Q: I grew up in the western part of El Salvador, where most of the Mayan ruins in my country have been found. When I was a kid, my friends and I would find Mayan artifacts by digging just a few feet down. I saw your segment in NOVA, and I became interested: How many archeological sites could the satellite be able to see in El Salvador? It's a part of our history that is being destroyed by looters or by time, and it needs to be discovered and protected. Mauricio Funes, Nashville, Tennessee
Bill Saturno: That is a difficult question to answer, as this particular technique is dependent upon a relatively intact tropical forest canopy. How many sites it could find in El Salvador would first depend on the area of intact forest present and then the density of sites within that forest. That said, there are other remote-sensing techniques that have been vital in the archeology of El Salvador, specifically those employed by Dr. Payson Sheets and his colleagues at El Ceren.
Q: Aren't you concerned that misguided NASA personnel might pass on satellite images of archeologically valuable ruins to looters in exchange for monetary considerations? We have seen top CIA officials and agents compromising U.S. security and American lives in exchange for money. Arnaldo Dumindin, San Antonia, Texas
Saturno: I am not particularly concerned for the following reasons: 1) The looters don't actually have any money; for the most part, they are rural poor with little other economic opportunity and sell artifacts only to barely meet their subsistence needs. The real money only exists farther up the illicit trade ladder. 2) Unfortunately, of all the sites we have located with this technology, none of them is unlooted. Looters already know where all the sites are; they just don't share that information.
Q: I visited a small Mexican village in the state of Chiapas along the Guatemalan border by the name of Benemerito de las Americas, Chiapas. The locals had found a site and, of course, had already looted, but the government had not stepped in yet. How long does it take before the government steps in to protect a site like that? It seems a shame that the beautiful statues and figures being taken out of there are being destroyed for lack of, well, a lot of things. Jon Cruz, Austin, Texas
Saturno: Unfortunately, the resources for government protection of each and every archeological site simply do not exist. In addition, in conditions of abject poverty, when faced with the choice of feeding one's family or protecting cultural resources, cultural resources rarely if ever win. It is a shame that other economic options aren't available and that those that fuel the market by collecting artifacts don't invest those same funds in the in situ preservation of the objects in which they see such value.
Q: Most name glyphs are used in Mayan murals to denote and identify royalty. Can it be assumed that the glyphs in this mural also name royals? These glyphs look like they are from early on in the progression of the Mayan writing system, but will they still be able to be translated in the future through etymological research? How much is known about the earlier stages of glyphs in general? Erin Donnelly, Pittsburgh, Pennsylvania
Saturno: The glyphs provide narrative detail to the scenes with which they are associated. This may come in the form of the name of an individual and/or his or her title, but may also include the date and other specifics (a verb, for instance) of the event. Not much is known about the earliest stages of Maya writing, because so little of it has been found. Without more examples, full translation remains unlikely.
Editor's note: The next three Q&As refer in part to the mural featured in the NOVA web feature "A Masterpiece Revealed."
Q: When you try to understand the meaning of the mural and assumptions are made, is the chance that the mural is representing a particular legend or myth, rather than representing a general scene, considered? And if so, how could this affect the process of interpreting of the mural? Leonardo, Padova, Italy
Saturno: In short, yes. Where the mural illustrates characters that are familiar to us from a broader study of Mesoamerican art and myth, we use both those representations and stories to help elucidate the actual goings on within the pictorial narrative before us at San Bartolo. This can have the effect of obscuring changes, but every effort is made to be aware of this. Where scenes and characters are unfamiliar, we are left only with the image and our own cultural biases to interpret it.
Q: What story does the mural tell? Is it a legend, a myth, social commentary, a depiction of daily life or special ceremony? Anonymous, Springfield, Missouri
Saturno: The mural tells many stories all tied to the mythology of creation. One such story is the myth of emergence seen on the North wall. Another scene is the coronation of a king upon a wooden scaffold from the West wall.
Q: What do the dark footprints along the base (right side) of the mural represent? Phyllis, Glendale, Missouri
Saturno: Footprints are often used in Mesoamerican art to denote "the path." In this instance it identifies the serpent as the path out of the underworld. Footprints are often shown heading both toward and away so don't necessarily indicate the direction of overall motion.
Q: Is there a book forthcoming on San Bartolo? Damaris, Connecticut
Saturno: I am working on it right now.
Q: What is your theory about why the Mayan civilization crumbled? Andy Alonso-Emanuel, Aurora, Illinois
Saturno: There is no single reason for the sociopolitical collapse experienced in the Maya Lowlands at the end of the Classic Period. An overtaxed environment was likely a major contributing factor. It should also be pointed out that the Maya experienced multiple rises and falls. Many cities of the Preclassic were abandoned or greatly reduced in size and importance during the Classic period. New cities also sprung up in the wake of the Classic Maya Collapse. Collapse in this sense is best understood as a system failure followed by reboot.
Q: What was the environment like before the deforestation in ancient Mayan times? Did the forests grow back the same? Or did the deforestation by the Mayans allow new species of plants/animals to colonize the area, creating the rain forests of today? I am asking because I wonder with the damage done to rain forests today what the prospects are for recovering them. Thanks. Colleen, Lansing, Michigan
Saturno: The evidence points to a dramatically different environment, not necessarily in the range of plants and animals that existed in the Maya area but certainly in the overall distribution of those species. For example, seasonal wetlands seem to make up a substantially larger portion of the landscape today than when the Maya first occupied the region. Likewise the rainforest today is far more expansive than it was when the Maya were practicing intensive agriculture and building large cities.
Q: How historically acurate is the movie Apocalypto? And have you read Guns, Germs and Steel by Jared Diamond, and if so, what do you think of his theories that the advance of a civilization is determined by its geographical location? Frank Tucci, Whitestone, New York
Saturno: I must confess to not having seen the film, but judging only from what I have seen in the previews, it cannot be particularly accurate.
As for your second question, certainly the natural environment places certain constraints on the societies that develop within it, but civilizations have always looked for ways to bypass those constraints to both their great benefit and their great detriment.
Q: Do you anticipate the use of satellite technology to search for further archeological ruins/sites not only in the jungles, but also those that may have been buried by volcanic eruptions or covered by water? Rae McEntyre, Frankfort, Kentucky
Tom Sever: Yes. In fact, Dr. Saturno and I are currently investigating tropical forest regions in Southeast Asia, Bolivia, and the Amazon forest in Brazil. We see features in the remote sensing data that we believe are indicators of prehistoric settlement. In addition, we are working with Dr. Payson Sheets, University of Colorado, to map prehistoric pathways and roadways in the volcanic regions of Costa Rica using satellite imagery. Although I myself have not participated in underwater archeological research, a number of my colleagues are, and they are making wonderful discoveries.
The use of remote sensing in archeological research is expanding. The second conference in Remote Sensing and Archeology was held last month in Rome, Italy. Dozens of papers were presented at this conference, which discussed aerial and ground-based remote-sensing research investigations that are being conducted around the world. You can find more about the conference at the following link: http://www.vhlab.itabc.cnr.it/space2place/
Q: Has there ever been a comprehensive satellite survey done of the Maya lands using radar or other sensors to try and find all the lost cities and structures? Anonymous, Herndon, Virginia
Sever: Several Maya investigators have been working both independently and together using remote sensing for the detection of ancient Maya sites. At this time a comprehensive inventory has not been accomplished. However, it remains a goal for the future. Not only would a comprehensive survey aid us in science and interpretation, it would also allow officials to know where these sites are so that they can monitor and protect them.
Q: We have had satellite imagery of Earth from space for at least two decades or more. Why did it take so long to apply it to archeology, and why was even Thomas Sever rather skeptical of its effectiveness? No offense, but is this not yet another example of how dogmatic views in science hamstring the researchers? Or, perhaps, territorial divisiveness? Paul Kuchynskas, Brooklyn, New York
Sever: I have been conducting remote-sensing archeological research for NASA since 1981 and having been working collaboratively with researchers around the world, and we have made many discoveries. In that time, we have mapped ancient Anasazi roadways in New Mexico that are invisible to the human eye using thermal imagery. Working with Dr. Payson Sheets, we have discovered the oldest known footpaths in the world using color infrared photography and aerial thermal imagery. These footpaths were buried beneath several layers of volcanic eruptions and were visible in the tropical forest as well as pasturelands. I have also detected ancient Maya archeological features including ancient roadways, water storage areas, and canals in the northern Peten of Guatemala. Other accomplishments include mapping an ancient tower signal communication in Israel, detecting the location of the 1910 hangar of the Wright Brothers at Wright Patterson Air Force Base in Ohio, and the detection of archeological features at the ancient earthworks at Poverty Point, Louisiana. You can read more about some of these by visiting my website at: http://weather.msfc.nasa.gov/archeology/
Archeologists have been using remote sensing, in the form of black-and-white aerial photography, for over 100 years. When satellite imagery became available in the 1970s, there was limited use for archeology since the spatial resolution was 80 meters, insufficient for the detection of most archeological features. In the last few years, high-resolution satellite imagery at one-meter resolution has become available, and archeologists have been flocking to make use of the innovative technology. For an excellent description of the history of early pioneers in aerial archeology, please read Flights Into Yesterday: The Story of Aerial Archeology, by Leo Deuel.
When Bill Saturno contacted me and stated that the satellite imagery was working 100 percent of the time, I was skeptical because he had found three sites around San Bartolo, a number too small to be statistically reliable. As a NASA scientist, I needed many more examples to document the flawless reliability of this technique. We conducted extensive research with Dr. Saturno and his research team and visited dozens of potential sites and verified that the technique was working every time. A NASA television crew joined us in the field and documented that we were able to predict the location, diameter, and perimeter of ancient Maya sites.
Q: Referring to the infrared imagery, what color or shade are the sites appearing as? Also, does the correlation between the sites and the color only appear when the locations have structures of limestone? What about smaller surrounding villages? Corey, Tampa, Florida
Sever: All color in remote-sensing imagery is artificial, since the digital data are recorded as numeric values. We artificially make our features of interest "yellow" because that color is readily visible against various backgrounds. A great Web site for the discussion and tutorial of remote sensing data can be found at: http://rst.gsfc.nasa.gov/Front/tofc.html
Yes, the correlation only appears when the structures contain lime plaster remnants. Whether it is an entire large site or an individual structure, we can detect it.
Q: Did you use geometry to do your research or to solve any of the problems you ran into? Mt. Anthony Middle School, Bennington, Vermont
Sever: Not only do we use geometry, but we use all forms of mathematics to help us in our data analysis, including algebra, linear regression, and statistics. Without these tools it would be impossible to make consistent discoveries from space.
Q: Fascinating presentation. How did Saturno and Sever meet to combine the NASA technology and on-the-ground research? Steven Snow, Gilbert, Arizona
Sever: A NASA colleague of mine at the Marshall Space Flight Center, Daniel Irwin, who is also a member of our research team, attended a conference in 2002 in Guatemala City where Dr. Saturno presented his results. He offered to send high-resolution IKONOS satellite maps to help Dr. Saturno and his team in their fieldwork. This high-resolution imagery had just been downgraded so that it could be used for commercial purposes, and this was the first time it had used it for archeology. Based upon Dr. Saturno's initial success in the field, he visited the Marshall Space Flight Center to review his discoveries with our remote-sensing experts. We became convinced and excited about the potential for this technique and developed a five-year NASA Space Act Agreement with the University of New Hampshire to collaborate on future surveys and inventories in the Maya region. We continue to have great success!