ABSTRACT: Current Space Launch Vehicles use chemical reactions (solid and liquid propellants) to achieve sufficient thrust to launch artifacts and humans into space. Propulsion technologies can be framed in three different categories: "escape propulsion", "in-space propulsion", and "deep space propulsion". The launch vehicles currently used for "escape propulsion" rely on mature technologies, which experienced only small incremental improvements over the last five decades, and breakthroughs for this kind of propulsion are not foreseen for the next two decades. This research gathered information on the main operational heavy-lift space launch vehicles with capacity over 5,000 kg that are used to reach GEO (Geostationary Earth Orbit) by the United States, Russia, Europe, China, Japan and India and compared their thrust capability. The results show that performance was improved mainly by adding boosters, increasing gross propellant weight, with larger diameter rocket motors and using more efficient liquid propellant pairs. Information regarding the frequency of published scientific articles and patents on Space Vehicles Propulsion Systems since the 1960s was also gathered, which demonstrates some progress in the last years, mainly in USA and Europe. "In-space" and "Deep space" spacecraft were also briefly examined in this article, resuming the main features of some new promising developments, mainly regarding the latter, which present prospects of significant technological advances; however, real progress in interplanetary missions will be possible only when technological breakthroughs towards other propulsion types become possible and feasible. So, two questions motivated the authors: why space propulsion development seems stagnant? Are there prospects for progress?

ABSTRACT: The statistical analysis of academic literature, also known as “bibliometrics”, is being increasingly applied to analyse research trends, to identify emerging areas of science and to find out where and how often specific articles are cited. The aim of this study was to identify technological innovation trend patterns in the aerospace sector applying bibliometric analysis over the period 2008 - 2015. In this study the keywords space technology, satellite, space launch vehicle, spacecraft, rocket and space station were used to scrutinize the database Web of Science (ISI). The obtained records were analysed using the Patent Insight Pro software (2015). It was observed that the researches related to aerospace technological development has been focused in satellites, giving also some directions for satellite launch vehicles. Bibliometric analysis revealed concern on new low-cost technologies development, and the applied logistic fit suggests that over the next five years the continuity on new space technologies development will be mostly related to small satellites, with also contributions associated with high-resolution imagery in order to improve Earth observation in low orbit.

ABSTRACT High-altitude platforms (HAPs) are aircraft, usually unmanned airships or airplanes positioned above 20 km, in the stratosphere, in order to compose a telecommunications network or perform remote sensing. In the 1990 and 2000 decades, several projects were launched, but very few had continued. In 2014, 2 major Internet companies (Google and Facebook) announced investments in new HAP projects to provide Internet access in regions without communication infrastructure (terrestrial or satellite), bringing back attention to the development of HAP. This article aims to survey the history of HAPs, the current state-of-the-art (April 2016), technology trends and challenges. The main focus of this review will be on technologies directly related to the aerial platform, inserted in the aeronautical engineering field of knowledge, not detailing aspects of the telecommunications area.