EDSN Development Lessons Learned

The Edison Demonstration of Smallsat Networks (EDSN) is a technology demonstration mission that provides a proof of concept for a constellation or swarm of satellites performing coordinated activities. Networked swarms of small spacecraft will open new horizons in astronomy, Earth observations and solar physics. Their range of applications include the formation of synthetic aperture radars for Earth sensing systems, large aperture observatories for next generation telescopes and the collection of spatially distributed measurements of time varying systems, probing the Earth’s magnetosphere, Earth-Sun interactions and the Earth’s geopotential. EDSN is a swarm of eight 1.5U Cubesats with crosslink, downlink and science collection capabilities developed by the NASA Ames Research Center under the Small Spacecraft Technology Program (SSTP) within the NASA Space Technology Mission Directorate (STMD). This paper describes the concept of operations of the mission and planned scientific measurements. The development of the 8 satellites for EDSN necessitated the fabrication of prototypes, Flatsats and a total of 16 satellites to support the concurrent engineering and rapid development. This paper has a specific focus on the development, integration and testing of a large number of units including the lessons learned throughout the project development

Nanosatellite Launch Adapter System (NLAS) Overview

An overview of the Nanosatellite Launch Adapter System (NLAS) is provided that contains information on NLAS' objectives and relevance, structural components and position in the launch vehicle stack, and details on its three main components

The atmospheric corrosion of 304L and 316L stainless steels under conditions relevant to the interim storage of intermediate level nuclear waste

The atmospheric corrosion of 304L and 3 16L austenitic stainless steels was investigated in conditions relevant to the storage of intermediate level nuclear waste (I L W). Thin electrolyte films were created via automated droplet deposition, allowing multiple tests to be conducted in parallel. In-situ monitoring of droplet arrays on stainless steel samples was conducted with the use of a flat-bed document scanner, allowing large-scale, automated monitoring of corrosion processes. The initiation time for individual corrosion processes was established, showing that corrosion was slower to initiate under less aggressive conditions, and allowing 'true corrosion site lifetimes to be recorded, and compared with their depths. The presence of precipitated species within an electrolyte film was shown to affect the corrosion processes within that film. Both NaCl precipitates and glass shards acted as barriers to ion transport. This affected both the propagation of corrosion, and the electrochemical potential within the droplets; a higher precipitate content decreased the average corrosion depth and the extent of corrosion. The presence of nitrate and sulphate salts, both known corrosion inhibitors in full- immersion conditions, was shown to inhibit atmospheric corrosion when the inhibitor:chloride ratio was above a certain value. This was independent of the absolute amounts of salts, but dependent on the exposure humidity of the test

NASA Facts: Nanosatellite Launch Adapter System (NLAS)

The Nanosatellite Launch Adapter System (NLAS) was developed to increase access to space while simplifying the integration process of miniature satellites, called nanosats or cubesats, onto launch vehicles. A standard cubesat measures about 4inches (10 cm) long, 4 inches wide,and 4 inches high, and is called a one-unit (1U) cubesat. A single NLAS provides the capability to deploy 24U of cubesats. The system is designed to accommodate satellites measuring 1U, 1.5U, 2U, 3U and 6U sizes for deployment into orbit. The NLAS may be configured for use on different launch vehicles. The system also enables flight demonstrations of new technologies in the space environment

EDSN - Edison Demonstration for SmallSat Networks: EDSN Overview

The EDSN overview provides information on the project's objectives, particular technologies being demonstrated, an overview of the structural components of the satellites, and the concept of operations

Dearth and the English revolution : the harvest crisis of 1647-50

This article reconstructs the nature and scale of dearth in the late 1640s, emphasizing the coincidence of economic distress with constitutional crisis. It reconsiders the parish register evidence for subsistence crisis; examines the responses of central and local government; analyses the role of popular agency, especially though petitioning campaigns, in prompting reluctant magistrates to regulate the grain markets along lines stipulated by the late Elizabethan and early Stuart dearth orders, which had not been proclaimed since 1630; and accordingly suggests that the late 1640s represents a missing link in the historiography of responses to harvest failure

Trajectory design, optimisation and guidance for reusable launch vehicles during the terminal area flight phase.

The next generation of reusable launch vehicles (RLVs) require significant improvements in guidance methods in order to reduce cost, increase safety and flexibility, whilst allowing for possible autonomous operation. Research has focused on the ascent and hypersonic re-entry flight phases. This thesis presents a new method for trajectory design, optimisation and guidance of RLVs during the terminal area flight phases. The terminal area flight phase is the transitional phase from hypersonic re-entry to the approach and landing phase. The trajectory design, optimisation and guidance methods within this thesis are an evolution of previous work conducted on the ascent and re-entry flight phases of RLVs. The methods are modified to incorporate the terminal area flight phase through the adaption of the problem definition and the inclusion of the speed brake setting as a steering parameter. The methods discussed and developed in this thesis are different to previous methods for the terminal area flight phase as they encompass optimisation, trajectory design and guidance based on the definition of the steering parameters. The NLPQL nonlinear optimiser contained within the International Mathematics Standards Library (IMSL) is utilised for trajectory design and optimisation. Real-time vehicle guidance is achieved using the restoration steps of an accelerated Gradient Projection Algorithm (GPA). The methods used are evaluated in a three degrees of freedom (3DOF) simulation environment. To properly evaluate the programs and gain a better understanding of the terminal area flight phase, two different vehicles are utilised within this study. These vehicles are the German sub-orbital Hopper concept vehicle, a previously proposed replacement for the Ariane series of launch vehicles and the recently cancelled joint National Aeronautics and Space Administration (NASA) and Lockheed Martin sub-orbital test bed vehicle, X-33. The two vehicles each have a terminal area flight phase, but their mission profiles and vehicle characteristics are significantly different. The Hopper vehicle is a winged re-entry vehicle, whereas the X-33 vehicle is a lifting body. The trajectory design method takes into account the initial and final conditions, in-flight restrictions such as dynamic pressure and vehicle loads as well as safety margins. The designed trajectories are evaluated to analyse the terminal area flight phase and to assist in the development of the guidance program. The guidance method is evaluated utilising an program consisting of two parts, a real world simulator with high order models and a representation of the on-board guidance computer, the predictor, which uses low order models for computational efficiency. The guidance method is evaluated against a variety of off-nominal conditions to account for dispersions within the high order real world models and common errors experienced by re-entry vehicles. These off-nominal conditions include atmospheric disturbances, winds, aerodynamic, mass, navigation, steering and initial condition errors. The results of this study include a detailed analysis of the terminal area flight phase highlighting the major influences for vehicle and trajectory design. The study also confirms the applicability of the non-linear programming method utilising the vehicle steering parameters as a viable option for trajectory design and guidance. A comparison to other available results highlights the strengths and weaknesses of the proposed method.Thesis (Ph.D.) -- University of Adelaide, School of Mechanical Engineering, 2007

Blue Marble: Remote Characterization of Habitable Planets

The study of the nature and distribution of habitable environments beyond the Solar System is a key area for Astrobiology research. At the present time, our Earth is the only habitable planet that can be characterized in the same way that we might characterize planets beyond the Solar System. Due to limitations in our current and near-future technology, it is likely that extra-solar planets will only be observed as single-pixel objects. To understand this data, we must develop skills in analyzing and interpreting the radiation obtained from a single pixel. These skills must include the study of the time variation of the radiation, and the range of its photometric, spectroscopic and polarimetric properties. In addition, to understand whether we are properly analyzing the single pixel data, we need to compare it with a ground truth of modest resolution images in key spectral bands. This paper discusses the concept for a mission called Blue Marble that would obtain data of the Earth using a combination of spectropolarimetry, spectrophotometry, and selected band imaging. To obtain imagery of the proper resolution, it is desirable to place the Blue Marble spacecraft no closer than the outer region of cis-lunar space. This paper explores a conceptual mission design that takes advantage of low-cost launchers, spacecraft bus designs and mission elements to provide a cost-effective observing platform located at one of the triangular Earth-Moon Lagrangian points (L4, L5). The mission design allows for the development and use of novel technologies, such as a spinning Moon sensor for attitude control, and leverages lessons-learned from previous low-cost spacecraft such as Lunar Prospector to yield a low-risk mission concept