Humans have dreamed of exploring the skies for thousands of years, but until the development of the liquid-propellant rocket in the 20th century, space exploration remained just fiction. Now, with the advancement of science and technology, space exploration is a reality. But is it a science?Space exploration, like astronomy in its classic form, is one of the main sources of space science. The first scientific discovery made with instruments that orbit in space was the existence of the Van Allen radiation belts, discovered by Explorer 1 in 1958. Outer planetary explorers carry a small amount of plutonium, whose slow decay produces heat to power electrical generators.
The technique finally chosen in both countries consisted of using a single large, multistage, liquid-propellant rocket to send two small spacecraft to the vicinity of the Moon, a capsule for the crew and a small landing vehicle in which part of the crew would make the last descent to the lunar surface. The focus of research in space physics was later extended to understanding the characteristics of the Sun, as an average star and as the main source of energy for the rest of the solar system, and to exploring the space between the Sun and the Earth and other planets (see the interplanetary environment). This was followed by NASA's Skylab space station, the first orbital laboratory where astronauts and scientists studied the Earth and the effects of spaceflight on the human body. While NASA has been reluctant to support “space tourism”, the Russian Space Agency has allowed several private citizens to travel in its Soyuz vehicles and on the ISS. NASA will continue its unprecedented work with the commercial industry and will expand an entire industry as private companies develop and operate safe, reliable, and affordable commercial systems for transporting crew and cargo to and from the International Space Station and low Earth orbit. Long before astronauts take off to leave the atmosphere, hundreds and hundreds of hours are spent developing new technologies designed for the unusual environment of space. The Soviet Union took the lead with its Salyut space stations, in which some cosmonauts orbited for hundreds of days.
The Explorer missions, chosen through intense competition to ensure cost-effectiveness, have also made it possible to design innovative instruments and have produced new and important scientific results of great importance for the advancement of space science. Finally, there is considerable speculation that the budgetary impact of the Moon and Mars influenced NASA's decision to cancel the Hubble Space Telescope service mission. As these stories demonstrate, interest in the possibility of space exploration preceded, for thousands of years, the science and technology needed to achieve it. Space exploration is carried out mainly by astronomers with telescopes. Its physical exploration is carried out both with unmanned robotic space probes and with manned space flights. During its first 50 years, many scientists argued that space travel with robotic vehicles would be best.
But now that we have achieved manned space travel, it is clear that space exploration is indeed a science.
