A new space-based instrument to study how effectively plants use water is being developed at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. The instrument, called the ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS), will monitor one of the most basic processes in living plants: the loss of water through the tiny pores in leaves.
people lose water through their pores, the process is called
sweating. The related process in plants is known as transpiration.
Because water that evaporates from soil around plants also affects
the amount of water that plants can use, ECOSTRESS will measure
combined evaporation and transpiration, known as evapotranspiration.
a person sweats during a workout, it helps cool their body, and if
they get enough water they can keep exercising," said Simon
Hook, a research scientist at JPL and the project's principal
investigator. "If they do not get enough water, they show signs
of overheating and stress and eventually collapse. Similarly, if
plants do not get enough water, they show signs of stress. By
measuring evapotranspiration, we get an early indicator of that
stress, and we can do something about it before the plants collapse."
science instrument is a high-resolution thermal infrared radiometer,
which works like a giant thermometer from space to measure the
temperature of plants and the amount of heat radiating from Earth's
surface. "If we find a plant is too hot, that's because it's not
getting enough water to cool itself down," said Josh Fisher, a
JPL research scientist and science lead for ECOSTRESS.
Existing satellite instruments that monitor evapotranspiration offer
either high spatial resolution but low time frequency (a couple of
measurements a month), or high time frequency and coarse spatial
resolution. Scientists, farmers and
water managers need both high resolution and high frequency.
International Space Station provides a particularly beneficial
vantage point not regularly available with traditional free-flying
(sun-synchronous polar-orbiting) satellites, which fly over the same
spot on Earth at the same time on each pass. The station's orbit
shifts so that it flies over any given spot on Earth at different
times. By looking at ECOSTRESS imagery of a certain location over the
course of days to weeks, scientists will be able to see how
evapotranspiration varies in that location throughout the day. This
is important, because plants that get enough water in the cool of the
morning might shut down in afternoon heat, just as a person stops
sweating under extreme heat stress.
for completion in 2017 and launch between 2017 and 2019, ECOSTRESS is
one of two instruments selected in July for NASA's Earth
Venture-Instrument series of missions. These missions are part of the
Earth System Science Pathfinder program, managed by NASA's Langley
Research Center in Hampton, Va., for NASA's Science Mission
Directorate. The ECOSTRESS team includes researchers from the U.S.
Department of Agriculture; Princeton University, Princeton, N.J.; and
the University of Idaho, Moscow, Idaho. The California Institute of
Technology, Pasadena, manages JPL for NASA.