the desired level of WFS accuracy. Using Monte Carlo simulations we explore the WFS error as a function of wavefront aberrations level, defocus-diversity level, optical bandwidth and imaging signal-to-noise ratio to establish the key imaging requirements. By taking into account practical integration time limits along with the distribution of the defocused point-spread functions, we establish the bright and faint star magnitude limits suitable for WFS target selection.

wavefront sensing↗
NASA NTRS2021

Mars 2020 Perseverance Edl Gnc Safe Target Selection Reconstruction

On February 18th, 2021, NASA landed Perseverance on the Jezero crater (on Mars) using a new Terrain Relative Navigation (TRN) capability. TRN is com-prised of a new sensor, the Lander Vision System (LVS), and a new GNC algo-rithm, the Safe Target Selection (STS). LVS localized the descent vehicle with respect to a map. STS selected the safe landing target within a reachable region from the on-board Safe Targets Map (STM). The landing target was then handed to the Mars Science Laboratory (MSL) heritage powered descent GNC system to execute the landing. This paper describes the design and the as-flown performance of the STS algorithm.

Dutta, Soumyo↗
NASA NTRS2006

ChemCam Automated Target Selection Status

Usage Scenarios: I) Identify candidate targets: a) Locate rocks; b) Select points on rocks. II) Identify and prioritize candidate targets: a) Locate rocks; b) Select points on rocks; c) Extract rock properties; and d) Prioritize points based on rock properties.

rock finding↗
NASA NTRS1984

CDTI target selection criteria

A Cockpit Display of Traffic Information (CDTI) is a cockpit instrument which provides information to the aircrew on the relative location of aircraft traffic in the vicinity of their aircraft (township). In addition, the CDTI may provide information to assist in navigation and in aircraft control. It is usually anticipated that the CDTI will be integrated with a horizontal situation indicator used for navigational purposes and/or with a weather radar display. In this study, several sets of aircraft traffic data are analyzed to determine statistics on the number of targets that will be displayed on a CDTI using various target selection criteria. Traffic data were obtained from an Atlanta Terminal Area Simulation and from radar tapes recorded at the Atlanta and Miami terminal areas. Results are given in the form of plots showing the average percentage of time (or probability) that an aircraft equipped with a CDTI would observe from 0 to 10 other aircraft on the display for range settings on the CDTI up to 30 n. mi. and using various target discrimination techniques.

Britt, C. L.↗
NASA NTRS1975

A two-level trajectory decomposition algorithm featuring optimal intermediate target selection

A decomposition algorithm is presented that optimizes complex missions by partitioning the trajectory into natural segments such as ascent or entry. Each segment defines a full-rank targeting subproblem. These are solved sequentially using the Newton-Raphson algorithm. The master problem, representing the complete mission, is to determine subproblem targets and master-problem controls that optimize the mission objective subject to intersegment constraints. The gradient projection algorithm solves this problem using derivatives obtained analytically from finite-difference subproblem sensitivities. Thus, the mission is optimized by coordinating the solution of tractible subproblems. Computational results for a synchronous equatorial mission are included.

Petersen, F. M.↗
NASA NTRS1977

A two-level trajectory decomposition algorithm featuring optimal intermediate target selection

A decomposition algorithm is presented which optimizes complex missions by partitioning the trajectory into natural segments such as ascent or entry. Each segment defines a full-rank targeting subproblem. These are solved sequentially using the Newton-Raphson algorithm. The master problem, representing the complete mission, is to determine subproblem targets and master-problem controls that optimize the mission objective subject to intersegment constraints. The gradient projection algorithm solves this problem using derivatives obtained analytically from finite-difference subproblem sensitivities. Thus, the mission is optimized by coordinating the solution of tractible subproblems. Computational results for a synchronous equatorial mission are included.

Petersen, F. M.↗
NASA NTRS2013

Effects of Type and Strength of Force Feedback on Movement Time in a Target Selection Task

Future cockpits will likely include new onboard technologies, such as cockpit displays of traffic information, to help support future flight deck roles and responsibilities. These new technologies may benefit from multimodal feedback to aid pilot information processing. The current study investigated the effects of multiple levels of force feedback on operator performance in an aviation task. Participants were presented with two different types of force feedback (gravitational and spring force feedback) for a discrete targeting task, with multiple levels of gain examined for each force feedback type. Approach time and time in target were recorded. Results suggested that the two highest levels of gravitational force significantly reduced approach times relative to the lowest level of gravitational force. Spring force level only affected time in target. Implications of these findings for the design of future cockpit displays will be discussed.

CDTI↗
NASA NTRS1971

Infrared spectrometry studies. Phase 4: Emittance spectra of selected targets from mission 108 airborne data

Infrared radiance measurements from geological materials were studied. These involved laboratory and field spectroscopic measurements, both on the ground and airborne. A proven, feasible system is presented for airborne use over terrains with minimal vegetation. It has been shown that the spectral emittance concepts can be utilized in emittance ratio imagery which depicts the silicate composition of the terrain.

Lyon, R. J. P.↗
NASA NTRS2006

Ground-Based Localization of Mars Rovers

The document discusses a procedure for localizing the Mars rovers in site frame, a locally defined reference frame on the Martian surface. MER onboard position within a site frame is estimated onboard and is based on wheel odometry. Odometry estimation of rover position is only reliable over relatively short distances assuming no wheel slip, sinkage, etc. As the rover traverses, its onboard estimate of position in the current site frame accumulates errors and will need to be corrected on occasions via relocalization on the ground (mission operations). The procedure provides a systematic process for ground operators to localize the rover. The method focuses on analysis of acquired images used to declare a site frame and images acquired post-drive. Target selection is performed using two main steps. In the first step, the user identifies features of interest from the images used to declare the current site. Each of the selected target s position in site frame is recorded. In the second step, post-traverse measurements of the selected features positions are recorded again, this time in rover frame, using images acquired post-traverse. In the third step, we transform the post-traverse target s positions to local level frame. In the fourth step, we compute the delta differences in the pre- and post-traverse target s position. In the fifth step, we analyze the delta differences with techniques that compute their statistics to determine the rover s position in the site frame.

Trebi-Ollennu, Ashitey↗
NASA NTRS2020

Results From the First Four Years of Aegis Autonomous Target-ing for Chemcam on Mars Science Laboratory and New Capability Planned for Supercam on Mars 2020 Rover

Autonomous Exploration for Gathering Increased Science (AEGIS) was uploaded on the NASA Mars Science Laboratory (MSL) Curiosity rover in 2015 for autonomous target selection. This paper presents results from the first four years of its regular opera-tion on Mars for autonomously selecting targets for the ChemCam remote geochemical spectrometer with a focus on the most recent findings. Results show that AEGIS has targeted the most desired material greater than 93% of the time vs 24% without onboard intelligent targeting. There has also been a notable increase in the rate of ChemCam observations. AE-GIS is also part of surface flight software for the NASA Mars 2020 Perseverance rover. This paper describes new AEGIS capabilities that will be availa-ble for autonomously targeting the SuperCam in-strument after the planned 18 February 2021 landing in Jezero crater on Mars.

Castano, R↗
NASA NTRS2008

Controlling the Growth of Future LEO Debris Populations with Active Debris Removal

Active debris removal (ADR) was suggested as a potential means to remediate the low Earth orbit (LEO) debris environment as early as the 1980s. The reasons ADR has not become practical are due to its technical difficulties and the high cost associated with the approach. However, as the LEO debris populations continue to increase, ADR may be the only option to preserve the near-Earth environment for future generations. An initial study was completed in 2007 to demonstrate that a simple ADR target selection criterion could be developed to reduce the future debris population growth. The present paper summarizes a comprehensive study based on more realistic simulation scenarios, including fragments generated from the 2007 Fengyun-1C event, mitigation measures, and other target selection options. The simulations were based on the NASA long-term orbital debris projection model, LEGEND. A scenario, where at the end of mission lifetimes, spacecraft and upper stages were moved to 25-year decay orbits, was adopted as the baseline environment for comparison. Different annual removal rates and different ADR target selection criteria were tested, and the resulting 200-year future environment projections were compared with the baseline scenario. Results of this parametric study indicate that (1) an effective removal strategy can be developed based on the mass and collision probability of each object as the selection criterion, and (2) the LEO environment can be stabilized in the next 200 years with an ADR removal rate of five objects per year.

Liou, J.-C.↗
NASA NTRS2012

Target Search & Selection for the DI/EPOXI Spacecraft

Upon completion of the Hartley 2 flyby in November 2010, the Deep Impact (DI) spacecraft resided in a solar orbit without possibility for gravity assist with any large body. Conservative estimates of remaining fuel were enough to provide only an 18 m/s impulse on the spacecraft. We present our method and results of our systematic scan of potential small body encounters for DI, and our criteria to narrow the selection to the asteroid 2002 GT as the target flyby body. The mission profile has two deterministic maneuvers to achieve the encounter, the first of which executed on November 25, 2011.

Grebow, Daniel J.↗
NASA NTRS1994

Transient analysis mode participation for modal survey target mode selection using MSC/NASTRAN DMAP

Many methods have been developed to aid analysts in identifying component modes which contribute significantly to component responses. These modes, typically targeted for dynamic model correlation via a modal survey, are known as target modes. Most methods used to identify target modes are based on component global dynamic behavior. It is sometimes unclear if these methods identify all modes contributing to responses important to the analyst. These responses are usually those in areas of hardware design concerns. One method used to check the completeness of target mode sets and identify modes contributing significantly to important component responses is mode participation. With this method, the participation of component modes in dynamic responses is quantified. Those modes which have high participation are likely modal survey target modes. Mode participation is most beneficial when it is used with responses from analyses simulating actual flight events. For spacecraft, these responses are generated via a structural dynamic coupled loads analysis. Using MSC/NASTRAN DMAP, a method has been developed for calculating mode participation based on transient coupled loads analysis results. The algorithm has been implemented to be compatible with an existing coupled loads methodology and has been used successfully to develop a set of modal survey target modes.

Barnett, Alan R.↗
NASA NTRS2018

Overview of SAND-E: Semi-Autonomous Navigation for Detrital Environments

Rovers are the state of the art for the exploration and detection of past habitability and life on other worlds. One of the most basic functions of a rover is terrain navigation. Information collected by the rover is used autonomously to mitigate terrain hazards such large rocks, while humans qualitatively assess hazardous geologic terrain such as soil type and degree of rock cover. Planetary scientists use the same information to select targets such as drill sites, and for basic scientific analysis such as characterization of rock outcrops. Although the data is complementary, data from terrain analysis for navigation and terrain analysis for scientific investigations are poorly integrated. The lack of integration creates science and operation inefficiencies that limit exploration of habitable environments. As new modes of exploration come online, such as unmanned aerial systems (UAS) (e.g., the Mars Helicopter Scout and Titan Dragonfly), a need exists to integrate terrain data and science analysis to improve operational and scientific outcomes during exploration. We present an overview of a project aimed at evaluating the effectiveness and capability rover and UAS-based semi-automated terrain analysis using the Automated Soil Assessment Systems (ASAS) developed by Mission Control Space Services for navigating, selecting targets for sampling, and characterizing mafic detrital sediments along glacio-fluvial-aeolian sand transport pathways in Iceland. We describe recent advances in automated terrain analysis in sandy environments and scientific uses of terrain assessment from sandy environments. We assess fluvial and aeolian terrains in Iceland and show how terrain analysis data can inform scientific characterization of these environments.

Ewing, Ryan C.↗