ABSTRACT Since Gagarin’s flight on April 12th, 1961, the dream of making human space flight routine and making Homo sapiens a multiplanetary species seemed to have become closer to reality. Nonetheless, on average less than 10 human flights a year have happened along the past 60 years. Unmanned spacecrafts, on the other hand, have changed the way the human race sees itself and the universe it is surrounded by. They have explored all planets in the solar system, as well as comets, asteroids and the Sun. Presently, there are four unmanned spacecrafts on Mars’ surface and eight satellites in its orbit. Since the launching of Sputnik in 1957, more than 11,000 satellites have been sent into Earth’s orbit. Nowadays, it is impossible to imagine life on Earth without the services provided by the space-based infrastructure resulting from the Space Age. They have changed the modus vivendi of the human civilization and become a commodity, like potable water and electricity. The so-called satellite industry generates around US$ 300 billion a year, mostly related to the sale of satellite services and ground equipment. The era of exponential growth and disruption has reached Earth’s orbit, and beyond, through the minds, initiatives and boldness of the NewSpace generation, from which Elon Musk is its exponent. Twenty-five thousand satellites are expected to be launched in the next 10 years to provide, among other applications, worldwide broadband internet access. The scientific community and the military, however, have already expressed their concerns regarding space debris and, as a consequence, space sustainability. For the scientific community, the long-waited launch of the James Webb Space Telescope (JWST) promises to be the 2021 main event. In a time in which Spaceship Earth faces so many challenges, the dream of making its dwellers a multiplanetary species got a revival trough the minds and actions of Elon Musk and Jeff Bezos. There are those who, through public-private partnerships, intend to establish a 1,000 people community working and living in space by 2045. Cooperation among nations has been usual in space, but they are still shy when compared to the efforts required to colonize the Moon, Mars and other places in the solar system. As the 21st century advances, Spaceship Earth faces its greatest challenge ever. Space-based assets provide all the tools required to monitor Earth’s health, but if the human species intends to survive as the only identified intelligent civilization, it will have to think and act united in a truly cooperative way. Otherwise, the civilizational and technological effort hitherto undertaken may prove to be useless.

ABSTRACT This paper presents an analysis of the scenario of small satellites and its correspondent launch vehicles. The miniaturization of electronics, together with reliability and performance increase as well as reduction of cost, have allowed the use of commercials-off-the-shelf in the space industry, fostering the Smallsat use. An analysis of the launched Smallsats during the last 20 years is accomplished and the main factors for the Smallsat (r)evolution, outlined. Based on historic data, future scenarios for different mass categories of Smallsats are presented. An analysis of current and future launch vehicles reveals that we are currently in a phase of transition, where old launch vehicles get retired and new ones enter the market. However, the satellite launch vehicle business has been established to carry payloads of thousands of kilos into low Earth orbit and has not adjusted itself to the market of Smallsats. As a result, there is only 1 launch vehicle for dedicated Smallsat launches commercially available, but it carries a high price tag. Several small low-cost launch vehicles under development are identified and the challenges to overcome, discussed. Since these small launch vehicles have similar complexity as huge launch vehicles, high development costs are intrinsic, leading to a high specific price (USD/kg payload).

A numerical procedure for solving the nongray radiative transfer equation (RTE) in two-dimensional cylindrical participating media is presented. Nongray effects are treated by using a narrow-band approach. Radiative emission from CO, CO2, H2O, CH4 and soot is considered. The solution procedure is applied to study radiative heat transfer in a premixed CH4-O2, laminar, flame. Temperature, soot and IR-active species molar fraction distributions are allowed to vary in the axial direction of the flame. From the obtained results it is possible to quantify the radiative loss in the flame, as well as the importance of soot radiation as compared to gaseous radiation. Since the solution procedure is developed for a two-dimensional cylindrical geometry, it can be applied to other combustion systems such as furnaces, internal combustion engines, liquid and solid propellant combustion.