International Archives of the Photogrammetry, Remote Sensing and Spatial Information Science, Volume XXXVIII, Part 8, Kyoto Japan 2010
TRUE STORY OF TRMM
-THE WORLD FIRST MISSION TO MEASURE RAIN
BY SATELLITE BORNE RADAR-
FUGONO, N.
President of Advanced Telecommunications Research Institute International
Commission VIII
ABSTRACT:
TRMM (Tropical Rainfall Measuring Mission) was successfully launched from Tanegashima Japan by H-l rocket in November
1997 and is still alive in good health. TRMM is continuing to accumulate global precipitation data even today. TRMM is one of the
longest life and most successful satellite projects.
TRMM is an US-Japan joint satellite project. Japan contributed the world first satellite borne radar and launching vehicle, and USA
provided other 3 instruments, satellite and telemetry command, tracking and control. And both sides equally participate and
cooperate in data analysis and utilization.
In the middle of 1970’s, the Radio Research Laboratories (RRL) decided to adopt remote sensing as a new major research area
following to satellite communications and broadcasting which was almost completing the initial phase, and selected rain to measure
by satellite borne radar. It was well known that rain was one of the most important parameters for our life but the accurate global
data had not been obtained yet. In one of the efforts to use higher frequencies, such as millimeter waves, for satellite
communications, RRL had made considerable efforts to know the radio wave attenuation by rain in high frequencies and to measure
the rain intensity. We had established revolutionary method of rain measurement by changing from classical time consuming statistic
method using data of rain gauges deployed below the radio wave path, to new rain radar method which enable us to obtain 3-
dimentional information almost instantly.
We began our effort to measure rain from space, exactly speaking, to obtain money for the purpose in 1977. It was 20 years before
the TRMM launch. The budget request was approved and we started to develop an air borne two frequencies
scatterometer/radiometer in the next year, as the first step. In the beginning of 1980, the air borne flight experiments were
successfully taken place. In the end of the year, collaboration was proposed by GSFC/NASA. In 1983 after we had enough
experiences, we started to discuss joint experiment. We sent our air borne radar/radiometer with a scientist to GSFC/NASA and
installed on NASA air plane (P3-C). The joint flight experiment started around Wallops Island in 1985. NOAA also joined to this
flight experiment with their radar installed P3-C. In September of the year, NASA proposed TRMM as a joint satellite project. I
responded that we planned to install 2 frequencies rain radar/radiometer on the space station. An official of NASA mentioned, “We
prefer small satellite project since the space station must be of the one in next century”. It was astonishing comment for us.
Everybody of Japan believed at the time that the space station will be in operation in 1992, because Mr. Reagan had just come to
Japan for requesting participation of Japan to the space station project and assured its 1992 operation to Mr. Nakasone. Today, we
know the NASA official was honest. I agreed with NASA to make TRMM as an US-Japan joint satellite project. And in the
November 1985, TRMM workshop was held in Maryland where the outline of TRMM mission, specification and sharing role of the
US and Japan were discussed and agreed.
TRMM was proposed SSLG (Standing Senior Liaison Group, the highest organization for space program cooperation between the
US and Japan) meeting in June 1986 from both side and approved. Immediately after the meeting, however, we realized nothing was
ready to move in the both side, especially in Japan side. In the August, I visited the office of Dr. Edelson, an Associate Administrator
with the US side colleagues of TRMM. The International Affairs division of HQ/NASA was reluctant especially to launch TRMM
by H-I rocket of Japan, but Dr. Edelson agreed to carry out TRMM project as proposed and to send his letter to Prof. Saito, his
counterpart of Japan side of SSLG. When the letter arrived, Japan side was in utterly confusion. After long discussion and
negotiation, the replying letter was sent from Japan (STA, Science and Technology Agency) to the US (NASA/HQ) proposing one
year feasibility study by Expert Panel.
The Expert Panel meetings were held 4 times in 1987 in Tokyo and Hawaii. Based on studies of the Expert Panel, “International
Symposium on Tropical Precipitation Measurement” was organized in Tokyo in October 1987. It was actually the announcement of
TRMM inauguration by scientists. The final report of TRMM Expert Panel study was sent to NASA and STA and signed by both
agencies in the spring of 1988. It was about 10 years before TRMM launch. The outline of history in the 10 years will be shown at
the presentation. It was tiresome and sometime even frustrated long way to the launch in November 1997. However, when I look
back to the 10 years now, I realize it gave us the key for great success of TRMM. We continued various air borne experiments
around Wallops, Caribbean and western Pacific, and study on development of algorithm for extracting rainfall information from
measured data. Now we are convinced that the 10 years efforts made us to be able to have better results and make excellent
contribution for meteorology by TRMM. Some of the flight experiments will be shown in the presentation.
International cooperation sounds nice but it is difficult and even troublesome in most case. TRMM was not the exception. There are
so many differences in systems, procedures, way of doing and thinking, habit and cultures between both sides which may cause
misunderstandings, mistakes, disappointments, frictions and disputes. As an example, the fiscal year starts from opposite side of year,
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