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Remote sensing is among the most powerful tools that space scientists have come to rely upon in studying other planets. With a range of equipments on board, satellites are able to send back a wealth of information about what the surfaces of planets look like and what they constitute. Further analysis of this information back on Earth can flesh out even more details, giving scientists a deeper look into the formation of the objects under study.
What are some of the latest techniques in planetary remote sensing? How do they help us learn about the planets in our solar system and how have they enhanced our understanding of our home planet Earth? What contributions are Muslim scientists making to this field so essential for space exploration?
Former researcher at Stanford University’s Space, Telecommunications, and Radioscience Laboratory (STARLab) Dr. Ahmed Kamal Sultan Salem joined IslamOnline.net for an interview to discuss planetary remote sensing and his contributions to the field.
IslamOnline.net (IOL): Could you start off by explaining to our audience what is remote sensing in general and how does it help us learn more about the planets in our solar system?
Dr. Ahmed Kamal Sultan Salem: Remote sensing, as the name implies, is to gain knowledge about bodies or objects that are inaccessible to our direct observation. Using many techniques of remote sensing we can know a lot about surfaces, atmospheres, rings, etc., of bodies of the solar system.
IOL: What specific field do you work in within remote sensing and what technique did you specialize in?
Salem: Here is a summary of what I am doing. You simply use an earth-based or space-borne antenna to direct a beam of electromagnetic radiation toward a planet like Venus or a moon like Titan. The incident wave is "scattered" by the surface and received either by the same transmitter or another antenna. If the receiver is a spacecraft, the data is sent to earth. Once you get the data, you compare the received signal with models of interaction between waves and surfaces. These models are parameterized by certain relevant surface parameters. Once you find a match, i.e., a model that adequately represents the received signals, then the surface parameters are obtained. These include the composition of the surface and can be used to construct its geologic history.
My research has been concerned with the development of models that better match the observed wave-surface interactions. Better models mean more meaningful and useful inferences about planetary surfaces. I applied the results to three data sets, one for Venus (via Magellan spacecraft), and two for Titan (one via Arecibo and the other via the Cassini spacecraft currently in orbit around Saturn.)
IOL: Your work at STARLab involved working with data coming from Venus and Saturn. What new discoveries have you made about these planets through your work?
Salem: I would not use the term “new discoveries.” More accurately, I think, is to say that the models I tried to develop for scattering from planetary surfaces yield better estimates for surface parameters. This means an increase in the accuracy of the information we have. This information is provided to geologists and geophysicists who incorporate it with results from other remote sensing experiments to construct a coherent, and scientifically sound, narrative about various bodies of the solar system.
Let me give just one example. One of the datasets of Titan I processed yielded a dielectric constant result for some part of the Titanian surface of more than 4 (dielectric constant of a material is simply a measure of how light slows down in the material: the more the dielectric constant, the slower the light.) This dielectric constant from experiments done on Earth at atmospheric conditions resembling those on Titan matches that of ammonia-rich water ice. This is a very relevant piece of information because ammonia added to water can make water act as lava material. That is, this result may indicate the presence of cryo-volcanoes on Titan---volcanoes ejecting water and ice!
IOL: What is the value of conducting such research on other planets, and does such research help us understand our own planet Earth?
Salem: Exactly, such research helps us understand more about our planet. Maybe all the remote sensing techniques employed in probing other planets can be applied to Earth. There is surely an element of curiosity driving planetary sciences---knowledge for knowledge. I am talking here about basic science, which may appear of no immediate use, but which certainly lays down the foundations of future innovations.
IOL: As more and more satellites are being placed in orbit around Earth for remote sensing and other purposes, do you see space around Earth getting congested anytime soon?
Salem: Don’t worry about this at all. There is masha’Allah plenty of space out there!
IOL: Egypt and Saudi Arabia launched their first remote sensing satellites a few weeks ago. How do you see this technology help people of the developing world?
Salem: Remote sensing can be used to produce topographic maps, in meteorological studies, to study vegetation, to investigate deserts and underground water, etc. There are numerous applications.
IOL: What has been your experience working as a Muslim at Stanford University in space-related research? And what other contributions are being made by Muslim scientists in this field?
Salem: My experience at Stanford was awesome, elhamdlellah [praise be to God]. I cannot say that I was, for instance, discriminated against or annoyed for being a Muslim. The team I worked with had deep respect for members’ various worldviews. (The situation is different if we are talking about life in the US in general.)
There are many Muslims working in the field. I will just mention one of them who finished his Ph.D. from the same lab more than 30 years ago! He is Prof. Essam Marouf, a pioneer in the study of planetary rings through remote sensing by radio waves. My advisor, who was also Essam’s, always praises Essam’s superb intellectual capabilities and engineering competence.
IOL: How easy or heard is it to get permission to use data from space missions to apply in your own research? Is there a clear process through which someone from any University from around the world can follow to acquire such data from NASA or is it reserved only for internal use?
Salem: Data are available (though with some delay for current missions). Please visit NASA's Planetary Data System.
IOL: After you finished your PhD you decided to return back to Egypt and teach at Alexandria University. Do you see many of your Muslim colleagues in space science doing the same thing or are more of them continuing to work abroad? And why?
Salem: As far as I know, the return rate is dismally low. There are many reasons for this. The systems of our countries are highly inefficient, almost in all domains. Universities, whether in teaching or research, are suffering like other sectors in society. Professors do not get enough money and, thus, waste their time just to provide for their families rather than conducting research, let alone cutting edge research, or delivering knowledge properly to future generations. It is a big mess here. Of course, part of the blame is on those who do not even try. (I am saying that in very general terms, because every one has her or his own circumstances.)
IOL: Some argue that without joining the space club and having an indigenous space program, many of the developing world’s countries will be in a more disadvantaged position than they are right now. Do you think Muslim countries should invest in their own space programs?
Salem: I disagree with this assessment. The issue is simply that we have very limited resources. A rigorous cost-benefit analysis (that is also not oriented toward serving the interests of some class of people) is what should be done to determine how to place our scientific and technological research priorities.
Regarding our disadvantage vis-à-vis developed countries, I do not see lack of space program as the underlying thrust. Pertinent factors, I claim, are more complicated and fundamental.
IOL: Having worked in the field of space for many years now, what is your future expectations for the human race in space exploration? Would you expect that in 100 years time human colonies would have formed on the surface of the moon if not also on Mars? Do you see space tourism picking up to become a major sector in the tourism industry?
Salem: I think human spaceflight to Mars and beyond would remain a big challenge. The main problem is cosmic rays. Exposure to these for a prolonged period is damaging to the human DNA. Proposed solutions, until now, are not realistic to implement.
On the other hand, space tourism within the natural shield protecting us from cosmic rays is feasible so long as some have money and resources and see this a better thing to do than, say, really helping the deprived.
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