Search NASA⌕ Search

SEARCH · Search NASA

Results for “Kepler”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS2016

Combining Photometry from Kepler and TESS to Improve Short-Period Exoplanet Characterization

Planets emit thermal radiation and reflect incident light that they receive from their host stars. As a planet orbits its host star the photometric variations associated with these two effects produce very similar phase curves. If observed through only a single bandpass, this leads to a degeneracy between certain planetary parameters that hinder the precise characterization of such planets. However, observing the same planet through two different bandpasses gives much more information about the planet. Here we develop a Bayesian methodology for combining photometry from both Kepler and the Transiting Exoplanet Survey Satellite. In addition, we demonstrate via simulations that one can disentangle the reflected and thermally emitted light from the atmosphere of a hot-Jupiter as well as more precisely constrain both the geometric albedo and day-side temperature of the planet. This methodology can further be employed using various combinations of photometry from the James Webb Space Telescope, the Characterizing ExOplanet Satellite, or the PLATO mission.

photometric variations↗
NASA NTRS2016

On the Performance of Adaptive Data Rate over Deep Space Ka-Bank Link: Case Study Using Kepler Data

Future missions envisioned for both human and robotic exploration demand increasing communication capacity through the use of Ka-band communications. The Ka-band channel, being more sensitive to weather impairments, presents a unique trade-offs between data storage, latency, data volume and reliability. While there are many possible techniques for optimizing Ka-band operations such as adaptive modulation and coding and site-diversity, this study focus exclusively on the use of adaptive data rate (ADR) to achieve significant improvement in the data volume-availability tradeoff over a wide range of link distances for near Earth and Mars exploration. Four years of Kepler Ka-band downlink symbol signal-to-noise (SNR) data reported by the Deep Space Network were utilized to characterize the Ka-band channel statistics at each site and conduct various what-if performance analysis for different link distances. We model a notional closed-loop adaptive data rate system in which an algorithm predicts the channel condition two-way light time (TWLT) into the future using symbol SNR reported in near-real time by the ground receiver and determines the best data rate to use. Fixed and adaptive margins were used to mitigate errors in channel prediction. The performance of this closed-loop adaptive data rate approach is quantified in terms of data volume and availability and compared to the actual mission configuration and a hypothetical, optimized single rate configuration assuming full a priori channel knowledge.

Gao, Jay L.↗
NASA NTRS2017

K2: Extending Kepler's Power to the Ecliptic-Ecliptic Plane Input Catalog

This document describes the Ecliptic Plane Input Catalog (EPIC) for the K2 mission (Howell et al. 2014). The primary purpose of this catalog is to provide positions and Kepler magnitudes for target management and aperture photometry. The Ecliptic Plane Input Catalog is hosted at MAST (http://archive.stsci.edu/k2/epic/search.php) and should be used for selecting targets when ever possible. The EPIC is updated for future K2 campaigns as their fields of view are finalized and the associated target management is completed. Table 0 summarizes the EPIC updates to date and the ID range for each. The main algorithms used to construct the EPIC are described in Sections 2 through 4. The details for individual campaigns are described in the subsequent sections, with the references listed in the last section. Further details can be found in Huber et al. (2016).

Huber, Daniel↗
NASA NTRS2015

Optimization of Selected Remote Sensing Algorithms for Embedded NVIDIA Kepler GPU Architecture

This paper evaluates the potential of embedded Graphic Processing Units (GPUs) in Nvidia's Tegra K1 (based on Kepler (TM) hardware) for onboard processing. The performance is compared to a general purpose multi-core CPU (Central Processing Unit) and a fully-fledged GPU accelerator. This study uses two algorithms: Wavelet Spectral Dimension Reduction of Hyperspectral Imagery and Automated Cloud-Cover Assessment (ACCA) Algorithm. Tegra K1 achieved 51 for the ACCA algorithm and 20 for the dimension reduction algorithm, as compared to the performance of the high-end 8-core server Intel Xeon CPU with 13.5 times higher power consumption.

data reduction↗
NASA NTRS2010

An Algorithm for the Fitting of Planet Models to Kepler Light Curves

We describe an algorithm which fits model planetary system parameters to light curves from Kepler Mission target stars. The algorithm begins by producing an initial model of the system which is used to seed the fit,with particular emphasis on obtaining good transit timing parameters. An attempt is then made to determine whether the observed transits are more likely due to a planet or an eclipsing binary. In the event that the transits are consistent with a transiting planet, an iterative fitting process is initiated: a wavelet-based whitening filter is used to eliminate stellar variations on timescales long compared to a transit; a robust nonlinear fitter operating on the whitened light curve produces a new model of the system; and the procedure iterates until convergence upon a self-consistent whitening filter and planet model. The fitted transits are removed from the light curve anda search for additional planet candidates is performed upon the residual light curve. The fitted models are used in additional tests which identify false positive planet detections: multiple planet candidates with near-identical fitted periods are far more likely to be an eclipsing binary, for example, while target stars in which the model lightcurve is correlated with the star centroid position may indicate a background eclipsing binary, and subtraction of all model planet candidates yields a light curve of pure noise and stellar variability, which can be used to study the probability that the planet candidates result from statistical fluctuations in the data.

Exoplanet↗
NASA NTRS2018

Understanding the Kepler Reaction Wheels & Satellite

Following the loss of two reaction wheels four years into its mission, the Kepler team was faced with reinventing an operational approach to continue to deliver compelling science using an unanticipated suite of actuators. Spacecraft thrusters were not designed for accurate pointing control, yet with only two reaction wheels, only two axes could be actively controlled. With solar pressure as the only disturbing force, and recognizing the innate symmetry of the spacecraft, the K2 mission points the spacecraft in the orbital plane for three months at a time, placing the antennas 90° from the earth. Mapping the solar balance ridge 70 M km from Earth, with limited communications and a reduced staff presented a significant operational challenge.

Engineering↗
NASA NTRS2014

On the Frequency of Potential Venus Analogs from Kepler Data

The field of exoplanetary science has seen a dramatic improvement in sensitivity to terrestrial planets over recent years. Such discoveries have been a key feature of results from the Kepler mission which utilizes the transit method to determine the size of the planet. These discoveries have resulted in a corresponding interest in the topic of the Habitable Zone and the search for potential Earth analogs. Within the solar system, there is a clear dichotomy between Venus and Earth in terms of atmospheric evolution, likely the result of the large difference (approximately a factor of two) in incident flux from the Sun. Since Venus is 95% of the Earth's radius in size, it is impossible to distinguish between these two planets based only on size. In this Letter we discuss planetary insolation in the context of atmospheric erosion and runaway greenhouse limits for planets similar to Venus. We define a "Venus Zone" in which the planet is more likely to be a Venus analog rather than an Earth analog. We identify 43 potential Venus analogs with an occurrence rate (η♀) of 0.32 (+0.05/-0.07) and 0.45 (+0.06/-0.09) for M dwarfs and GK dwarfs, respectively.

planetary systems↗
NASA NTRS2015

Neptune’s Dynamic Atmosphere from Kepler K2 Observations: Implications for Brown Dwarf Light Curve Analyses

Observations of Neptune with the Kepler Space Telescope yield a 49-day light curve with 98% coverage at a 1-minute cadence. A significant signature in the light curve comes from discrete cloud features. We compare results extracted from the light curve data with contemporaneous disk-resolved imaging of Neptune from the Keck 10-meter and Hubble Space Telescope. The direct comparison validates the zonal wind profile and cloud feature variability information extracted from the light curve. Neptune’s clouds vary in location and intensity on short and long time scales, with large discrete storms dominating the light curves; smaller or fainter clouds contribute to its variability. This has implications for the interpretation of information extracted from light curves of directly imaged exoplanets and cloudy brown dwarfs.

Simon, Amy A.↗
NASA NTRS2020

A Nucleosynthetic Origin for the Southwestern Fe-rich Structure in Kepler's Supernova Remnant

Chandra X-ray observations of Kepler's supernova remnant indicate the existence of a high-speed Fe-rich ejecta structure in the southwestern region. We report strong K-shell emission from Fe-peak elements (Cr, Mn, Fe, Ni), as well as Ca, in this Fe-rich structure, implying that those elements could be produced in the inner area of the exploding white dwarf. We found Ca/Fe, Cr/Fe, Mn/Fe, and Ni/Fe mass ratios of 1.0%–4.1%, 1.0%–4.6%, 1%–11%, and 2%–30%, respectively. In order to constrain the burning regime that could produce this structure, we compared these observed mass ratios with those in 18 one-dimensional Type Ia nucleosynthesis models (including both near-M Ch and sub-M Ch explosion models). The observed mass ratios agree well with those around the middle layer of incomplete Si burning in Type Ia nucleosynthesis models with a peak temperature of ~(5.0–5.3) × 10(exp 9) K and a high metallicity, Z > 0.0225. Based on our results, we infer the necessity for some mechanism to produce protruding Fe-rich clumps dominated by incomplete Si-burning products during the explosion. We also discuss the future perspectives of X-ray observations of Fe-rich structures in other Type Ia supernova remnants.

Toshiki Sato↗
NASA NTRS2016

Kepler Planet Detection Metrics: Statistical Bootstrap Test

This document describes the data produced by the Statistical Bootstrap Test over the final three Threshold Crossing Event (TCE) deliveries to NExScI: SOC 9.1 (Q1Q16)1 (Tenenbaum et al. 2014), SOC 9.2 (Q1Q17) aka DR242 (Seader et al. 2015), and SOC 9.3 (Q1Q17) aka DR253 (Twicken et al. 2016). The last few years have seen significant improvements in the SOC science data processing pipeline, leading to higher quality light curves and more sensitive transit searches. The statistical bootstrap analysis results presented here and the numerical results archived at NASAs Exoplanet Science Institute (NExScI) bear witness to these software improvements. This document attempts to introduce and describe the main features and differences between these three data sets as a consequence of the software changes.

Bootstrap↗