The view from above

This weekend, I sweated up to the top of Oh-Be-Joyful pass, a charmingly named ridge in Raggeds Wilderness near the town of Paonia, where I live. From there, my comrades and I could see mountains upon mountains -- and way down below, the green slash of the valley where we live.

If we were to make that hike at the same time every year, for many years, and take a photograph from the same spot each time, we'd be able to visually track changes to our home valley, in a sort of long-term time lapse photography project. Perhaps we'd note how climate change alters the time of year when the orchards blossom, or how limited water supplies transform once-verdant hayfields into dun-colored squares. We'd also see how development -- be it energy or residential -- reshaped the mesa tops and floodplains we now call home.

Forty years ago, the National Aeronautics and Space Administration had the idea to do something similar to this, but for the entire Earth. On July 23, 1972, they launched the Landsat program, which sent satellites high into orbit, where they would take images of the same location every 16 days, year after year.

Since then, the reliability and availability of these regular images have allowed scientists to make many surprising discoveries. Landsat images showed scientists how climate change affected glaciers near the North Pole, well before climate change impacts were visible elsewhere. Landsat documented the explosion of Phoenix as a population center, and its images marked the mountain pine bark beetle's devastating march through Western forests.

Image of beetle kill in 2001 and 2011 courtesy USDA EROS Data Center.

This May, Landsat became a little more real to me, as I researched a story I'm writing about cheatgrass. Scientists at the University of Nevada, Reno are using Landsat images to track areas where cheatgrass, an invasive and fire-prone weed, is undergoing spontaneous die-offs. Landsat's consistent photos allow them to see where cheatgrass is growing each year, and also where it is dying off. The idea behind tracking this is, if researchers know where the die-offs are happening and how those areas spread and move, they might be able to figure out what's causing the cheatgrass to die -- and use that as another tool to fight it.

So Landsat is pretty amazing. It's also pretty costly. At a Monday media event on the program, which is celebrating its 40^th anniversary, it was estimated to cost 80 cents per American per year, or about $240 million annually, if you use our current population for that calculation. And the program has experienced some problems lately. Last November, the U.S. Geological Survey, who shared the program with NASA, announced that their Landsat 5 satellite, which has been in orbit since 1984, was experiencing data transmission problems, and it probably won't work much longer. Landsat 6, launched in 1993, failed to reach orbit. Landsat 7, the most recent satellite, mostly works but also has some data collection problems. Landsat 8 is scheduled to be launched in February of 2013. Researchers -- who rely on the satellites' abilities to regularly capture an image of the same spot -- are notably nervous about the potential for data holes.

As NASA chief scientist Waleed Abdalati said at Monday's celebration, the program is "in a fiscally limited environment and we're trying to make the best of those resources."

When the question on cost was asked, Abdalati also said this: "It's plainly obvious that … the return on investment for the nation vastly exceeds, by orders of magnitude, the investment."

Of course, that's easy enough for Abdalati, the scientist, to say. Here's hoping those who hold the purse strings are willing to say it too.

Stephanie Paige Ogburn is the online editor at High Country News.

View many beautiful Landsat images at the USGS EROS Earth As Art image gallery.

Image of the author and her sister at Oh-Be-Joyful pass, with the view behind them toward the North Fork valley, courtesy the author.