International Collaboration in Astronomy

Speaker: Minoru Oda
   President, Tokyo University of Information Science

KOSHIBA

 We now ask Professor Oda to give his talk. He is one of the pioneers in X-ray Astrophysics. There are numerous awards he has received, including theimperial medal of culture and he used to be the Director General of the institute mentioned in Prof. Sata's talk, RIKEN which is a very old, very fine research institution. He was also the Director General of the Space Science Institute. Well, I'll ask Prof. Oda to start his talk.

ODA

 Good morning. Distinguished guests, Ladies and Gentlemen, I'd like to introduce the progress of astronomy and astrophysics in the context of international cooperation or U.S.-Japan collaboration. Science and applications in space activities in Japan are clearly decoupled, because they have developed independently. I do not go into the detail of Figure 1. The figure shows how science and application in space is separated and has a different origin in history. You may simply look at it.

 Space science in Japan, including rocketry and spacecraft technology for space science mission was originally born in the University of Tokyo as academic researches on the occasion of IGY (International Geophysical Year) from 1957 to 58. Since then, space science has been managed and promoted by the Institute of Space and Astronautical or Aeronautical Science under the Ministry of Education, Science, Sports and Culture (Monbusho).

 Part of the strategy of Japan's space science, places emphasis upon continuation and frequency of missions, and we have taken so much care that intervals of certain missions should not exceed five years. "Five years" is a life cycle of the graduate students. Now, space application, for example communications satellite, meteorological satellite, broadcasting satellite and the development of space infrastructure of Japan have been managed by NASDA (National Space Development Agency) under Science and Technology Agency. Efforts towards these two directions, science and application, are coordinated by the Space Activities Commission under the Prime Minister's Office.

 Entering the latter half of the twentieth century, astrophysics has supplied fundamental breakthroughs to the basis of physics. Among a variety of revolutionary steps, provided by astrophysics throughout the recent two to three decades, X-ray astronomy has been surprisingly fruitful as Freeman Dyson of Princeton stated clearly in his article (Figure 2). I'd like to introduce the early history of X-ray astronomy in the context of international collaboration.

 In order to make the story to be fictitous, quoting personal names and personal episodes are excluded. Indeed, international collaborations are often or usually initiated by person to person contacts and then by formal or official organizational agreements or understandings. Let me show a series of cartoon version of the story of history of X-ray astronomy.

 When Bruno Rossi of MIT, Riccardo Giacconi and others of the American Science and Engineering Inc. first discovered strong celestial x-rays with small sounding rocket experiments, he could not understand what physics is behind. Bruno discussed the matter with a number of visitors to his lab, which then was a Mecca of cosmic ray physics. This nude picture (Figure 3) was taken when Bruno was telling me about the mystery of the x-ray sky at the Cape Cod. One of the visitors Geoff Burbridge of UCSD is very famous for inventing one theory per day. His model suggests that the stars at the galactic center must be crashing around and then producing a very hot plasma which then radiates x-rays (Figure 4).

 Soon, Herb Friedman of the, at the Naval Research Laboratories in Washington D.C. who was one of the pioneers and founders of X-ray astronomy, performed a sounding rocket experiment when the galactic center was just below the horizon. Hence, it might not be seen. He then found the x-ray sky was still very bright when the Scorpioconstellation was above the horizon. I then searched around the Scorpio constellation to see if there was anything strange in this constellation. The question: was the x-ray source diffuse or was it star-like object.

 So, we came up with an ideas. Suppose we have a rotating cage (Figure 5), and we look through this rotating cage, if the source is a star-like object, it should beblinking. If this is diffuse, certainly it should look diffuse. So, we produced this machine replacing the mouse by a little motor, and then we installed the instrument on X-15, but NASA changed its policy to make the speed record with X-15 rather than altitude record so we had to give up as we needed the altitude for the x-ray observation.

 Then, Riccardo Giacconi spared a small space on board his rocket. Instead of the rotating cage, we installed a two layered grid and by the rotation of the rocket or tumbling of the rocket, we observed that this x-ray source in the Scorpio constellation was blinking; therefore, it should be star-like (Figure 6).

 Then we asked Professor Str¿mgren from Denmark, who was then at MIT, a question. How precisely should we locate this strong x-ray source so that astronomers would point their telescope to that direction to see if there is anything strange? Professor Str¿mgren requested it should be, say, 10 arc minutes or more precise (Figure 7). So, Herb Gurskey, then at the American Science and Engineering, and myself designed an experiment and we noticed that it was really star-like and we determined the error box of its location in the stellar sky. In the figure, negative plates of the sky are shown. We already knew that if this x-ray source radiates the optical light, it should be extremely blue, unbelievably blue. Tokyo Astronomical Observatory and Palomar Observatory looked for extremely blue objects, and indeed we found the blue object in this error box of x-ray source.

 This was the first marriage between X-ray astronomy and optical astronomy. So much for the chasing of the strongest x-ray source in Scorpio constellation then. Next, we were very puzzled by the strange temporal variation of an x-ray source in the Cygnus constellation. In the late 1960's and early 70's, the chasing of the location of this strange x-ray source in Cygnus constellation was a hot issue among x-ray astronomers (Figure 8). Since then, there have been many balloon experiments in Japan, many rocket experiments, and the satellite experiments in the U.S. We gradually pinned the source to a particular region as indicated by an arrow where radio astronomers and optical astronomers found a very strange thing which later turned out to be the best candidate of the black hole.

 Rapid development of X-ray astronomy which was born in 1962-65 may be exhibited by a graph (Figure 9). It shows the development of the number of publications in the Astrophysical Journal. The number of papers on X-ray astronomy per year rapidly grew. There is still rapid growth now. At the top of the curve, names or nicknames of the spacecraft are shown. The red marks are the Japanese spacecrafts. Japan's first X-ray astronomy satellite, Hakuchou, was helped by our MIT, American Science and Engineering, and British and European friends.

 Another series of episodes on the international collaboration in X-ray astronomy started in early 1980, when Japan's Institute for Space and Astronautical Science (ISAS) was planning an X-ray astronomy satellite not very big, but of reasonable scale. Japan, however, suffered from serious lack of man-power of scientists. On the other hand, our British friends in X-ray astronomy, led by Ken Pounds of Leicester University, had no flight opportunity. So, we decided to compensate each other (Figure 10). We provide the spacecraft and they provide the powerful scientist power.

 After this decision, I received telephone calls from MIT friends asking the same question: Why the U.K., and not the U.S.? The reason for this decision was due to some kind of bureaucracy, British colleagues were easier to collaborate with compared to American friends from a point of bureaucracy. Then, with my NASA friends, we invented a new bureaucracy, the Tamamushi agreement. Tamamushi is a Japanese insect which looks blue from one side and looks red from another side. So, we made an agreement, which suited both NASA and ISAS. A picture (Figure 11) shows a view of the U.S.-Japan X-ray astronomy seminar five years later with many Europeans.

 The next picture, Figure 12, shows the spacecraft, X-ray astronomy satellite later named Ginga (Ginga is galaxy in Japanese), under collaboration between the U.K., U.S., and Japan. This collaborative spacecraft was produced on the campus of ISAS and was assembled on one of Japan's University's rocket. It was launched from the southern part of Kyushu.

 Ginga was launched on February 5, 1987. Figure 13 shows the views of launching. You can see students or young assistant professors at work. Ten minutes later, British and American colleagues anxiously watched the Telemetry records, and ninety minutes later, we were all relaxed.

 Three weeks later, a supernova exploded in the Large Maellanic Clouds of the southern sky and was named SN 1987 A. This supernova appeared after quiescence of centuries. The last supernova explosion in the sky was in A.D.1604. The supernova is well-known as a fantastic spectacle in the celestial sphere. It is a heavenly nuclear explosion. I summarized what happened in my Christmas cards of 1987 (Figure 14). Then, there were three facilities in the whole world which could have observed this explosion of supernova on February 23, 1987. One was Ginga, and the the other was the Qvant satellite which were on board the Mir Space Station of, then, Soviet. Of course, nobody expected that a supernova would happen because it is a very rare event that occurs once per several centuries. In fact, jokingly we were saying that since the sky was so quiet for centuries, supernova would probably appear while we're alive, and indeed it happened.

 Today's Chairman, or Host, Professor Toshi Koshiba was watching a three thousand ton water tank one thousand meter underground of the Kamioka mine, hoping to detect a spontaneous decay of protons that are nuclei of hydrogen atoms in the water. The decay is very rare, at most once per year or once per three years in three thousand tons of water. This facility, however, happened to be a perfect detector of neutrino particles which may be produced in gigantic nuclear phenomenon as a supernova and come through the earth.

 Professor Koshiba was a lucky person. This happened only a week or two weeks before his retirement from the University of Tokyo. And indeed, this three thousand ton water tank detected eleven events within a few seconds. I recall a student of Professor Koshiba called me and asked me a question: "What is the exact time of the explosion?" Then I asked, "So, you have detected it". Then the student said that Professor Koshiba told him not to tell anybody! So I knew since then, Koshiba-san had become the godfather of neutrino astronomy. Figure 15 and 16 show the Koshiba-san's facility of three thousand tons watertank.

 Since neutrino astronomy is expected to be a very fruitful discipline in astrophysics, several places in the world are at work. There is one at Rutherford-Appleton Laboratory in England, one in Russia, one at Grand Sasso in Italy, and one at Sudburry in Canada. Koshoiba-san's students and successors recently completed a new facility of one order of magnitude larger scale, also at Kamioka mine. Now, the amount of water has increased from three thousand tons to fifty thousand tons (Figure 17). The world's largest photomultipliers, which had been developed by Hamamatsu Photonics Co., are used for these facilities. The new facility was completed recently and water will be supplied within a few months. So much for neutrino astronomy.

 Now, following Ginga satellite, two major X-ray astronomy observatories are orbiting around the earth. One is a German observatory ROSAT. Figure 18 is another X-ray astronomy satellite which is orbiting right now and is called ASCA. ASCA stands for Advanced Satellite for Cosmology and Astronomy. ASCA also means something for Japanese. Asca is from 7th and 8th century era in Japan, when Buddhism art most flourished. Now, since the university's rocket is not very big, you cannot launch a spacecraft of this size so it has to be folded into a smaller volume for launch and then stretched in the orbit. I call it Pirate's Telescope, stretched telescope.

 Since our U.S. colleagues opened their astronomy satellite for the world astronomer community, now it has become fashionable or rather habitual to regard the spacecraft as a common facility for the whole world's community. This ASCA satellite provides everyday information to laboratories worldwide. I will show one example of the telefax, which is sent around the world to, maybe, ten laboratories (Figure 19). Nowadays, MIT's graduate students can understand Japanese to this extent: George Clark of MIT interpreted this Japanese word as "ureka".

 Let me introduce a few other collaborative astronomical projects. Figure 20 shows the so called Yokoh satellite which was launched in 1991. This carried Japanese, U.S., and U.K. solar observatories as indicated in the figure. In Figure 21, exhibited are soft x-ray and hard x-ray pictures of the sun. We could produce one picture of those per one tenth of a second, therefore, we can really make a movie picture.

 Figure 22 shows a radio heliograph in Nobeyama. This had to be produced at particular year when the solar activity would be maximum. And for this solar maximum we needed to launch the solar x-ray satellite. Japanese bureaucrat hates to support two major projects in one year. So they asked the question "Which you really want to do?". Then I said "both". Incidentally, I personally was involved in none of these projects; just I was waving flags for them. So this question went back and forth three times and I kept saying "Yes we need both" and in fact the both were approved; Mr. Osaki was then in the government. So, this radio heliograph and x-ray satellite both works very well together. I must confess that, by then, I used to think that solar physics is a kind of old physics and nothing very new, but since then, I changed my mind and now solar physics is totally revitalized.

 At the latest collaboration, if you remember in January 13th, Mr. Wakata was on board the Space Shuttle Endeavor, they recovered a big spacecraft, which is produced by the collaboration of ISAS, Science and Technology Agency and MITI, and launched by NASDA, National Space Development Agency, and recovered by NASA's Endeavor. So this is the trilateral close collaboration across agencies in Japan and NASA of the United States.

 Next is the space radio astronomy. Figure 23 shows the very early microwave telescope in 1949-50, constructed with war surplus, radar parts. For this telescope, I made a primitive mistake in design and our radio astronomy did not achieve the progress as we had hoped; although, the concept of the radio interferometer was then born. As a further extension, after four to five decades, of this primitive interferometer, perhaps within several months from now, there will be a collaboration among world's radio astronomers to launch the umbrella looking Parabola antenna into the orbit and we'll make these telescopes with the ground-based telescope. Figure 24 shows an artist's concept of the design of space VLBI to be flown within several months under collaboration among ISAS, National Astronomical Observatory, JPL, NARO, Australian Telescope, and European colleagues. The name VSOP was insisted by our colleagues at JPL to honor Professor Morimoto, who is a world famous liquor lover. So, this name came first to stand for VLBI Space Orbiting Program.

 On Hawai Island, Big Island, at the top of Mauna Kea, there are many telescopes, we call Telescope Ginza. Now, next to the KEK telescope, Japan has been given land to build a big 10m telescope which will be called Subaru. Subaru is a 12th century Japanese word for Pleiades star cluster.

 I have introduced a variety of U.S-Japan collaborations by which we have produced and will produce a variety of breakthroughs in astrophysics and space science.

  Thank you very much for your attention.

KOSHIBA

 One question this moment and ...

Q. FROM AUDIENCE

 This will be in the nature of a couple of brief comments. First, that Professor Oda has been exceedingly modest in his whole account. He has actually had several careers in science. I knew of a couple of them. Eminent working cosmic rays and then in the x-ray field but I only learned today about your early work with micro waves. This rather surprised me, but you neglected to tell that actually, I guess out of modesty that you really were the pioneer in Japan in setting up, setting up the field of x-rays. I would like to make a comment about the nature of the satellite experiments in general and x-ray's in particular in Japan. The United Stated could have learned sooner a great deal from Japan in this field because rather belatedly, the present administration of NASA is pushing hard for what they call small, and fast, and cheap, and our Japanese colleagues have been doing this right along with amazingly fruitful results.

PROF. ODA

 Thank you very much for your kind comment, thank you.