NASA Social #EarthNow: SMAP


We’ve devoted two previous post to the #EarthNow NASA Social that took place at NASA’s Jet Propulsion Laboratory (JPL) on Monday, November 4th. (Start with Part 1 HERE.) This week’s post is all about SMAP, yet another NASA mission acronym, this one standing for Soil Moisture Active Passive.

That climate change has some kind of effect on agriculture is obvious. The EPA webpage entitled Climate Impacts on Agriculture and Food Supply says, “Agriculture and fisheries are highly dependent on specific climate conditions.” Just what those effects entail is less obvious. SMAP is designed to collect data that will aid scientists around the world in answering that question. To do this, SMAP is designed to interrogate the top two inches of the world’s soil in order to determine all-important moisture levels.

That’s right. From an instrument in space, we can find out how much moisture is in the uppermost level of soil all the world over.

The SMAP mission page lists the following science objectives:

  1. Understand processes that link the terrestrial water, energy and carbon cycles
  2. Estimate global water and energy fluxes at the land surface
  3. Quantify net carbon flux in boreal landscapes
  4. Enhance weather and climate forecast skill
  5. Develop improved flood prediction and drought monitoring capabilities
SMAP Tools
SMAP Tools


SMAP’s mission profile calls for it to be launched from California’s Vandenberg launch facility in October 2014 on top of a Delta II rocket. The Delta II launch vehicle is nearly 130 feet tall, and it can weigh more than 500,000 pounds. Although it doesn’t have a perfect launch record (for a somewhat melodramatic video of a Delta failure, check THIS), it is currently recognized as the world’s most reliable launch vehicle. Doug saw a Delta II launch in September 2011 when he attended the NASA Social for the GRAIL mission.

When SMAP enters Earth’s orbit, it will be in what is known as a sun-synchronous orbit. Roughly, this means that, each time it passes over a particular spot on Earth, SMAP, the Sun, and Earth will be in the same orientation to each other. This regular and consistent orientation provides the same lighting angle each time the satellite passes over a given spot. Narendra Das and Erika Podest, the research scientists on the SMAP mission who presented this session at #EarthNow, indicated that this orbit was designed to have SMAP completely image the earth approximately every three days.

That’s right. From an instrument in space, we can find out how much moisture is in the uppermost level of soil all the world over. And we can do it every three days.

JPL Clean Room Attire
JPL Clean Room Attire

SMAP employs an unusual pair of instruments to make its measurements of soil moisture. In general, remote sensing instruments come in two flavors, active and passive. Active instruments employ their own electromagnetic waves to make observations. Passive instruments rely on gathering naturally occurring electromagnetic waves. SMAP makes use of both types of instruments, radar (active) and radiometer (passive). Both instruments share what is arguably SMAPS’s most distinguishing physical characteristic, a single 6–meter antenna. The antenna, rotating above the rest of the satellite 14-½  times per minute, alternates between the active and passive modes: radar on – radiometer on – radar on – and so on. According to speakers Das and Podest, the instruments can image a 1000-kilometer swath.

Earth-observing satellites like SMAP and RapidScat (which we discussed last week) are important for some of the science work being done at our home institution, Chapman University. In 2011, a team of Chapman University scientists led by Dr. Menas Kafatos won an important grant from the USDA to study the effects of climate change on California agriculture. At the time, Kafatos was quoted as saying, “Some of the most profound impacts of climate change are the regional effects on natural and managed ecosystems, namely agriculture, and on the services such as food, water, fiber and energy that we all derive from them.”

The Lofty Duo is always thrilled when our day jobs as academics at Chapman Unversity intersect with our passion for science, space, and NASA. The NASA Social events that we’ve attended in the past (and that we hope to attend in the future) have been a fantastic vehicle for bringing those two worlds together.

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