| Charles Elachi |
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Questions & Answers
Yasuoka(Chairman):
Thank you very much Dr. Elachi for your nice presentation on the microwave sensing. We would receive the question now. We would like to proceed to the discussion if you have questions, please raise your hand because you have to speak through the microphone and please identify yourself and then please proceed to the question. We still may have time to question like may be 5 minutes so let me invite questions from the audiences.
Questioner 1:
You have shown many images today. When did you firmly have the concept that these images will be able to be acquired? How did you confirm the concept? I guess the background result in the imaging that you have shown today. Could you please tell us the prehistory?
Elachi:
Like any major discovery, usually not one individual which come with ideas - people come with ideas and then other people build up on the ideas.
The basic concept of imaging radar was developed in the 50s - in matter of fact some of it was even earlier than the 50s. When I started at JPL in 1970 - I was still a student, working there - we started doing research on how can we use the technique from satellites? Because it was being used by the military from aircraft. So progressively, we started first thinking about using it for Venus. Because we wanted to see below those clouds. So my first research was on looking at a way of putting a radar on satellite to send to Venus. Then we started thinking about applying it to our own planet after we thought about doing it, for Venus. And at the beginning people did not believe that it would work from satellite. So we spent about 5 years trying to convince NASA that this technique would work from satellite. And to allow us to demonstrate it on a satellite called SEASAT that was launched in 1978. That was the first time that that we had an imaging radar flying on a satellite. Then after that, we started slowly each time improving on it by adding at first polarimetry, and then adding the interferometry technique.
That was result of a team effort - I was heading the team. Different people come with different ideas and we sit down discuss them and debate them. Some ideas never work. So typically if one idea out of ten actually works, that is very good. So we always encourage people who come up with ideas even if at the beginning they seem to be very unreasonable or very wild ideas. It's that encouragement of always thinking of new ideas even if most of them don't work, which leads to these kinds of activity.
Questioner 2:
I think it is fantastic that such kind of beautiful images can be acquired like these.
My question is about business applications of these images. Recently, in Japan, people are strongly interested in privatization, or commercialization for space development has been discussed. How about in NASA? Is NASA distributing or selling these images for commercial use? If it is permissive, please tell us about such kind of activities of NASA.
Elachi:
Thank you for the question. Basically, all earth-orbiting images that are generated by NASA are in the public domain. That mean you can acquire copies of those images through, in this case, the geologic survey, there is an EROS data center which is in South Dakota. And you can get copies of those images. And the cost, I think, it's very minimal because just for reproduction cost. Also I'm sure you can get the images from the Japanese satellite. I don't know exactly the detail - how to get it - but I'm sure through NASDA you can get it.
Now let me talk about the privatization issue. On many of the satellites, they are very expensive, to develop them and fly them. Therefore it's important that the government enable them first. It's very hard for the private companies to actually develop the satellites and fly them without government financing. Where I think the privatization comes is in using the data and developing ideas and techniques to actually utilize the data. For instance, in the ones I showed you for three dimensions, what we do at JPL is to generate the data and distribute it. But then companies use it, for instance, for placing repeaters for cell phones. Or they use it to generate three-dimensional visualization for their home cityfor engineering construction project. So we see the government make an investment to develop the basic data and then the users actually utilizing that data for their application.
But still I believe that for the foreseeable future, it requires the government to actually do the basic investment for this kindof satellite.
Questioner 3:
We research on human potential. And Dr. Elachi what we would like ask you is your "Ideas into Action" program at JPL. Is that a formal program or is it informal? Can you please highlight how it works and you know are those kind of wild ideas you mention - are they always discarded or are those kept some kind of a record?
Elachi:
We do not keep a record of them. But usually kind of new ideas come from just sitting down and having discussions. You know having a coffee or having a discussion about something. Usually what happens is we have an objective. For instance, somebody says we need to find the way to do geological mapping from satellites, and then we have a series of meeting where people discuss the different ideas. Or we go to conferences where people are making presentation about their different ideas. And then as we get together and look at these different ideas - see how feasible are they to implement.
Particularly in case of satellite, where things are very expensive. Then if an idea seems to be reasonable, usually we test it on an airplane first. After we write the equations and make sure it works, we test on the airplane. Then if it works on an airplane, then we start thinking about doing it on a satellite. That process typically takes 5-6 years from the idea that you believe that it works, to the test on an airplane and then try it on the satellite.
So the key message here is not necessarily recording it, but the key message is having an open forum for people to be able to discuss ideas. Because they build on each other. Somebody comes with a small idea, somebody else take that idea, build a little bit on it, somebody else comes with another idea and builds a little bit on it. So I think the openness of our society in the US and here in Japan and the symposia and meetings that occur where people present their ideas are very critical to this process of coming up with this major project. These do not happen by one person just sitting in their office and just thinking about all of these things.
Questioner 4:
Thank you very much for your showing impressive images. Concerning to the three dimensional images, could you tell me how accurate they are in height, width, depth of them and how do you assure the accuracy of the data?
Elachi:
It is also a very good question. Let me answer it in two pieces.
The accuracy of the images, the three-dimensional images, is what we call "posting" that means every 25 meters on the surface we make a measurement. And then the height is five meters accuracy. The way we do the accuracy measurement in it is by comparing it to topographic maps, which are developed by the Defense Mapping Agency.
Now you notice that the mission was flown in the year 2000. And we are just starting to generate the data. The reason is, over the last two years, first we did the topography over a very small region and we went and compared it with ground topographic maps. Then we did it over a larger region and compared that one. Then we started producing larger amount of data. So that took us about a year and a half to verify every point over the small region. We call it a reference region.
Now, you talked about the penetration. Three-dimensional images are all of the surface topography. They were acquired at the frequency, one of the short frequencies, which is in this case five centimeters. The one which penetrate below the surface, that we don't have global coverage, It's only over limited region. That was a different mission which allowed us to penetrate for about 2-4 meters in the Sahara desert. That we have only limited amount of data of the penetration below the surface. But the topography one, we have global coverage for that one. Did that answer your question?
Yasuoka(Chairman):
Though it is the time to summarize this session, I have the last question. Now we have deepened understanding about the significantly high potential of the radar.
I believe it also has broad application in environmental fields. One of the applications is global warming.
Could you tell me which kind of application does the synthetic aperture radar, microwave radar, potentially have? If you have any ideas for the projects in JPL, could you please share with us?
Elachi:
In the case of global warming, where the radar can help - one example - is by monitoring the glaciers, both in high mountains as well as in Greenland and as well as in Antarctica. So by monitoring, on a regular basis, the extension of the glaciers, or the reduction or the expansion of glaciers, then this can be used as information for people who are doing modeling of global warming. And the radar has benefit of being able to map, on a continuous basis, these glaciers. Irrelevant if it's cloud covered or when half of the year is dark like Antarctica or polar region.
Yasuoka(Chairman):
Thank you very much. I think you may have questions more. But it is the time to go to the next presentation. Thank you very much Dr. Elachi.
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