Editing Hermann Oberth (section)

== Basic research and technical drafts ==
=== The rocket in spaceflight ===
[[File:H.Oberth Modell-B.jpeg|thumb|upright|Oberth's Model B design for a two-stage rocket]]
In 1923, Oberth's book ''The Rocket to the Planetary Spaces'' was published.<ref name="Oberth_a"/> This publication is generally regarded as a kind of initial spark for rocket and space travel enthusiasm in Germany. Many later rocket engineers were inspired by his precise and comprehensive theoretical considerations and his bold conclusions.<ref name="Brandau">{{Cite book |last=Brandau |first=Daniel |title=Raketenträume, Raumfahrt- und Technikenthusiasmus in Deutschland 1923–1963 (Rocket dreams, space and technology enthusiasm in Germany 1923–1963) |date=2019 |publisher=Schöning & Bill, Paderborn, FRG}}</ref> The work sparked heated debates, known at the time as the Battle of the Many Formulas. The second edition appeared in 1925, and it was also sold out after a short time.<ref name="Barth"/>
In his book, Oberth puts forward the following theses:
* ''Premise 1:'' With the current level of science and technology, the construction of machines that can fly higher than the Earth's atmosphere is likely.
* ''Premise 2:'' With further refinement, these machines can reach such speeds that they do not have to fall back to the Earth's surface and are even able to leave the Earth's sphere of attraction.
* ''Premise 3:'' Such machines can be built in such a way that people (probably without health problems) can ride up with them.
* ''Premise 4:'' Under certain economic conditions, the construction of such machines can be worthwhile. Such conditions can occur in a few decades.

With the launch of [[Sputnik]] (1957) and the flight of [[Yuri Gagarin]] (1961) into space, these ideas, which were still completely utopian at the beginning of the 1920s, became a reality less than four decades later.
Marsha Freeman writes, "The rockets were only a means to an end, his goal was space travel."<ref name="Freeman">{{Cite book |last=Freeman |first=Marsha |title=How we got to the Moon, the Story of the German Space Pioneers |url=https://books.google.com/books?id=-E5GAAAAYAAJ |date=January 1, 1993 |publisher=21st Century Associates|location=Washington, D.C.|isbn=9780962813412 |page=3}}</ref> Oberth thought of interplanetary space travel, of a multiplanetary humanity. In his first book in 1923 he gives the first "outlook":
He goes into more detail on physical and physical-chemical, as well as physiological experiments in weightless space, on the space telescope, research into the solar corona, the space station for Earth observation and the space mirror in Earth orbit for influencing the weather<ref name="Oberth_a"/>
The third, greatly expanded edition of his first book was published by Oberth in 1929 with the new title ''Ways to Spaceflight''.<ref name="Oberth_b" /> In the years that followed, the book became the standard work for space exploration and rocket technology and was called the "Bible of scientific [[astronautics]]" by the French aviation and rocket pioneer [[Robert Esnault-Pelterie]].<ref name="Barth">{{Cite book |last=Barth |first=Hans |date=1985 |title=Hermann Oberth, Leben-Werk-Wirkung |publisher=Uni-Verlag, Feucht/FRG}}</ref>{{rp|117}}
In this book, Oberth describes possible uses of his two-stage rocket, among other things on pages 285 to 333 the [[crewed space flight]] including [[space suit]] for external use, the [[space telescope]] for [[Earth observation]] and the duration of interplanetary flights, on pages 333 to 350 his ideas and the theoretical basis for [[space station]]s in [[Low Earth orbit|near Earth orbit]] from 700 to 1200&nbsp;km above the ground for Earth and weather observation and as a starting point for flights to the Moon and to the planets, on pages 336 to 351 he explains the construction and function of the space mirror<ref name="Oberth_a" /><ref name="Oberth_b" /> he invented in 1923 with 100 bis 300&nbsp;km in diameter in Earth orbit, with which, among other things, the weather is to be influenced in a targeted regional manner or the solar radiation is to be weakened in a targeted regional manner.
On pages 350 to 386 in the chapter "Journeys to Strange Worlds", Hermann Oberth presents his scientific considerations and calculations for flights (including landings) to the [[Moon]], to [[asteroid]]s, to [[Mars]], to [[Venus]], to [[Mercury (planet)|Mercury]] and to [[comet]]s.

=== Space Mirror ===
In 1923, Oberth initially outlined the concept of his space mirrors in his book ''Die Rakete zu den Planetenräumen'' (''The Rocket to Interplanetary Space''). These mirrors, with diameters ranging from 100 to 300&nbsp;km, were envisioned to be composed of a grid network consisting of individually adjustable facets.

Oberth's concept of space mirrors in orbit around the Earth serves the purpose of focusing sunlight on specific regions of the planet's surface or redirecting it into space. This approach differs from creating shaded areas at the Lagrange point between the Earth and the Sun, as it does not involve diminishing solar radiation across the entire exposed surface. According to Oberth, these colossal orbital mirrors possess the potential to illuminate individual cities, safeguard against natural disasters, manipulate weather patterns and climate, and even create additional living space for billions of people. He places significant emphasis on their capacity to influence the trajectories of barometric high and low-pressure areas. However, it is important to acknowledge that the implementation of such [[climate engineering]] interventions, including space mirrors, requires further extensive research before their practical applicability can be fully realized.

Further publications followed in which he took into account the technical progress achieved up to that point: ''Ways to Spaceflight'' (1929), ''Menschen im Weltraum. Neue Projekte für Raketen-und Raumfahrt'' (''People in Space. New Projects for Rocket and Space'', 1957), and ''Der Weltraumspiegel'' (''The Space Mirror'', 1978).

To optimize costs, Oberth's concept proposes the utilization of lunar minerals for producing components on the Moon. The Moon's lower gravitational pull necessitates less energy for launching these components into lunar orbit. Additionally, the Earth's atmosphere is spared the burden of numerous rocket launches. The envisioned process involves launching the components from the lunar surface into lunar orbit using an electromagnetic lunar slingshot, subsequently "stacking" them at a 60° libration point. These components could then be transported into orbit via electric spaceships, designed by Oberth with minimal recoil. Once in orbit, the components would be assembled into mirrors with diameters ranging from 100 to 300&nbsp;km. Oberth's estimate in 1978 suggested that the realization of this concept could occur between 2018 and 2038.

Oberth emphasized that these mirrors could potentially serve as weapons. Given this aspect, coupled with the complexity of the project, the realization of these mirrors would only be feasible as a peace initiative undertaken by humanity.<ref name="Oberth_a"/><ref name="Oberth_b"/>{{rp|87–88}}<ref name="Oberth_c">{{Cite book |last=Oberth |first=Hermann |date=1957 |title=Menschen im Weltraum |language=german |publisher=Econ Duesseldorf Germany |pages=177–506}}</ref><ref name="Oberth_d">{{Cite book |last=Oberth |first=Hermann |date=1957 |title=Man into Space |language=en |publisher=Harper&Brothers |pages=125–182}}</ref><ref name="Oberth_e">{{Cite book |last=Oberth |first=Hermann |date=1978 |title=Der Weltraumspiegel |language=german |publisher=Kriterion Bucharest}}</ref>

In 2023, the space mirror devised by Oberth is categorized within the field of Climate Engineering, specifically under Solar Radiation Management (SRM) as a subset of Space-Mirrors. The associated risks of these deliberate interventions in weather and climate are also examined and deliberated upon within this classification.

=== The Moon Car ===
Hermann Oberth published his concept of a moving and jumping lunar vehicle for future, extensive lunar exploration in 1953.<ref>{{cite magazine |last=Oberth |first=Hermann |title=Vom Ruhm allein kann man nicht leben |trans-title=You can't live on fame alone |language=de |magazine=Revue |issue=32 |publisher=Bauer |location=Hamburg |year=1953}}</ref><ref>{{cite magazine |last=Büdeler |first=Werner |title=Das Mond-Auto kann springen |trans-title=The moon car can jump |magazine=Weltbild |issue=1 |language=de |publisher=Th. Martens |year=1954}}</ref> In his considerations, he assumed that large distances should be covered quickly and that extensive fissures/ravines or impassable terrain that block the way should be overcome so that large detours can be avoided.
The vehicle, which would weigh about 10000&nbsp;kg on Earth and only 1654&nbsp;kg on the Moon due to the weak gravitational pull, would be built on Earth, transported to the Moon and dropped on the lunar surface. The tower-like structure has only one leg and it stands on a tracked chassis with a footprint of 2.5 m x 2.5 m. A motor with
51.5&nbsp;kW of power is sufficient to drive at a speed of up to 150&nbsp;km/h, depending on the terrain. The required energy in the form of electrical current is supplied by the solar power plant above the crew cabin and the gyroscope. The leg is a gas-tight cylinder in which the 4.5 m long "jumping leg" can move up and down like a piston in a shock absorber and can be extended and retracted for jumping. The powerful gyroscope above the crew cabin keeps the vehicle vertical and ensures that the vehicle can never tilt more than 45 degrees. The jumps could be up to 125 m high and several 100 m wide. Jumping would occur if the vehicle had to overcome an impassable area or fissures/ravines, or if it had to get from a higher location (e.g. a mountain terrace) to a lower location or vice versa.<ref name="Oberth_f">{{cite book |last= Oberth |first=Hermann |title=The Moon Car |publisher=Harper & Brothers|location=New York |date=1959 |page=41}}</ref>
Oberth writes: "I wanted to present my readers not just with a rough sketch of the lunar car, but with drawings and descriptions based on precise calculations and designs. So I racked my brains over hundreds of details, calculated, compared, constructed, rejected and re-planned until the design was such that I could present it with a clear conscience. Now I can say: I am sure that my moon car can be built."
Feasibility studies or development work on Oberth's lunar vehicle have not begun until 2023 because there are no concrete plans for lunar exploration in which such a large vehicle could be used.

=== Ion propulsion for interplanetary spaceflight ===
The principle of ion propulsion was first presented in 1929 by the space pioneer Hermann Oberth in his work ''Ways to Spaceflight'',<ref name="Oberth_b"/> which is referred to as the "Bible of Space Technology",<ref name="Barth"/>{{rp|117}} in which he describes for the first time the physics, the function, the construction and the use for the interplanetary flight of an ion engine on pages 386 to 399.
Oberth also presented at the 12th Rocket and Space Conference of the Deutsche Raketen-Gesellschaft (DRG) (German Rocket Society) in September 1963 in Hamburg, FRG a new idea for the electric spaceship.<ref name="Oberth_g">{{Cite book |last=Oberth |first=Hermann |date=1963 |title=The electric spaceship |publisher=EBÖ-Druck und Verlag der DRG, Hannover, FRG, Bölkow-Library}}</ref> Quote: "My proposal concerns an electric spaceship that does not emit ions and electrons, but rather nebula droplets that are 1,000 to 100,000 times larger in size depending on the project and to form an ion or electron as a condensation nucleus."