Milestone-Proposal:Apollo Unified S-Band Communications System, 1969

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Docket #:2017-12

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To the proposer’s knowledge, is this achievement subject to litigation? No

Is the achievement you are proposing more than 25 years old? Yes

Is the achievement you are proposing within IEEE’s designated fields as defined by IEEE Bylaw I-104.11, namely: Engineering, Computer Sciences and Information Technology, Physical Sciences, Biological and Medical Sciences, Mathematics, Technical Communications, Education, Management, and Law and Policy. Yes

Did the achievement provide a meaningful benefit for humanity? Yes

Was it of at least regional importance? Yes

Has an IEEE Organizational Unit agreed to pay for the milestone plaque(s)? No

Has the IEEE Section(s) in which the plaque(s) will be located agreed to arrange the dedication ceremony? No

Has the IEEE Section in which the milestone is located agreed to take responsibility for the plaque after it is dedicated? No

Has the owner of the site agreed to have it designated as an IEEE Milestone? No

Year or range of years in which the achievement occurred:


Title of the proposed milestone:

Apollo Unified S-Band Communications System, 1960-1969

Plaque citation summarizing the achievement and its significance:

"The Eagle has landed." On July 20, 1969, half-a-billion television viewers heard astronaut Neil Armstrong live from the moon, across a quarter-million miles of space. The Apollo 11 Unified S-Band communication system, pioneered by NASA's Jet Propulsion Laboratory and MIT's Lincoln Laboratory, delivered his voice while simultaneously relaying command, tracking, and imagery data between multiple spacecraft and a global network of land-based, airborne, and seaborne tracking stations.

200-250 word abstract describing the significance of the technical achievement being proposed, the person(s) involved, historical context, humanitarian and social impact, as well as any possible controversies the advocate might need to review.

IEEE technical societies and technical councils within whose fields of interest the Milestone proposal resides.

In what IEEE section(s) does it reside?

Region 6, Metropolitan Los Angeles Section (Jet Propulsion Laboratory)

IEEE Organizational Unit(s) which have agreed to sponsor the Milestone:

IEEE Organizational Unit(s) paying for milestone plaque(s):

IEEE Organizational Unit(s) arranging the dedication ceremony:

IEEE section(s) monitoring the plaque(s):

Milestone proposer(s):

Proposer name: Lori Jeromin
Proposer email: Proposer's email masked to public

Proposer name: David Michelson
Proposer email: Proposer's email masked to public

Please note: your email address and contact information will be masked on the website for privacy reasons. Only IEEE History Center Staff will be able to view the email address.

Street address(es) and GPS coordinates in decimal form of the intended milestone plaque site(s):

NASA JPL, Building 230, DSN Road, Pasadena, CA; 34.201086111111 N 118.173613888888 W

Describe briefly the intended site(s) of the milestone plaque(s). The intended site(s) must have a direct connection with the achievement (e.g. where developed, invented, tested, demonstrated, installed, or operated, etc.). A museum where a device or example of the technology is displayed, or the university where the inventor studied, are not, in themselves, sufficient connection for a milestone plaque.

Please give the address(es) of the plaque site(s) (GPS coordinates if you have them). Also please give the details of the mounting, i.e. on the outside of the building, in the ground floor entrance hall, on a plinth on the grounds, etc. If visitors to the plaque site will need to go through security, or make an appointment, please give the contact information visitors will need. The Milestone plaque will be placed outside the main doors of JPL's Space Flight Operations Center. A National Historic Landmark plaque is mounted nearby on the building stonework. JPL has supplied a photo which is attached below.

Are the original buildings extant?


Details of the plaque mounting:

The Milestone plaque will be placed either to the left or right of the main doors at JPL's Space Flight Operations Center. The existing glass panels have been blackened and will be a good background for the plaque.

How is the site protected/secured, and in what ways is it accessible to the public?

Visitors will need to be cleared through the JPL entrance gate but the plaque will be visible to the many, many visitors who tour NASA's Jet Propulsion Lab and the Space Flight Operations Center each year.

Who is the present owner of the site(s)?

California Institute of Technology

What is the historical significance of the work (its technological, scientific, or social importance)? If personal names are included in citation, include justification here. (see section 6 of Milestone Guidelines)

Although the Apollo Program was conceived under President Dwight Eisenhower, as a step-up program from the single-man Mercury capsules [7], it dramatically changed when President John F. Kennedy began his term in 1961. Kennedy inherited all the ills of the Cold War, Arms Race, and Space Race from the previous administration. The Cold War and Arms Race were clearly militarized and had been dragging on since World War II. But the Space Race was relatively new, having begun with Russia's launch of the world's first artificial satellite on October 4, 1957. While America was quick to respond to each new Russian achievement in space, we still trailed at each juncture. American morale was at stake, as was America's global status in the Cold War. Kennedy seized on a goal for America that the people could get behind: Land a man on the moon and return him safely to Earth. In a speech to a joint session of the houses of congress on May 25, 1961, he outlined the program and called for its accomplishment by the end of the decade [6]. He reiterated the goal on November 21, 1963, in his "...cap over the wall..." pronouncement as part of his dedication of the USAF School of Aerospace Medicine, in San Antonio, Texas [8]. The following day, President John F. Kennedy was assassinated in Dallas, Texas. His challenge to the American people persisted.

An estimated half-billion world-wide television viewers were glued to their sets on July 20, 1969 when Apollo 11 Commander Neil Armstrong verified that the Lunar Module (LM) had touched-down on the surface of the moon. "The Eagle has landed." After a few hours of systems checks and preparations, Armstrong descended the LM's ladder and became the first human to set foot on the moon. At that historic moment, Armstrong uttered the now-famous (and widely debated) "That's one small step for a man, one giant leap for mankind." [1] Crystal clear, from a quarter-million miles away, those words arrived within two seconds of being spoken, in homes and other viewing venues around the world. While many viewers remember the exact words, as well as where they were at that moment, few were aware of all that had transpired earlier to deliver those words from the moon to their television sets. The short answer is the Unified S-Band Communications System. But, that does not begin to reveal the technology and complexity that connected Armstrong's spacesuit microphone to the speakers of hundreds-of-millions of television receivers on Earth—while simultaneously passing command, control, telemetry, voice, and television signals between the multiple world-wide networks of earth-stations (fixed, airborne, and seaborne) and the complement of Apollo modules: (CSM, LM, and SIV-B) in space and on the moon. The goals of a unified communication network, extravehicular activities, and the docking of modules in space were first addressed earlier in the Gemini project. [2] [3] Communications requirements for American manned space flights had grown incrementally more complex with each new space program but, for Apollo 11, the communications requirements far exceeded those of all prior manned missions. The challenges stemmed largely from the multiple spacecraft modules (CSM - Command and Service Module, LM - Lunar Module, and SIV-B - the final stage of the Saturn V launch vehicle). The initial launch, low earth orbit (LEO), and final recovery events were typical of the many prior manned orbital missions, but not without heightened scrutiny. One example was the exhaust plume of the Saturn V launch vehicle (all stages to greater or lesser degrees). It was common knowledge that rocket plumes attenuated and refracted radio signals, but with the criticality of the Apollo LEO insertion and the need for reliable communications for three modules, additional ground stations would be required along the initial flight path and additional ships would be needed for the re-entry and recovery phase. [2] The outbound trans-lunar injection (TLI), lunar-orbit, and inbound trans-earth injection (TEI) were anything but typical. They were more akin to the deep-space exploratory missions conducted by NASA's Jet Propulsion Laboratory (JPL—a U.S. Army sponsored laboratory prior to 1958.) Near-earth and deep-space operations required quite different communication technologies, and manned missions came with a heightened concern for reliability and redundancy. With multiple docking and transfer maneuvers came multiple opportunities for off-nominal situations that could leave some, or even all, crew members stranded, unable to return to Earth. Three souls on board (SOB), a quarter-million miles from home, called for unprecedented attention to detail and contingency planning. Candidate communications networks included the Manned Space Flight Network (MSFN) utilized for the Mercury, Gemini, and early Apollo missions; the Spaceflight Tracking and Data Acquisition Network (STADAN) utilized for LEO missions, and the Deep Space Network (DSN) utilized by JPL for deep space probes. Each of the three existing networks would suffice for one or more segments of a lunar landing mission, but none would cover all segments. With meetings among JPL, MIT Lincoln Laboratory (LL), and Project Apollo engineers and scientists beginning in late 1960, ongoing discussions of alternatives ensued. JPL had the most experience and capability in deep space operations but was reluctant to risk that to a manned spacecraft program that might degrade or restrict their network if used extensively or exclusively by Apollo during the mission. Several solutions were proposed— each with its own impact on cost, schedule, and other programs, such as JPL's ongoing deep space probes—but the final decision was a blend of the three, plus considerable expansion of existing stations and the addition of new stations to cover the critical earth-launch and earth-recovery operations. The result was total coverage, with redundancy and flexibility for contingencies, while preserving JPL's concurrent missions. While leaving most of the DSN intact by minimizing modifications of equipment and time out of service. DSN would be the backup mode, while expansion of the MSFN would provide increased capability in the initial and final stages and add redundancy at the three DSN locations without sharing facility space or personnel. (The existing 26m dish antennas centered on the LM on the lunar surface would suffer a 9-12 dB degradation at the lunar horizon where the CSM would be acquired as it came from behind the moon. Collocated 26m dishes would allow individual 3dB performance on the LM and CSM for critical tracking necessary for the rendezvous maneuver.) [4] In summary, seven existing stations were expanded; seven new stations were constructed; airborne and seaborne stations were added. LL was commissioned to develop and demonstrate a Unified Carrier concept by year's end, 1962. The demonstration took place in mid-year and by the end of the year, Motorola's Scottsdale, AZ Military Electronics Division was selected to design and manufacture the Unified S-Band Transponder—a key element for implementing the Unified Carrier concept. JPL's Mark 1 S-band ranging system was chosen for the deep space ranging and their DSN was designated as a backup for the augmented MSFN. Collins Radio, a familiar provider of state-of-the-art communications solutions and a major provider of fixed and mobile tracking solutions for all prior manned spaceflights [5], was chosen as the Unified S-Band systems integrator.

What obstacles (technical, political, geographic) needed to be overcome?

Existing systems for command, control, communications, and tracking needed to be combined into a single system; not just for one extraterrestrial vehicle, but up to four (Command Module, Lunar Lander, and third-stage booster initially, with the later addition of the Lunar Rover) in multiple flights within the Apollo series. Time was of the essence—primarily due to political factors (Space Race)—and proposed solutions could not require the development of new technologies. The JPL experiences were viewed as providing a superior technological solution with minimal new development. Additionally, earth-based tracking stations would have to be augmented with a number of land-based and ship-based sites to maintain a "clear view" of the flight vehicles, both en-route to and from the moon, and while loitering in lunar orbit, or performing operations on the lunar surface. Of utmost concern was the ability to "see" the lunar lander on the surface of the moon simultaneously with the lunar orbiter as it emerged from behind the moon. The concept of a re-insertion into lunar orbit for the return of the landing craft, with its occupants, to the orbiting command and service module was untested prior to the Apollo series. Very precise and timely tracking data was mandatory for success. Fuel margins were linked to weight and size of the modules, leaving little room for error in maneuvering the vehicles. Of particular concern in the near-earth operations was maintaing a clear communications path between the mission modules and tracking stations. The addition of stations helped but another factor gave cause for concern:

"Attenuation of communication signals by the Saturn V rocket plume placed some limitations on the spacecraft's S-band antenna. USB stations had to be placed closer together than first planned. The problem was not only one of needing to be geographically positioned correctly to see the vehicle from the ground, but also one of being able to maintain a reliable low-bit error rate and continuous telemetry link between the two." [2]

What features set this work apart from similar achievements?

Everything had to work right the first time—design and operational parameters left little to no room for error or contingencies. With the lunar landing module separating from the command module, there were two spacecraft to be tracked simultaneously: the command module parked in a lunar orbit, and the lunar landing module transitioning between lunar orbit and the lunar surface. The lunar ascent and re-docking maneuver was even more critical. An intercept trajectory had to be computed and flown, with the rising LM intercepting the CSM, whose precise position was unknown until it appeared on the lunar horizon from the back of the moon. None of the existing tracking networks met all the requirements. Augmentations to existing networks were required for the level of reliability and redundancy needed.

Supporting texts and citations to establish the dates, location, and importance of the achievement: Minimum of five (5), but as many as needed to support the milestone, such as patents, contemporary newspaper articles, journal articles, or chapters in scholarly books. 'Scholarly' is defined as peer-reviewed, with references, and published. You must supply the texts or excerpts themselves, not just the references. At least one of the references must be from a scholarly book or journal article. All supporting materials must be in English, or accompanied by an English translation.

1. NASA EP-72 Log of Apollo 11: accessed 30 December 2018.

2. Tsiao, Sunny, Read You Loud and Clear: the story of NASA's spaceflight tracking and data network. Washington, DC: NASA History Division, 2008. Print.

3. Granath, Bob, Gemini's First Docking Turns to Wild Ride in Orbit. Kennedy Space Center, NASA, 2016.

4. Corliss, William R, Histories of the Space Tracking and Data Acquisition Network (STADAN), The Manned Space Flight Network (MSFN), and The NASA Communications Network (NASCOM). NASA-CR-140390, 1974.

5. Shanklin, James, Collins Role in Space Communications. 2012

6. Address to Joint Session of Congress May 25, 1961 (Excerpt) Accessed 31December 2018.

7. Project Apollo: A Retrospective Analysis Accessed 31 December 2018.

8. Remarks at the Dedication of the Aerospace Medical Health Center, San Antonio, TX, November 21, 1963 Accessed 31 December 2018.

Supporting materials (supported formats: GIF, JPEG, PNG, PDF, DOC): All supporting materials must be in English, or if not in English, accompanied by an English translation. You must supply the texts or excerpts themselves, not just the references. For documents that are copyright-encumbered, or which you do not have rights to post, email the documents themselves to Please see the Milestone Program Guidelines for more information.


Please email a jpeg or PDF a letter in English, or with English translation, from the site owner(s) giving permission to place IEEE milestone plaque on the property, and a letter (or forwarded email) from the appropriate Section Chair supporting the Milestone application to with the subject line "Attention: Milestone Administrator." Note that there are multiple texts of the letter depending on whether an IEEE organizational unit other than the section will be paying for the plaque(s).

Please recommend reviewers by emailing their names and email addresses to Please include the docket number and brief title of your proposal in the subject line of all emails.