Modeling, designing and simulating a pointing control system for balloon-borne solar experiments

A simplified model of a pointing control system for balloon-borne solar experiments is chosen. Equations of motion for this model are derived and a feedback control law is defined. A digital computer simulation of the system is developed. Simulation results show favorable system response characteristics

A nonlinear estimator for reconstructing the angular velocity of a spacecraft without rate gyros

A scheme for estimating the angular velocity of a spacecraft without rate gyros is presented. It is based upon a nonlinear estimator whose inputs are measured inertial vectors and their calculated time derivatives relative to vehicle axes. It works for all spacecraft attitudes and requires no knowledge of attitude. It can use measurements from a variety of onboard sensors like Sun sensors, star trackers, or magnetometers, and in concert. It can also use look angle measurements from onboard tracking antennas for tracking and data relay satellites or global positioning system satellites. In this paper, it is applied to a Sun point scheme on the Hubble Space Telescope assuming all or most of its onboard rate gyros have failed. Simulation results are presented for verification

Definition and design of an experiment to test raster scanning with rotating unbalanced-mass devices on gimbaled payloads

An experiment designed to test the feasibility of using rotating unbalanced-mass (RUM) devices for line and raster scanning gimbaled payloads, while expending very little power is described. The experiment is configured for ground-based testing, but the scan concept is applicable to ground-based, balloon-borne, and space-based payloads, as well as free-flying spacecraft. The servos used in scanning are defined; the electronic hardware is specified; and a computer simulation model of the system is described. Simulation results are presented that predict system performance and verify the servo designs

When two become one: Marital couples\u27 public performances and couple identity

Communication researchers know little about marital couples\u27 public performances, or how marital couples communicate as a nonsummative whole when in the presence of important others (e.g., friends, family, co-workers). Two studies were conducted to examine marital couples\u27 public performances from a Communication Theory of Identity (CTI) (Hecht, 1993) framework. In the first study, 153 marital couples completed self-report measures to assess how marital couples\u27 attachment styles and relationship awareness are related to identity gaps during public performances as well as how identity gaps relate to a variety of outcomes including communication satisfaction, feelings of being understood, conversational appropriateness, relationship satisfaction, and commitment. In the second study, 46 marital couples\u27 public performances were examined for varying degrees of communal, individual, and impersonal content themes, continual and hierarchical communication, communication integration, and nonverbal immediacy. This study also assessed how attachment styles, public and private self-consciousness, and couple identity are associated with marital couples\u27 communication behaviors during their public performances. After interactions, marital couples completed identity gap, communication satisfaction, feeling of being understood, and conversational appropriateness measures while reflecting on their public performance. Together, these two studies introduced the study of marital couples\u27 public performances while testing their salience to marital couples as guided by CTI. Results indicated married couples are less likely to experience identity gaps when they are similar in their attachment styles, when they are both secure in their attachment styles, when couples have a greater degree of relationship awareness, and when they communicate according to communal and impersonal themes during public performances. Identity gaps are damaging to couples\u27 feelings of communication satisfaction, being understood, and conversational appropriateness. When identity gaps are a more common experience, married couples\u27 ratings of relational satisfaction and commitment were negatively affected

JWST Lessons Learned

While there is a lot of focus on how a few key parameters like aperture size and pixel count drive costs of large space telescopes, the JWST experience suggests that a lot more insight is needed to understand and control costs

Breaking the Cost Curve: Applying Lessons Learned from the James Webb Space Telescope Development

This paper looks at the key programmatic and technical drivers of the James Webb Space Telescope and assesses ways to building more cost-effective telescopes in the future. The paper evaluates the top level programmatics for JWST along with the key technical drivers from design through integration and testing. Actual data and metrics from JWST are studied to identify what ultimately drove cost on JWST. Finally, the paper assesses areas where applying lessons learned can reduce costs on future observatories and will provide better insights into critical areas to optimize for cost

Optical Budgeting for LUVOIR

Future large astronomical telescopes in space will have architectures that will have complex and demanding requirements to meet the science goals. The Large UV/Optical/IR Surveyor (LUVOIR) mission concept being assessed by the NASA/Goddard Space Flight Center is expected to be 8 to 16 meters in diameter, have a segmented primary mirror, active control, and be diffraction limited at a wavelength of 500 nanometers. The optical stability is expected to be in the picometer range for minutes to hours. Architecture studies to support the NASA Science and Technology Definition teams (STDTs) are underway to evaluate systems performance. A wave front error budget has been developed to help define the technology needs and assess performance. The budget includes both spatial and temporal domain aspects for the active, adaptive and passive elements in the optical design

Nurses Attitudes Towards the Use of Restraints in the Critical Care Setting

The use of restraints is especially prevalent in critical care units in order to decrease patients’ interference with their medical care. Although there are quality improvement studies to reduce the frequency of restraints, nurses are reluctant to implement this into their practice when considering restrint safety. Our research question states, in critical care patients, how does the nurse’s attitude and experience affect the use of restraints? There is limited education provided to nurses regarding the determinants of restraints in the acute care setting. We conducted a systematic review of literature to investigate how the attitudes of nurses affect patient outcomes in relation to restraints. We developed a practice protocol to explore the differences in the mindset of nurses and how these attitudes affected the decisions of nurses within a critical care unit

A Fractionated Space Weather Base at L_5 using CubeSats and Solar Sails

The Sun–Earth L_5 Lagrange point is an ideal location for an operational space weather forecasting mission to provide early warning of Earth-directed solar storms (coronal mass ejections, shocks and associated solar energetic particles). Such storms can cause damage to power grids, spacecraft, communications systems and astronauts, but these effects can be mitigated if early warning is received. Space weather missions at L5 have been proposed using conventional spacecraft and chemical propulsion at costs of hundreds of millions of dollars. Here we describe a mission concept that could accomplish many of the goals at a much lower cost by dividing the payload among a cluster of interplanetary CubeSats that reach orbits around L5 using solar sails

Origins Space Telescope: Baseline mission concept

The Origins Space Telescope will trace the history of our origins from the time dust and heavy elements permanently altered the cosmic landscape to present-day life. How did galaxies evolve from the earliest galactic systems to those found in the Universe today? How do habitable planets form? How common are life-bearing worlds? To answer these alluring questions, Origins will operate at mid-and far-infrared (IR) wavelengths and offer powerful spectroscopic instruments and sensitivity three orders of magnitude better than that of the Herschel Space Observatory, the largest telescope flown in space to date. We describe the baseline concept for Origins recommended to the 2020 US Decadal Survey in Astronomy and Astrophysics. The baseline design includes a 5.9-m diameter telescope cryocooled to 4.5 K and equipped with three scientific instruments. A mid-infrared instrument (Mid-Infrared Spectrometer and Camera Transit spectrometer) will measure the spectra of transiting exoplanets in the 2.8 to 20 μm wavelength range and offer unprecedented spectrophotometric precision, enabling definitive exoplanet biosignature detections. The far-IR imager polarimeter will be able to survey thousands of square degrees with broadband imaging at 50 and 250 μm. The Origins Survey Spectrometer will cover wavelengths from 25 to 588 μm, making wide-area and deep spectroscopic surveys with spectral resolving power R ∼ 300, and pointed observations at R ∼ 40,000 and 300,000 with selectable instrument modes. Origins was designed to minimize complexity. The architecture is similar to that of the Spitzer Space Telescope and requires very few deployments after launch, while the cryothermal system design leverages James Webb Space Telescope technology and experience. A combination of current-state-of-the-art cryocoolers and next-generation detector technology will enable Origins\u27 natural background-limited sensitivity