Mapping Earth's hidden water

A new NASA satellite will measure the planet's soil moisture.

 

On Jan. 29, at California's Vandenberg airforce base, a rocket will shoot a satellite into space where it will unfurl an antenna shaped like a giant circular fence. From its orbit, 426 miles above Earth, the Soil Moisture Active Passive instrument, or SMAP, will collect observations of the hidden water in the dirt beneath our feet.

A new NASA satellite will measure the moisture lodged in the earth's soil and help scientists understand how ecosystems are responding to global warming.
NASA/JPL-Caltech

It’s NASA’s fifth ever “mission to planet Earth,” a fitting tagline, says Dara Entekhabi, a professor at Massachusetts Institute of Technology and the project’s lead scientist. “There’s some stuff that we know more about on other planets than on our own.”

Now scientists are turning to a space-bound observatory to fill in the gaps of their understanding.

Soil moisture is one of those gaps.

It’s also a key barometer for everything from plant growth to daily weather, to where floods are likely to occur. Variations in soil moisture affect weather by adding or limiting moisture to the atmosphere, enabling cloud formation or intensifying dry spells during periods of drought. Understanding the availability of that water is crucial if we are to predict how landscapes are responding to a warming climate, says Alejandro "Lejo" Flores, a geoscience professor at Boise State University.

For decades, scientists studied the land and atmosphere separately, but the advent of super computers in the late 1980s helped reveal that hydrological and carbon cycles are actually connected. The lynchpin of that connection is soil moisture.

The trouble was that existing ground-based measurements were too sparse to show detailed variations, and in many parts of the world they were non-existent. What researchers needed was a way of taking a snapshot of moisture levels around the entire globe across time and space. 

Five years ago, the European Space Agency launched a soil moisture satellite that provided data at a spatial resolution of about 25 miles – not nearly small enough to capture the true variability in places like the Western U.S., where moisture levels can differ radically across small areas.

Scientists anticipate that a more accurate account of soil moisture will have a variety of applications – from improving weather forecasting and natural disaster predictions to bolstering climate models.

More than two decades after the idea for SMAP took hold, and after an initial attempt failed in 2005, their efforts are about to take off. The final price tag: $915 million.

Once in orbit, SMAP will fly between the poles and peer – via microwave radiation – into the layer of soil that covers the earth everywhere it’s not frozen or under water. Using the data NASA will construct two maps for scientists to use: a soil moisture map with a resolution of 6.2 miles and a map tracking the freeze-thaw state of the soil with a resolution of 1.9 miles.

To understand why such high resolutions matter, take the flash floods that hit Fort Collins, Colorado, in 1996.  Since no one anticipated the severity of the flooding, scientists have used the event as a case study to see what would it would have taken to make better predictions – a process know as “hindcasting.”

Researchers knew that they needed better measurements to capture the true variability of soil moisture of the surrounding land: a patchwork of wet and dry ground, from irrigated fields to forest burns. They hope SMAP will provide the kind of resolution they need to better predict future floods.

And as temperatures rise, these kinds of measurements will prove even more crucial – particularly in places prone to extreme weather. To understand drought, for instance, scientists need to understand how certain soils dry out during times of water stress. SMAP’s data could also help probe some longstanding climate-related mysteries, like whether there’s a correlation between rainy Aprils in the Pacific Northwest and dry Julys in the Great Plains.

“It’s being able to flick a switch and see a whole new part of the landscape,” Lejos says. 

Sarah Tory is an editorial intern at High Country News.

High Country News Classifieds
  • EXECUTIVE DIRECTOR
    If you are deeply committed to public service and would like to become part of our high performing, passionate and diverse team, NCAT is looking...
  • TRIPLEX .8 ACRE KANAB, UT
    Create a base in the center of Southern Utah's Grand Circle of National Parks. Multiple residential property with three established rental units and zoning latitude...
  • FORGE & FAB SHOP
    with home on one beautiful acre in Pocatello, ID. Blackrock Forge - retiring after 43 years! Fully equipped 5,500 sf shop including office, gallery and...
  • SMALL FARM AT THE BASE OF MOUNT SHASTA
    Certified organic fruit/berry/veggie/flower farm. Home, barns, garage, separate apt, more. Just under 2 ac, edge of town. Famously pure air and water. Skiing, mountaineering, bike,...
  • FOREST STEWARDSHIP PROJECT DIRECTOR
    Become a force for nature and a healthy planet by joining the Arizona Chapter as Forest Stewardship Project Director. You will play a key role...
  • EXECUTIVE DIRECTOR
    Ranchers Stewardship Alliance is accepting applications for an Executive Director. This position will provide leadership to RSA, develop a fund raising plan, and effectively communicate...
  • WRITING PLACE: THE ANIMAS RIVER REGION WRITING WORKSHOP
    REGISTER ONLINE BY: Friday, June 15 WHERE: Durango, CO (location TBD) WHEN: Monday, July 16 Youth workshop: 10 a.m. - 12 p.m. (18 and under,...
  • EQUITY IN THE OUTDOORS COORDINATOR
    The Equity in the Outdoors Coordinator will lead community engagement, program implementation and development, and data collection for the Eagle Valley Outdoor Movement (EVOM). EVOM...
  • COMMUNITY ENGAGEMENT ASSISTANT
    The Idaho Conservation League is seeking a personable individual who is passionate about conservation to join our Sandpoint Field Office. The Community Engagement Assistant will...
  • LIGHTWEIGHT FLY ROD CASES
    4 standard or custom lengths. Rugged protection for backpacking. Affordable pricing.
  • EXPERIENTIAL EDUCATION INTERN/ASSISTANT
    Actively introduce students to Experiential Education, Outdoor Recreation, and Sustainability while engaging and challenging them to learn and participate in these diverse opportunities. Room, board,...
  • STAFF ATTORNEY
    STAFF ATTORNEY POSITION OPENING IN TAOS, NEW MEXICO www.westernlaw.org/about-us/clinic-interns-careers The Western Environmental Law Center (WELC) is a nonprofit public interest environmental law firm with a...
  • ENVIRONMENTAL INVESTIGATIVE MEDIA SERVICES
    In-depth investigations of polluters, lobbyists, regulators, elected officials and others focused on environmentally damaging projects in the U.S. and internationally. We specialize in mining projects,...
  • UNDEVELOPED 40 ACRES - SOUTHWEST COLORADO
    in beautiful Montezuma County.
  • TRUCK DRIVER
    Class A & B drivers, pass all DOT requirements and clean driving record
  • MARIA'S BOOKSHOP FOR SALE
    - Thriving Indie bookstore in the heart of Durango, Colorado. General bookstore with 34-year history as a community hub for Southwest region of CO. 1800...
  • ASSOCIATE DIRECTOR OF DEVELOPMENT
    HawkWatch International seeks an experienced fundraiser to join our awesome team! This position will provide support in all aspects of the department. We are looking...
  • DIRECTOR OF DEVELOPMENT
    will develop and execute Wild Utah Projects fundraising plan. Call, email or check full description of job online for more details:
  • HAND CRAFTED LOG HOME IN TETON VALLEY
    on ten acres. Full view of the Grand Teton. 35 miles to Yellowstone and 20 minutes to Grand Targhee Ski Area.
  • ACREAGE WITH HOME, SHOP, BARN FOR SALE!
    Must see for sng/extd fam or corp retreat in pines! $1,030,000