336
Chapter 11 Images from Space
available data from Landsats 1 through 5, would be made freely available and
distributed via GloVis. This decision allows free worldwide access to a vast library of remote sensing data for everyone, and this availability of the data can
only help with furthering research and education in remote sensing.
In 2003, Landsat 7’s SLC (Scan Line Corrector) failed and could not be
repaired. Due to the malfunctioning SLC, the ETM+ produces imagery containing missing data. Without a working SLC, an ETM+ image contains only
about 75% of the data that should be there. ETM+ data is still used by substituting pixels from other Landsat 7 scenes from the same area but a different date, or by using other methods to fill in the gaps for the missing pixel
values. With these types of issues, Landsat 5 TM imagery is still being used by
some researchers for a source of remotely sensed Landsat data. However, with
Landsat 5 being years beyond its mission life (and having had some mechanical issues in recent years) and Landsat 7 having issues with collecting imagery
due to the SLC failure, the question that has to be raised is: What is the future
of the Landsat program, as there has been no Landsat launch since 1999?
The next planned Landsat launch is the Landsat Data Continuity Mission
(LDCM) scheduled for the end of 2012. The LDCM satellite’s instrument will be
the next iteration of Landsat sensors (similar to ETM+), called the OLI (Operational Land Imager). Unlike ETM+, a thermal band will not be part of OLI, but
two new bands, aimed at monitoring clouds and coastal zones, will be developed
instead. A separate instrument on the satellite, called TIRS (the Thermal InfraRed Sensor), will collect remotely sensed thermal data. LDCM is estimated to
collect about 400 images per day. There’s a strong need for continuing to obtain
Landsat imagery for monitoring larger-scale phenomena such as environmental
effects, land-use changes, and urban expansion. Long-term gaps in the dates of
imagery would have a huge negative impact on these types of studies.
Being able to monitor large-scale conditions on Earth on a regular basis
(at 30-meter resolution) with a variety of multispectral bands (including nearinfrared, middle infrared, and thermal characteristics) will provide a rich dataset for numerous applications. With Landsat imagery stretching back for more
than 30 years providing a constant source of observations, long-term tracking
of environmental phenomena (such as ongoing land-use or land-cover changes
for an area) can be performed. For instance, the growth of urban areas over
time can be observed every 16 days (cloud cover permitting, of course), enabling planners to determine the spatial dimensions of new developments
across a region. Figure 11.12 shows an example of utilizing Landsat imagery
over time to track the patterns of deforestation in Brazil through examination of
clear-cut areas and new urban areas built up in the forest. The color composite
images show the rainforest in dark green shades, while the deep-cut patterns of
forest clearing are clearly visible and the encroachment of development into the
forest can be tracked and measured over time.
Beyond examining land-cover changes over time, the multispectral capabilities of Landsat imagery can be used for everything from measuring crop
drought conditions to glacier features to the aftermath of natural disasters.
By examining the different band combinations provided by Landsat imagery,
SLC the Scan Line
Corrector in the ETM+
sensor. Its failure in
2003 causes Landsat 7
ETM+ imagery to not
contain all data from a
scene.
LDCM the Landsat
Data Continuity
Mission—the future of
the Landsat program,
scheduled to be
launched in 2012.
OLI the Operational
Land Imager, the
multispectral sensor
that will be onboard
LDCM.
Chapter 11 Images from Space
available data from Landsats 1 through 5, would be made freely available and
distributed via GloVis. This decision allows free worldwide access to a vast library of remote sensing data for everyone, and this availability of the data can
only help with furthering research and education in remote sensing.
In 2003, Landsat 7’s SLC (Scan Line Corrector) failed and could not be
repaired. Due to the malfunctioning SLC, the ETM+ produces imagery containing missing data. Without a working SLC, an ETM+ image contains only
about 75% of the data that should be there. ETM+ data is still used by substituting pixels from other Landsat 7 scenes from the same area but a different date, or by using other methods to fill in the gaps for the missing pixel
values. With these types of issues, Landsat 5 TM imagery is still being used by
some researchers for a source of remotely sensed Landsat data. However, with
Landsat 5 being years beyond its mission life (and having had some mechanical issues in recent years) and Landsat 7 having issues with collecting imagery
due to the SLC failure, the question that has to be raised is: What is the future
of the Landsat program, as there has been no Landsat launch since 1999?
The next planned Landsat launch is the Landsat Data Continuity Mission
(LDCM) scheduled for the end of 2012. The LDCM satellite’s instrument will be
the next iteration of Landsat sensors (similar to ETM+), called the OLI (Operational Land Imager). Unlike ETM+, a thermal band will not be part of OLI, but
two new bands, aimed at monitoring clouds and coastal zones, will be developed
instead. A separate instrument on the satellite, called TIRS (the Thermal InfraRed Sensor), will collect remotely sensed thermal data. LDCM is estimated to
collect about 400 images per day. There’s a strong need for continuing to obtain
Landsat imagery for monitoring larger-scale phenomena such as environmental
effects, land-use changes, and urban expansion. Long-term gaps in the dates of
imagery would have a huge negative impact on these types of studies.
Being able to monitor large-scale conditions on Earth on a regular basis
(at 30-meter resolution) with a variety of multispectral bands (including nearinfrared, middle infrared, and thermal characteristics) will provide a rich dataset for numerous applications. With Landsat imagery stretching back for more
than 30 years providing a constant source of observations, long-term tracking
of environmental phenomena (such as ongoing land-use or land-cover changes
for an area) can be performed. For instance, the growth of urban areas over
time can be observed every 16 days (cloud cover permitting, of course), enabling planners to determine the spatial dimensions of new developments
across a region. Figure 11.12 shows an example of utilizing Landsat imagery
over time to track the patterns of deforestation in Brazil through examination of
clear-cut areas and new urban areas built up in the forest. The color composite
images show the rainforest in dark green shades, while the deep-cut patterns of
forest clearing are clearly visible and the encroachment of development into the
forest can be tracked and measured over time.
Beyond examining land-cover changes over time, the multispectral capabilities of Landsat imagery can be used for everything from measuring crop
drought conditions to glacier features to the aftermath of natural disasters.
By examining the different band combinations provided by Landsat imagery,
SLC the Scan Line
Corrector in the ETM+
sensor. Its failure in
2003 causes Landsat 7
ETM+ imagery to not
contain all data from a
scene.
LDCM the Landsat
Data Continuity
Mission—the future of
the Landsat program,
scheduled to be
launched in 2012.
OLI the Operational
Land Imager, the
multispectral sensor
that will be onboard
LDCM.