Sensor Data Qualification System (SDQS) Implementation Study

The Sensor Data Qualification System (SDQS) is being developed to provide a sensor fault detection capability for NASA s next-generation launch vehicles. In addition to traditional data qualification techniques (such as limit checks, rate-of-change checks and hardware redundancy checks), SDQS can provide augmented capability through additional techniques that exploit analytical redundancy relationships to enable faster and more sensitive sensor fault detection. This paper documents the results of a study that was conducted to determine the best approach for implementing a SDQS network configuration that spans multiple subsystems, similar to those that may be implemented on future vehicles. The best approach is defined as one that most minimizes computational resource requirements without impacting the detection of sensor failures

Discrete Data Qualification System and Method Comprising Noise Series Fault Detection

A Sensor Data Qualification (SDQ) function has been developed that allows the onboard flight computers on NASA s launch vehicles to determine the validity of sensor data to ensure that critical safety and operational decisions are not based on faulty sensor data. This SDQ function includes a novel noise series fault detection algorithm for qualification of the output data from LO2 and LH2 low-level liquid sensors. These sensors are positioned in a launch vehicle s propellant tanks in order to detect propellant depletion during a rocket engine s boost operating phase. This detection capability can prevent the catastrophic situation where the engine operates without propellant. The output from each LO2 and LH2 low-level liquid sensor is a discrete valued signal that is expected to be in either of two states, depending on whether the sensor is immersed (wet) or exposed (dry). Conventional methods for sensor data qualification, such as threshold limit checking, are not effective for this type of signal due to its discrete binary-state nature. To address this data qualification challenge, a noise computation and evaluation method, also known as a noise fault detector, was developed to detect unreasonable statistical characteristics in the discrete data stream. The method operates on a time series of discrete data observations over a moving window of data points and performs a continuous examination of the resulting observation stream to identify the presence of anomalous characteristics. If the method determines the existence of anomalous results, the data from the sensor is disqualified for use by other monitoring or control functions

Constraints on the Atmospheric Circulation and Variability of the Eccentric Hot Jupiter XO-3b

We report secondary eclipse photometry of the hot Jupiter XO-3b in the 4.5~$\mu$m band taken with the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. We measure individual eclipse depths and center of eclipse times for a total of twelve secondary eclipses. We fit these data simultaneously with two transits observed in the same band in order to obtain a global best-fit secondary eclipse depth of $0.1580\pm 0.0036\%$ and a center of eclipse phase of $0.67004\pm 0.00013$. We assess the relative magnitude of variations in the dayside brightness of the planet by measuring the size of the residuals during ingress and egress from fitting the combined eclipse light curve with a uniform disk model and place an upper limit of 0.05$\%$. The new secondary eclipse observations extend the total baseline from one and a half years to nearly three years, allowing us to place an upper limit on the periastron precession rate of $2.9\times 10^{-3}$ degrees/day the tightest constraint to date on the periastron precession rate of a hot Jupiter. We use the new transit observations to calculate improved estimates for the system properties, including an updated orbital ephemeris. We also use the large number of secondary eclipses to obtain the most stringent limits to date on the orbit-to-orbit variability of an eccentric hot Jupiter and demonstrate the consistency of multiple-epoch Spitzer observations.Comment: 14 pages, 11 figures, published by Ap

Expression of three forms of melanoma growth stimulating activity (MGSA)/gro in human retinal pigment epithelial cells

PURPOSE: To characterize mRNA expression and protein production of the cytokine MGSA/gro in human retinal pigment epithelial (RPE) cells and to determine whether expression of MGSA/gro is modulated by serum and the cytokines interleukin 1 beta (IL-1 beta), tumor necrosis factor alpha (TNF alpha), or transforming growth factor beta (TGF beta) mediators implicated in proliferative vitreoretinopathy (PVR). METHODS: Reverse-transcription polymerase chain reaction was used to determine the steady-state mRNA expression of three forms of MGSA/gro, alpha, beta, and gamma, by cultured human RPE cells in the presence or absence of recombinant IL-1 beta, TNF alpha, or TGF beta, or when serum-starved cells were re-fed with medium containing serum. Immunocytochemistry was used to characterize RPE cell-associated MGSA/gro protein, and immunoprecipitation of MGSA/gro from cell-conditioned medium was used to demonstrate MGSA/gro secretion. RESULTS: MGSA/gro mRNA was expressed minimally under basal conditions. Expression for all three forms of MGSA/gro mRNA was induced in a dose- and time-dependent manner after exposure to IL-1 beta, to a lesser extent after exposure to TNF alpha, but not after exposure to TGF beta. Serum induced MGSA/gro alpha and gamma transcripts, but not beta transcripts. Cell-associated MGSA/gro was identified on RPE cells grown in the absence of cytokines, but MGSA/gro was not secreted under these conditions. Exposure to IL-1 beta did not consistently cause increased cell-associated MGSA/gro; however, IL-1 beta induced secretion of MGSA/gro in a time-dependent manner. CONCLUSION: MGSA/gro is produced by human RPE in response to mediators implicated in PVR. Because MGSA/gro is a pleiotropic modulator of cell proliferation and inflammation, it may contribute to the intraocular wound healing response that characterizes PVR

3.6 and 4.5 μ\mum Spitzer{\it Spitzer} Phase Curves of the Highly-Irradiated Hot Jupiters WASP-19b and HAT-P-7b

We analyze full-orbit phase curve observations of the transiting hot Jupiters WASP-19b and HAT-P-7b at 3.6 and 4.5 $\mu$m obtained using the Spitzer Space Telescope. For WASP-19b, we measure secondary eclipse depths of $0.485\%\pm 0.024\%$ and $0.584\%\pm 0.029\%$ at 3.6 and 4.5 $\mu$m, which are consistent with a single blackbody with effective temperature $2372 \pm 60$ K. The measured 3.6 and 4.5 $\mu$m secondary eclipse depths for HAT-P-7b are $0.156\%\pm 0.009\%$ and $0.190\%\pm 0.006\%$, which are well-described by a single blackbody with effective temperature $2667\pm 57$ K. Comparing the phase curves to the predictions of one-dimensional and three-dimensional atmospheric models, we find that WASP-19b's dayside emission is consistent with a model atmosphere with no dayside thermal inversion and moderately efficient day-night circulation. We also detect an eastward-shifted hotspot, suggesting the presence of a superrotating equatorial jet. In contrast, HAT-P-7b's dayside emission suggests a dayside thermal inversion and relatively inefficient day-night circulation; no hotspot shift is detected. For both planets, these same models do not agree with the measured nightside emission. The discrepancies in the model-data comparisons for WASP-19b might be explained by high-altitude silicate clouds on the nightside and/or high atmospheric metallicity, while the very low 3.6 $\mu$m nightside planetary brightness for HAT-P-7b may be indicative of an enhanced global C/O ratio. We compute Bond albedos of 0 ($<0.08$ at $1\sigma$) and $0.38\pm 0.06$ for WASP-19b and HAT-P-7b, respectively. In the context of other planets with thermal phase curve measurements, we show that WASP-19b and HAT-P-7b fit the general trend of decreasing day-night heat recirculation with increasing irradiation.Comment: 22 pages, 29 figures, accepted by Ap

The Full Kepler Phase Curve of the Eclipsing Hot White Dwarf Binary System KOI-964

We analyze the full Kepler phase curve of KOI-964, a binary system consisting of a hot white dwarf on an eclipsing orbit around an A-type host star. Using all 18 quarters of long-cadence photometry, we carry out a joint light-curve fit and obtain improved phase-curve amplitudes, occultation depths, orbital parameters, and transit ephemeris over the previous results of Carter et al. A periodogram of the residuals from the phase-curve fit reveals an additional stellar variability signal from the host star with a characteristic period of 0.620276 ± 0.000011 days and a full amplitude of 24 ± 2 ppm. We also present new Keck/HIRES radial velocity observations, which we use to measure the orbit and obtain a mass ratio of q = 0.106 ± 0.012. Combining this measurement with the results of a stellar isochrone analysis, we find that the masses of the host star and white dwarf companion are 2.23 ± 0.12 M⊙ and 0.236^(+0.028)_(−0.027) M⊙, respectively. The effective temperatures of the two components are 9940^(+260)_(−230) K and 15,080 ± 400 K, respectively, and we determine the age of the system to be 0.21^(+0.11)_(−0.08) Gyr. We use the measured system properties to compute predicted phase-curve amplitudes and find that while the measured Doppler-boosting and mutual illumination components agree well with theory, the ellipsoidal distortion amplitude is significantly underestimated. We detail possible explanations for this discrepancy, including interactions between the dynamical tide of the host star and the tidal bulge and possible nonsynchronous rotation of the host star