Orbit-localised thermosphere density prediction using a Kalman filter based calibration of empirical models

Accurate estimation of thermosphere mass density is critical to determining how satellite orbits evolve over time and thus to planning and managing space missions. Empirical thermosphere models are commonly employed for this purpose, but have substantial uncertainties. In this work, a Kalman filter method for calibrating these models along a particular satellite's trajectory is described. This method was applied to calibrate the NRLMSISE-00, JB2008, and DTM-2020 models with respect to densities measured by the Swarm-C and GOCE satellites. Substantial improvements in root mean squared density residuals were obtained using the technique when compared with either uncalibrated model output or calibration using a linear regression on previous data. Further improvement was obtained by combining estimates from different models using a best linear unbiased estimator method

Surface mineral crusts: A priority target in search for life on Mars

Mineral crusts are strong candidates in the search for evidence of life during planetary exploration, and should be an important target for examination in impact craters. Crusts in the Haughton crater readily yield a biological signature

Quantum Communication Through an Unmodulated Spin Chain

We propose a scheme for using an unmodulated and unmeasured spin-chain as a channel for short distance quantum communications. The state to be transmitted is placed on one spin of the chain and received later on a distant spin with some fidelity. We first obtain simple expressions for the fidelity of quantum state transfer and the amount of entanglement sharable between any two sites of an arbitrary Heisenberg ferromagnet using our scheme. We then apply this to the realizable case of an open ended chain with nearest neighbor interactions. The fidelity of quantum state transfer is obtained as an inverse discrete cosine transform and as a Bessel function series. We find that in a reasonable time, a qubit can be directly transmitted with better than classical fidelity across the full length of chains of up to 80 spins. Moreover, the spin-chain channel allows distillable entanglement to be shared over arbitrarily large distances.Comment: Much improved versio

Numerical Modelling and GNSS Observations of Ionospheric Depletions due to a Small-Lift Launch Vehicle

Space launches produce ionospheric disturbances which can be observed through measurements such as Global Navigation Satellite System signal delays. Here we report observations and numerical simulations of the ionospheric depletion due to a Small-Lift Launch Vehicle. The case examined was the launch of a Rocket Lab Electron at 22:30 UTC on March 22, 2021. Despite the very small launch vehicle, ground stations in the Chatham Islands measured decreases in line-of-sight total electron content for navigation satellite signals following the launch. General Circulation Model results indicated ionospheric depletions which were comparable with these measurements. Line-of-sight measurements showed a maximum decrease of $2.7$~TECU in vertical total electron content, compared with a simulated decrease of $2.6$~TECU. Advection of the exhaust plume due to its initial velocity and subsequent effects of neutral winds are identified as some remaining challenges for this form of modelling.Comment: 12 pages, 8 figure

Measuring Organizational Effectiveness: The Role Of The Organizational Community Index

The purpose of this research is to help understand the value of presuppositions through the development of a community index for organizations, that employees bring certain community appeals to organizational life.  Those appeals are entrenched in ancestral paradigms of the past as a natural part of the human psyche (Nicholson, 1997).  This research attempts to understand the appeals with the development of the Organizational Community Index (OCI) with three subscales: Measure of Influence; Sense of Belonging; and Feeling of Recognition.  The subscales were developed based on previous research from the influence of anthropology, sociology, and psychology on organizational studies.  One hundred and forty-six business professionals were surveyed as an initial sample.  Results of reliability coefficients, skewness, and kurtosis indicated that the subscales are reliable and serve psychometric purposes.  The OCI should be further tested with larger samples sizes and in a variety of organizations.  Initial conclusions suggest that organizations might want to assess their sense of community among employees before they proceed with planned change involving organizational effectiveness