In this article I have put together a collection of information in regard to the technology of the 1960s. Many people believe that it was technologically impossible to get a manned spacecraft to land on the Moon and return to Earth safely. Before Apollo 11 there were attempts to land probes on the Moon to gather images and soil samples – some were successful. These probes were very much smaller than the Apollo Lunar Landing modules.

Computer technology used onboard the LMs was very limiting compared with today’s standards. However, IBM had a fast growing technological industry dealing with mainframe computers. These very large machines could easily have been used to predict flight paths to, and landings on, the Moon’s Surface. So the argument about computer power must really be centred on the rope memory computers used in the LMs and not overall computing technology in the 1960s.

It’s Just Rocket Science


World War II 

A German V-2 rocket on a Meillerwagen

Layout of a V-2 rocket

In 1943, production of the V-2 rocket began in Germany. It had an operational range of 300 km (190 mi) and carried a 1,000 kg (2,200 lb) warhead, with an amatol explosive charge. It normally achieved an operational maximum altitude of around 90 km (56 mi), but could achieve 206 km (128 mi) if launched vertically. The vehicle was similar to most modern rockets, with turbopumps, inertial guidance and many other features. Thousands were fired at various Allied nations, mainly Belgium, as well as England and France. While they could not be intercepted, their guidance system design and single conventional warhead meant that it was insufficiently accurate against military targets. A total of 2,754 people in England were killed, and 6,523 were wounded before the launch campaign was ended. There were also 20,000 deaths of slave labour during the construction of V-2s. While it did not significantly affect the course of the war, the V-2 provided a lethal demonstration of the potential for guided rockets as weapons.[67][68]

In parallel with the guided missile programme in Nazi Germany, rockets were also used on aircraft, either for assisting horizontal take-off (RATO), vertical take-off (Bachem Ba 349″Natter”) or for powering them (Me 163,[69] etc.). During the war Germany also developed several guided and unguided air-to-air, ground-to-air and ground-to-ground missiles (see list of World War II guided missiles of Germany).

The Allies rocket programs were much less sophisticated, relying mostly on unguided missiles like the Soviet Katyusha rocket.

Post World War II 

Dornberger and Von Braun after being captured by the Allies

R-7 8K72 “Vostok” permanently displayed at the Moscow Trade Fair at Ostankino; the rocket is held in place by its railway carrier, which is mounted on four diagonal beams that constitute the display pedestal. Here the railway carrier has tilted the rocket upright as it would do so into its launch pad structure — which is missing for this display.

At the end of World War II, competing Russian, British, and US military and scientific crews raced to capture technology and trained personnel from the German rocket program at Peenemünde. Russia and Britain had some success, but the United States benefited the most. The US captured a large number of German rocket scientists, including von Braun, and brought them to the United States as part of Operation Paperclip.[70] In America, the same rockets that were designed to rain down on Britain were used instead by scientists as research vehicles for developing the new technology further. The V-2 evolved into the American Redstone rocket, used in the early space program.[71]

After the war, rockets were used to study high-altitude conditions, by radio telemetry of temperature and pressure of the atmosphere, detection of cosmic rays, and further research; notably the Bell X-1, the first manned vehicle to break the sound barrier. This continued in the US under von Braun and the others, who were destined to become part of the US scientific community.

Independently, in the Soviet Union’s space program research continued under the leadership of the chief designer Sergei Korolev.[72] With the help of German technicians, the V-2 was duplicated and improved as the R-1, R-2 and R-5 missiles. German designs were abandoned in the late 1940s, and the foreign workers were sent home. A new series of engines built by Glushko and based on inventions of Aleksei Mihailovich Isaev formed the basis of the first ICBM, the R-7.[73] The R-7 launched the first satellite- Sputnik 1, and later Yuri Gagarin-the first man into space, and the first lunar and planetary probes. This rocket is still in use today. These prestigious events attracted the attention of top politicians, along with additional funds for further research.

One problem that had not been solved was atmospheric reentry. It had been shown that an orbital vehicle easily had enough kinetic energy to vaporize itself, and yet it was known that meteorites can make it down to the ground. The mystery was solved in the US in 1951 when H. Julian Allen and A. J. Eggers, Jr. of the National Advisory Committee for Aeronautics(NACA) made the counterintuitive discovery that a blunt shape (high drag) permitted the most effective heat shield. With this type of shape, around 99% of the energy goes into the air rather than the vehicle, and this permitted safe recovery of orbital vehicles.[74]

The Allen and Eggers discovery, initially treated as a military secret, was eventually published in 1958.[75] Blunt body theory made possible the heat shield designs that were embodied in the Mercury, Gemini, Apollo, and Soyuz space capsules, enabling astronauts and cosmonauts to survive the fiery re-entry into Earth’s atmosphere. Some spaceplanes such as the Space Shuttle made use of the same theory. At the time the STS was being conceived, Maxime Faget, the Director of Engineering and Development at the Manned Spacecraft Center, was not satisfied with the purely lifting re-entry method (as proposed for the cancelled X-20 “Dyna-Soar”).[76] He designed a space shuttle which operated as a blunt body by entering the atmosphere at an extremely high angle of attack of 40°[77] with the underside facing the direction of flight, creating a large shock wave that would deflect most of the heat around the vehicle instead of into it.[78] The Space Shuttle essentially uses a combination of a ballistic entry (Blunt body theory) and then at an altitude of about 122,000 m (400,000 ft), the re-entry interface takes place. Here the atmosphere is dense enough for the Space Shuttle to begin its lifting re-entry by reducing the angle-of-attack, pointing the nose down and using the lift its wings generate to “start flying” (gliding) towards the landing site.[79]

Prototype of the Mk-2 Reentry Vehicle (RV), based on blunt body theory

Cold War 

French Diamant rocket, the second French rocket program, developed from 1961[80]

Rockets became extremely important militarily as modern intercontinental ballistic missiles (ICBMs) when it was realized that nuclear weapons carried on a rocket vehicle were essentially impossible for existing defense systems to stop once launched, and ICBM/Launch vehicles such as the R-7, Atlas and Titan became the delivery platform of choice for these weapons.

Von Braun’s rocket team in 1961

Fueled partly by the Cold War, the 1960s became the decade of rapid development of rocket technology particularly in the Soviet Union (Vostok, Soyuz, Proton) and in the United States (e.g. the X-15[81] and X-20 Dyna-Soar[82] aircraft). There was also significant research in other countries, such as France, Britain, Japan, Australia, etc., and a growing use of rockets for Space exploration, with pictures returned from the far side of the Moon and unmanned flights for Mars exploration.

In America the manned programmes, Project Mercury, Project Gemini and later the Apollo programme culminated in 1969 with the first manned landing on the moon via the Saturn V, causing the New York Times to retract their earlier editorial implying that spaceflight couldn’t work:

Further investigation and experimentation have confirmed the findings of Isaac Newton in the 17th century and it is now definitely established that a rocket can function in a vacuum as well as in an atmosphere. The Times regrets the error.

— New York Times, 17 June 1969 – A Correction[83]

In the 1970s America made further lunar landings, before cancelling the Apollo program in 1975. The replacement vehicle, the partially reusable ‘Space Shuttle’ was intended to be cheaper,[84] but this large reduction in costs was not achieved. Meanwhile, in 1973, the expendable Ariane programme was begun, a launcher that by the year 2000 would capture much of the geosat market[Wikipedia_1].

Saturn V

[Wikipedia_2]From Wikipedia, the free encyclopedia



List of lunar probes

From Wikipedia, the free encyclopedia

Surveyor 3 on the Moon.

This is a list of space probes that have flown by, impacted, or landed on the Moon for the purpose of lunar exploration, as well as probes launched toward the Moon that failed to reach their target. Confirmed future probes are included, but missions that are still at the concept stage, or which never progressed beyond the concept stage, are not.

The list does not include the manned Apollo missions.


Lunar probes by date 


Spacecraft Organization Date Type Status Notes Image Ref
Pioneer 0 United States DOD 17 August 1958 orbiter failure first attempted launch beyond Earth orbit; launch vehicle failure; maximum altitude 16 km Pioneer able.png [2]
Luna E-1 No.1 Soviet Union USSR 23 September 1958 impactor failure launch vehicle failure [3]
Pioneer 1 United States NASA/
No image.svg DOD
11 October 1958 orbiter failure second stage premature shutdown; maximum altitude 113,800 km; some data returned Pioneer I on the Launch Pad - GPN-2002-000204.jpg [4]
Luna E-1 No.2 Soviet Union USSR 12 October 1958 impactor failure launch vehicle failure [5]
Pioneer 2 United States NASA/
No image.svg STL
8 November 1958 orbiter failure third stage failure; maximum altitude 1,550 km; some data returned Pioneer able.png [6]
Luna E-1 No.3 Soviet Union USSR 4 December 1958 impactor failure launch vehicle failure [7]
Pioneer 3 United States NASA/
No image.svg DOD
6 December 1958 flyby failure fuel depletion; maximum altitude 102,360 km; some data returned Pioneer-3-4.gif [8]
Luna 1 Soviet Union USSR 4 January 1959 flyby partial success first spacecraft in the vicinity of the Moon (flew within 5,995 km, but probably an intended impactor) [9]
Luna E-1A No.1 Soviet Union USSR 18 June 1959 impactor failure failed to reach Earth orbit Luna 2 Soviet moon probe.jpg [10]
Pioneer 4 United States NASA/
No image.svg DOD
4 March 1959 flyby partial success achieved distant flyby; first US probe to enter solar orbit Pioneer-3-4.gif [11]
Luna 2 Soviet Union USSR 14 September 1959 impactor success first impact on Moon Luna 2 Soviet moon probe.jpg [12]
Pioneer P-1 United States NASA 24 September 1959? orbiter? failure designation sometimes given to a failed launch or launchpad explosion during testing; conflicting information between sources Pioneer-5.jpg
Luna 3 Soviet Union USSR 6 October 1959 flyby success first images from the lunar farside Lunik 3.jpg [13]
Pioneer P-3 United States NASA 26 November 1959 orbiter failure disintegrated shortly after launch Pioneer-5.jpg [14]
Luna 1960A Soviet Union USSR 15 April 1960 flyby failure failed to attain correct trajectory Lunik 3.jpg [15]
Luna 1960B Soviet Union USSR 16 April 1960 flyby failure launch vehicle failure Lunik 3.jpg [16]
Pioneer P-30 United States NASA 25 September 1960 orbiter failure second stage failure; failed to reach Earth orbit Pioneer-5.jpg [17]
Pioneer P-31 United States NASA 15 December 1960 orbiter failure first stage failure Pioneer-5.jpg [18]


Spacecraft Organization Date Type Status Notes Image Ref
Ranger 3 United States NASA 28 January 1962 impactor failure missed target 1964 71392L.jpg [19]
Ranger 4 United States NASA 26 April 1962 impactor failure hit the lunar farside; no data returned 1964 71394L.jpg [20]
Ranger 5 United States NASA 21 October 1962 impactor failure power failure, missed target 1964 71395L-Ranger.svg [21]
Sputnik 25 Soviet Union USSR 5 January 1963 lander failure failed to escape Earth orbit [22]
Luna 1963B Soviet Union USSR 2 February 1963 lander? failure failed to reach Earth orbit [23]
Luna 4 Soviet Union USSR 5 April 1963 lander? failure missed target, became Earth satellite [24]
Ranger 6 United States NASA 2 February 1964 impactor partial success impacted, but no pictures returned due to power failure The Ranger Spacecraft GPN-2000-001979.jpg [25]
Luna 1964A Soviet Union USSR 21 March 1964 lander failure failed to reach Earth orbit [26]
Luna 1964B Soviet Union USSR 20 April 1964 lander failure failed to reach Earth orbit [27]
Ranger 7 United States NASA 31 July 1964 impactor success returned pictures until impact The Ranger Spacecraft GPN-2000-001979.jpg [28]
Ranger 8 United States NASA 20 February 1965 impactor success returned pictures until impact The Ranger Spacecraft GPN-2000-001979.jpg [29]
Cosmos 60 Soviet Union USSR 12 March 1965 lander failure failed to leave Earth orbit [30]
Ranger 9 United States NASA 24 March 1965 impactor success TV broadcast of live pictures until impact The Ranger Spacecraft GPN-2000-001979.jpg [31]
Luna 1965A Soviet Union USSR 10 April 1965 lander? failure failed to reach Earth orbit? [32]
Luna 5 Soviet Union USSR 12 May 1965 lander failure crashed into Moon [33]
Luna 6 Soviet Union USSR 8 June 1965 lander failure missed Moon [34]
Zond 3 Soviet Union USSR 20 July 1965 flyby success possibly originally intended as a Mars probe, but target changed after launch window missed [35]
Luna 7 Soviet Union USSR 7 October 1965 lander failure crashed into Moon [36]
Luna 8 Soviet Union USSR 6 December 1965 lander failure crashed into Moon [37]


Spacecraft Organization Date Type Status Notes Image Ref
Luna 9 Soviet Union USSR 3 February 1966 –
6 February 1966
lander success first soft landing; first images from the surface [38]
Cosmos 111 Soviet Union USSR 1 March 1966 orbiter failure failed to escape Earth orbit Luna-10.jpg [39]
Luna 10 Soviet Union USSR 3 April 1966 –
30 May 1966
orbiter success first artificial satellite of the moon Luna-10.jpg [40]
Luna 1966A Soviet Union USSR 30 April 1966 orbiter? failure failed to reach Earth orbit Luna-10.jpg [41]
Surveyor 1 United States NASA 2 June 1966 lander success first US soft landing; Surveyor program performed various tests in support of forthcoming manned landings Surveyor NASA lunar lander.jpg [42]
Explorer 33 United States NASA 1 July 1966 –
15 September 1971
orbiter partial success studied interplanetary plasma, cosmic rays, magnetic fields and solar X rays; failed to attain lunar orbit as intended, but achieved mission objectives from Earth orbit IMP-D.jpg [43]
Lunar Orbiter 1 United States NASA 14 August 1966 –
29 October 1966
orbiter success photographic mapping of lunar surface; intentionally impacted after completion of mission Lunar orbiter 1 (large).jpg [44]
Luna 11 Soviet Union USSR 28 August 1966 –
1 October 1966
orbiter success gamma-ray and X-ray-based observations of Moon’s composition; gravity, radiation and meteorite studies [45]
Surveyor 2 United States NASA 23 September 1966 lander failure crashed into Moon Surveyor NASA lunar lander.jpg [46]
Luna 12 Soviet Union USSR 25 October 1966 –
19 January 1967
orbiter success lunar surface photography [47]
Lunar Orbiter 2 United States NASA 10 November 1966 –
11 October 1967
orbiter success photographic mapping of lunar surface; intentionally impacted after completion of mission Lunar orbiter 1 (large).jpg [48]
Luna 13 Soviet Union USSR 24 December 1966 lander success TV pictures of lunar landscape; soil measurements [49]
Lunar Orbiter 3 United States NASA 8 February 1967 –
9 October 1967
orbiter success photographic mapping of lunar surface; intentionally impacted after completion of mission Lunar orbiter 1 (large).jpg [50]
Surveyor 3 United States NASA 20 April 1967 –
4 May 1967
lander success various studies, primarily in support of forthcoming manned landings Surveyor 3 on the Moon.jpg [51]
Lunar Orbiter 4 United States NASA May–October 1967 orbiter success lunar photographic survey Lunar orbiter 1 (large).jpg [52]
Explorer 35 United States NASA July 1967 –
24 June 1973
orbiter success studies of interplanetary plasma, magnetic fields, energetic particles and solar X rays IMP-E.jpg [53]
Surveyor 4 United States NASA 17 July 1967 lander failure crashed into Moon Surveyor NASA lunar lander.jpg [54]
Lunar Orbiter 5 United States NASA 5 August 1967 –
31 January 1968
orbiter success lunar photographic survey; intentionally impacted after completion of mission Lunar orbiter 1 (large).jpg [55]
Surveyor 5 United States NASA 11 September 1967 –
17 December 1967
lander success various studies, primarily in support of forthcoming manned landings Surveyor NASA lunar lander.jpg [56]
Zond 1967A Soviet Union USSR 28 September 1967 failure lunar capsule test flight; launch failure Zond L1 drawing.png [57]
Surveyor 6 United States NASA 10 November 1967 –
14 December 1967
lander success various studies, primarily in support of forthcoming manned landings Surveyor NASA lunar lander.jpg [58]
Zond 1967B Soviet Union USSR 22 November 1967 failure lunar capsule test flight; launch failure Zond L1 drawing.png [59]



IBM mainframe


IBM mainframes are large computer systems produced by IBM since 1952. During the 1960s and 1970s, the term mainframe computer was almost synonymous with IBM products due to their marketshare. Current mainframes in IBM’s line of business computers are developments of the basic design of the IBM System/360.

First and second generation 

IBM 704 mainframe at NACA in 1957

From 1952 into the late 1960s, IBM manufactured and marketed several large computer models, known as the IBM 700/7000 series. The first-generation 700s were based on vacuum tubes, while the later, second-generation 7000s used transistors. These machines established IBM’s dominance in electronic data processing (“EDP”). IBM had two model categories: one (701, 704, 709, 7090, 7040) for engineering and scientific use, and one (702, 705, 705-II, 705-III, 7080, 7070, 7010) for commercial or data processing use. The two categories, scientific and commercial, generally used common peripherals but had completely different instruction sets, and there were incompatibilities even within each category.

IBM initially sold its computers without any software, expecting customers to write their own; programs were manually initiated, one at a time. Later, IBM provided compilers for the newly developed higher-level programming languages Fortran and COBOL. The first operating systems for IBM computers were written by IBM customers who did not wish to have their very expensive machines ($2M USD in the mid-1950s) sitting idle while operators set up jobs manually. These first operating systems were essentially scheduled work queues. It is generally thought that the first operating system used for real work was GM-NAA I/O, produced by General Motors’ Research division in 1956. IBM enhanced one of GM-NAA I/O’s successors, the SHARE Operating System, and provided it to customers under the name IBSYS.[1][2] As software became more complex and important, the cost of supporting it on so many different designs became burdensome, and this was one of the factors which led IBM to develop System/360 and its operating systems.[3]

The second generation (transistor-based) products were a mainstay of IBM’s business and IBM continued to make them for several years after the introduction of the System/360. (Some IBM 7094s remained in service into the 1980s.)

Smaller machines 

IBM 1401 undergoing restoration at the Computer History Museum

Prior to System/360, IBM also sold computers smaller in scale that were not considered mainframes, though they were still bulky and expensive by modern standards. These included:

  • IBM 650 (vacuum tube logic, decimal architecture, drum memory, business and scientific)
  • IBM 305 RAMAC (vacuum tube logic, first computer with disk storage; see: Early IBM disk storage)
  • IBM 1400 series (business data processing; very successful and many 1400 peripherals were used with the 360s)
  • IBM 1620 (decimal architecture, engineering, scientific, and education)

IBM had difficulty getting customers to upgrade from the smaller machines to the mainframes because so much software had to be rewritten. The 7010 was introduced in 1962 as a mainframe-sized 1410. The later Systems 360 and 370 could emulate the 1400 machines. A desk size machine with a different instruction set, the IBM 1130, was released concurrently with the System/360 to address the niche occupied by the 1620. It used the same EBCDIC character encoding as the 360 and was mostly programmed in Fortran, which was relatively easy to adapt to larger machines when necessary.

Midrange computer is a designation used by IBM for a class of computer systems which fall in between mainframes and microcomputers.

IBM System/360 

IBM System/360 Model 50

All that changed with the announcement of the System/360 (S/360) in April, 1964.[4] The System/360 was a single series of compatible models for both commercial and scientific use. The number “360” suggested a “360 degree,” or “all-around” computer system. System/360 incorporated features which had previously been present on only either the commercial line (such as decimal arithmetic and byte addressing) or the engineering and scientific line (such as floating point arithmetic). Some of the arithmetic units and addressing features were optional on some models of the System/360. However, models were upward compatible and most were also downward compatible. The System/360 was also the first computer in wide use to include dedicated hardware provisions for the use of operating systems. Among these were supervisor and application mode programs and instructions, as well as built-in memory protection facilities. Hardware memory protection was provided to protect the operating system from the user programs (tasks) and the user tasks from each other. The new machine also had a larger address space than the older mainframes, 24 bits addressing 8-bit bytes vs. a typical 18 bits addressing 36-bit words.

The smaller models in the System/360 line (e.g. the 360/30) were intended to replace the 1400 series while providing an easier upgrade path to the larger 360s. To smooth the transition from second generation to the new line, IBM used the 360’s microprogramming capability to emulate the more popular older models. Thus 360/30s with this added cost feature could run 1401 programs and the larger 360/65s could run 7094 programs. To run old programs, the 360 had to be halted and restarted in emulation mode. Many customers kept using their old software and one of the features of the later System/370 was the ability to switch to emulation mode and back under operating system control.

Operating systems for the System/360 family included OS/360 (with PCP, MFT, and MVT), BOS/360, TOS/360, and DOS/360.

The System/360 later evolved into the System/370, the System/390, and the 64-bit zSeries, System z, and zEnterprise machines. System/370 introduced virtual memory capabilities in all models other than the very first System/370 models; the OS/VS1 variant of OS/360 MFT, the OS/VS2 (SVS) variant of OS/360 MVT, and the DOS/VS variant of DOS/360 were introduced to use the virtual memory capabilities, followed by MVS, which, unlike the earlier virtual-memory operating systems, ran separate programs in separate address spaces, rather than running all programs in a single virtual address space. The virtual memory capabilities also allowed the system to support virtual machines; the VM/370 hypervisor would run one or more virtual machines running either standard System/360 or System/370 operating systems or the single-user Conversational Monitor System (CMS). A time-sharing VM system could run multiple virtual machines, one per user, with each virtual machine running an instance of CMS [Wikipedia_4].

[Wikipedia_5] Multiprogramming with a Variable number of Tasks (MVT)[15] was the most sophisticated of three available configurations of OS/360’s control program, and one of two available configurations in the final releases.[16] MVT was intended for the largest machines in the System/360 family. Introduced in 1964, it did not become available until 1967. Early versions had many problems and the simpler MFT continued to be used for many years. Experience indicated that it was not advisable to install MVT on systems with less than 512 KiB of memory [Wikipedia_5].

Guidance system


guidance system is a virtual or physical device, or a group of devices implementing a guidance process used for controlling the movement of a ship, aircraft, missile, rocket, satellite, or any other moving object. Guidance is the process of calculating the changes in position, velocity, attitude, and/or rotation rates of a moving object required to follow a certain trajectory and/or attitude profile based on information about the object’s state of motion.[1][2][3]A guidance system is usually part of a Guidance, navigation and control system, whereas navigation refers to the systems necessary to calculate the current position and orientation based on sensor data like those from compasses, GPS receivers, Loran-C, star trackers, inertial measurement units, altimeters, etc. The output of the navigation system, the navigation solution, is an input for the guidance system, among others like the environmental conditions (wind, water, temperature, etc.) and the vehicle’s characteristics (i.e. mass, control system availability, control systems correlation to vector change, etc.). In general, the guidance system computes the instructions for the control system, which comprises the object’s actuators (e.g., thrusters, reaction wheels, body flaps, etc.), which are able to manipulate the flight path and orientation of the object without direct or continuous human control.

One of the earliest examples of a true guidance system is that used in the German V-1 during World War II. The navigation system consisted of a simple gyroscope, an airspeed sensor, and an altimeter. The guidance instructions were target altitude, target velocity, cruise time, engine cut off time.

A guidance system has three major sub-sections: Inputs, Processing, and Outputs. The input section includes sensors, course data, radio and satellite links, and other information sources. The processing section, composed of one or more CPUs, integrates this data and determines what actions, if any, are necessary to maintain or achieve a proper heading. This is then fed to the outputs which can directly affect the system’s course. The outputs may control speed by interacting with devices such as turbines, and fuel pumps, or they may more directly alter course by actuating ailerons, rudders, or other devices.


Inertial guidance systems were originally developed for rockets. American rocket pioneer Robert Goddard experimented with rudimentary gyroscopic systems. Dr. Goddard’s systems were of great interest to contemporary German pioneers including Wernher von Braun. The systems entered more widespread use with the advent of spacecraft, guided missiles, and commercial airliners.

US guidance history centers around 2 distinct communities. One driven out of Caltech and NASA Jet Propulsion Laboratory, the other from the German scientists that developed the early V2 rocket guidanceand MIT. The GN&C system for V2 provided many innovations and was the most sophisticated military weapon in 1942 using self-contained closed loop guidance. Early V2s leveraged 2 gyroscopes and lateral accelerometer with a simple analog computer to adjust the azimuth for the rocket in flight. Analog computer signals were used to drive 4 external rudders on the tail fins for flight control. Von Braun engineered the surrender of 500 of his top rocket scientists, along with plans and test vehicles, to the Americans. They arrived in Fort Bliss, Texas in 1945 and were subsequently moved to Huntsville, Al in 1950 (aka Redstone arsenal).[4][5] Von Braun’s passion was interplanetary space flight. However his tremendous leadership skills and experience with the V-2 program made him invaluable to the US military.[6] In 1955 the Redstone team was selected to put America’s first satellite into orbit putting this group at the center of both military and commercial space.

The Jet Propulsion Laboratory traces its history from the 1930s, when Caltech professor Theodore von Karman conducted pioneering work in rocket propulsion. Funded by Army Ordnance in 1942, JPL’s early efforts would eventually involve technologies beyond those of aerodynamics and propellant chemistry. The result of the Army Ordnance effort was JPL’s answer to the German V-2 missile, named MGM-5 Corporal, first launched in May 1947. On December 3, 1958, two months after the National Aeronautics and Space Administration (NASA) was created by Congress, JPL was transferred from Army jurisdiction to that of this new civilian space agency. This shift was due to the creation of a military focused group derived from the German V2 team. Hence, beginning in 1958, NASA JPL and the Caltech crew became focused primarily on unmanned flight and shifted away from military applications with a few exceptions. The community surrounding JPL drove tremendous innovation in telecommunication, interplanetary exploration and earth monitoring (among other areas).[7]

In the early 1950s, the US government wanted to insulate itself against over dependency on the Germany team for military applications. Among the areas that were domestically “developed” was missile guidance. In the early 1950s the MIT Instrumentation Laboratory (later to become the Charles Stark Draper Laboratory, Inc.) was chosen by the Air Force Western Development Division to provide a self-contained guidance system backup to Convair in San Diego for the new Atlas intercontinental ballistic missile. The technical monitor for the MIT task was a young engineer named Jim Fletcher who later served as the NASA Administrator. The Atlas guidance system was to be a combination of an on-board autonomous system, and a ground-based tracking and command system. This was the beginning of a philosophic controversy, which, in some areas, remains unresolved. The self-contained system finally prevailed in ballistic missile applications for obvious reasons. In space exploration, a mixture of the two remains.

In the summer of 1952, Dr. Richard Battin[8] and Dr. J. Halcombe (“Hal”) Laning Jr., researched computational based solutions to guidance as computing began to step out of the analog approach. As computers of that time were very slow (and missiles very fast) it was extremely important to develop programs that were very efficient. Dr. J. Halcombe Laning, with the help of Phil Hankins and Charlie Werner, initiated work on MAC, an algebraic programming language for the IBM 650, which was completed by early spring of 1958. MAC became the work-horse of the MIT lab. MAC is an extremely readable language having a three-line format, vector-matrix notations and mnemonic and indexed subscripts. Today’s Space Shuttle (STS) language called HAL, (developed by Intermetrics, Inc.) is a direct offshoot of MAC. Since the principal architect of HAL was Jim Miller, who co-authored with Hal Laning a report on the MAC system, it is a reasonable speculation that the space shuttle language is named for Jim’s old mentor, and not, as some have suggested, for the electronic superstar of the Arthur Clarke movie “2001-A Space Odyssey.” (Richard Battin, AIAA 82-4075, April 1982)

Hal Laning and Richard Battin undertook the initial analytical work on the Atlas inertial guidance in 1954. Other key figures at Convair were Charlie Bossart, the Chief Engineer, and Walter Schweidetzky, head of the guidance group. Walter had worked with Wernher von Braun at Peenemuende during World War II.

The initial “Delta” guidance system assessed the difference in position from a reference trajectory. A velocity to be gained (VGO) calculation is made to correct the current trajectory with the objective of driving VGO to Zero. The mathematics of this approach were fundamentally valid, but dropped because of the challenges in accurate inertial navigation (e.g. IMU Accuracy) and analog computing power. The challenges faced by the “Delta” efforts were overcome by the “Q system” of guidance. The “Q” system’s revolution was to bind the challenges of missile guidance (and associated equations of motion) in the matrix Q. The Q matrix represents the partial derivatives of the velocity with respect to the position vector. A key feature of this approach allowed for the components of the vector cross product (v, xdv,/dt) to be used as the basic autopilot rate signals-a technique that became known as “cross-product steering.” The Q-system was presented at the first Technical Symposium on Ballistic Missiles held at the Ramo-Wooldridge Corporation in Los Angeles on June 21 and 22, 1956. The “Q System” was classified information through the 1960s. Derivations of this guidance are used for today’s military missiles. The CSDL team remains a leader in the military guidance and is involved in projects for most divisions of the US military.

On August 10 of 1961 NASA Awarded MIT a contract for preliminary design study of a guidance and navigation system for Apollo program.[9] (see Apollo on-board guidance, navigation, and control system, Dave Hoag, International Space Hall of Fame Dedication Conference in Alamogordo, N.M., October 1976 [10]). Today’s space shuttle guidance is named PEG4 (Powered Explicit Guidance). It takes into account both the Q system and the predictor-corrector attributes of the original “Delta” System (PEG Guidance). Although many updates to the shuttles navigation system have taken place over the last 30 years (ex. GPS in the OI-22 build), the guidance core of today’s Shuttle GN&C system has evolved little. Within a manned system, there is a human interface needed for the guidance system. As Astronauts are the customer for the system, many new teams are formed that touch GN&C as it is a primary interface to “fly” the vehicle.[11] For the Apollo and STS (Shuttle system) CSDL “designed” the guidance, McDonnell Douglas wrote the requirements and IBM programmed the requirements.

Much system complexity within manned systems is driven by “redundancy management” and the support of multiple “abort” scenarios that provide for crew safety. Manned US Lunar and Interplanetary guidance systems leverage many of the same guidance innovations (described above) developed in the 1950s. So while the core mathematical construct of guidance has remained fairly constant, the facilities surrounding GN&C continue to evolve to support new vehicles, new missions and new hardware. The center of excellence for the manned guidance remains at MIT (CSDL) as well as the former McDonnell Douglas Space Systems (in Houston).


Guidance systems consist of 3 essential parts: navigation which tracks current location, guidance which leverages navigation data and target information to direct flight control “where to go”, and control which accepts guidance commands to effect change in aerodynamic and/or engine controls.

Navigation is the art of determining where you are, a science that has seen tremendous focus in 1711 with the Longitude prize. Navigation aids either measure position from a fixed point of reference (ex. landmark, north star, LORAN Beacon), relative position to a target (ex. radar, infra-red, …) or track movement from a known position/starting point (e.g. IMU). Today’s complex systems use multiple approaches to determine current position. For example, today’s most advanced navigation systems are embodied within the Anti-ballistic missile, the RIM-161 Standard Missile 3 leverages GPS, IMU and ground segmentdata in the boost phase and relative position data for intercept targeting. Complex systems typically have multiple redundancy to address drift, improve accuracy (ex. relative to a target) and address isolated system failure. Navigation systems therefore take multiple inputs from many different sensors, both internal to the system and/or external (ex. ground based update). Kalman filter provides the most common approach to combining navigation data (from multiple sensors) to resolve current position. Example navigation approaches:

  • Celestial navigation is a position fixing technique that was devised to help sailors cross the featureless oceans without having to rely on dead reckoning to enable them to strike land. Celestial navigation uses angular measurements (sights) between the horizon and a common celestial object. The Sun is most often measured. Skilled navigators can use the Moon, planets or one of 57 navigational stars whose coordinates are tabulated in nautical almanacs. Historical tools include a sextant, watch and ephemeris data. Today’s space shuttle, and most interplanetary spacecraft, use optical systems to calibrate inertial navigation systems: Crewman Optical Alignment Sight (COAS),[12] Star Tracker.[13]
  • Inertial Measurement Units (IMUs) are the primary inertial system for maintaining current position (navigation) and orientation in missiles and aircraft. They are complex machines with one or more rotating Gyroscopes that can rotate freely in 3 degrees of motion within a complex gimbal system. IMUs are “spun up” and calibrated prior to launch. A minimum of 3 separate IMUs are in place within most complex systems. In addition to relative position, the IMUs contain accelerometers which can measure acceleration in all axes. The position data, combined with acceleration data provide the necessary inputs to “track” motion of a vehicle. IMUs have a tendency to “drift”, due to friction and accuracy. Error correction to address this drift can be provided via ground link telemetry, GPS, radar, optical celestial navigationand other navigation aids. When targeting another (moving) vehicle, relative vectors become paramount. In this situation, navigation aids which provide updates of position relative to the target are more important. In addition to the current position, inertial navigation systems also typically estimate a predicted position for future computing cycles. See also Inertial navigation system.
  • Astro-inertial guidance is a sensor fusion/information fusion of the Inertial guidance and Celestial navigation.
  • Long-range Navigation (LORAN) : This was the predecessor of GPS and was (and to an extent still is) used primarily in commercial sea transportation. The system works by triangulating the ship’s position based on directional reference to known transmitters.
  • Global Positioning System (GPS) : GPS was designed by the US military with the primary purpose of addressing “drift” within the inertial navigation of Submarine-launched ballistic missile(SLBMs) prior to launch. GPS transmits 2 signal types: military and a commercial. The accuracy of the military signal is classified but can be assumed to be well under 0.5 meters. GPS is a system of 24 satellites orbiting in unique planes 10.9-14.4 Nautical miles above the earth. The Satellites are in well defined orbits and transmit highly accurate time information which can be used to triangulate position.
  • Radar/Infrared/Laser : This form of navigation provides information to guidance relative to a known target, it has both civilian (ex rendezvous) and military applications.
    • active (employs own radar to illuminate the target),
    • passive (detects target’s radar emissions),
    • semiactive radar homing,
    • Infrared homing : This form of guidance is used exclusively for military munitions, specifically air-to-air and surface-to-air missiles. The missile’s seeker head homes in on the infrared (heat) signature from the target’s engines (hence the term “heat-seeking missile”),
    • Ultraviolet homing, used in FIM-92 Stinger – more resistive to countermeasures, than IR homing system
    • Laser guidance : A laser designator device calculates relative position to a highlighted target. Most are familiar with the military uses of the technology on Laser-guided bomb. The space shuttle crew leverages a hand held device to feed information into rendezvous planning. The primary limitation on this device is that it requires a line of sight between the target and the designator.
    • Terrain contour matching (TERCOM). Uses a ground scanning radar to “match” topography against digital map data to fix current position. Used by cruise missiles such as the Tomahawk (missile).

Guidance is the “driver” of a vehicle. It takes input from the navigation system (where am I) and uses targeting information (where do I want to go) to send signals to the flight control system that will allow the vehicle to reach its destination (within the operating constraints of the vehicle). The “targets” for guidance systems are one or more state vectors (position and velocity) and can be inertial or relative. During powered flight, guidance is continually calculating steering directions for flight control. For example, the space shuttle targets an altitude, velocity vector, and gamma to drive main engine cut off. Similarly, an Intercontinental ballistic missile also targets a vector. The target vectors are developed to fulfill the mission and can be preplanned or dynamically created.

Control. Flight control is accomplished either aerodynamically or through powered controls such as engines. Guidance sends signals to flight control. A Digital Autopilot (DAP) is the interface between guidance and control. Guidance and the DAP are responsible for calculating the precise instruction for each flight control. The DAP provides feedback to guidance on the state of flight controls [Wikipedia_6].

Unified S-band Radio Frequency System

[Wikipedia_7] The Unified S-band (USB) system was a tracking and communication system developed for the Apollo program by NASA and the Jet Propulsion Laboratory (JPL). It operated in the S band portion of the microwave spectrum, unifying voice communications, television, telemetry, command, tracking and ranging into a single system to save size and weight and simplify operations. The USB ground network was managed by the Goddard Space Flight Center (GSFC). Commercial contractors included Collins Radio, Blaw-Knox, Motorola and Energy Systems.


The previous programs, Mercury and Gemini, had separate radio systems for voice, telemetry, and tracking. Uplink voice and command, and downlink voice and telemetry data were sent via ultra high frequency (UHF) and very high frequency (VHF) systems.[1] The tracking capability was a C band beacon interrogated by a ground-based radar. With the much greater distance of Apollo, passive ranging was not feasible, so a new active ranging system was required. Apollo also planned to use television transmissions, which were not supported by the existing systems. Finally, the use of three different frequencies complicated the spacecraft systems and ground support. The Unified S-band (USB) system was developed to address these concerns.

The USB system did not completely replace all other radio transmitters on Apollo. While it was the sole mode for deep space communications, Apollo still used VHF for short range voice and low rate telemetry between astronauts and the Lunar Module (LM) and lunar rover during extra-vehicular activity; between the LM and Command/Service Module (CSM or CM); and between the CSM and Earth stations during the orbital and recovery phases of the mission. The CM had a backup capability to range the LM over its VHF voice links.

Apollo also carried several radars that operated independently of the USB on their own frequencies, including the landing and rendezvous radars on the LM and a C-band radar transponder on the CM.

Technical summary 

From a NASA technical summary:[2]

The design of the USB system is based on a coherent doppler and the pseudo-random range system which has been developed by JPL. The S-band system utilizes the same techniques as the existing systems, with the major changes being the inclusion of the voice and data channels.

A single carrier frequency is utilized in each direction for the transmission of all tracking and communications data between the spacecraft and ground. The voice and update data are modulated onto subcarriers and then combined with the ranging data […]. This composite information is used to phase-modulate the transmitted carrier frequency. The received and transmitted carrier frequencies are coherently related. This allows measurements of the carrier doppler frequency by the ground station for determination of the radial velocity of the spacecraft.

In the transponder the subcarriers are extracted from the RF carrier and detected to produce the voice and command information. The binary ranging signals, modulated directly onto the carrier, are detected by the wide-band phase detector and translated to a video signal.

The voice and telemetry data to be transmitted from the spacecraft are modulated onto subcarriers, combined with the video ranging signals, and used to phase-modulate the downlink carrier frequency. The transponder transmitter can also be frequency modulated for the transmission of television information or recorded data instead of ranging signals.

The basic USB system has the ability to provide tracking and communications data for two spacecraft simultaneously, provided they are within the beamwidth of the single antenna. The primary mode of tracking and communications is through the use of the PM mode of operation. Two sets of frequencies separated by approximately 5 megacycles are used for this purpose […]. In addition to the primary mode of communications, the USB system has the capability of receiving data on two other frequencies. These are used primarily for the transmission of FM data from the spacecraft.


The Unified S-Band System used the 2025-2120 MHz band for uplinks (earth to space transmissions) and the 2200-2290 MHz band for downlinks (space to earth transmissions). Both bands are allocated internationally for space research and operations, though by 2014 standards the ALSEP uplink was in the wrong part of the band (Deep Space instead of Near Earth).

Apollo S-band frequency assignments
Spacecraft Uplink (MHz) Downlink (MHz) Coherent ratio
Command Module PM 2106.40625 2287.5 221/240
Command Module FM 2272.5
Lunar Module 2101.802083 2282.5 221/240
S-IVB PM 2101.802083 2282.5 221/240
S-IVB FM 2277.5
Lunar Rover 2101.802083 2265.5
Apollo 11 Early ALSEP 2119 2276.5
Apollo 12 ALSEP 2119 2278.5
Apollo 14 ALSEP 2119 2279.5
Apollo 15 ALSEP 2119 2278.0
Apollo 15 subsatellite 2101.802083 2282.5 221/240
Apollo 16 ALSEP 2119 2276.0
Apollo 17 ALSEP 2119 2275.5

Each Apollo spacecraft was assigned a frequency pair. For certain phase modulation (PM) downlinks, the uplink to downlink frequency ratio was exactly 221/240. The ALSEP lunar surface experiments shared a common uplink and did not, insofar as is known, implement a coherent transponder. (The passive laser retroreflectors left by the Apollo 11, 14 and 15 missions provide much greater accuracy, and have far outlived the active electronics in the other ALSEP experiments.) The Lunar Communications Relay Unit (LCRU) on the Lunar Rover had its own downlink frequency (to avoid interference with the LM) but shared the LM’s uplink frequency as it did not implement a coherent transponder. To keep the VHF transmitters on the LM and LCRU from both trying to relay uplink voice and interfering with each other, separate voice subcarriers were used on the common S-band uplink: 30 kHz for the LM and 124 kHz for the LCRU.

The CSM had two separate transmitters, one PM and one FM. The LM had only one S-band transmitter that could operate in PM or FM, but not both simultaneously.

The S-IVB upper stage had its own USB transponder so it could be tracked independently after Apollo spacecraft separation until the stage either flew past the moon (Apollos 8, 10, 11, 12) or, starting with Apollo 13, hit the moon. This tracking data greatly aided the analysis of the impact as recorded by the seismometers left by earlier Apollo crews.

The S-IVB shared its S-band frequency pair with the LM. This created no problem in a normal mission as the LM remained dormant until lunar orbit, by which time the S-IVB had already hit the moon or flown off into orbit around the sun. However, it created an operational problem during the Apollo 13 mission when the LM had to be used as a lifeboat well before Apollo and the S-IVB reached the moon.[3]

The LM frequency pair was also used by the subsatellites left in lunar orbit by the later J-missions. They were deployed by the CSM shortly before leaving lunar orbit and after the LM had completed its mission.

The use of two separated frequency bands made full duplex operation possible. The ground and the spacecraft transmitted continuously. Microphone audio was keyed either manually or by VOX, but unlike ordinary half duplex two-way radio both sides could talk at the same time without mutual interference.


The S-band uplinks and downlinks usually (but not always) used phase modulation (PM). PM, like FM, has a constant amplitude (envelope) regardless of modulation. This permits the use of nonlinear RF amplifiers that can be considerably more efficient than RF amplifiers that must maintain linearity.

The PM modulation index is small, on the order of 1 radian, so the modulated signal more closely resembled double sideband amplitude modulation (AM) except for the carrier phase. A PM signal can be approximated for analysis purposes as an AM signal with the carrier (and only the carrier) rotated 90 degrees from its original phase. One important difference is that in AM, the carrier component has a constant amplitude as the sidebands vary with modulation while in PM the total signal (the envelope) is constant amplitude. This means that PM shifts power from the carrier to the information-carrying sidebands with modulation, and at some modulation indices the carrier can disappear completely. This is why Apollo uses a low modulation index: to leave a strong carrier that can be used for highly accurate velocity tracking by measurement of its Doppler shift.

Coherent transponders and Doppler tracking 

Allocating uplink/downlink frequency pairs in a fixed ratio of 221/240 permitted the use of coherent transponders on the spacecraft. The spacecraft tracked the uplink carrier with a phase locked loop and, with a series of frequency dividers and multipliers, multiplied the uplink carrier frequency by the ratio 240/221 to produce its own downlink carrier signal.

When no uplink was detected, the transponder downlink carrier was generated from a local oscillator at the nominal frequency.

This “two-way” technique allowed extremely precise relative velocity measurements (in centimeters/sec) by observing the Doppler shift of the downlink carrier without a high accuracy oscillator on the spacecraft, although one was still needed on the ground.


As mentioned above, the uplink and downlink carriers played a critical role in spacecraft tracking. Sidebands generated by the information also carried by the system had to be kept away from the carriers to avoid perturbing the phase locked loops used to track them. This was done through the use of various subcarriers.

The uplink had subcarriers at 30 kHz and 70 kHz. The 30 kHz subcarrier was modulated with uplink (Capcom) voice using narrowband FM (NBFM) and the 70 kHz carrier was modulated with command data for the onboard computer. This latter capability, which could be blocked by the astronauts, was used primarily to update the state vectors maintained by the computers with accurate values determined by ground tracking. It was also used to execute maneuvers in an unmanned spacecraft, e.g., deorbiting the lunar module after it had been jettisoned in lunar orbit.

Either or both subcarriers could be turned off when not needed, e.g., the voice subcarrier could be turned off during astronaut sleep periods. This improved the signal margins for the other information streams such as telemetry data.

The downlink normally had subcarriers at 1.25 MHz (NBFM voice) and 1.024 MHz (telemetry data). The telemetry could be at one of two rates, 1.6 kilobits/sec (low rate, 1/640 of the subcarrier frequency) and 51.2 kilobits/sec (high rate, 1/20 of the subcarrier frequency). High rate was used unless low rate was forced by poor link conditions, e.g., the use of a small earth receiving antenna, an omni spacecraft antenna, or the need to conserve spacecraft power by turning off its RF power amplifier. (The S-band transponder on the S-IVB had no voice subcarrier.)

A “backup voice” mode was available that shut off the 1.25 MHz NBFM voice subcarrier and transmitted voice at baseband on the main PM S-band carrier. This provided a few more dB of margin when the link was unusually degraded but worse voice quality than the normal voice mode when conditions were good.

The two modes can be easily distinguished by how they react to signal fades. In the normal (NBFM subcarrier) voice mode the audio SNR is usually very high. But as the link degrades below threshold, impulse or “popcorn” noise appears suddenly and builds up rapidly until it overwhelmed the astronauts’ voices. An excellent example occurred during the Apollo 11 lunar landing when the lunar module structure occasionally obstructed the antenna’s view of Earth.

The backup voice mode behaved more like AM; there is a constant background “hiss” and the astronauts’ voices vary with signal strength. This mode was used extensively during the Apollo 13 emergency to conserve battery power in the LM Aquarius and during Apollo 16 because of the failure of the steerable S-band antenna on the lunar module Orion.

Voice transmissions used Quindar tones for in-band signaling.

Emergency key 

The Apollo USB downlink also provided an “emergency key” capability consisting of a manually on-off keyed subcarrier oscillator at 512 kHz. Presumably this would have been used by the crew to transmit Morse Code if the downlink were too severely degraded to support even the backup voice mode. Although this mode had been tested (on Apollo 7) and most of the astronauts were trained in its use, this mode was never actually needed during any Apollo mission. (Apollo 13 made extensive use of the “backup voice” mode, as did the Apollo 16 lunar module Orion due to a failed high gain antenna).

A similar uplink capability did not exist because the uplink budget had far more margin than the downlink. A typical Apollo S-band spacecraft transmitter produced 20 watts; a typical uplink transmitter produced 10 kW, a ratio of 27 dB.


The Apollo S-band system provided for accurate range (distance) measurements. The ground station generated a pseudorandom noise (PN) sequence at 994 kilobit/s and added it to the baseband signal going to the PM transmitter. The transponder echoed this PN signal back to earth on the downlink, and by correlating the received and transmitted versions the precise round trip light time to the spacecraft could be determined very accurately (within 15 meters).[4]

The PN sequence, although deterministic, had the properties of a random bit stream. Although the PN sequence was periodic, its period of about 5 seconds exceeded the largest possible round trip time to the moon so there would be no ambiguity in its received timing.

Modern GPS receivers work somewhat similarly in that they also correlate a received PN bit stream (at 1.023 Mbit/s) with a local reference to measure distance. But GPS is a receive-only system that uses relative timing measurements from a set of satellites to determine receiver position while the Apollo USB is a two-way system that can only determine the instantaneous distance and relative velocity. However, an orbit determination program can find the unique spacecraft state vector or orbital element set that most closely matches (usually in a least squares sense) a set of range, range-rate (relative velocity) and antenna look angle observations made over a period of time by one or more ground stations assuming purely ballistic spacecraft motion over the observation interval.

Once the state vector has been determined, the spacecraft’s future trajectory can be fully predicted until the next propulsive event.

Transponder ranging turn-around had to be manually enabled by an astronaut. It consumed an appreciable fraction of the downlink capacity and it was only needed occasionally, typically during handover from one ground station to the next. After the new uplink station achieved a 2-way coherent transponder lock in which the spacecraft generated its carrier at 240/221 times the received uplink frequency, the new ground station ranged the spacecraft. Then the ranging signal was turned off and the range measurement was continually updated by Doppler velocity measurements.

If for some reason a ground station lost lock during a pass, it would repeat the ranging measurement after re-acquiring lock.

FM and video 

The normal operating mode of an Apollo S-band downlink transmitter was PM. This mode provided for coherent Doppler tracking, uplink commands, downlink telemetry and two-way voice—but not television. Video signals, even that from the slow scan camera used during the Apollo 11 EVA, are much wider in bandwidth than the other Apollo downlink signals. The PM link margin simply could not provide an acceptable picture, even when the largest available dishes were used.

A means was also needed to transmit wideband engineering and scientific data, such as that recorded on a tape recorder and played back at high speed.

The answer to both needs was wideband FM – frequency modulation. FM with a large modulation index exhibits a capture or threshold effect. The output signal-to-noise ratio (SNR) can be significantly greater than the RF channel SNR provided that the RF SNR remains above a threshold, typically around 8-10 dB.

This enhancement comes at a price: below the FM threshold, the output SNR is worse than the RF channel SNR. Reception is “all or nothing”; a receiving antenna too small to capture the video cannot capture the narrowband elements either (e.g., voice).

The CSM carried separate FM and PM transmitters that could operate simultaneously, so voice and telemetry continued to be transmitted by PM while the video came down by FM. The LM only carried a single transmitter that could operate in either FM or PM, but not both. FM cannot be used for Doppler tracking, so the LM always transmitted PM during flight, reserving FM for when video was required (e.g., during a surface EVA).

Until the transition to digital, satellite television also used wideband FM.


It is historically understood that the USSR did intercept the Apollo missions telemetry on the territory of the USSR, but until 2005,[5] no source in the former USSR military or intelligence services has come forth with any evidence of this happening. The USSR used different frequency bands for its own space missions, so by default its deep space network did not readily have equipment able to receive Apollo telemetry. Whether China or any other non-Western (or non-aligned) country at the time chose to intercept any of the Apollo telemetry is unclear. Amateur radio and affiliated telecommunications sector persons could listen to the Apollo telemetry the world over—provided they could afford the reception equipment.

Within the territory of the US it was legally possible for amateur radio operators to monitor the telemetry, but the FCC did issue a directive that required all disclosure of Apollo telemetry interception be cleared by NASA.[citation needed] Paul Wilson and Richard T. Knadle, Jr. received voice transmissions from the Command Service Module of Apollo 15 in lunar orbit on the morning of August 1, 1971. In an article for QST magazine they provide a detailed description of their work, with photographs.[6] At least two different radio amateurs, W4HHK and K2RIW, reported reception of Apollo 16 signals with home-built equipment [Wikipedia_7].[7][8]




  1.  Hunt 1991, pp. 72–74
  2.   Béon 1997[page needed]
  3.   “Messerschmitt Me 163 Komet.” World War 2 Planes. Retrieved: 22 March 2009.
  4.   “Joint Intelligence Objectives Agency. US National Archives and Records Administration”. 2011-10-19. Retrieved 2012-12-10.
  5.   von Braun 1963, pp. 452–465
  6.   “International Space Hall of Fame: Sergei Korolev”. Retrieved 2012-12-10.
  7.   “Rocket R-7”. S.P.Korolev RSC Energia.
  8.   Hansen 1987 Chapter 12.
  9.  Allen & Eggers 1958
  10.  Launius, Roger D.; Jenkins, Dennis R. (2012). Coming home : reentry and recovery from space (PDF). Washington, DC: National Aeronautics and Space Administration. p. x. ISBN 978-0-16-091064-7. Retrieved 4 April 2015.
  11.   Viviani, Antonio; Pezzella, Giuseppe (January 3, 2011). “Heat Transfer Analysis for a Winged Reentry Flight Test Bed”. International Journal of Engineering (IJE)3 (3): 341. CiteSeerX Freely accessible.
  12.  Launius, Roger D.; Jenkins, Dennis R. (2012). Coming home : reentry and recovery from space (PDF). Washington, DC: National Aeronautics and Space Administration. p. 187. ISBN 978-0-16-091064-7. Retrieved 3 April 2015.
  13.  “Returning from Space: Re-entry” (PDF). Federal Aviation Administration. U.S. Department of Transportation. Washington, DC 20591. FOIA Library. pp. 4.1.7-335. Retrieved 7 April 2015.
  15.   “(PDF) ”Hypersonics Before the Shuttle: A Concise History of the X-15 Research Airplane” (NASA SP-2000-4518, 2000)” (PDF). Retrieved 2012-12-10.
  16.   Houchin 2006[page needed]
  17.   Kuntz, Tom (2001-11-14). “New York Times 17 June 1969 – A Correction”. Retrieved 2012-12-10.


  1.  IBM 7090/94 IBSYS Operating System
  2.  Gray, G. (1999). “EXEC II”. Unisys History Newsletter1 (3).
  3.   Chuck Boyer, The 360 Revolution
  4.   IBM Archives: System/360 Announcement
  5.   IBM corp. (2005). “Mainframe concepts (page 31)” (PDF).
  6.   Radding, Alan. “Bye bye zPrime on System z”. DancingDinosaur. Retrieved May 5, 2012.
  7.   “Technical Overview: FLEX-ES”.
  8.   “IBM System z Personal Development Tool”. IBM.


  1.  IBM System/3S0 Operating System MVT Guide OS Release 21(PDF). Fifth Edition. IBM. March 1972. GC28-6720-4.
  2.   OS/360 Introduction (PDF). IBM Systems Reference Library. IBM. 1972. pp. 50–51. GC28-6534-3. there are two configurations of the [OS/360] control program: … MVT configuration