[Archival VO] Thrusting outward into space, we gain a new perspective on ourselves.
Perhaps no new development in space is more significant than ERTS – short for Earth Resources Technology Satellite.
[Narrator] ERTS, later named Landsat 1, was one of
the first satellites to take regular snapshots of the Earth.
Onboard were two sensors: a camera, and a multispectral scanner.
While the camera showed the world as we see it—
in the visible spectrum of light—the multispectral scanner also captured data in
the near-infrared spectrum.
Researchers at NASA anticipated that data from this sensor
could help monitor the health of vegetation.
[Archival VO] Here’s a black and white photo of the Monterey Bay area in California produced
by the infrared channel on the ERTS multispectral scanner. Now if we project this image through
a green filter, the lighter grey tones, which are vegetation, such as the farm areas in
the Great Valley will show up more green.
Today, data of reflected light beyond the
visible spectrum have been used for a variety of applications: from measuring the productivity
of plants to assessing the microbial inhabitants in soil.
Many satellites are equipped with more advanced sensors and cameras, such as Landsat 8 and 9,
and Sentinel 2A and 2B. Other ways to survey the earth, such as LiDar scanners which use
lasers to measure distances from Earth, generate 3D imagery.
In recent decades, researchers have used remote sensing data to understand the biodiversity of an ecosystem.
Researchers studying the Lägern mountains near Zurich, Switzerland,
have harnessed a bevy of these techniques to characterize the forest's health.
By calculating leaf area from satellite imagery
and gauging tree heights using LiDAR, researchers estimated the productivity of the forest,
They also flew over the area using an airplane
equipped with hyperspectral sensors, which picked up hundreds of bands of light. By grouping
By grouping similar signatures of light together, researchers calculated the abundance of different species of trees.
These data also helped them capture finer scale details.
Trees have unique concentrations of pigment, water content and chlorophyll
that cause them to reflect light differently. The unique combination of these physiological
traits allowed researchers to map the functional diversity of the forest floor.
Diverse ecosystems are better equipped to handle changes, such as drought or disease outbreaks.
In combination with these techniques from high in the sky,
researchers collected samples on the ground to validate their findings.
Combining these approaches allows for a more comprehensive way to understand the health of an ecosystem,
and in turn, where to prioritize conservation efforts.
One conservation project for endangered Siberian white cranes used remote sensing to evaluate suitable habitats.
After examining a small 3-km square area where
the birds bred, the researchers found that the cranes avoided breeding in areas where
shrubs were invading the wetlands. The researchers used satellite images to scan
a 16,000-square-kilometer area, mostly inaccessible by foot, to find more promising areas where
the cranes could thrive.
Scientists hope to extend these techniques to even more species.
One project, Map of Life, lays out the distribution of over 44k species of flora and fauna using
a combination of remote sensing techniques Since there are limited numbers of conservationists
and ecologists to physically survey species, remote sensing allows biodiversity researchers
to more quicky get an idea of potential at-risk populations, as well as areas where organisms
are thriving and biodiversity is high. Many researchers are excited about the possibility
of what they can monitor as the resolution and frequency of remote sensing data improves.