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 My name's Robert Kennedy. I'm an Assistant Professor in the Department of Earth and Environment at Boston University.

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All of these images are numbers.

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Now we can display them on a monitor as different colors.

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but what we work with, analytically, are the numbers themselves.

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When we're looking at how processes affect landscapes

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you need to understand how the processes unfold over time.

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Hindsight's 20/20. Landsat gives you that hindsight.

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In the Pacfic Northwest, known for its timber, right for producing lumber.

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So you've got a stable forest and it looks kind of the same to the satellite over time

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and then you come along and cut down all the trees – boom, it's a lot brighter.

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So you can think of sutracting one part of the information.

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And the other thing is that you've revealed something new which is the soil, the rocks.

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So you've added this soil in there, this signal that

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sort of bursts out at you like a flag.

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That soil signal that was there, that you saw right after the clear cut,

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immediately starts getting obscured - grass will come in, shrubs will come in....

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So as that happens the soil gets covered up. So you can actually watch that whole process happen,

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from an older forest to this bright soil to recovering vegetation

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So the progression in the bark beetle case, we have a fairly stable lodgepole forest.

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There'll be sort of an explosion, and epidemic of these beetles. 

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Our color scheme goes from stable forest which is in tones of blue

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to this bright red coming from the soil and from branches and things

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that are revealed when the trees lose their needles and when the needles change color.

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One of the insects thats increasingly important is

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Western Spruce Budworm. They don't go in and kill the tree outright,

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but come in and eat the buds or the young needles off a tree.

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So the satellite sees that as a bit of a darkening of the picture over time.

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By the end of the time period, we see pure yellow and that's associated with broadleaf shrubs,

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it could even be a shrub field, just dense.

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Those bugs have changed the environment for everything else there,

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and the Everything Else there in this part of the world are shrubs: rhododendrons, other shrubs

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that are usually hanging out underneath the trees

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where its kind of dark and shady. Boom, they get all this light, they love it, they grow like gangbusters.

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One of the interesting things about managing forests in the Pacific northwest,

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you can see a very strict delineation on your landscape

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from the satellite's perspective, and that's just

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a manifestation of the policy differences, of the ownership differences.

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The idea behind science is to develop understanding,

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ultimately to be able to predict and understand processes.

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When we look at a change, when we look at those graphs of life histories

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of individual pixels, it's that the numbers that drive everything.

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It's the numbers that we use to look at how severe things are, it's the numbers that we to quantify how long did it take

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or when did that start or how big was that clear cut.

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The Landsat perspective is really the only tool that lets you look at what's going on

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at the scale that you're interested in where you can see individual events and

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harvests and roads and houses – and at the same time look at the whole landscape.

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