A lot of satellites are launched these days - 2012 saw at least 75 acknowledged rockets head for orbit. Many of these form the backbone for modern society - communications, weather, television. Even if I wanted to, I couldn't cover them all. Few launches this year, however, will be more important than the one that happened today. At 1:02 PM EST the Landsat 8 satellite left Vandenberg Air Force Base in California aboard an Atlas-V rocket. It successfully attained orbit minutes later.
It would be difficult to overstate the value of the Landsat program. Beginning in 1972, a series of six satellites have provided continuous imagery of the Earth's surface. Landsat 8 will become the seventh (Landsat 6 was destroyed in a launch accident). Sound mundane? It shouldn't. Think of a place on Earth (your house, maybe?) and Landsat has taken an image of it every 16 days (give or take) for forty-one years. Wondering about deforestation in Brazil? The retreat of Greenland's glaciers? The water level of Lake Superior? The urban sprawl of Shanghai? Landsat can tell you all that.
Best of all, Landsat images are provided free of charge for any non-commercial purpose. All this was in danger if today's launch didn't succeed. Landsat 7, now 14 years old, is on its last legs. The program's greatest value lies in its continuity. A gap of even a year could result in events like Hurricane Katrina or the 2011 Tohoku earthquake being missed entirely. With globally-reaching phenomena like the retreat of the Antarctic ice sheet, such a gap could be devastating. Fortunately, that's all been avoided. Landsat 8 will soon begin sending about 400 images a day back to Earth as it orbits every couple of hours.
Want to take a look at some Landsat images? Visit their website or just open Google Earth - yep, much of that is Landsat, too.