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Exploring Earth from Space:
Land
Dr.
Darrel Williams, NASA/GSFC
National Air and Space Museum
September 14, 2000 |
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| Thank
you Dr. Asrar, and good evening ladies and gentlemen. I would like to thank
you for coming tonight to share in the excitement that we feel given the
significant accomplishments within NASA's Earth Science Enterprise over
the past 24 months. As our Space Science colleagues continue to look outward,
exploring the universe, seeking signs of life, the images and animations
that you will see tonight will reveal several unique perspectives of our
own life-sustaining planet -- perspectives that we have acquired looking
back at Earth from space. The vast majority of these compelling visuals
were derived from recent Earth observation missions and related R&D
activities funded by NASA's Earth Science enterprise. |
View Movie:
[1.1 MB QuickTime] [5.6 MB MPEG-1] |
| I
think that it is appropriate that we start off tonight by taking an "up
close and personal" look at our own backyard. This spectacular image of
the Mall area was acquired on Saturday, April 1st by Space Imaging's IKONOS
sensor, which was launched about a year ago. Here we are moving across the
Mall, from west to east and we will pause over the Capitol Building. Let's
just sit back for a few seconds and enjoy the view. We will then gradually
pull back from this highly localized view from space, to obtain a more regional
perspective provided by Landsat 7, which was placed in orbit 18 months ago.
This regional view permits us to follow the entire length of the Potomac
River, from its headwaters in the Shenandoah's, 'til it flows into the Chesapeake
Bay. We can also see the full extent of the Chesapeake and Delaware Bays
as they flow into the Atlantic. We will continue to pull back farther to
obtain more continental and global views of the Earth as provided by a new
instrument known as MODIS, or the Moderate Resolution Imaging Spectroradiometer,
the primary instrument on the Terra spacecraft launched just last December.
Then, nearly daily global coverage acquired by the SeaWiFS instrument on
OrbImage's OrbView2 satellite has been mosaicked to create a cloud-free
time series to monitor the seasonal fluctuations in global productivity. |
View Movie:
[2.2 MB QuickTime] [11.4 MB MPEG-1] |
| Let's
now look at the same data, but in the reverse sequence. While doing so,
I believe that a good analogy which everyone can relate to is to consider
the Earth as our patient, and we, as doctors, now have a variety of new
tools to monitor our patients health. For example, the daily, global looks
provided by MODIS and SeaWiFS are analogous to monitoring a patients pulse,
respiration rate, and temperature. Landsat then provides a higher spatial
resolution data set permitting us to conduct a "quarterly, seasonal checkup
or physical" of our patient. The super high-resolution imagery provided
by an IKONOS class instrument is equivalent to our microscope, permitting
us to zoom in and do a biopsy of limited, specific areas. By manipulating
this robust compliment of Earth observation data with today's powerful computers,
we can now examine the linkages between global-scale Earth system processes
and man's activities on the surface of the Earth. |
View Movie:
[1.4 MB QuickTime] [6.2 MB MPEG-1] |
| Any
doctor taking on a new patient likes to review records to develop a patients
case history. Fortunately, we have been monitoring our patient's surface
features since 1972, when we launched the first Landsat satellite. In essence,
we have been creating a digital family photo album of the Earth's surface
to monitor changes over time. This provides the primary database from which
a variety of our patients' health issues can be addressed. As I've been
speaking, we have started to cycle through a few examples of significant
change as seen by tapping into the incredible archive of Landsat data. These
examples include images showing massive deforestation of tropical forests
near Santa Cruz, Bolivia, near the headwaters of the Amazon, we then show
images acquired before and during the 1993 flood of the Missouri River.
Finally, we take a look at change over a 27-year period around the nations
fastest growing city, Las Vegas, Nevada. The rationale behind the creation
of an image database of the Earth embodies the concept that imagery collected
today are an irreplaceable investment in assessing the health of our planet
now and in the future. Clearly, the value of this database increases with
time. |
View Movie:
[1.1 MB QuickTime] [5.7 MB MPEG-1] |
| In
this next image sequence we start off with a MODIS view of the United States,
then home in on the San Francisco Bay area, first using the new 250 meter
bands of MODIS. We then zoom further into the Bay area with imagery acquired
at the same time by another Terra sensor known as ASTER, which was contributed
to the Terra mission by the Japanese. Data from the infrared bands have
been used in this rendition, resulting in the bright red coloration. The
ASTER instrument offers multiple high-resolution thermal bands for assessing
land and water temperature, as illustrated here for the waters of the Sacramento
River, the San Francisco Bay and the Pacific Ocean. |
View Movie:
[1.0 MB QuickTime] [5.3 MB MPEG-1] |
| Next,
we illustrate the visual power of combining such data with topographic data
of the Bay area. By draping the imagery over a computer generated model
of the landscape we obtain a three dimensional perspective of the local
terrain to help us better understand such things as storm run-off and land
use patterns. Such terrain data have only been available for limited portions
of the Earth's surface. However, a high-resolution topographic data set
for ~ 80% of the Earth's land area was acquired recently during the Shuttle
Radar Topography Mission, conceived and managed at the Jet Propulsion Laboratory.
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View Movie:
[0.8 MB QuickTime] [3.7 MB MPEG-1] |
| We
will now see an example of merged Landsat and shuttle radar topography data
for an area in central New York State. We start off looking east, over the
Mohawk Valley. The eastern shore of Lake Ontario appears in the lower left
corner. Perhaps you can also pick out a couple of the Finger Lakes in the
lower right hand corner of the screen? We will fly past Syracuse, then head
north and east over the Adirondack Mountains. You might be wondering if
the Adirondacks are really that rugged, and the answer is NO. This is the
Adirondacks on steroids -- we have exaggerated the vertical dimension to
accentuate the terrain relief in this area. We turn further east and south
toward Albany, New York, then continue down the Hudson River Valley, past
the Catskill Mountains on the right, and on toward New York City at the
top of the screen. The merger of such digital terrain data with Earth observation
data enhances our ability to more realistically visualize and assess our
patient's land surface conditions. |
View Movie:
[1.2 MB QuickTime] [5.8 MB MPEG-1] |
| The
all-weather imaging capabilities afforded by radar were also used to acquire
a high resolution data set of the continent of Antarctica in 1997 using
a Canadian-built radar system. Radarsat Int'l acquired these data at the
specific request of NASA. It was the first time that Antarctica was imaged
in such detail. Since these data were acquired, some huge icebergs, one
the size of the state of Rhode Island, have broken away from the continental
shelf. Therefore, a special effort was made a few months ago to image Antarctica
during the first year of Landsat 7 operations. |
View Movie:
[1.2 MB QuickTime] [6.1 MB MPEG-1] |
| From
the barren lands of Antarctica we will transition to a time sequence of
SeaWiFS data for the southern Atlantic region. This monthly time series
of data permits us to monitor the seasonal and interannual fluctuations
in oceanic productivity and vegetative growth on the continents. David Adamec
will say more about monitoring ocean productivity later. Utilizing such
data within a modeling framework, scientists have been able to predict the
outbreak of devastating diseases, such as Rift Valley Fever in Africa, several
months before the actual outbreak of the disease. This humanitarian application
of satellite data permits authorities to order the medicines and supplies
needed to lessen the impact of such disease outbreaks once they do occur.
Of perhaps more local interest is the city of Baltimore, where a similar
pathfinding application of remotely sensed data is currently being developed.
We are trying to better understand the combination of environmental and
geo-spatial factors associated with the occurrence of asthma attacks among
Baltimore City school children. |
View Movie:
[1.5 MB QuickTime] [7.6 MB MPEG-1] |
| This
next video sequence relies on Landsat 7 data to illustrate the severity
of the floods experienced in Mozambique this past March. The "before" image
was acquired in August of 1999, and the "flooded" image was acquired on
March 1st, 2000, near peak flood stage. A silhouette of the Washington,
DC "diamond" has been digitized and superimposed on the flooded image to
help the viewer better appreciate the scale of this natural disaster. Basically,
a new water body roughly the size of the Delaware Bay was created in a matter
of days. Authorities in the region were desperate to obtain timely imagery
such as this, not only to assess the extent of the flood, but to assist
them in deciding where to stage humanitarian relief efforts to best provide
food and drinking water to the survivors. |
View Movie:
[0.7 MB QuickTime] [3.3 MB MPEG-1] |
| In
summary, there is no question that today's space technologies have altered,
forever, our sense and understanding of our patient, the planet Earth. Over
the last 1-3 years, the successful launches of the Landsat-7 and Terra missions,
along with commercial systems such as the Space Imaging IKONOS venture,
and industry/government partnerships like OrbImage's SeaWiFS mission, has
resulted in the deployment of a new set of instruments that permit us to
revisit nearly all regions of our planet daily, and seasonally, with better
precision than ever before. The dynamic character of our planet, and the
intimate relationship between its environmental systems and we who live
here are now better appreciated and understood than ever before. Does that
mean we know it all? The answer is a resounding NO! -- we still have a lot
to learn. For example, in addition to improved monitoring of our patients'
surface conditions, we also have equal interest in monitoring and modeling
the dynamics of the Earth's atmosphere and oceans. You will hear more about
these topics from the next two speakers. I will now turn the podium over
to Dr. Marshall Shepherd, who will help us better understand why certain
weather events, such as the severe flooding in Mozambique, may have occurred
in the first place. I thank you for your attention and I hope you enjoyed
the ride. |
View Movie:
[2.0 MB QuickTime] [10.1 MB MPEG-1] |
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Go Back to the Introduction
Go Forward to the Atmosphere Presentation
Go Forward to the Oceans Presentation
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