 Because what satellite data provides is a snapshot in time, and you can think of them as a series of photographs of where you have glaciers, where you have sea ice, and where you don't. But you have these in a time sequence over 30 or 40 years, over 40 years if we use Landsat data. And so the very same things which James Baylog, which James Baylog was explaining and chasing ice, we do similar things but using satellite data. And frequently we collaborate with James Baylog because they'll have photographs about specific aspects of certain glaciers. And we can use that information to tell where the boundaries are and the satellite data at those specific times where he has their chasing ice photographs. So all these things tie together and they're part of the same approach to study earth science where you need information on the ground. And then you couple that with satellite data and then get a much more comprehensive understanding of what's happened over time.