CHIPS Articles: Capt. Tim Gallaudet Ph.D.

Q: Can you talk about the USNO's mission and the services it provides to the Navy and public at large?

A: The United States Naval Observatory's mission is to provide astronomical and timing data that is essential for accurate and effective navigation, command and control, communications, targeting, and operation of space and cyber systems. USNO's operations are vital to the Navy and Department of Defense, the Intelligence Community (IC), other government agencies, and the public at large. USNO's mission of Precise Time and Astrometry (PTA) is really part of the key infrastructure upon which DoD operations are built, and USNO is the only organization with the mission to provide PTA. The interesting thing about infrastructure is that most people take it for granted, until it's degraded or gone — just talk to the people recently hit by Hurricane Sandy.

Q: Does the GPS and time data that the USNO provides interface with the Navy navigation system?

A: Yes, it does. Are you familiar with ECDIS, Electronic Chart Display and Information System? Our ships that use the electronic charting system currently receive their time through a ship’s internal navigation system called NAVSSI (Navigation Sensor System Interface); it is in the process of transitioning to the GPS Positioning, Navigation, and Timing System (GPNTS). Their time is provided primarily by the GPS constellation through an onboard GPS antenna. We provide that time to the GPS constellation.

Q: So any Navy system that uses GPS and time data, for example, combat systems and Navy networks, rely on data provided by USNO, and it doesn’t matter which vendor developed it or what system it is?

A: Yes, and that is the Defense Department policy. There is a Joint Chiefs of Staff Instruction and an OSD CIO instruction that directs the department to use our time and directs us to provide the time as the authorized provider of DoD time, and that is for all the services.

Q: As the official timekeeper for the Defense Department, can you explain the concept of an atomic clock? How do warfighters use the precision time data that USNO provides?

A: Our atomic clocks are based upon the fact that atoms such as cesium, hydrogen and rubidium are composed of electrons that have spin, and that spin can be aligned with their nucleus's spin in more than one way. As the electrons switch between different spins, they give off or absorb a very precise amount of energy. By a law of quantum mechanics, the energy can take the form of microwave radiation whose frequency is directly proportional to the energy (via Planck's constant). We measure the frequency of these microwaves. Once we know the frequency, it is a technologically simple matter to compute time.

In practice, the atomic microwave frequencies are converted to a 5 MHz signal, which is an electric signal that goes up and down five million times a second. Then we feed that signal into equipment that is designed to output a voltage spike every five millionth time the 5 MHz signal goes up. The rising edge of that spike signals the start of each second — to an accuracy of a billionth of a second.

Our Master Clock is actually a system with dozens of independent free-running atomic clocks. In any given system the more independent numbers or elements you have in the ensemble, the better the information you get when you average them; that’s why we have so many clocks. We have different types because each type of atomic clock has a different characteristic. Clocks that use the cesium atom are very noisy on the short term but very stable on the long term, always centering around the correct average time. Another type of clock we employ uses hydrogen and has very low short-term noise but in the long term it tends to drift off, so we use a balance of different clocks with different characteristics to produce what is called an operational time scale.

We’ve also just added four new clocks, with an atom called rubidium, which are the most precise operational clocks in the world. We designed them ourselves primarily because the GPS III program, the next GPS system, has a more stringent time requirement, which is precision to a nanosecond, which is a billionth of second. So to meet that requirement we had to build our own clocks; we just reached initial operational capability this year. We call them the Navy Rubidium Fountains (NRF).

Many of the world’s labs that provide time don’t run continuously, but because we have a Defense Department requirement, our clock system is always operational, 24/7, always online, and it is the most precise operational clock system in the world. Warfighters use the precise time we provide them for communication systems, command and control systems, intelligence operations, network operations, and data fusion.

Q: There have been a lot of press reports lately about hackers being able to spoof or hack GPS data; I imagine your security is very stringent?

A: It is, and that is the purpose of the new GPS III program. We participated in the development of the monitor station receivers for this system because of our expertise in timing technology, through which we monitor time of the GPS network.

The new signal that GPS III will use is more robust to jamming. In terms of computer hacking into the system or the vulnerabilities of GPS, I can say we are making efforts at a DoD level to reduce those vulnerabilities.

Another interesting thing — GPS operates through a system of satellites that transmit radio signals to the user's receiver where a trilateration is performed to determine a position based on the time difference of arrival of those signals. The signals are electromagnetic waves that travel at the speed of light. The speed of light travels about a foot [in one nanosecond], so if the precision of our clocks is within a billionth of a second, that provides for the theoretical positioning accuracy of one foot.

For any kind of positioning and consequent targeting applications, if you want to be accurate within a small area, precise time is important. The same goes for any kind of communications or command and control, whether satellite, sea or shore based: to communicate effectively, a source and a receiver must be synchronized. When you lose synchronization, you lose 'comms.' The term is drop sync; that’s the frequent reason why a shipboard radio, for example, might lose comms — whether through an error or signal delay or loss — and why precise time is so necessary to maintain continuous communications. The same goes for computer networks too.

Q: Speaking of atomic clocks, the U.S. Army Research, Development and Engineering Command is developing miniature atomic clocks to be used by Soldiers. Is the USNO playing a role in this development? Are they used in the Navy?

A: We call these Chip Scale Atomic Clocks. We have assisted OSD and DARPA (Defense Advanced Research Projects Agency) in preparing their program, in evaluating the development proposals, and in measuring progress. USNO has also been involved in measuring the performance of CSAC technology against the master clock. Since then we have consulted for other DoD groups in specific implementations. They aren’t used much operationally in the Navy now but much research is being done. They are not as accurate and precise but at a tactical level (for the dismounted Soldier or SEAL team member) they may meet certain applications and that’s why a lot of research is being done.

The Army and Navy labs are looking at them and we have advised them both. We have a team of atomic physicists and engineers that work in our time department that have been asked about performance standards and certain research issues.

Q: USNO's website states that "the highest precision and accuracy in time dissemination is provided through Two-Way Satellite Time Transfer (TWSTT)." Can you explain how the two-way time transfer method works?

A: The idea is that we send time signals up to a geostationary communications satellite, which retransmits them to the user in the field. The user simultaneously shoots time signals towards us. Because the two signals travel over the same section of sky and ionosphere, the atmospheric distortions are almost the same each way. Therefore they cancel, and that makes it easier to compare our clocks with the remote clocks so as to keep users on time.

To put this in context, we begin with our master clock that keeps precise time. But we then have to disseminate that time to users. We have several ways of disseminating time that vary with respect to accuracy. Some of your readers might remember dialing the number for time on rotary phones several decades past. We still provide a telephone time dissemination service that about 60,000 customers use each week. That is only accurate to a fraction of a second. Then there is Network Time Protocol (NTP), accurate to about 1 millisecond, for dissemination to DoD computer networks. Dissemination via GPS is the most prevalent means used globally by our forces, with an accuracy of about 10 nanoseconds. The most accurate is TWSTT with nanosecond level accuracy. Our customers within the Intelligence Community use this form of time dissemination.

Q: The “great equatorial refracting telescope” was first used in 1873. What updates have been made to this telescope? Does it work exactly the same way as it did when it was first built, aside from the added cameras?

A: The telescope is interesting. It is the oldest piece of Navy operational equipment still in commission. Of course, you have the USS Constitution in Boston — but that historic vessel is not really operational — it doesn’t deploy and lacks modern combat capability. This telescope has been used for Navy astronomical needs and data collection since 1873. Then it was the largest telescope in the world. A number of great discoveries have been found with it, including the two moons of Mars by a USNO astronomer.

A major update of the telescope was performed back in the 1890s when the USNO moved from the Foggy Bottom area of D.C. up to our current location in Georgetown Heights. Of course, the telescope has been periodically refurbished since then, but you are correct, to a large extent the telescope works in much the same way it did when it was first built.

However, the real heart of an astronomical telescope is the device at the end of the telescope that records the focused image. Initially USNO astronomers used their eyes and notebooks to record what they saw through the telescope. Photographic film was used with great success with the 26-inch throughout the years, and had the advantage that film is more sensitive to light than the human eye. Currently, we use a high speed digital camera with the 26-inch telescope and utilize a technique called ‘speckle interferometry’ to compensate for the blurring effect of the Earth’s atmosphere.

One interesting aspect of the science of astronomy is that a very old telescope like the 26-inch, when coupled with a modern camera, produces a cutting-edge instrument. NASA did the same thing with the Hubble Space telescope, performing several servicing missions to replace and modernize Hubble's cameras, providing new and exciting capabilities in a very cost-effective manner. Although it looks like a late 19th century piece of equipment (because it is!), and it is not like some of the state-of-the-art telescopes that we have in our dark-sky site in Flagstaff, Arizona, it still remains relevant. It has a great lens and we still use it to collect bright star data for catalogs used by Trident missiles to navigate.

What is a star catalog and why does DoD care? To explain, we get into this topic of astrometry — not astronomy. Astrometry is concerned with determining the very precise positions, motions, and brightnesses of stars. We use those for navigation, positioning and targeting applications. An example is that we use the astrometry data that we collect with the 26-inch refractor telescope for the Navy’s Trident missile program that I mentioned before. Trident missiles have star trackers on them that use the star catalog information basically to navigate and reach their targets. That’s how it was done in the early days of the U.S. Navy during the Age of Sail using celestial navigation. There were tables constructed based on the given position of astronomical bodies, stars and planets, to chart your position on the Earth. We have missile systems still using that technology today.

Q: Fascinating. I read on the USNO website, that the Naval Observatory is one of the oldest scientific institutions in the U.S.?

A: That’s true, it was originally established in 1830; it predates the Smithsonian and national labs. It is a great place with a lot of history and a great mission. The contrast is interesting, we have this 19th century telescope and the Superintendent’s original house (now the vice president’s house at Number One Observatory Circle) — it’s a wonderful Victorian era mansion. But then next door, we have the very modern, cutting-edge Nobel Prize-winning physics and engineering that goes into the Master Clock system. This year’s Nobel Prize in physics went to Dave Wineland. The physics he won it for is central to our clock system. He works for a collaborator of ours, the National Institute of Standards and Technology, and he was working in atomic clock development. So we have recent Nobel Prize-winning physics work being done here juxtaposed against this Victorian-era beautiful setting.

Q: I read that a new survey camera was incorporated into the astrograph telescope. What can you tell me about the advantages of the new camera?

A: A typical digital camera you can buy online or in n electronics store has about 10 to 20 million pixels. The new camera we are using with our astrograph telescope has almost 500 million pixels. With a camera that large, we can image a much larger area of the sky in a single exposure, and in the end producemuch more accurate star positions and star catalogs for the nation. Our astrograph with the new camera is currently observing the northern sky from the USNO dark-sky site in Flagstaff. Part of the USNO PTA mission is to produce astrometric catalogs of the entire sky.

The neat thing about it is it has the largest charged-couple device (CCD) array in the world. Again, we developed this technology in-house. In the Navy, there is no supply system stock number for an atomic clock or astrograph telescope. So we had to develop it ourselves. We get some help from DARPA and ONR, but much of it is so specialized, a niche area, so we do most of it ourselves. The traditional DoD acquisition system is tailored to large platforms and weapons systems, and not necessarily the unique applications we address. We circumvent that difficulty by speeding technology to operational applications quickly with our own internal research and development efforts.

Q: Are there any other new technologies that will affect the products USNO provides?

A: I did talk about the rubidium fountain clocks. It would be hard for me to simplify the advances in physics for the atomic clock system. We don’t like to advertise [our advanced technologies] because we don’t want to give adversaries a competitive advantage. We tend to talk about advances in generic terms so we retain that expertise and advantage.

As far as the astrometric telescope that we are putting online, the technology is very new and we are working to spread the technology across the DoD at large. There are DoD systems that use our star catalogs with star trackers. There are a number of strategic air systems that use our star catalogs, the B-2 and the RC-135 Rivet Joint are strategic aircraft and there are a couple of other applications as well. The star trackers have to be accurate just like the star catalogs. We are working across DoD and the national military labs to improve the detectors and sensors.

Q: In 1989, the USNO developed the Navy Precision Optical Interferometer to produce space imagery and astrometry. Could you talk about its capabilities and how it differs from its predecessor, the Mark III Interferometer?

A: Using the modern technique of astronomical interferometry, the USNO produces very precise astrometric images of celestial objects, both at the radio and optical ends of the electromagnetic spectrum. The NPOI is our optical wavelength interferometer located in Flagstaff. The Mark III, located on Mount Wilson near Pasadena, Calif., was the developmental predecessor of the NPOI. The technique of interferometry works by combining the light from a number of separate individual telescopes into a coherent single data stream, and the more telescopes that are used in that combination the better the result. So the principal difference between the NPOI and its predecessor, the Mark III, is in the number of telescopes that can be combined; the NPOI can combine the light from six separate telescopes simultaneously to make higher quality images and improve astrometry.

It really is a telescope array with a number of elements that when you add them together produce a highly resolved image. You can apply the same principle for acoustic arrays on Navy ships. You have receiving elements or transducers and that’s how Navy ships or submarines find other ships or submarines, they use these arrays of sensors. We do the same thing at USNO, we have an array of telescopes and this one is our most precise telescope. We are trying to determine the accurate positioning of stars and the best way to do that is by using angular width. To understand this, the angular width of the entire sky from horizon to horizon is 180 degrees. But that’s a pretty wide [measurement] and we need to determine star positions much more precisely. Each degree in the 180 degrees is composed of 60 minutes, and each minute is composed of 60 seconds, and a thousandth of a second is a milliarcsecond. That's about the angular width of Neil Armstrong when he was standing on the moon, as seen from the Earth. The NPOI has a resolution of about 16 milliarcseconds. It is a very minute resolution.

We have a number of different telescopes for different targeting and positioning applications, all of which require catalogs of different types of stars. We support the Air Force Space Command, and we give them star catalog data for what they call SSA, or Space Situational Awareness. They track space objects so our satellites don’t run into them. So how do they know what those objects are? They need a reference background so they know that an object, for example, is an asteroid and not a satellite or space junk — and there is a lot of space junk out there. So we update that reference background every year because the stars move. We are in a galaxy that is rotating and moving. Stars in the galaxy move [in orbits] around the center, stars outside the galaxy move apart, and they all change which is why we continuously sense their positions.

Q: USNO has an amazing mission — is there anything else you would like to discuss?

A: The Naval Observatory is under the Commander, Naval Meteorology and Oceanography Command (CNMOC), which is under U.S. Fleet Forces Command, and we are part of the larger information dominance community. Our role, much like the CNMOC, is that we characterize the battlespace. Conventionally, the maritime battlespace consists of surface sea and undersea missions to the seabed, and it goes up in the atmosphere if you are doing BMD, ballistic missile defense, strike, ISR, and other missions. But in today’s information age, with increasing demands for faster communications and more precise positioning, our battlespace has extended far beyond the atmosphere to include the stars in the sky that we use to position our own satellites and sensors.

Our role is predictive battlespace awareness so my command covers the battlespace that is above the atmosphere out to space — and we not only determine their current positions and movement, but we also predict their future positions and movement. Also, USNO represents an extremely high return on investment. For a modest annual budget of less than $20 million a year for all types of appropriations, we ensure the effective and safe operation of numerous multibillion-dollar DoD capabilities, including GPS, ISR satellites, the department’s unclassified and classified computer networks, and the navigation and targeting systems that depend upon them.

The time thing is really interesting; it is becoming more and more important for us due to the increased requirements for precise time and its dissemination in the DoD. That is why I was named the DoD PTTI (Precise Time and Time Interval) Manager, with direct reporting authority to the OSD CIO for all requirements, S&T plans and policies regarding DoD precise time.

Even in the days of the Pony Express, information traveled slowly. We are approaching the 200th anniversary of the Battle of New Orleans, which didn’t even have to be fought because a peace treaty had been signed in England two weeks earlier. Nowadays, information is so much more pervasive and it travels so much more quickly; now we can’t function without precise time. If we didn’t have precise time and rapid exchange of information we wouldn’t be able to do our mission. There is a book by a guy named James Gleick, called 'Faster' ("The Acceleration of Just About Everything") that talks about how that is just the nature of modern life.

Q: I was reading about how the U.S. pivot to Asia is going to require better satellite and communications coverage.

A: Yes, and as I discussed, our role is to support that capability with precise time. But a related issue is the anti-access, area denial (A2/AD) threats in the region that might prevent communications and even navigation with GPS through jamming. So we are involved in a number of efforts to provide for the ability for PNT, positioning, navigation and timing, in these A2/AD environments. Our focus is for more information to better leverage the alternate, non-GPS means of PNT I mentioned; TWSTT is one example.

I want to conclude with a frequently quoted phrase 'People are our most valuable asset.' Nowhere is this more true than at USNO. Highly skilled, trained and educated. Innovative and disciplined. We conduct much of our own research to speed technology to capability.

Q: Is everyone a scientist at the observatory?

A: No, but we do have the sharpest atomic physicists, mathematicians, astronomers and engineers in the Navy. Several have worked with a number of Nobel Prize-winning physicists and are doing cutting-edge work. I am very proud to represent such interesting, hard-working people. But, we also have financial, personnel, and IT professionals all working as a team. We have a former yeoman in the Navy running personnel. It is very diverse command in that respect, a wonderful mix of people.

Q: Do you worry about recruiting scientists for USNO?

A: I do. It is a concern everywhere. The DoD pay scales can’t compete with industry or the big national labs but our staff is committed, and it isn’t about the money for them. It is a lot of work, but we know where to go to find the scientists and engineers we need.

Q: Have you always been interested in science?

A: I always wanted to be an oceanographer, but I generally like science. Coming to this command has been a blessing for me. I watch shows on the Science Channel, like 'Through the Wormhole' and shows about space and cosmology at home. So working here doesn’t feel like work — it’s fun.

The U.S. Naval Observatory

USNO is a fourth echelon operational command reporting to the Commander, Naval Meteorology and Oceanography Command. The observatory's headquarters are located in Washington, D.C., with field activities located at the Naval Observatory Flagstaff Station (NOFS) in Flagstaff, Ariz., and the USNO Alternate Master Clock located at Schriever Air Force Base near Colorado Springs, Colo.

The U.S. Naval Observatory performs an essential scientific role for the United States, the Navy and the Department of Defense. Its mission includes determining the positions and motions of the Earth, sun, moon, planets, stars, and other celestial objects, providing astronomical data; determining precise time; measuring the Earth's rotation; and maintaining the Master Clock for the United States. Observatory astronomers formulate the theories and conduct the relevant research necessary to improve these mission goals. This astronomical and timing data, essential for accurate navigation and the support of communications on Earth and in space, is vital to the Navy and Department of Defense. It is also used extensively by other agencies of the government and the public at large.

The observatory consists of four scientific departments: Astrometry, Astronomical Applications, Earth Orientation and Time Service. Each Department is responsible for specific products and services tailored to our end-users within both the DoD and civilian environments.

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