Planet Earth Online - Science from the Skies

Earth observation from satellites is an extremely important way of examining everything from glaciers to tree cover in the Amazon. But sometimes, satellite measurements aren’t...
31 May 2011

Interview with 

David Davis, James Johnson and Carl Joseph from the NERC Airborne Research and Survey Facility


Chris -   Earth observation from satellites is an extremely important way of examining everything from glaciers to tree cover in the Amazon.  But sometimes, satellite measurements aren't quite enough.  Planet Earth podcast presenter Sue Nelson met members of the Natural Environment Research Council's Airborne Research and Survey Facility and spoke to pilot Carl Joseph.

Carl -   What makes this aeroplane special is that it was actually manufactured as a scientific platform.  So instead of really actually fitting the cabin area with seats, we've got a 2.1m hole in the floor that allows us to put a load of scientific instruments in.

Sue -   One of the crew members is James Johnson who's an instrument operator.  What instruments do you actually operate onboard this 'plane?

James - The instruments that we're going to operate which is the main core suite we have onboard are the LIDAR - the LIght Detecting And Ranging System - and the Eagle and Hawk sensors, which are hyperspectral systems looking at shortwave infrared and very near infrared.

Sue - Let's go on board the plan briefly before we take off...  It's quite narrow isn't it, less than a couple of metres across, and we're both having to stoop.

James -   The instruments down the end there, the sensor that you can see there, that is the LIDAR, which basically...

Dornier Do 228-200 twin-turboprop aircraftSue -   The silver box.

James -   The silver box at the end there, yeah.  That will produce a digital elevation model of the ground.  So it's a laser that fires down to the ground and we pick up the return and can actually map the ground and see the contours of the ground.

Sue -   What would that information be used for?

James -   I suppose that they would use the information for looking at various different things such as erosion.  You can see the difference that something has moved, for example a glacier; you can actually see from six months ago if we've surveyed a glacier in Iceland or Greenland you can then go back and do another LIDAR survey and you can see how it's changed, its features have changed, over a period of time.

Sue - In front of the silver box, the LIDAR, we've got a bigger, sort of an old-fashioned 1990s stereo really isn't it, like a stack of black boxes.

James -   Yes, that is the hyperspectral system.  So what that does is looks at the ground again and it looks at it in the shortwave infrared and the very near infrared bands.  So it's not looking at what you can see with your eyes specifically, it's looking at, for example, yes that's a green leaf but what kind of green is it, is it an oak tree or a beech or something like that?

Sue - That can tell the difference?

James - Yes, you can look at stuff like that.

Sue -   Good grief!  Now, the pilot Carl said there's a hole in the middle of the aircraft, but I can't actually see that hole, is that because this instrument is placed over the hole?

James - Yes, all of these instruments are placed over the trench that is in the middle of the aircraft.  There's no danger of anything or anybody falling out.

Sue -   Well I'm very glad to hear that because we're about to take off to do a calibration flight, is that right?

James -   Yes, that's correct.  What we're actually doing here is we are checking the instrumentation, checking it is working.


Sue -   Well we're several thousand feet above Southwest England now.  Rather unusually, we are sat with our backs to the pilot instead of facing the direction of travel which I must admit, even for somebody like me who loves flying, it's not that great on the stomach.

James -   That's right.  I know what you mean.

Sue -   And you've got 6 computer screens in front of you as well as a more mobile flexible one in front of me where we can see the ground beneath us.

James -   Basically, what we have here is the webcam.  So this is a continuous reel of all of the ground that we're flying over and then the LIDAR, we have the LIDAR controls which is a laser, that's firing to the ground and taking an elevation model of everything that we are flying over.  On this screens here, one of them is the eagle which is one of the hypospectral systems onboard, and the hawk.  And as you can see, as we're going across the ground, it is looking on what we are flying over.


Sue -   Remote sensing missions can last up to 5 hours.  But all the information collected helps fill the gap between what scientists can obtain in both satellites and on the ground.  Pilot and electronics officer David Davis.

David -   There's a lot of work completed post-flight by our data node in Plymouth Marine Laboratory.

Sue -   So it's not just land use, glaciers, climate change - it can be oceans as well?

David -   Yes, we can cover everything from marine, archaeology, geology, ecology and anything in between.  So if the scientists can think of a good project for it and put their application in, providing their science graded to a high enough standard, we'll fly it.

Chris -   David Davis, James Johnson, and Carl Joseph from the Airborne Research and Survey Facility talking with Planet Earth Podcast presenter Sue Nelson. 


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