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Ehricke
Kraft Ehricke posing with spacecraft models in 1957, the same year he wrote a memo about tradeoffs among missiles and other long-range weapons concepts. (credit: San Diego Air and Space Museum Archives)

Satellite bombs, gliders, or ICBMs? Krafft Ehricke and early thinking on long-range strategic weapons


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During recent historical research at the National Air and Space Museum (NASM) Archives, I located a document as part of the Krafft Ehricke Papers titled “Basic Analysis of Global Weapon Systems & Space Weapon Systems” from 1957.[1] At that time, ICBMs were still under development and satellites had not yet flown. There were questions on how to achieve the best deterrence to protect the United States. There were even questions regarding whether and how to position nuclear bombs in orbit. This newly discovered memo provides an interesting perspective on these issues.

Although he emphasized the Moon and space for peaceful exploration and colonization later in his career, the 1957 memo clearly shows that Ehricke was no stranger to the military implications of rockets, space gliders, and space stations.

When the Soviet Union launched Sputnik in 1957, existing United States rocketry and high-altitude airplane work went into high gear.[16-18] Even before Sputnik, to innovate and stay ahead, the Air Force started a series of studies in the late 1950s by Air Force contractors about basing nuclear weapons in space. They were titled the System Requirement (SR) studies. Coordinated by the Air Research and Development Command (ARDC), the Air Force made essentially no restrictions on the content of the SR studies. More than six decades later, the SR studies remain classified and only their titles and minimal content is known.[8-12]

The memo discussed below is dated just before the Sputnik launch, preceding the Air Force SR studies by about a year. This memo was authored by Krafft Ehricke at Convair, a company working on Atlas rockets, and gives us some new insights in US Air Force thinking as well as nuclear deterrence in the late 1950s and the crossover between civilian and military spaceplanes. Ehricke’s memo is similar to SR-181, titled the “Strategic Earth System” or “Strategic Orbital System.”[8]

Krafft A. Ehricke was an American engineer and scientist, born 1917 in Germany.[2] Like many Nazi German rocket scientists during World War II, such as Wernher Von Braun, Walter Dornberger, and Ernst Stuhlinger, he came to America in 1946 via Operation Paperclip. Ehricke’s romantic interest in space seems to go back to Jules Verne and the 1929 movie Frau im Mond.

His German heritage is relevant here as these ex-German scientists knew each other and shared many rocket ideas and other space inspiration from before World War II. They were also aware of other German designs such as the Silverbird (Silbervogel) bomber. The Silverbird design by Eugen Sänger from the 1930s was meant to bomb the United States from Germany while skipping on the upper atmosphere at the edge of space.

By 1952, Ehricke worked on Bell’s Orbital Glider project with Dornberger. In 1954, he joined the Convair Division of General Dynamics for about a decade, where he was a key engineer on the Atlas rocket and Centaur upper stage, working with Karl Bossart on Atlas.[5] Other contributions by Ehricke include a four-man orbital station concept in 1954, the General Dynamics studies of early manned planetary-interplanetary roundtrip expedition (EMPIRE) to Mars and Venus in 1962, project Orion, as well as other space commercialization studies. Although he emphasized the Moon and space for peaceful exploration and colonization later in his career, the 1957 memo clearly shows that Ehricke was no stranger to the military implications of rockets, space gliders, and space stations.

At the same time, the US Army was working in the 1950s with Wernher von Braun on V-2 rocket derivatives as well as other military space applications. As historian Michael J. Neufeld writes, “Yet the centerpiece of Wernher von Braun’s plan was a manned space station that would serve as reconnaissance platform and orbiting battle station for achieving ‘space superiority’ over the USSR. One of its roles could be the launching of nuclear missiles.”[13] The Army even reached for the Moon via the “Horizon lunar outpost” study in 1959. It is known that von Braun talked sometimes with Karl Bossart at Convair.[13] Bossart is also on the distribution list of the memo discussed below.

While Gen. Curtis LeMay pushed the Air Force for “faster and higher bombers,” Gen. Henry (Hap) H. Arnold pushed the Air Force for more innovation, to look into the future, and said, “The Third World War will be different. It will be won by brains.”[14] Gen. Bernard Schriever was recruited as liaison between the Air Force and civilian scientists, such as from MIT, working on Air Force projects.[6,14] From about 1953, it became clear to Schriever that hydrogen bombs of rapidly decreasing weight could be delivered by rockets from the US mainland and he became heavily involved with Air Force’s strategic missile projects.

Ehricke used the word “satelloid” as well as “satellite”. The term “satelloid” was introduced by him in 1955, and designates a powered vehicle—half airplane, half spaceship—with sustained thrust that operates in circular orbits roughly between 100 to 200 kilometers.

As Schriever became head of the newly created Western Development Division (WDD) to manage the ICBM development effort, he was close to Convair and managed the Atlas rocket project, where Ehricke was working as well. Schriever was assistant to the commander of ARDC from 1954 to 1957 and deputy commander for ballistic missiles at ARDC starting in 1958.[7,14] At the same time, Gen. Marvin C. Demler was a colleague and appointed deputy commander for ARDC research and development in 1956.[3]

While there is no direct evidence that Ehricke and Schriever knew each other personally, they must have known each other indirectly via the Atlas work and Jim Dempsey at Convair. The memo discussed below shows that Ehricke and Demler knew each other, which is supported by the fact that Ehricke visited ARDC in October 1957.[2]

The memo is titled “Basic Analysis of Global Weapon Systems and Space Weapon Systems” by K.A. Ehricke, dated June 21, 1957. Ehricke was employed by Convair at the time. The memo bears an identification ASM-1. According to a designation list,[15] ASM relates to “Guided Air-launched Missile (ASM)”. The memo is 50 pages long, of which 20 are text, plus tables, plots, and images. The timing is significant as this is a few months before the launch of Sputnik on October 4, 1957.

It is unclear why the memo is not more widely known in context of the early Air Force spaceflight but it might simply be because Ehricke was a prolific writer and the sheer volume of his papers at NASM might have been a reason that is was overlooked.[1]

Ehricke wrote, “Presently we are developing at great cost to the taxpayer two ICBM systems representing two philosophies of design.”[1] (page 7). However, he cautions about building a “bigger” ICBM as the state of the art is changing very fast with respect to manned gliders and nuclear propulsion. “In view of the fluidity of the present R & D situation, these questions cannot be answered readily. However, another approach can be taken immediately and indications are that this is being favored by the Air Force now and in the next few years (‘think-period’).” This quote looks like a prediction for the Air Force SR studies that started a year later.

Schreiver and Dempsey
Gen. Bernard Schriever (second from left) and Convair’s James Dempsey (third from left) at a 1965 event, from a 1965 General Dynamics corporate newsletter. (credit: Archive.org)

The memo is prefaced by a handwritten note from Ehricke saying, “Jim, I appreciate your comments on this memo, particularly in the light of Marvin’s request. Krafft.” This handwritten note has a stamp “Received, Jul 1st 1957, J.R. Dempsey.”

Jim or James Dempsey headed the development of the Atlas missile at Convair. As one bio of him states, “In 1953, then-Colonel Dempsey was recommended by government insiders as an ideal manager for the not-yet official intercontinental ballistic missile program.”[4] “This mammoth project, with 30,000 people at Convair, and another 60,000 at subcontractors, simultaneously developed all-new rocket and guidance technologies, while designing, building, and commissioning 133 missile launch sites at eleven bases spread across the continental United States.” Dempsey was Ehricke’s boss at Convair. Based on his Convair work, Jim Dempsey was in touch with various Air Force leaders.

The identity of “Marvin” is not entirely clear, but it seems likely that he was Gen. Marvin C. Demler, deputy commander at ARDC at the time. This is supported by a secondary source that stated Ehricke visited ARDC headquarters in October 1957, though it is not clear where that particular item is sourced from.[2] From a timing perspective, that is a great match for the handwritten note prefacing the memo.

Ehricke at Convair was talking actively with Bossart, Dempsey, and ARDC, and the memo went to Convair personnel who had good contacts with the Air Force and ARDC.

The memo starts with a summary that states, “The results of a basic comparative study of global weapon systems (GWS) and space weapon systems (SWS) are presented. Among the GWS the three basic delivery methods, ballistic, glide and satelloidal delivery are considered.”

Ehricke used the word “satelloid” as well as “satellite”. The term “satelloid” was introduced by him in 1955 with his awarded presentation titled “The Satelloid” at the IAF 6th International Astronautical Congress in Copenhagen.[19] A satelloid designates a powered vehicle—half airplane, half spaceship—with sustained thrust that operates in circular orbits roughly between 100 to 200 kilometers where there is still a noticeable atmospheric drag. That region is too high for gliders and too low for satellites. The motion under power is the significant difference compared to a satellite.

On top of the comparison of delivery systems, the memo discusses accuracy, aerodynamic heating, range, growth potential, versatility, reliability, detectability, and potential obsolescence and development efforts. These discussions are summarized in two insightful tables. The abbreviation space weapon system (SWS) is unseen in other contemporary reports, which seems to indicate that Ehricke was putting his personal thoughts on the matter into this memo.

Ehricke wrote that “the purpose of this memorandum is to present a number of basic facts relevant to the different systems so that their salient features and, hence, relative merits can be appraised more readily.” This is followed by definitions of the GWS as “technical means of delivering a warhead to any or almost any point of the Earth from the zone of the interior of the continental United States” and SWS as “technical means of warfare from or in space. Emphasis lies here on the fact that the system is and stays spaceborne in the course of its missions.” Then GWS and SWS are then combined into an Advanced Weapon System (AWS) classification, which is either manned or unmanned.

On the side of the SWS, a distinction is made between reconnaissance, bombing, psychological warfare, missile guidance, and electronic countermeasure satellites, all very similar to today’s classifications.

The “psychological warfare” aspect for satellites is a novel aspect though and related to deterrence and overflight. Today, this seems wild and outlandish, but it was considered in the 1950s. “An important factor in spreading confusion and destroying morale can be satellite-transmitted enemy warnings to certain areas predicting nuclear attacks and calling for evacuation. In many other ways the population can be confused and demoralized by satellite-borne messages,” Ehricke wrote.

On the topic of reconnaissance satellites, Ehricke wrote, “Reconnaissance type (a a) can well be done from altitudes around 300 n. mi. The ARS project by Lockheed represents a typical mapping satellite.” ARS probably referred to “Advanced Reconnaissance System.” [18] (page 46)

The comparison of a manned satelloid versus a manned glider seems a bit like a prediction of the demise of Dyna-Soar.

On the topic of why satellites are useful for missile guidance and terminal approach, Ehricke wrote, “The main reason why it appears attractive is its capability of ‘seeing’ the target as the missile approaches it and therefore conceivably being capable of correcting the missile’s path of its approach is found to be inaccurate (terminal guidance).”

As mentioned earlier, Ehricke must have been familiar with the ideas of a glider or spaceplane, including the early “Silbervogel” studies in Germany, the ideas by his previous boss Walter Dornberger at Bell, the X-15, and the early manned space bomber known as a “Hypersonic Strategic Weapon System,” aka X-20 Dyna-Soar.

Ehricke wrote about manned and unmanned gliders as only one type of delivery vehicles for nuclear bombs. Long comparisons between the satelloid, ballistic, and gliders followed for all missions mentioned earlier for SWS. The glider was perceived as a versatile vehicle but he identifies challenges: “The unmanned glider is inherently a complex weapon system, because it has to cope with the not readily predictable effects of chemospheric and stratospheric dynamics and with the velocity-dependent and density-dependent aerodynamic characteristics of control surfaces in hypersonic flow.” He added, “For gliders and satelloids the accuracy is, in principle, independent of range.” In other words, the atmosphere was a hindrance in the accuracy of delivering bombs.

Ehricke seemed to prefer manned delivery systems over unmanned, probably because the computers of the 1950s were in their infancy. He also stated that gliders required significant development.

Ehricke stated that the ICBM was the “best option right now” at the time the memo was written. Ehricke believed that ICBMs ranked high for state-of-the-art utilization and reliability. However, ICBMs were perceived as easy to track. On accuracy, range, and growth potential, satelloids and gliders were judged to be superior to ICBMs. Due to its maneuverability, an unmanned glider was seen as hardest to detect, which relates to contemporary discussion decades later regarding hypersonics and fractional orbital bombardment systems (FOBS).

Ehricke’s conclusion was that in comparison of the delivery mechanisms, ballistic, glide, and satelloid had the same number of good features but differed in the number of disadvantages or problems, especially for non-manned gliders and ballistic. Therefore, the satelloid delivery appeared relatively most attractive. Also, a manned satelloid seemed more attractive than a manned glider. ICBMs won in this development race of weapon systems, probably because it was seen advantageous and more versatile to host them in the United States on the ground.

The comparison of a manned satelloid versus a manned glider seems a bit like a prediction of the demise of Dyna-Soar. Ehricke also exhibited a preference for rocket programs with capsules. He wrote that “capsules can be fired into low altitude orbits, using essentially ICBM hardware presently under development.”

Ehricke’s memo preceded the Air Force SR studies and is a thorough analysis of ballistic versus orbital weapon systems.[1,8–14] The summary Tables 1 and 2 are insightful and more complete than other known topical documents from that era. However, it is clearly a product of the 1950s, when computers were in their infancy and when space-based 24/7 Earth observation early warning satellites were a distant dream of the future. The memo is a snapshot in time for historians.

Presumably, the memo would have gone from the head of Convair/Atlas, Jim Dempsey, to ARDC personnel such as Gen. Demler and Gen. Schriever, and served as a precursor to the Air Force SR studies. Ehricke wrote, “The analysis of the SWS is to be continued in a second memorandum.” However, that second memo remains unseen and could be hiding elsewhere in the archives. Based on Ehricke’s knowledge, one question that comes to mind is whether the second memo would also cover nuclear weapons on the Moon like some of the SR studies. Archival research continues and more chapters will undoubtedly follow in future.

In conclusion, the memo sheds some new light on the development of nuclear deterrence in the 1950s and 1960s, the tradeoff between nuclear weapons in space versus on the ground, ICBMs versus satellites and gliders, the people involved, and the thinking of one of the brightest space engineers in the United States at the time.

References

  1. Krafft A. Ehricke Papers, Accession 2003-0025, National Air and Space Museum (NASM), Smithsonian Institution, Box 4, Folder 1 and 2, “Basic Analysis of Global Weapon Systems & Space Weapon Systems” (Ehricke to Distribution; Convair Memo ASM-1, 21 Jun 1957)
  2. Ehricke, Krafft Arnold
  3. Maj. Gen. Marvin C. Demler
  4. Dempsey, James Raymon
  5. Bossart, Karel
  6. “Bernard Schriever and Early US Military Spaceflight”, Wing Commander Gerry Doyle RAF October 2016
  7. Appointment of General B.A. Schriever as a Member of the National Commission on Space
  8. “SR-181 Strategic orbital System”, AD-337 659L 3-4-2 DIV. 18A, NTRS 19660089145, volume i final report, 1961
  9. “SR-182 Strategic Interplanetary System”, AD-340 765 3-4-5 DIV. 22A, NTRS 19640058204 volume 1 final report, 1960
  10. “USAF Explores Strategic Space Plans”, Aviation Week, Sep 28, 1959
  11. “Take off and nuke the site from orbit (it’s the only way to be sure…)”, Dwayne A. Day, The Space Review, June 2007.
  12. “Nuking the site from orbit: when the Air Force wanted a base on the Moon”, Dwayne A. Day, The Space Review, November 2019.
  13. “Space superiority: Wernher von Braun’s campaign for a nuclear-armed space station, 1946–1956”, Michael J. Neufeld, Space Policy 22 (2006) 52–62
  14. A Fiery Peace in a Cold War: Bernard Schriever and the Ultimate Weapon, Neil Sheehan, 2009, ISBN 0679422846
  15. Designation List
  16. Boeing X-20 Dyna-Soar
  17. Museum Pieces: Dyna-Soar
  18. “AN AIR FORCE HISTORY OF SPACE ACTIVITIES 1945 - 1959”, L. Bowen, SHO-C-64/ 50, AFD-110321-031, USAF Historical Division, August 1964.
  19. “The Satelloid”, IAF 6th International Astronautical Congress, Copenhagen, 1–6 August 1955, published in Astronautica Acta, Vol. 2, No. 2, 1956, pp. 63–100 and Aero Digest, Vol. 73, pp 46-48,50,52,54, July 1956.

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