O-1: There is a formal definition given near the beginning
of the Introduction Section. But try this for the moment: Remote sensing involves
the use of instruments or sensors to "capture" the spectral and spatial
relations of objects and materials observable at a distance - typically from
above them. Or, said another way: Remote sensing is the process of acquiring data/information about objects/substances not in direct contact with the sensor, by gathering its inputs using electromagnetic radiation, acoustical waves, or force fields that emanate from the targets of interest. An aerial photograph is a common example of a remotely sensed (by
camera and film, or now digital) product. There are probably hundreds of applications - these
are typical: 1) determining the status of a growing crop; 2) defining urban
patterns; 3) delineating the extent of flooding; 4) recognizing rock types;
5) pinpointing areas of deforestation. BACK
O-2: The scene shows an area near Breckenridge, Colorado. This is a major ski area. The white streaks are open ski slopes covered with snow. The dark areas also have snow but the evergreen trees mask the snow so that those areas appear almost blackish. BACK
O-3: The higher one goes, the more of the surface
comes into view (i.e., area of coverage increases) but the size of the features
that can be detected and separated (resolution) decreases. BACK
O-4: The camera was programmed to start snapping pictures
at a certain time after pigeon release and continued to take more pictures automatically.
But there was very little control over where the pigeon would fly or even whether
the pigeon would be positioned to have the camera looking down. Most photos
tended to be oblique (looking at an angle). BACK
O-5: During the Weather segment of local or network
news. The moving cloud patterns, for example, are observables relayed to Earth
from (usually geostationary) satellites orbiting 23000 miles above Earth); water
vapor images also are common. The radar images of the region are usually obtained
from ground radar stations. Since this question was first posed, there has been a trend that now brings another use to the fore: Google Earth has become popular on the Internet and on network and cable news, with satellite images being used to provide scenes of areas in the headlines; Iraq scenes are examples; disaster scenes are another common application. BACK
O-6: Of course, you as an individual may have seen
a Landsat image any number of places - they now appear in a variety of practical
uses (e.g., the book I have on the History of Ireland uses a cluster (mosaic)
of Landsat images to picture the island on its front cover). But, a good place
to look now and then is in certain TV ads or programs or in magazine ads (the
classic example I've seen on TV shows the same subscene of the San Francisco
Bay area as on the Coverpage of this Tutorial, but with the picture turned sideways
[north on right side] which confirms my suspicions about the limitations of
people at ad agencies). BACK
O-7: The fitting is subjective but as additional fix
points note that Ogden is near the top of the image and Provo is just to the upper right
of the smaller Utah Lake. Deserts appear whitish; areas of cropland are a patchwork
red and buff; the Wasatch mountains on the right side are rendered red because
they are heavily vegetated with pines, aspen, etc. (red is the hallmark of vegetation
in the so-called false color Landsat images). Kennecott Mining Company's famout open pit mine, referred to as the Bingham Canyon mine, is a bluish-white
patch in the mountain range just west of Salt Lake City. This Landsat-1 image was taken
in 1972. Since then, the Great Salt Lake's surface elevation has been raised by several feet (contrary to the usual history of a lake which trends towards drying up).
In my 1998 Rand-McNally atlas, the shoreline has changed
shape notably, so that two islands now appear as water rises to a higher surface, and the large peninsula
extending into the lake from the southeast has become once again Antelope Island. The Salt Lake
City environs extend well beyond the central downtown area, which appears a dark bluish representing light reflected from buildings and streets - this central area has few trees, hence little vegetation to contribute their signature reds to this false color composite. Downtown as seen in the oblique aerial
photo to contain many tall buildings. Look
at the photo - you will notice that the residential areas have an abundance
of trees, so many that, in the summer Landsat scene, their foliage shows up
as the characteristic red signature of vegetation. BACK
O-8: Let's start with the two bridges. Part of the Bay Bridge is left of top center; at the east end of its western span is Yerba Buena island, connected to Treasure Island. The west end begins near downtown San Francisco. The famed Golden Gate bridge is near the lower left. It carries autos into or from Marin County. On the San Francisco side is the wooded Presidio, once a military base and now a park. The long rectangular green area is the Golden Gate Park. Near its eastern tip is Twin Peaks. Lake Merced is evident in the residential area in the lower right. Alcatraz (once a prison) is the small landmass in the Bay. To its north (left) is part of Angel Island. Candlestick Park, home of the San Francisco Giants, is near the upper right corner. BACK
O-9: By the middle of the first decade of the 21st century, the network news programs, led by CNN, began making extensive use of commercial space imagery as a background or geographic framework for appropriate stories, such as battlegrounds or disaster areas. Next time you see such an image, look for the faint Google Earth logo in the upper right. BACK
O-10: Most nations with space launch capabilities subscribe to the "Freedom of the Skies" policy. Commercial satellites in particular offer the products to anyone who can pay the fees for specific images (these can be under $1000). Using third parties to purchase such images, terrorists can utilize satellite data to plan and execute their attacks. While the "good guys" believe the "bad guys" have obtained imagery of areas of potential targets, there is no direct evidence (at least not made public) that this type of use is part of terrorist activity. BACK
O-11: The Shuttle's most frequent use has been to haul parts of the International Space Station to the ISS itself, where assembly continues into 2009. The Shuttle also can reach certain satellites in need of repair. The chief complaint about the STS and ISS, both requiring humans to operate, is that too few really practical and viable activities - both scientific and technological - are being conducted. This will probably change with time (improve) as the ISS is completed and then manned with skilled personnel (not necessarily just astronauts and cosmonauts) who will conduct experiments (in a minimum gravity environment) and even start manufacturing useful products. The critics contend that the money spent on human space presence would have a better payoff if directed towards unmanned missions (like those to Mars). There is no doubt in the writer's mind that at the present, and previous, stage(s) of space exploration, probes and landers to other planets, and observational satellites orbiting Earth, have had huge positive effects - well worth the investment. But in the long run manned exploration is inevitable. Placing humans on Mars is a clearly worthwhile goal, as was the Apollo program on the Moon.BACK
O-12: This is, of course, a highly subjective type of question. But, in my opinion, the answer is a resounding YES!! Why? Consider these lines of evidence: 1) As mentioned, we now have very accurate weather forecasts owing to satellite observations; potentially, billions of dollars are saved each year because of early warnings for dangerous storms from meteorological satellites; 2) communications satellites are involved in our TV programming; 3) GPS satellites are invaluable in helping us get around; 4) our IPODs, Blackberrys and cell phones are based on satellite relays; digital cameras are now routinely part of our photography tools 5) computer technology and computers themselves have been advanced to a large extent by the needs of the national and international space programs; 6) earth resources and especially global warming and climate control are strongly dependent on satellite monitoring; 7) our understanding of the planets has thrived from exploration programs over the last four decades; the payoff from this in scientific knowledge has already been great and may be much more so in the future if we need to escape to another planet if nuclear war or climate destruction become real threats; and 8) our understanding of the Universe has been greatly enhanced by the launching into space of the orbiting astronomical observatories that have revolutionized the cosmological perspective of our place in the grand scheme underlying the Cosmos. This list and other spinoffs from the space programs take on new meaning - a new sense of benefits and value - when compared with costs (several trillions of dollars) that have underwritten the economic recovery packages that marked the recession and financial meltdown in the U.S. economy in 2008. This rings especially true in light of the fact that the U.S. space program's budget is just under 1% of the total federal budget. And, during its 50 year history, the accumulated budgets managed by NASA have amounted to less than 700 billion dollars.BACK