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Remote Sensing

For the longest time, the only tools that a mapmaker had to help them portray the shape of the Earth were their writing implements and their own two legs. It is truly amazing how accurate maps were considering their limited technology. But in recent decades, technologies have improved dramatically. Those like remote sensing allow them to create more precise maps.
 

An image of an old map of the world.

A map of the world.

What is Remote Sensing?

Remote sensing is any technology that can gather data without having to physically touch the object it measures. This kind of technology is important because it can allow people to gather data without placing themselves in danger. For instance, traveling to the top of an active volcano might be too risky for a person to do. But with the help of a drone or a satellite, we can take accurate images of the volcano from a safe distance. 

An image of lava on Hawaii.

Volcanoes aren’t a safe place for anyone!

Remote Sensing Technology

Remote sensing technologies are often deployed from an airplane, drone, or satellite. Airplanes, drones, and satellites will carry the appropriate sensors that will receive information. Depending on the type of remote sensing technology, they might also carry a source of light. 

An image of a satellite in space over the Earth.

An image of a satellite.

 
Satellite sensing has a few specific characteristics. For example, it’s defined by the spatial resolution of the sensor, or how defined the image is. GPS is a well-known example of this type of sensing. So whenever you’re in your car getting directions from your GPS, you have remote sensing to thank!
 

Types of Remote Sensing

Active

One type of remote sensing is active sensing. This type of sensor has its own source of light that it shines on an object it needs to measure. Its sensors measure the energy that reflects back. LIDAR is an example of an active sensor. It stands for Light Detection and Ranging. LIDAR uses light in the form of a laser to measure distances to the Earth. It allows us to gather information on the shape of the Earth’s surface and its ocean floor.
 

Passive

Passive sensing is the other type of remote sensing. Unlike active sensors, passive ones don’t have their own light source. So, they depend on light from outside sources, usually the Sun. Passive sensors measure reflected light emitted from outside sources. 
 
One example of a passive sensor is a spectrometer. This sensor measures the wavelengths of light that interacts with a sample you’re trying to study. It uses prisms or gratings to split up the light and measures the spectrum of light that results. We can identify the material based on the spectrum it gives off.
 
Another important example of a passive sensor is an accelerometer. As you might have guessed from the name, it measures the acceleration of an object. The two types of accelerometer are those that measure changes in acceleration in straight lines or in rotations
 
<An accelerometer sensor chip>
 

Remote Sensing Jobs

As you might have guessed, this method of gathering information has a huge number of applications. We can use it to track the growth of a city over time or map the ocean’s bottom. We can also use it for weather predictions, hazard assessment of natural disasters, or military intelligence.

Other Great Resources

(Video) How An Accelerometer Works! – Afrotechmods: https://www.youtube.com/watch?v=i2U49usFo10&t=5s

(Video) Mapping the Invisible: Introduction to Spectral Remote Sensing – NEON Science: https://www.youtube.com/watch?v=3iaFzafWJQE

NASA on Remote Sensors: https://earthdata.nasa.gov/user-resources/remote-sensors

 

Written by: Sylvia Choo