No abstract

Plutonium-238 is currently still the best fuel to power satellites to be sent to deep space in regions where the solar panels can no longer efficiently receive the sunlight. For 50 years, the National Aeronautics and Space Administration (NASA) has used this radioisotope as a fuel in radioisotope thermoelectric generators (RTGs) installed on satellites such as Pioneer 10 and 11, Voyager 1 and 2, Cassini-Huygens and New Horizons, as well as the various rovers sent to the Moon and to Mars, among others. Plutonium-238 is not a naturally occurring isotope on the planet, it was produced in greater quantity during the Cold War period as a by-product of the production of Plutonium-239 used for nuclear bombs. However, after the shutting down of the Savannah River reactors in 1988 and the ending of the Soviet Union in 1991, the United States stock of Plutonium-238 has been increasingly reduced, which threatens NASA's future space projects. This paper presents a brief bibliographic review about the subject, as well as commentaries on the options available to the United States, from restarting the production of this fuel, to possible alternatives for a new type of fuel or equipment that may supply the spacecrafts.

Some researchers point out the decline in contemporary cities of the use of public spaces, whether free or restricted access. In this sense, the present essay proposes a reflection on a "public sphere of organized presence", according to Habermas classification, as a rescue of the importance of this space for the exercise of citizenship and social-environmental responsibility. The reflection was based on the results obtained from a study in the district of Riacho Grande, São Bernardo do Campo, São Paulo, Brazil, in which the environmental perception of the participants of the meetings about the region was known by documentary analysis, direct observation and interviews with questionnaires. It was possible to verify that this public space can facilitate a greater integration between the public administrators and citizens, helping even in the defense to the environment.

Studies of risk perception and risk communication concerning the nuclear area are quite common in scientifi c literature. However, though numerous studies on this topic point to the importance of scientifi c and technological knowledge in facilitating the reduction of perceived risks, there are few papers that effectively discuss the role of education in risk communication on the subject, particularly in Brazil. The objective of the present work was to refl ect on this problem by analyzing the results obtained from two case studies on the implementation of the Brazilian Multipurpose Reactor, in the city of Iperó, in the state of São Paulo, Brazil. As was verifi ed in the investigation, most participants of the study had high perception of risk with respect to the implementation of the reactor. Nevertheless, although important in the project of the reactor implementation, it was verifi ed that the state, municipal and community schools of the city of Iperó had not participated, in the public hearings nor had they discussed the issue inside the school community, until the moment of the research.