Zitat Elon Musk@elonmusk For those unaware, SpaceX has already shifted focus to building a self-growing city on the Moon, as we can potentially achieve that in less than 10 years, whereas Mars would take 20+ years.
The mission of SpaceX remains the same: extend consciousness and life as we know it to the stars.
It is only possible to travel to Mars when the planets align every 26 months (six month trip time), whereas we can launch to the Moon every 10 days (2 day trip time). This means we can iterate much faster to complete a Moon city than a Mars city.
That said, SpaceX will also strive to build a Mars city and begin doing so in about 5 to 7 years, but the overriding priority is securing the future of civilization and the Moon is faster. 12:24 AM · Feb 9, 2026
Zitat Elon Musk@elonmusk Mars will start in 5 or 6 years, so will be done in parallel with the Moon, but the Moon will be the initial focus 1:26 PM · Feb 9, 2026
Zitat ApoStructura@ApoStructura The Moon, then Mars, then the belt, then Jupiter and Saturn, then the stars. 10:29 AM · Feb 9, 2026
Zitat Aaron Burnett@aaronburnett Big Mass driver on the moon would speed colonization up on Mars I assume. 1:28 PM · Feb 9, 2026
Elon Musk@elonmusk The Moon would establish a foothold beyond Earth quickly, to protect life against risk of a natural or manmade disaster on Earth.
We would continue to launch directly from Earth to Mars while possible, rather than Moon to Mars, as fuel is relatively scarce on the Moon. 2:00 PM · Feb 9, 2026
Zitat Anand Swaminathan@AnandSwa This is probably going to accelerate a self sustaining city on Mars by a decade. The deltav* difference to get to Mars from the moon is ~1/5th that of going from Earth to Mars.
If we did not have heavy industry on the moon, it means we would have to lift every single ton of material from the insane gravity well of the Earth for a Mars city.
If we do have heavy industry on the moon, then we only have to lift organics, people and Earth specific equipment to Mars. The rest, (metals, silicates, water etc) can be sent for 1/5th the cost from the moon.
Essentially, building a Moon industrial base is a compounding factor to a Mars city. Absolutely not needed if you want to visit Mars - but the Moon is a "planet" sized resource depo, close to us in time, but far from us in the gravity well. We should invest into developing it into a heavy industry base.
The gravity well of the Earth is a fools errand to fight, but the moon is our "all your base are belong to us". 1:52 AM · Feb 9, 2026
* Mal in Annäherungswerten: das benötigte Δv für einen Erde-Mars-Transfer beläuft sich auf 3,6 - 4,3 km/s für Start + Transferbahn und summiert sich mit der Bremszündung für einen Marsorbit und die Landung auf 5,5 - 6 km/s. Für einen Transfer Erdmond > Mars reduziert sich das auf 0,74 - 1 km/s.
PS.
Zitat Elon Musk@elonmusk The priority shift is because I’m worried that a natural or manmade catastrophe stops the resupply ships coming from Earth, causing the colony to die out.
We can make the Moon city self-growing in less than 10 years, but Mars will take 20+ years due to the 26 month iteration cycle.
That is what matters most.
There is also an AI bonus element, but the prime directive must be ensuring the long-term survival of consciousness. 6:20 PM · Feb 9, 2026
Zitat LilHumansBigImpact@BigImpactHumans You, your children and grandchildren have a real chance at actually going to the Moon one day 5:41 PM · Feb 9, 2026
Elon Musk@elonmusk·2h We hope to make the Moon accessible to anyone who wants to go there
Und in diesem Zusammenhang erlaube ich mir mal frivolerweise ein Selbstzitat aus meinem ursprünglichen Blogbeitrag von 11. Mai 2020:
Zitat Doch zunächst zum Wichtigen: Die Frage: "wer ist Elon Musk?" läßt sich recht schlüssig bescheiden. Die Antwort lautet:
Elon Musk ist D. D. Harriman.
D. D. Harriman nun ist der Protagonist von Heinleins dritter veröffentlichter Kurzgeschichte "Requiem", in der Januarnummer 1940 zuerst in Astounding SF erschienen (nach "Life-Line" im August 1939 und "Misfit" vom November). ... Im Konnex dieser Future History ist D. D. Harriman der amerikanische Unternehmer, dessen Intitiative der Menschheit den Zugang zum All erschlossen hat; ohne seine Umtriebigkeit und seinen Erfindergeist hätte sich dieses Unterfangen nie vom Boden erhoben. Der spätere, gut 100 Seiten lange Text, der der gerade erwähnten Sammlung den Titel verliehen hat, zeigt die Winkelzüge, die Bluffe und Finten, mit denen Harriman der Welt "den Mond verkaufte", wie er seine Konkurrenz ausschaltete, mit als Partner an Bord nahm, von seinen Ingenieuren die technischen Lösungen entwickeln und zur Serienreife bringen ließ - nicht zuletzt angetrieben vom Stolz, weil die gesamte Geschäftswelt ein solches Ziel - und noch dazu von einem Privatmann betrieben, ohne die Unterstützung einer Regierung oder des Militärs! - apodiktisch zu einem Ding der Unmöglichkeit erklärt hatte.
"The Man Who Sold the Moon" ist zuerst als Titelgeschichte des gleichnamigen Erzählungsbandes beim Kleinverlag Shasta Publishers im Februar 1950 erschienen (Shasta, 1948 von drei SF-Fans, Erle Korshak, Ted Dikty und Mark Reinsberg gegründet, war neben Gnome Press (ebenfalls ab 1948) und Arkham House (ab 1939), einer der drei Verlage, die sich darum bemühten, die in den Pulp-Magazinen publizierten SF- und Horror-Erzählungen in etwas dauerhaftere Buchform zu bringen. Antiquarische Angebote für diese Erstausgabe sind zwischen 950 und 2500 US-Dollar ausgepreist. Das Thema "Jeder, der möchte, soll zum Mond fliegen können" hat Heinlein explizit in zwei Kurzgeschichten behandelt: "The Black Pits of Luna" (Saturday Evening Post, 10. Januar 1948) und "The Menace from Earth" (The Magazine of Fantasy & Science Fiction, August 1957, die sich auf die Ereignisse in "Black Pits" bezieht). Im Roman The Moon Is a Harsh Mistress (1966), der im Jahr 2075 spielt und der den Kampf der Mondkolonien um Unabhängigkeit von der Erde schildert - und den Musk als entscheidende Inspiration in seiner Jugend genannt hat, ist in dieser Hinsicht natürlich Schluß-mit-lustig.
Zitat One of his favorites was Robert Heinlein's The Moon Is a Harsh Mistress, a novel about a lunar penal colony. It is managed by a super-computer, nicknamed Mike, that is able to acquire self-awareness and a sense of humor. The computer sacrifices his life during a rebellion in the lunar colony. The book explores an issue that would become central to Musk's life: Will artificial intelligence in ways that benefit and protect humanity, or will machines develop intentions of their own and become a threat to humans? (Walter Isaacson, Elon Musk, Simon & Schuster, 2023, S. 31)
Der Kleine Zyniker™ notiert, daß in den letzten Tagen im Zusammenhang mit Musks Mond-Plänen viel die Rede von "magnetischen Massenbeschleunigern" (magnetic mass drivers) war, um die auf dem Mond entweder geschürften Rohstoffe oder in automatisierten Fabriken gefertigten Satelliten in eine Erdumlaufbahn zu bringen. In Heinleins Roman gibt es zwei solcher Magnetstartbahnen, und sie dienen den aufständigen Kolonisten dazu, die Erde zu bombardieren.
Zitat Elon Musk reposted Nic Cruz Patane@niccruzpatane Electromagnetic mass drivers on the Moon that shoot AI Satellites into deep space.
This stuff is happening in our lifetime, woah. 3:47 AM · Feb 8, 2026
Musk said orbital data centers would provide “the lowest cost way to generate AI compute” within two to three years.” He suggested that future AI satellites could be built on and launched from the moon.
“By using an electromagnetic mass driver and lunar manufacturing, it is possible to put 500 to 1,000 TW/year of AI satellites into deep space, meaningfully ascend the Kardashev scale and harness a non-trivial percentage of the sun’s power,” Musk wrote. “The capabilities we unlock by making space-based data centers a reality will fund and enable self-growing bases on the moon, an entire civilization on Mars and ultimately expansion to the universe.”
Kleine Korrektur zu Shasta Publishers: es gab drei Amateur-Verlagsgründungen dieser Art in der unmittelbaren Nachkriegszeit, nicht zwei. Die erste war Fantasy Publishers, 1947 von Arthur Lloyd Eshbach aufs Gleis gesetzt, der die ersten Buchausgaben der "Lensman"-Romane von E.E."Doc"Smith herausgebracht hat und 1948 Heinleins Roman "Beyond This Horizon" publiziert hat (Magazinabdruck 1942), seine erste Buchveröffentlichung neben der seit 1947 laufenden jährlichen Reihe von Jugendromanen für Scribner's.
Im Katalog von Heinleins Archiv finde ich diesen Eintrag:
Zitat Title: Black Pits of Luna - Short Story Written: April - May 1947 Pages: 156 Description: File contains 16 pages of notecards. 3 pages of synopsis notes for story titled “Boy In the Moon”. Draft titled “Little Boy Lost”. Three more drafts of manuscript. Letter from publisher followed by apparently publisher-edited draft with handwritten notation saying “356 sentences changed out of 456! God!”. Published story in Saturday Evening Post, January 10, 1948.
Das erinnert ein wenig an Standard-Klagen der Autoren für Galaxy Science Fiction, dessen Herausgeber Horace L. Gold von der Gründung 1950 bis zur Staffelweitergabe an Frederik Pohl 1961 auch die Angewohnheit hatte, mitunter in jedem einzelnen Absatz der eingereichten Texte irgendetwas umzuformulieren, zu streichen, umzustellen. Pohl schreibt in seinen Erinnerungen (The Way the Future Was, 1978, daß Gold, der sich auch angelegentlich als Autor betätigte, kurz nach dem Wechsel eine Kurzgeschichte eingereicht habe. Das war vor der Zeit, zu der Bürokopierer üblich wurden. Pohl hat die Sekretärin bei Galaxy Publishing angewiesen, eine saubere Kopie zu tippen und ist dann mit der gesamten Mannschaft daran gegangen, in Gold Original-Typoskript jeden einzelnen Satz zu verhunzen und zu verunstalten und ihm das Resultat zur Begutachtung einzuschicken. Gold veranstaltete noch aus der Zeit seiner Herausgeberschaft eine wöchentliche Pokerrunde (es waren seine einzigen persönlichen Kontakte in dieser Hinsicht) und beim Treffen am folgenden Mittwoch hat ihm Pohl strahlend eröffnet, die Story in dieser "revidierten Fassung" zur Veröffentlichung angenommen. Gold habe nur völlig zerknirscht gemurmelt: "Ja, vielen Dank auch ... aber Fred: MUSSTE das wirklich sein?" Pohl hat dann natürlich die eingereichte Version gebracht.
"Les hommes seront toujours fous; et ceux qui croient les guérir sont les plus fous de la bande." - Voltaire
Zitat Aaron Burnett@aaronburnett Big Mass driver on the moon would speed colonization up on Mars I assume.
Zitat:Nic Cruz Patane@niccruzpatane On the stage during xAI’s all-hands meeting, @elonmusk shared an image of how the Lunar Mass Driver would look on Moonbase Alpha. 😎
“Shooting AI satellites into deep space. I can’t imagine anything more epic than a mass driver on the Moon and a self-sustaining city on the Moon. Then going beyond the Moon to Mars, visiting all the star systems— maybe we will meet aliens. Maybe we will see civilizations that lasted millions of years and find the remnants of ancient alien civilizations.
The only way we’re going to do that if we go out there and explore. This is the path to making it happen.” 9:56 PM · Feb 11, 2026
Der kleine Pedant merkt an, daß solch eine Magnetbeschleunigungsstartbahn auch in Duncan Jones Kammerdrama "Moon" (2009) vorkommt, wo sie dazu dient, das auf dem Mond geschürfte Helium-3 in einer Erdumlaufbahn zu schießen. Am Ende des Films wird Sam, der einzige (wirkliche) Astronaut auf der Mondstation, mit Hilfe dieser Magnetbahn Richtung Heimat geschossen. Hier zu sehen bei Min 3:00-3:03: https://www.youtube.com/watch?v=B1KzPm8wHoQ
Allerdings wäre angesichts der Kürze der Bahn die benötigte Beschleunigung so hoch, daß er den Start nicht überleben würde. Der Mond hat eine Fluchtgeschwindigkeit von 2,38 km/s; die Länge des Startkatapults sieht im Film knapp 50m, auf jeden Fall keine 100m lang aus. Kleiner Überschlag ergibt, daß bei einer Länge von 100 m eine Beschleunigung von gut 2800 g auftreten würde. Das Problem tritt in vergleichbarer Form bekanntlich in der ersten "durchgerechneten" Mondreise auf, Jules Verne "De la terre á la lune"/"Autour de la lune" (1865/1870), wo Michel Ardan & Gefährten realiter das Abfeuern des Projektils mit Hilfe einer Kanone mit Kaliber XXL (Verne gibt die Geschützlänge mit exakt 274,3 m an) auch nicht heil überstehen würden.
"Les hommes seront toujours fous; et ceux qui croient les guérir sont les plus fous de la bande." - Voltaire
Zitat die Rede von "magnetischen Massenbeschleunigern" (magnetic mass drivers) war, um die auf dem Mond entweder geschürften Rohstoffe oder in automatisierten Fabriken gefertigten Satelliten in eine Erdumlaufbahn zu bringen. In Heinleins Roman gibt es zwei solcher Magnetstartbahnen
In Sachen "Raumfahrtkolonisierungspläne" ist das Konzept im Zusammenhang mit den L5-Plänen von Gerard K. O'Neill für "The High Frontier" aus der Mitte der 70er Jahre popularisiert worden, die vorsahen, das Baumaterial für seine gigantischen Raumkolonien an den Lagrange-Punkten (meist L5, L4 würde sich auch eignen), auf dem Mond zu schürfen und mit solchen Magnetbahnen zu starten. Zur Vorgeschichte des Konzepts in der Science Fiction:
Zitat Mass-Driver Catapult: An escape-speed induction catapult to launch material into orbit.
Zitat:Operation could not be secret. You can't buy or build a hydrogen-fusion power plant for such and not have it noticed. (Sunpower was rejected for obvious reasons.)... Can't build a stator for a kilometers-long induction field without having it noticed, either. But most important you cannot do major construction hiring many people and not have it show. Sure, catapults are mostly vacuum; stator rings aren't even close together at ejection end. But Authority's 3-g catapult was almost one hundred kilometers long. It was not only an astrogation landmark, on every Luna-jump chart, but was so big it could be photographed or seen by eye from Terra with not-large telescope. It showed up beautifully on a radar screen. We were building a shorter catapult, a 10-g job, but even that was thirty kilometers long, too big to hide... We hid it in literal sense, too; this catapult had to be underground, so that it would not show to eye or radar. But had to be hidden in more subtle sense; selenographic location had to be secret.
Location of that catapult is still most closely guarded secret in Luna. Can't be seen from space, by eye or radar. Is underground save for ejection and that is a big black shapeless hole like ten thousand others and high up an uninviting mountain with no place for a jump rocket to put down.
Technovelgy from The Moon is a Harsh Mistress, by Robert Heinlein. Published by GP Putnam in 1966
It turns out that hurling multi-ton cargo containers down to Earth has an alternative use during conflicts.
Prototype mass-drivers were first constructed in 1976. Mass Driver 1 was an early prototype mass driver. It consisted of a series of coils through which a small bucket would travel, pushed by the magnetic field of each coil as it was energized. It was created by Gerard K. O'Neill, Henry Kolm, and a variety of students at MIT. It was able to achieve accelerations of around 30Gs.
Compare to the earliest reference to the idea, the electric gun from Munro's 1897 novel A Trip to Venus.
See also the hybrid mass-driver from Robert Heinlein's 1950 novel The Man Who Sold The Moon and the Cyclotronic Ore-Hurler from "Exit From Asteroid 60" (1940) by D.L. James. Finally, take a look at a weaponized version of this idea, the stiletto beam from Arthur C. Clarke's 1955 novel Earthlight.
In John Munros "A Trip to Venus" wird das Konzept so umrissen:
Zitat I. "We could even have an electric gun. Conceive a bobbin wound with insulated wire in lieu of thread, and having the usual hole through the axis of the frame. If a current of electricity be sent through the wire, the bobbin will become a hollow magnet or 'solenoid,' and a plug of soft iron placed at one end will be sucked into the hole. In this experiment we have the germ of a solenoid cannon. The bobbin stands for the gun-barrel, the plug for the bullet-car, and the magnetism for the ejecting force. We can arrange the wire and current so as to draw the plug or car right through the hole or barrel, and if we have a series of solenoids end to end in one straight line, we can switch the current through each in succession, and send the projectile with gathering velocity through the interior of them all. In practice the barrel would consist of a long straight tube, wide and strong enough to contain the bullet-car without flexure, and begirt with giant solenoids at intervals. Each of the solenoids would be excited by a powerful current, one after the other, so as to urge the projectile with accelerating speed along the tube, and launch it into the vast."
G. "That looks still better than the pneumatic gun."
I. "A magnetic gun would have several advantages. For instance, the currents can be sent through the solenoids in turn as quickly as we desire by means of a commutator in a convenient spot, for instance, at the butt end of the gun, so as to follow up the bullet with ease, and give it a planetary flight. By a proper adjustment of the solenoids and currents, this could be done so gradually as to prevent a starting shock to the occupants of the car. The velocity attained by the car would, of course, depend on the number and power of the solenoids. If, for example, each solenoid communicated to the car a velocity of nine yards per second, a thousand solenoids, each magnetically stronger than another in going from breech to muzzle, would be required to give a final velocity of five miles a second. In such a case, the length of the barrel would be at least 1,000 yards. Economy and safety would determine the best proportions for the gun, but we are now considering the feasibility of the project, not its cost. With regard to position and supports, the gun might be constructed along the slope of a hill or mound steep enough to give it the angle or elevation due to the aim. As the barrel would not have to resist an explosive force, it should not be difficult to make, and the inside could be lubricated to diminish the friction of the projectile in passing through it. Moreover, it is conceivable that the car need never touch the sides, for by a proper adjustment of the magnetism of the solenoids we might suspend it in mid-air like Mahomet's coffin, and make it glide along the magnetic axis of the tube."
Zitat We hid it in literal sense, too ... But had to be hidden in more subtle sense
Die "Loonies" in Heinleins Roman sprechen eine ziemlich gewöhnungsbedürftige futuristische Variante der Englischen, die stark vom Russischen beeinflußt ist und etwa das Weglassen der Hilfsverben und der bestimmten und unbestimmten Artikel daraus übernimmt (wie in dem dummen Witz: "wenn du hast Frau mit Bart, kann sein ist Mann!") und zahlreiche Übernahmen daraus aufweist: "Lunaya Pravda," "stilyagi," "bog," "bolshoyeh thanks!" Die erste Lokalität, die genannt wird, im Kapitel 3: "I was booked for a hotel - Gostaneetsa Ukraina. I don't know where it is." Russisch: гости́ница, Ukrainisch гости́ниця, Gostinitsa/Hostinitsja, wörtlich das "Gasthaus", eben ein Hotel. Das erinnert natürlich sehr an das "Nadsat," das in Anthony Burgess' A Clockwork Orange (1962) gesprochen wird - und aus demselben Grund. Burgess hat im Juni und Juli 1961 mit seiner Frau Lynne eine Reise durch die UdSSR unternommen und sich dafür Anfangsgründe des Russischen beigebracht; Heinlein und seine Frau Virginia haben eine ähnliche Reise im April und Mai 1960 unternommen. Burgess hat seine Reiseimpressionen aus Leningrad beschrieben in "The Human Russians," The Listener, 28. Dezember 1961; Heinlein in "'Pravda' Means 'Truth'", The American Mercury, Oktober 1960.
"Les hommes seront toujours fous; et ceux qui croient les guérir sont les plus fous de la bande." - Voltaire
"Electromagnetic Launch of Lunar Material," William R. Snow and Henry H. Kolm
Zitat Lunar Oxygen Supply Concept
Various methods by which lunar oxygen could be delivered from the surface of the Moon to lunar orbit and on to LEO have been studied by a number of investigators (Clarke 1950; Salkeld 1966; Andrews and Snow 1981; Snow, Kubby, and Dunbar 1982; Davis 1983; Bilby et al. 1987; Snow et al. 1988; LSPI 1988). A diagram of the Earth-Moon system showing the orbits and missions for the lunar oxygen delivery concept that we recommend is shown in figure 12 [Lunar Oxygen Delivery Orbits and Missions].
The mission scenario starts with the launching of tanks containing 1 metric ton or more of liquid oxygen from an electromagnetic launcher (superconducting quenchgun) on the lunar surface into low lunar orbit (100km altitude), as shown in figures 13 [Lunar Launcher Mission] and 14 [Lunar-Based Superconducting Quenchgun]. When the tank reaches apolune (maximum altitude), a small thruster is fired to circularize its orbit and keep it from crashing back into the lunar surface. With a launch rate of one every 2 hours, the liquid oxygen tanks collect at one spot in lunar orbit. After a number of these tanks accumulate in orbit, they are recovered and the liquid oxygen is transferred to an aerobraked lunar ferry (shown in figure 15 [Aerobraked Lunar Ferry), which delivers it to low Earth orbit. This lunar ferry returns to lunar orbit, bringing back with it some liquid hydrogen. A lunar module returns the empty tanks to the lunar surface so that they can be reused. This lunar module as well as the lunar ferry is fueled by the liquid oxygen coming from the lunar surface and the liquid hydrogen brought back by the lunar ferry. With the empty tanks now back at the electromagnetic launcher site, the process repeats itself.
Electromagnetic Launcher History
The first reported effort to construct and test an electromagnetic launcher was that of Professor Kristian Birkeland at the University of Oslo in 1901 (Egeland and Leer 1986). He received the first world patent for. an electromagnetic gun and formed a company, "Birkeland's Firearms," to research and produce them. His largest gun, constructed in 1902, launched 10-kg iron projectiles. The barrel was 10 meters long with a bore of 6.5 centimeters and achieved projectile velocities of 80 to 100 meters per second. He envisioned building guns that would have ranges of 100 to 1000 km. He abandoned his efforts due to a lack of funds and his realization that there were no available pulsed power sources to operate his guns. This would continue to be the case for the next 70 years.
The next reported efforts were made by Professor Edwin F. Northrup at Princeton University in the 1930s (Northrup 1937). He constructed a number of electromagnetic launchers in the early 1930s. His launchers were linear three-phase induction motors (like their rotary counterparts), the same type as Birkeland's guns. He envisioned an ideal electromagnetic launcher in which only a small part of the barrel would be energized at any one time and the energized part would be synchronized with the passage of the projectile, thus minimizing heat losses and being more efficient. This idea required fast high-power opening and closing switches, which did not exist at that time. But the idea would later be used in the mass driver and other launcher designs (coilguns) of the 1970s. He also recognized the effect of magnetic levitation on the projectile; this magnetic force capable of centering the projectile would eliminate friction between the projectile and the barrel. This effect would also be used in the 1970s, with modifications, in the magnetically levitated (maglev) highspeed ground transportation vehicles.
As a variation on Jules Verne's approach, Northrup proposed using an electromagnetic launcher on the Earth to send a capsule with two people onboard on a trip around the Moon. In his book this was to have taken place in the early 1960s and under the condition of a race with Russia to get to the Moon first.
Die Referenz oben aus "Clark 1950" bezieht sich auf
Clarke, Arthur C. 1950. "Electromagnetic Launching as a Major Contribution to Space-Flight," J. British Interplanetary Soc. 9 (6) (November 1950): 261-267. Reprinted in Arthur C. Clarke, Ascent to Orbit: A Scientific Autobiography (New York: John Wiley & Sons, 1984).
"Les hommes seront toujours fous; et ceux qui croient les guérir sont les plus fous de la bande." - Voltaire
Clarkes Paper von 1950 kann hier nachgelesen werden:
Zitat Journal of the British Interplanetary Society - Vol. 9 No. 6 XXXVII November, 1950
ELECTROMAGNETIC LAUNCHING AS A MAJOR CONTRIBUTION TO SPACE-FLIGHT - By ARTHUR C. CLARKE, B.Sc.
The idea of using some form of ground-based launching system for spaceships, such as a very long electromagnetic accelerator, has often been suggested in the literature. There are two fundamental objections to such a device which make it very improbable that it will ever be used in practice to provide much of the escape energy from Earth, though it may well be used to get winged spaceships airborne. In the first place, a body moving at anything like escape velocity in the lower atmosphere would be rapidly destroyed by friction (note that the extreme nose of a V.2 became red-hot at about 2,000 m.p.h., and as escape velocity is 25,000 m.p.h. the heating would be at least 100 times as great). This could be only partly reduced even if the launcher was built on the highest mountain.
A second equally serious objection is raised by the impossibility of using very high accelerations for manned spaceships. Even if we assume that 10 g. could be tolerated by a properly protected crew, the launcher would have to be no less than 600 kilometres in length, and proportionately longer if lower accelerations were used. It is, therefore, obvious that an accelerating device of any practicable length could provide only a very small part of the total velocity needed to escape from Earth, and that at such vast expense and inconvenience that the whole job would be better done by rockets.
This is particularly unfortunate, for an electromagnetic launcher or catapult would have great advantages, the most important of which arise from the fact that the energy of take-off would be provided by fixed and not mobile power-plants. Such a system is fundamentally more efficient than any arrangement using rockets, where the greater part of the fuel is required merely to accelerate more fuel, and therefore, in a sense, does no useful work at all. Electrical energy, on the other hand, possesses no mass and so it requires no extra power to apply it to a body in motion. ... The Moon’s low escape velocity (2:3 km./sec. as against 11-2 km./sec. for the Earth, with a consequent reduction of kinetic energy per unit mass to 1 /20), and its virtual absence of atmosphere, make it an ideal site for an accelerator. If we are considering only the projection of fuel supplies, and not manned space-ships, then large accelerations can be employed, and the launching track need be only a few kilometres long. At 100 g, for instance, escape velocity would be reached in a distance of less than 3 km., and a gently rising track of this length must be regarded as a reasonable engineering proposition. (It could even be horizontal if it was constructed on a plateau or open plain with no mountains in the line of sight.) The operation and technical characteristics of such a system will now be investigated. ... If a constant acceleration of 100 g were used, this speed would be attained after 2 seconds and in a distance of 2 km. 100 g is quite a modest acceleration — artillery shells experience accelerations of the order of 10,000 g, which would give circular velocity in 20 metres! However, power and constructional problems would be more easily met if values of not more than 100 g were utilised.
To give a mass of 1 tonne a velocity of 2 km./sec. would require the expenditure of 2 x 10! ergs, or 2 x 10° joules—an average power, over 2 seconds, of 1,000,000 kW. With the use of a uniform acceleration, the power required would rise linearly from zero to 2,000,000 kW at the end of the 2 seconds. (Fig. 1.) It must be realised, however, that there would be no need to build electric generators with a continuous rating of anything like this value. All the energy required for a “‘shot’’ would be stored up—perhaps over several hours—by bringing large flywheels up to speed and then coupling them to generators designed to deliver high currents for very short periods, and hence capable of withstanding enormousoverloads. (This was the technique used by Kapitza at the Mond Laboratory to obtain very intense magnetic fields for his experiments in low-temperature physics.) ... In principle, therefore, if we assume that in due course it is possible to set up a self-supporting lunar colony, and that all the normal minerals can be found on the Moon; it would appear possible to establish large fuel reserves in space almost entirely by means of electrical energy. One could imagine the setting up of an orbital satellite, at a height of a few thousand kilometres, whose task it would be to collect the fuel carriers as they were propelled upwards into its orbit. (It might be equipped with a number of small tanker rockets whose duty it was to make the transfer, thus obviating the need for any propulsive mechanism in the carriers.) It is hardly necessary to point out that some care would be needed to avoid “shooting-up”’ the space-station! The high degree of control possible with an electric launcher would help to avoid such unfortunate accidents.
The possibilities opened up by a moon-based launcher are by no means exhausted here. Dynamical considerations indicate that to project a body from the Moon into an orbit round the Earth requires only about 20 percent more initial velocity than to project it into a path around the Moon. Hence spaceships after take-off from the Earth could be refuelled more economically from lunar sources than from the planet only a few hundred kilometres below. This would certainly involve severe problems in missile control, but little expenditure of rocket power. If this technique becomes feasible, then the problem of Earth-Moon travel is enormously simplified. No spaceship need ever be designed for any mission more difficult than the entry of a circular orbit round the Earth, since refuelling would be possible both in circum-terrestrial and circum-lunar orbits. The total amount of propellant required would be reduced to a small fraction of that needed if rocket power was used exclusively, for if sub-orbital techniques were employed as normally envisaged, colossal quantities of propellant would still be required to get small amounts of fuel into position.
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Das Problem tritt in vergleichbarer Form bekanntlich in der ersten "durchgerechneten" Mondreise auf, Jules Verne "De la terre á la lune"/"Autour de la lune" (1865/1870), wo Michel Ardan & Gefährten realiter das Abfeuern des Projektils mit Hilfe einer Kanone mit Kaliber XXL (Verne gibt die Geschützlänge mit exakt 274,3 m an) auch nicht heil überstehen würden.