Space transportation systems, launch systems, and propulsion for the Space Exploration Initiative: Results from Project Outreach

A number of transportation and propulsion options for Mars exploration missions are analyzed. As part of Project Outreach, RAND received and evaluated 350 submissions in the launch vehicle, space transportation, and propulsion areas. After screening submissions, aggregating those that proposed identical or nearly identical concepts, and eliminating from further consideration those that violated known physical princples, we had reduced the total number of viable submissions to 213. In order to avoid comparing such disparate things as launch vehicles and electric propulsion systems, six broad technical areas were selected to categorize the submissions: space transportation systems; earth-to-orbit (ETO) launch systems; chemical propulsion; nuclear propulsion; low-thrust propulsion; and other. To provide an appropriate background for analyzing the submissions, an extensive survey was made of the various technologies relevant to the six broad areas listed above. We discuss these technologies with the intent of providing the reader with an indication of the current state of the art, as well as the advances that might be expected within the next 10 to 20 years

Committing to Exercise: Contract Design for Virtuous Habit Formation

Sedentary lifestyles, obesity, and obesity-related chronic diseases have become increasingly common among U.S. adults, posing a major health policy challenge. While individuals may be interested in exercising more to reduce these health risks, they often have difficultly forming long-term exercise habits. Behavioral economic devices like commitment contracts aid individuals make repeated actions in situations where there are upfront costs and the benefits, though substantial, are delayed. It is not known whether such contracts can help individuals to sustain increased exercise. We conducted a randomized controlled trial to test whether nudges and anchoring could be used to shift the types of exercise commitment contracts people entered into using a web-based contract creation tool. At the time of contract creation, users selected a contract length (duration); number of times a week to exercise (frequency); and a financial penalty for failing to live up to the contract in a given week (stake). We randomly set the default duration shown to users (8 weeks, 12 weeks, or 16 weeks). Outcomes include: contract acceptance; chosen duration, frequency, total exercise sessions; and chosen financial stake. We analyzed the data using multivariable regressions and also developed a theoretical model of active choice in the context of nudges, fitting the model to the data using non-linear optimization. 619 users, age 18-69, were included in the study, of whom 61% accepted/signed an exercise commitment contract. Users who were shown a longer default contract durations were significantly more likely to choose a contract of longer duration. There was no difference in the likelihood of accepting contracts or in the chosen exercise frequency or financial stakes. Our model of active choice suggested that almost 50% of users were highly susceptible to default values for contract duration, with the greatest effect for users interested in exercise contracts with durations nearer to the nudged defaults. This implication of the model was confirmed by quantile regressions (greatest effect of nudges for contract durations between the 40th and 80th percentiles). With changes in default values, individuals can be nudged into longer exercise commitment contracts that obligate them to greater numbers of exercise sessions.

Exploring the Unknown: Selected Documents in the History of the US Civilian Space Program

One of the most important developments of the twentieth century has been the movement of humanity into space with machines and people. The underpinnings of that movement -why it took the shape it did; which individuals and organizations were involved; what factors drove a particular choice of scientific objectives and technologies to be used; and the political, economic, managerial, and international contexts in which the events of the space age unfolded- are all important ingredients of this epoch transition from an earthbound to spacefaring people. This desire to understand the development of spaceflight in the United States sparked this documentary history series. 'Exploring the Unknown' is a multi-volume series containing a selection of key documents in history of the U.S. civil space program. This current volume, Volume III, focusing on the use of space for practical applications, prints 112 key documents on the history of satellite communications, remote sensing of earth, and space as an investment in economic growth, edited for ease of use. Each is introduced by a headnote providing context, bibliographical information, and background information necessary to understanding the document

Linguistic incompetence: giving an account of researching multilingually

This paper considers the place of linguistic competence and incompetence in the context of researching multilingually. It offers a critique of the concept of competence and explores the performative dimensions of multilingual research and its narration, through the philosophy of Judith Butler, and in particular her study Giving an account of oneself. It explores aspects of risk, justice, narrative limit and a morality of multilingualism in emergent multilingual research frameworks. These theoretical dimensions are explored through consideration of ‘linguistically incompetent’ ethnographic work with refugees and asylum seekers, in contexts of hospitality and in life long learning research in the Gaza Strip, and of early attempts to learn new languages. The paper offers a prospect of a relational approach to researching multilingually and affirms the vulnerability at the heart of linguistic hospitality

Universal stowage module for future space exploration

The design effort to develop, design, and fabricate a prototype Universal Stowage Module with universal restraints that are readily adaptable for most sizes and shapes of items that would be launched into space and returned aboard shuttle payloads is presented