ECOSTRESS Launch Piques Interest At EROS

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NASA launched its ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) instrument early Friday morning in Florida, and the event piqued the interest of several scientists at the Earth Resources Observation and Science (EROS) Center.

Illustration of ECOSTRESS satellite imagery

A simulation of ECOSTRESS land surface temperature data around California’s Salton Sea (dark blue area, upper left). Cooler areas appear in blue and green, warmer areas are in yellow and red. The region south of the lake that appears green is mostly agricultural fields, and other surrounding areas are desert. (Public domain.)

NASA’s Land Processes Distributed Active Archive Center (LP DAAC) at EROS is the designated archive for data and products acquired from ECOSTRESS, and scientists at EROS are intrigued by the possibilities offered by the new sensor.

“Since ECOSTRESS is a mission that the LP DAAC is going to be supporting, we’ve been building a relationship with the (ECOSTRESS) science team for a couple of years now,” said Tom Maiersperger of LP DAAC, who attended Friday’s launch. “We’ve been doing operational readiness tests here at the LP DAAC. We’ve had a couple of years of planning and scoping for putting in the storage volumes that we need. So, we’ve been involved quite a bit.”

ECOSTRESS hitched a ride to the International Space Station on a NASA-contracted Space X cargo resupply mission. It will be robotically installed on the exterior of the station’s Japanese Experiment Module Exposed Facility Unit, and will undergo a monthslong commissioning phase.

One of its primary missions is to acquire data that help with the understanding of how plants are responding to today’s warming world. Plants pump water up from their roots, transpire extra water vapor through their pores to cool, and take in carbon dioxide through the same pores. They then use the carbon dioxide and water to make carbohydrates for food.

Some plants naturally close their pores every hot afternoon to conserve water—even though closing their pores shuts down photosynthesis. Others don't close their pores, or close them infrequently. Some plants use more water in hot weather; others don't.

Scientists have seen these differences in transpiration during laboratory and local field studies, but they don't know the water-use efficiency of every plant or global ecosystem. ECOSTRESS will help address that.

As Earth's climate changes, some global regions are undergoing longer and more frequent droughts and heat waves, with more extreme conditions expected in the future. If plants in these regions can't keep their pores open long enough to take in carbon dioxide and feed themselves, some will die of carbon starvation.

From 400 kilometers in space, the ECOSTRESS multispectral radiometer will measure thermal infrared energy coming from an area on land below that is about the size of a small farm, 40 by 70 meters, and at an accuracy of within a few tenths of a degree.

Used in combination with other satellite weather data, these precise temperature measurements will allow scientists to determine how much water plants are releasing through transpiration.

That’s a concept of interest to Gabriel Senay, a U.S. Geological Survey (USGS) scientist based out of EROS. Senay developed the Operational Simplified Surface Energy Balance (SSEBop) model that uses remote sensing along with weather and climate data inputs to track water availability and consumption based on evaporation and plant transpiration—also known as ET.

“Although it is not going to be a priority data source for our operational applications,” Senay said of ECOSTRESS, “we will be interested in evaluating the data stream once the data is made available.”

ECOSTRESS will follow a precessing, or equatorial orbit, unlike the near-polar sun-synchronous orbits of Landsat and NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS). ECOSTRESS won’t pass over the same region of Earth at the same times of day like Landsat and MODIS. Instead, it will operate between about 50 degrees North and South latitudes, passing over Earth every few days at different times of day, at the Space Station’s low Earth orbit.

That ECOSTRESS orbit will enable a diurnal cycle that gives scientists the ability to see when transpiration does and does not occur throughout the day around the globe. Ground measurements taken at the same time as the satellite overpasses will help confirm the accuracy of the new dataset. Knowing then when plants are still green and healthy, but struggling to stay cool, can give agriculture water managers time to intervene with irrigation relief.

“It’s very exciting for ET,” Senay said. “The main challenge for us is its variable image acquisition time from day to day. We just need to figure out how we can handle the varying time stamps in our modeling scheme. But it’s a great data source for ecological studies that benefit from rich diurnal information.”

While in Florida at the launch, Maiersperger presented to the ECOSTRESS science team on the LP DAAC and what it has to offer. Along with archiving MODIS, ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer), and VIIRS (Visible Infrared Imaging Radiometer) acquisitions, the LP DAAC now will include ECOSTRESS data. And it also is scheduled to archive data from NASA’s GEDI (Global Ecosystem Dynamics Investigation) laser instrument after it launches late in 2018.

All that makes for an exciting time for those working here at EROS with the LP DAAC, Maiersperger indicated. And for him as well.

“I’ve actually never been to a launch before, so to be tied in with something new like this, kind of from its initiation, has been great,” he said.