Milestone-Proposal:Development of Ultra-Stable Oscillator’s for deep space exploration
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Docket #:2025-26
This proposal has been submitted for review.
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)? Yes
Has the IEEE Section(s) in which the plaque(s) will be located agreed to arrange the dedication ceremony? Yes
Has the IEEE Section in which the milestone is located agreed to take responsibility for the plaque after it is dedicated? Yes
Has the owner of the site agreed to have it designated as an IEEE Milestone? Yes
Year or range of years in which the achievement occurred:
1977-2024
Title of the proposed milestone:
Development of Ultrastable Quartz Crystal Oscillators for Deep Space Exploration
Plaque citation summarizing the achievement and its significance; if personal name(s) are included, such name(s) must follow the achievement itself in the citation wording: Text absolutely limited by plaque dimensions to 70 words; 60 is preferable for aesthetic reasons.
In the 1970s, Frequency Electronics Incorporated (FEI) partnered with NASA’s Jet Propulsion Laboratory to develop Ultra-Stable Oscillators (USOs), which flew on both Voyager spacecraft. These USOs were vital for science, tracking, and communication. Since then, USO technology has become standard for space missions, enabling precise measurements of planetary features. Voyager 2’s USO set a record, operating continuously for 48.2 years—the longest any spaceborne clock has ever functioned.
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.
Frequency Electronics, Inc. (FEI), founded in 1962, has long been a leader in designing and manufacturing high-precision, highly reliable clocks with exceptional frequency stability. FEI’s technology has played a vital role in many historic and current space missions, with its clocks featured on spacecraft for the Apollo Program, Saturn Rockets, Pioneer and Voyager Probes, the Space Shuttle, and planetary missions to Jupiter, Venus, and Mars. Their clocks also supports military and commercial satellite constellations like MILSTAR, AEHF, TDRSS, GlobalStar, and IridiumNEXT. At the heart of FEI’s contributions are their Ultra-Stable Oscillators (USOs). These oscillators use Q-swept quartz crystals to reduce the impact of space radiation, ensuring reliable long-term performance. Over the past 62 years, FEI has delivered clock systems to more than 1,200 satellites, amassing over 337 million operational hours, with short-term frequency stability between 7 parts per 10^14 and low aging rates in the 10^–13 range. FEI also supplies space-proven Rubidium Clocks, accumulating 1.8 million hours since 1995. Notably, both Voyager I and II launched in 1977, had FEI-designed USOs capable of withstanding more than 100 krads of radiation. Voyager II, which operated until October 2024, set the record for the longest-operating clock in space—48 years and 2 months—was turned off only for power management, not performance. Traveling over 12 billion miles at speeds exceeding 34,000 mph, the Voyager missions serve as a testament to FEI’s legacy of durability and precision, a record unlikely to be broken in our lifetime.
IEEE technical societies and technical councils within whose fields of interest the Milestone proposal resides.
AIAA, IEEE Long Island, AESS, SYSC
In what IEEE section(s) does it reside?
IEEE Long Island Section
IEEE Organizational Unit(s) which have agreed to sponsor the Milestone:
IEEE Organizational Unit(s) paying for milestone plaque(s):
Unit: IEEE Long Island Section
Senior Officer Name: Rhonda Green
Unit: {{{Unit}}}
Senior Officer Name: {{{Senior officer name}}}
IEEE Organizational Unit(s) arranging the dedication ceremony:
Unit: IEEE Long Island Section
Senior Officer Name: Rhonda Green
IEEE section(s) monitoring the plaque(s):
IEEE Section: IEEE Long Island Section
IEEE Section Chair name: Rhonda Green
Milestone proposer(s):
Proposer name: Jerry Cogen
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):
55 Charles Lindberg Blvd. Mitchell Field New York, 11553 Latitude: 40.723703 Longitude: -73.603637
124 Shutter Lane, Village of Oyster Bay Cove, Oyster Bay, NY 11771, Latitude: 40.859157 Longitude: -73.506759
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 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. 1. Frequency Electronics, Inc Corporate Headquarters at the above address. This site is where all the development, design, manufacturing and test occurs for all space productions for its customer. 2. 124 Shutter Lane, Village of Oyster Bay Cove, Oyster Bay, NY 11771 is the residence of Martin Bloch, founder and past CEO of FEI and principle designer of the Voyager USO. Martin is now retired at this address. FEI will pay for the mini plaque for Martin.
Are the original buildings extant?
Yes
Details of the plaque mounting:
This will be mounted in FEI's entrance hallway on the ground floor and in Martin Bloch's home
How is the site protected/secured, and in what ways is it accessible to the public?
There is 24x7 security
Who is the present owner of the site(s)?
Frequency Electronics, Inc.
What is the historical significance of the work (its technological, scientific, or social importance)? If personal names are included in citation, include detailed support at the end of this section preceded by "Justification for Inclusion of Name(s)". (see section 6 of Milestone Guidelines)
We propose an IEEE Milestone to commemorate almost 50 years of continuous operation for the Voyager spacecraft Ultra-Stable Oscillator (USO), launched on August 20, 1977, that was developed at Frequency Electronics Incorporated in collaboration with NASA/JPL. Historical Significance: What if NASA/JPL came to you in the early 1970s and announced a mission to the 4 outer planets of our solar system, that had science payloads to study the planets, especially their atmospheres and rings with quality radio links to ground stations, where a team from JPL and Stanford University proposed a hypothesis to study the atmosphere and rings by radio occultations, but needed a very stable signal source? Enter Frequency Electronics, the world renowned clock manufacturer for space applications. Importance to the evolution: With this challenge, FEI designed, developed, manufactured and tested the "USO". The Voyager Radio Science Team coined the term USO ..."Ultra Stable Oscillator" . These USO's flew in deep space on the two Voyager spacecraft. Voyager 1 USO operated till September 1, 1992 (15 years) and Voyager 2 USO operated till October 2024, 47 years 2 months, both beyond the Sun's heliosphere, over 12.3 billion miles (20 billion kilometers) from Earth. Voyager 2 is the only spacecraft to have visited Jupiter, Saturn, Uranus, and Neptune. The USO needed to meet the stability requirements for the Radio Science Experiments that were needed for occultation experiments using the Voyager spacecraft. The telecommunication up and down links, between spacecraft and Earth, locked to the FEI USO highly stable clock, was used to investigate changes in phase/frequency, amplitude, and polarization of radio signals, to study: • Planetary atmospheres • Planetary rings • Planetary surfaces • Planetary interiors • Solar corona and wind • Comet mass flux • Fundamental Physics This USO needed to be a high precision (low phase noise, allan deviation and spurious spectrum) low weight, low power and highly reliable, first of its kind, oscillator. For this, the design incorporated a pierce oscillator included a proportionally controlled, double oven oscillator, using a premium Q swept cultured quartz crystal to minimize the effects of space radiation for oscillator stability. Special attention was focused on choice of components used and the quartz crystal itself. The strict requirements were needed, so that occultation experiments could determine the physical properties of planets and its satellites (ionospheres, atmospheres, masses, gravity fields, densities) and the amount, size and distribution of material in Saturn's rings and the ring dimensions.
What obstacles (technical, political, geographic) needed to be overcome?
Technical Obstacles: Vibration: Internal shock mounted construction rendered the USO impervious to the shock encountered during space launch operations Size and low power: A double oven, proportionally controlled oscillator was used to enhance allan deviation at .1 to 1000 sec and 1Hz phase noise at -100 dBc . Radiation concerns: Overcome harsh radiation environments at Jupiter/Saturn with shielding and the use of a premium Q swept cultured quartz crystal. An AT cut quartz was used at a frequency is 6.38MHz. This frequency is then processed to be the voyager downlink frequency of 8.42GHz. Reliability: If the USO failed, an aux oscillator generated a 1-way downlink. Use of the less stable aux oscillator restricted transmitting downlink in the residual carrier mode only, but could be not be used for Radio Science experiments. Part reliability factors were also part of the design, as well as, NASA imposed manufacturing techniques to enhance mission life. Last known performance in space: The last set of data measured from the Voyager 2 USO was on 4/23/2010. The allan deviations at 1, 10 and 100 seconds were an order of magnitude better and the frequency aging was a magnitude less than specified.
What features set this work apart from similar achievements?
The Voyager USO's were the first crystal oscillators to withstand extreme natural radiation environments and are the longest recorded working USO's in the our short history of space exploration. No crystal oscillator known had lasted in the harsh environment of space for 48+ years. These USO's were the first man-made oscillators of this stability to be used on a launch system for interplanetary exploration. At the time, these USO's were manufactured with state of the art parts with hi-reliability requirements and along with NASA focused manufacturing techniques, common place in today's environment. The USO's were an integral part of the Radio Science System on the Voyager Probes. The Radio Science System was used to determine the physical properties of planets and satellites (ionospheres, atmospheres, masses, gravity fields, densities) and the amount and size distribution of material in Saturn's rings and the ring dimensions.
Why was the achievement successful and impactful?
Another USO, made at the same time as the USO's for the Voyager spacecraft, flew on the Galileo probe. Through the dedicated work of the teams from Frequency Electronics and NASA/JPL, the development of the now named "Ultra Stable Oscillator" has paved the way for future deep space probes and their experiments. The science learned during this mission, understanding the outer reaches of our solar system, was invaluable. NASA has not turned off Voyager 2's radio science system. Instead, it turned off the Plasma Science instrument on September 26, 2024, to save power for essential systems as the probe's radioactive power supply diminishes its life. The USO, part of this system, was turned off on October 2024, not because of malfunction, but to conserve Voyager 2 spacecraft power. In its place, a lesser performing oscillator is now running for downlink purposes. Quote from Sami Asmar of JPL "Voyager USO is the super clock in space for decades, broke records and resulted in numerous scientific discoveries"
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.
Special thanks to: --John Vig, USO Expert and former IEEE President --Martin Bloch, Founder/Former President and CEO of Frequency Electronics, Inc. FEI Voyager USO Chief Developer --John Ho, Chief Design Engineer and manufacturing liason --Sami Asmar, Manager of Strategic Partnerships for the Interplanetary Network Directorate at NASA’s Jet Propulsion Laboratory, California Institute of Technology, and the General Secretary of the Consultative Committee for Space Data Systems. He has over thirty years’ experience in the field of radio science and, among other recognition, has been awarded three NASA Exceptional Achievement Medals. -- Radio Science Techniques for Deep Space Exploration (JPL Deep-Space Communications and Navigation Series) 2022 --Roger Ludwig/Jim Taylor, JPL DESCANSO -- Deep Space Communications and Navigation Systems Center of Excellence-- Design and Performance Series
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 ieee-history@ieee.org. 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 ieee-history@ieee.org 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 ieee-history@ieee.org. Please include the docket number and brief title of your proposal in the subject line of all emails.
