Back to School With Planet: Week 5 | Lights, Camera, Space!
Tags: Back To School, Stem Education, Planet Labs, Optics, Satellite Imagery

Dove satellites hold a 47MP camera. This is four times the resolution of the best smartphones in circulation, and it has a much better view. This week, with some help from an Optical Engineer, we’ll learn about the cameras inside the Dove satellites, and how they can see things which aren’t even visible to the human eye!

Career Spotlight: Optical Instrumentation

Optical Instrumentation Engineers like Planeteer Carly study the images that Dove cameras produce, and design ways to improve the next group of satellites.

Carly Pritchett

Optical Instrumentation Engineer

Carly will describe the responsibilities of an optical instrumentation engineer, what kind of knowledge the job requires and how this applies to designing cameras that take valuable measurements of light!

What is your job at Planet?

I work on the system that takes the pretty pictures! This system is called the payload, which includes the telescope and camera. My job involves checking the payload on each satellite to make sure everything is working correctly. Also, after more satellites are launched into space and we receive their images, I work to find ways to improve our images for the next group of satellites. As with everything, there’s always room for improvement!

What did you study to learn your specialty?

Officially, the major I studied in college is called Engineering Physics. Basically, I studied matter and energy and how they interact (the physics part) and learned how to apply my knowledge to hands-on applications (the engineering part)! Also, I gained experience by applying my studies through a rocketry club during college where we actually built and launched small rockets!

What inspired you to start a career in spacecraft?

In elementary school, I had an assignment to do a book report on an inspirational person. My mom suggested I pick Sally Ride, the first American woman in space, and I was hooked. I was 100 percent that kid who wanted to become an astronaut. Growing up in the Bay Area, I remember driving up Highway 101 and seeing the giant hangar at Moffett Field and the rest of NASA Ames and thinking about how so much cool stuff must happen there. These people work with things in space!

How are the cameras on Doves different from an ordinary camera?

One important difference involves the wavelengths of light captured in a picture. Humans are able to see wavelengths in the visible spectrum:red, green, blue and so on. However our Doves can see wavelengths that our human eye cannot see!

By being able to take images with near-infrared light, we gain new information about our dynamic world, such as planet health. Near-infrared light measurements provide warning signs of a dying plant before our human eyes can notice it.

How do you think the world would look if you could see more wavelengths of light?

What can you see in Dove images?

So many things! The level of detail in a Dove image provides a clear picture of buildings, roads, ships and even fun events like rocket launches. But the best part of Dove imagery is that there are daily images of the entire Earth! This allows us to view change from day to day. We monitor changes like new roads and coral reef health, and track natural disasters like wildfires and floods. In addition to these examples, researchers are continually finding new ways to use our imagery. The possibilities are endless as to what you can discover with our Doves.

If Doves move so fast, how do you not take blurry images of the Earth?

There are two parts to this!

First, consider trying to take a picture of your friend running past you. If your friend is only two feet away from you as they run in front of your camera, you have a small period of time in which you can take the picture. However, if your friend is 20 feet away from you, you have more time to take the picture, even though they’re running at the same speed! The further away a moving object is (in this case your friend), the slower it appears to you! So despite how fast our Doves move, remember how high up above the Earth they are!

For the second part, have you ever seen those images where people write a word using a flashlight or a sparkler? They do so by increasing the exposure time, essentially increasing the amount of time their camera is taking one picture. This causes any movement in front of the camera to be seen within one picture. In the case of the flashlight, that movement ends up as a written word. In the case of your friend running in front of you, that would end up as a blurry picture of your friend. However, if you can decrease the amount of time used to take one picture, or decrease the exposure time, you capture less movement. So in the case of the flashlight, the final picture would just be one letter rather than an entire word. And in the case of your friend, you’d end up with a clearer picture of them. In the same way, the Doves take images with a short enough exposure time so that our images are not blurry!

Dove cameras produce, and design ways to improve the next group of satellites. Carly will describe the responsibilities of an optical instrumentation engineer, what kind of knowledge the job requires and how this applies to designing cameras that take valuable measurements of light!

Activity: Making Rainbows

Cameras like those on a Dove satellite work by measuring one wavelength of light at a time. Each pixel of color in an image is a combination of the blue, green, red and non-visible waves of sunlight that bounce off that area on the ground and come back up where the satellite sensor can measure it. A prism is an object that can sort a source of light into all the colors inside of it. These activities guide you into creating prisms of your own and observing them in the world around you.

Project 1: Water Prism

You can send a beam of light through water and project a rainbow onto paper. This process is called refraction.

You will need:

A clear, straight-sided glass; the top of the glass should be the same size as the bottom

A flashlight or a window on a sunny day

A piece of sturdy card stock

Scissors and tape

A white piece of paper

Steps

Cut a slit 1 cm wide in the card, and tape it to the glass.

Fill the glass with water.

Place the white piece of paper next to the window, on a very sunny day.

Place the glass on the paper, so the card is between the window and the glass.

Look for rainbows on the paper!

Project 2: Soapy Shapes Prism

A soapy film in a customized shape allows you to express your creativity and create refractive prisms, all while having some good clean fun. Here are some examples to get you started!

Soap Bubble Shapes | Cellular Soap Opera

You will need:

Shape making supplies, including:

Thin, flexible wire

Plastic straws and string

Plastic straws and pipe cleaners

A pan or bucket to hold the soapy substance

Dishwasher Soap (If you have bubble solution on hand, this works as well!)

Optional: Sugar or Glycerin

Steps

Fill the bucket with a mixture of one part dishwasher soap to 10 parts water.

Optional: For thicker, more viscous film, try adding 2–3 tablespoons of sugar, or a tablespoon of glycerin.

Use your imagination and the straws, wire and string to make 2D or 3D shapes.

For best results, tie a string to the top of your shape, to make it easier to hold the structure without popping the soapy film.

Dip the shapes into the soapy solution and hold it up to the light!

Project 3: Make a prism and rainbow journal!

Look around this week for different objects that cast rainbows onto walls. Crystals, rings, windows, sometimes even smartphone screens can sort light as it bounces. When you look at a rainbow in the sky, is the Sun above you or behind you? Take pictures and make guesses about where you think the source of the light is!

More Prisms: Here are some prisms people have made with glass, mirrors and flashlights!

Your Turn!

You can customize these experiments with different shapes of wire, sources of light and width of the slit in the card. What happens if you use red light or colored soap? Does your prism work with weak sources of light? What happens if you use colored paper for the water prism instead of white paper? Or your own multicolored art on the white paper? Some people have even made 3D wire shapes! What kind of fun 2D or 3D shapes can you use for a soap prism?