[Doc Ewen looks into the horn antenna, 1950]
Image courtesy of Doc Ewen


Harvard Cyclotron: 1948-1951

Detection of HI Line: 1951

Harvard 24ft and 60ft and NRAO founding: 1952-1956

1950s and 1960s: Two Roads that Crossed

Microwave & Millimeter Wave Applications in the 1970s and 1980s

Mm Wave Radiometry in the 1990s

May 2001 visit to NRAO Green Bank



[Doc Ewen and horn antenna, 2001]
Image courtesy of Doc Ewen

Doc Ewen: The Horn, HI, and Other Events in US Radio Astronomy

by Doc Ewen, © 2003

The Harvard 24 and 60 Foot Radio Telescopes, and the Founding of NRAO

The discovery of 21 cm interstellar hydrogen line radiation in 1951 generated little interest at Harvard. In the Physics Department it was considered an interesting experiment, particularly the result. However, the cyclotron, the pending Korean conflict, and other matters of significance took center stage. The Astronomy Department awaited the return of Bart Bok from South Africa. While Ed Purcell was shuttling back and forth to Washington, DC, I was completing my thesis write up, preparing for my doctorate oral and studying for an exam in German. This had to be done rather quickly, because the Navy was expecting me in Washington, DC by mid May.

Though the general tone of hectic activity on a variety of subjects was ever present, there was a strict adherence to certain rules concerning the award of a PhD in Physics. At that time, the basic requirements were a proficiency in two foreign languages and a masterís knowledge of three separate subjects in physics, in addition to the doctorate subject. The doctorate subject required a written thesis and an oral exam. Two of the three other subjects would be accepted on the completion of selected advanced courses at a grade level of B or better. An oral exam was required on the third subject. For my "three subjects", I selected Math, Quantum Mechanics, and Meteorology. The courses in Quantum Mechanics were with Schwinger and occupied much of my time in 1949. In 1948, I selected Meteorology for qualification by oral exam. This was shortly after Purcell had accepted me as a doctorate candidate. He immediately rejected Meteorology as a topic in the field of physics. He considered it to be a "pseudo-science". I pursued him on the subject for several weeks. Finally, he agreed and asked that I loan him a few of the books on the subject that I thought particularly relevant. While studying physics at Harvard, I had audited all of the major graduate courses in meteorology at MIT. I gave Purcell the books that I had purchased while auditing the courses at MIT. I learned a bit more about Ed Purcell when I walked into the room for my oral exam. The Examination Committee included all of the authors of the books I had given to Ed. They were all professors at MIT. We had a lively discussion. It was quite a thrill to stand in front of that much talent, to discuss a subject I thoroughly enjoyed. The highlight was a question concerning the nature of the radar return from a cloud layer just above the zero degree isotherm. I offered a number of possible explanations. As I struggled to get approval from the questioner, Purcell interrupted and asked the professor to give the answer. The professor said the answer was not known, but was being studied as a doctorate subject at MIT. He did say that my answers were good and that he would be happy to arrange further discussions between myself and the graduate student. Ed quickly replied that it was important to recall that all questions be based on a master's knowledge of the subject and that the answers be known.

At the time the hydrogen line was discovered, the remaining tasks to be completed for the doctorate were an exam in German, the written thesis, and the doctorate oral. I studied German for two weeks and passed the exam, with some help from the examinerís insight. Oldenberg gave me a small chapter in a text book on electricity and magnetism to translate. There was a figure on every page. I translated the titles of the figures and wrote a text around the figures based on my knowledge of electricity and magnetism. Oldenberg enjoyed the translation; however, he did mention that I had included some details not known at the time the book was written. He suggested that in the future I check the date of publication. Writing the thesis took three days and it was less than fifty pages. By design it was two pages less than Edís thesis when he submitted to Ken Bainbridge. Up to that time, Purcellís thesis held the record for brevity.

Ed was Ed when it came time for the doctorate oral. The Examination Committee consisted of Ed Purcell and Hank Van de Hulst. After a few casual comments, the three of us tangled with the main question. "Why was the line detectable?" After an hour of discussion, it was evident that we were going around in circles searching for an answer, only to reach agreement with Van de Hulstís original prediction that the line would not be detectable. It wasnít until the following year that Ramsey and Weiskopf discovered the reason why it was detectable, during a seminar on the subject chaired by Purcell.

By late May all of requirements for the degree had been satisfied and I went off to Washington, DC to rejoin the Navy. As discussed elsewhere, I spent the summer of 1951 on a 65ft yacht cruising Boston Harbor and Buzzards Bay looking for submarines as a Navy contractor, not a member of the Navy. All of that changed when Bok returned from South Africa.

Horse Meat at the Faculty Club

In the spring of 1952, I received an urgent call from Bok to join him for lunch at the Faculty Club. I found on arrival that others had been called to join Bok. Around a large circular table were Harlow Shapley, Don Menzel, Ed Purcell, and Bart Bok. I took the remaining seat and Bart promptly announced that the purpose of the meeting was to discuss the initiation of a "Radio Project" in the Astronomy Department. He suggested we all have horse meat in keeping with the importance of the discussion. In the familiar Bok style, he listed four topics for discussion along with conclusions and action items for each topic, prior to discussion.

  • The Harvard Astronomy Department will initiate a Radio Project and provide graduate courses of instruction and thesis guidance, leading to a PhD in Radio Astronomy. Harvard would be the first U.S. university to offer this opportunity to graduate students.
  • Bart and Doc will be Co-Directors, with Doc responsible for the radio part and Bart for the astronomy part of radio astronomy.
  • Harvard, with assistance from NSF, would build a 24' equatorially mounted radio telescope at the Harvard Agassiz Station located in Harvard, Mass.
  • Who would build the receiver? On this fourth and last subject Bok did not provide an answer. He suggested we discuss it; however, he was quick to point out that the Astronomy Department would not develop an in house capability in electronics, which would require electrical engineers, technicians, electronic test equipment and all that goes with an in house radio capability. My suggestion to solicit the aid of MIT was received without comment. Participation by the Cruft Lab at Harvard was received with a similarly subdued enthusiasm. When all seemed hopeless, Ed Purcell said that he had a solution. In Purcellís words, "The answer is quite simple."
    • Doc will form a company to build the receiver.
    • When the receiver is ready, he will ship it to Agassiz.
    • Doc will then disband the company and become a permanent member of the faculty in the Department of Astronomy.
The response of all was in strong support of Edís recommendation. There was no further discussion. Harlow Shapley told me to contact him as soon as I had formed the company and he would work out financial arrangements. The meeting was adjourned.

Ewen Knight Corporation

Within a few days of the Horse Meat Meeting I received written notification of my appointment to the faculty in the Astronomy Department and the position of co-director of the Radio Project. I met with several close associates to develop a plan. Geoff Knight, a close friend since our Amherst days, offered to put up the $1000. I picked the name Ewen Knight Corporation to honor Geoffís generosity. Bill Pritchard of Raytheon offered to provide assistance with parts vendors, Walt Selove agreed to review all electrical designs, Dick Smith signed up for system integration and testing. Al Pote, Tex Holt, and Lee Davenport provided sage advice on how to run a business. On their advice, the first one hired was an accountant. We rented space on the second floor of a furniture store in Central Square, at 698 Mass Ave just above the Honey Bee Cafe. Central Square is strategically located half way between Harvard and MIT. We began to recruit technicians on a part time basis from MIT, to work off hours at EK. A professor at Harvard Law and long time friend at the law school squash courts offered to incorporate EK at no charge other than State fees. Within a few days of the Horse Meat Meeting we were in business.

I called Harlow, told him the name of the company and asked when we could discuss financial arrangements. He suggested breakfast the following morning. All of my meetings with Harlow, and there were several, were breakfast meetings. I confirmed my cost estimate of $15,000. Harlow handed me a check from Harvard to the Ewen Knight Corporation for $15,000, as payment in advance for a "Radio Telescope Radiometer". That was not anticipated, but it was much appreciated.

John Hagen from the Naval Research Laboratory visited EK during our first month of business. A few weeks later, EK received a purchase order from NRL for a "Radio Telescope Radiometer similar to the Harvard Radiometer". We planned to build the two radiometers together and disband the company within the first year. Then requests were received from University of Michigan, University of California, Lincoln Laboratory, Air Force Cambridge Research Laboratory, etc. When the Polaris Program ordered a radiometric sextant receiver and Lincoln Lab began to order 10 KW transmitters, we knew we would have a problem shutting down EK.

The 24ft Radio Telescope

The idea of an equatorially mounted 24' parabolic antenna was considered a challenge. The budget was $10,000. Bob Grenzback joined the D.S. Kennedy Co. in Cohasset, MA when he left the staff of the Cyclotron Lab. He said it was technically feasible, but to meet the budget the antenna reflector would have to be assembled in one piece and moved from Cohasset to Harvard, MA. The Radio Project ordered the antenna system, with the antenna in one piece, from the D.S. Kennedy Co. with delivery to be FOB, Cohasset, in the fall of 1952. The price was $9,000. As the hardware co-director, it was my job to get the antenna to Harvard, MA. As I left for the URSI-IAU meetings in Australia and England, I told Bart that I planned to fly the antenna to the Agassiz site in the fall.

The solution to many of the seemingly impossible problems was the work of our first two graduate students. We were blessed to have Dave Heeschen and Ed Lilley on the staff. They kept things moving with a great hands-on attitude. Bob Grenzback and the D.S. Kennedy Co. came to know them quite well. They took good care of things while I was out of town, or in town.

On my return from England in the fall of 1952, arrangements were made for Air Sea Rescue to send a helicopter and flight crew to Westover Air Force Base for training, in preparation for moving the antenna from Cohasset to Harvard, MA. They designed a parachute for the antenna in the event that it was needed. All was ready to go, when I received a call from a VP at Harvard who informed me that the flight would not be allowed unless covered under liability insurance of at least $2,000,000. There was no use in arguing: I was talking to the messenger. The cost of the insurance would exceed the entire NSF grant for the project. If not by air, then by land. From the Chief of the State Police to the Governorís Office we tried for weeks to get approval to move over state roads, in particular Route 128. But we had to wait until November, when Christian Herter, a "Harvard Man", became Governor of Massachusetts. The license was awarded immediately and we moved the antenna early on a Sunday morning. It was a memorable trip. Photos of some highpoints are included in the accompanying slides.

The 60ft Radio Telescope and NRAO

The need for larger antenna apertures and more regionally located antennas became a hotly debated issue in the early to mid-1950s. Larger became the goal. The number of large antennas needed to meet regional appetites fed the discussion. The 24' antenna at Harvard was bigger than the Wurtzberg at Leiden, but the 60' antenna, at Harvard would soon be overshadowed by a 75' antenna at Leiden. Plans for a 210' antenna in Australia were being implemented. The 85' antennas developed for White Alice were considered off the shelf items that would soon populate regional centers. As we broke ground for the 60' Radio Telescope at Harvard, the era of regional competition was slowly coming to an end under the burden of cost. The need for the universities to join together behind a National Radio Astronomy Observatory initiative had became obvious to most. The National Radio Astronomy Observatory would be operated by the universities under the existing Associated Universities Inc., with funding provided by the National Science Foundation.

I spent endless hours on the AUI Site Selection Committee with colleagues from around the nation reviewing various pork-belly site recommendations. Good deer hunting, and a great vacation spot etc were among the reasons for selecting some sites. Preparing negative reports became an important site selection activity, because of the high level at which some recommendations originated. Finally, it was agreed that the selection would be based on the lowest level of radio noise. The winner was Green Bank, West Virginia.

The 60' Telescope at Harvard was dedicated in the same year that NSF awarded a contract to AUI to build and operate the NRAO at Green Bank, West Virginia. The dedication of the 60' Telescope provided a unique opportunity for those actively participating in the national effort to get together and review the NRAO plans. One of the key elements of those discussions was the need for the Observatory to establish and operate an in-house electronics laboratory capable of challenging the state-of-the-art and advancing the frontiers of electronics as a recognized center of excellence. Under the leadership of Sandy Weinreb and assistance from fellows like Jack Campbell, NRAO became that center of excellence.

My support for an in-house electronics capability at NRAO was based on the dismal failure by EK to deliver the radio telescope receiver for the 60' Telescope. It was physically delivered, but it was in poor operating condition. It was based on a sound concept, but a bit before its time. It was a multi-channel receiver with digitized output that was stored and printed out on an electric typewriter. Easy today, but an oddity 50 years ago. A $44K fixed price contract, with delivery in four months was not reasonable. Less reasonable was my insistence that all EK assets be devoted to the project, which seriously crippled the company.

The day of the 60' Radio Telescope dedication was the beginning of the end of an era of regional competition. It was the beginning of the NRAO. It was the beginning of an in-house capability in the Harvard Astronomy Department to develop and maintain radiometric receivers. Hays Penfield led that effort with the able assistance of Jack Campbell.

The interplay of the various scenarios described above is recorded in the accompanying slides. The first eighteen slides show the assembly of the 60' antenna in the days just before dedication. Slide 13 shows a schematic of the ill fated 1044 radiometer. Slide 14 is a photograph of the Signal Display Console, with the digital display and typewriter. The last ten slides describe the 60' dedication day. Most of the speakers were actively engaged at that time with the NRAO initiative, which would become a reality that fall (November 17, 1956). The importance of a national observatory was a common thread in all of the presentations.

Harvard 24' slides

Harvard 60' slides

Modified on Friday, 15-Jul-2005 11:31:51 EDT by Ellen Bouton