NASA’S SMAP Begins Science Operations

SMAP’s global radar image, showing moisture in thawed parts of the Earth’s topsoil. Image Credit: NASA

On Jan. 31, 2015, NASA launched the Soil Moisture Active Passive (SMAP ) mission from Space Launch Complex 2 at Vandenberg Air Force Base in California, on a Delta II rocket. For the next three years, the solar-powered SMAP satellite will study moisture in the soil and detect whether that moisture is frozen or thawed. The satellite is in a polar orbit and has spent its first three months in a commissioning phase, during which the solar panels were unfurled, the 20-foot reflector antenna was deployed, and the instruments were spun up to full speed. Now the SMAP spacecraft has begun its science operations.

The SMAP satellite measures the Earth’s moisture in the top two inches (five centimeters) of topsoil. It measures the moisture in the soil every two to three days in order to observe over time the changes from major storms and the changing of the seasons. The spacecraft measures moisture in parts of the world that are not underwater or frozen and distinguishes between ground that is frozen or thawed.

SMAP’s measurements will help scientists to understand the circulation of water and carbon. The carbon cycle has more branches than the water cycle; it transfers from the air, in the form of carbon dioxide, to the soil, rocks, surface water and frozen surfaces.

Additionally, the amount of water that evaporates into the air depends largely on soil moisture. Currently, very little is known about the variability of soil moisture, either regionally or globally.

SMAP’s radar and radiometer share the same antenna, a 20-foot (6-meter) dish, providing the most accurate and highest-resolution soil moisture maps ever obtained from space. A reflector collects radio waves and focuses them into a feed horn which collects echoes from the radar and sends them to the radiometer electronics where they are processed.

“Fourteen years after the concept for a NASA mission to map global soil moisture was first proposed, SMAP now has formally transitioned to routine science operations. SMAP’s science team can now begin the important task of calibrating the observatory’s science data products to ensure SMAP is meeting its requirements for measurement accuracy,” said Kent Kellogg, SMAP project manager at Pasadena’s Jet Propulsion Laboratory (JPL).

Dara EntekhabiSMAP science team leader at the Massachusetts Institute of Technology (MIT), added, “SMAP data will be combined with data from other missions like NASA’s GPM (Global Precipitation Measurement), SAC-D/Aquarius and GRACE (Gravity Recovery and Climate Experiment) to reveal deeper insights into how the water cycle is evolving at global and regional scales.”

SMAP has revealed a new global map of soil moisture. It shows dry conditions in the southwestern United States and Australia’s interior. In the Midwest and eastern United States, the map shows moist soil, as well as in Europe and Asia. In areas where the ground is frozen, such as the far northern regions, soil moisture measurements are not shown.

This data can be used to help forecast the weather, droughts, and floods. Over the next year, data from SMAP will be compared with ground measurements from sites around the world, as well as soil moisture measurements from aircraft-mounted instruments. These measurements will serve to validate SMAP’s data. Once the data is calibrated, in August 2015, it will be made available to the public at public-access data archives. Validated measurements of soil moisture and freeze/thaw cycles will be available for use by the general scientific community in summer of 2016.


Mars Curiosity Rover finds evidence of a daily water cycle on Mars

 Image courtesy: NASA/JPL-Caltech/MSSS

Scientists say new research seems to support the theory that what looks like a bone-dry red planet during the day could be dotted with tiny puddles of salty water at night. Experts have long thought that a particular kind of salt detected in Martian soil could pull water vapor from the planet’s thin atmosphere into the soil at night and then keep it from freezing despite the extreme cold. Researchers aren’t saying they’ve seen direct evidence of brine hiding out in the Martian night. But they say the new study — based on a full year of monitoring of temperature and humidity conditions by the Mars Curiosity rover in Gale Crater — does seem to bear the theory out.

“Gale Crater is one of the least likely places on Mars to have conditions for brines to form, compared to sites at higher latitudes or with more shading,” said Alfred McEwen of the University of Arizona at Tucson, a co-author of the new report. “So if brines can exist there, that strengthens the case they could form and persist even longer at many other locations,” possibly explaining channels seen on Mars that appear be formed by running water, he said.

Researchers say Mars may once have had an sea as extensive as Earth’s Atlantic Ocean, and Curiosity has found evidence of ancient streambeds and a lake on the planet. The vast majority of that water has been lost to space over the eons, leaving Mars an overwhelmingly dry and inhospitable place. The new study doesn’t change the picture for life on Mars. The researchers say the temperatures they measured are too low and water too scarce “to support terrestrial organisms”. But scientists say evidence of water ice at the planet’s poles and now more evidence toward the theory of widespread brines keeps them hoping they’ll find evidence that life at least once existed there. “Liquid water is a requirement for life as we know it, and a target for Mars exploration missions,” lead author Javier Martin-Torres said in a statement. “Conditions near the surface of present-day Mars are hardly favorable for microbial life as we know it,” he said, “but the possibility for liquid brines on Mars has wider implications for habitability and geological water-related processes.”

In other words, we’ll keep looking.

Source: Michael Pearson, CNN

Soil Moisture Active Passive (SMAP) is scheduled for launch on January 29


The Soil Moisture Active Passive (SMAP) mission, scheduled for launch on Jan. 29, will measure the moisture in Earth’s soil with greater accuracy and higher resolution than any preceding mission, producing a global map of soil moisture every three days. Here are five quick facts about the spacecraft and what it studies.

1. Soil moisture is a tiny fraction of water with a big punch. Only 0.001 percent of Earth’s total water is lodged in the top few feet of soil. That tiny percentage, however, affects all living things on land and plays an important role in moving water, carbon and heat between land and atmosphere.

2. Soil moisture can compound water risks. A flood follows a heavy rainfall — but only if the ground cannot soak up the rain. Waterlogged soil makes a region more flood-prone. Going to the opposite extreme, a drought can parch soil to such an extent that plants are unable to grow even after a few rains have fallen. Knowing soil moisture allows hydrologists to make better decisions related to the risk of flooding and drought, such as how much water to retain in reservoirs.

3. Soil moisture controls the on-off switch for carbon dioxide cleanup. The world’s vast northern forests remove carbon dioxide from the air as they grow, helping to clean up our emissions from burning fossil fuels. But when the ground freezes, that process switches off. Carbon dioxide builds up in the atmosphere until the ground thaws in the spring and plants begin growing again. Knowing where and for how long the ground is frozen or thawed is an important part of understanding the role of the northern forests in reducing greenhouse warming. SMAP will map frozen and thawed soils north of 45 degrees north latitude (about the latitude of Minneapolis), around the globe.

4. SMAP is a twofer. The spacecraft’s radiometer produces an accurate reading of how much moisture is in the top two inches (five centimeters) of soil, but it has low spatial resolution, that is, one measurement covers a large area. A radar instrument produces an image with higher spatial resolution, but it can’t measure soil moisture as accurately as a radiometer. Through sophisticated data processing, SMAP combines observations from the two instruments into a very accurate measurement with high spatial resolution.

5. SMAP has a huge, folding, spinning antenna. At 19 feet 8 inches (6 meters) in diameter, SMAP’s rotating mesh antenna dwarfs the size of the instruments and spacecraft and is the largest rotating antenna of its kind that NASA has yet deployed. But the entire dish furls into a cylinder one foot (diameter) by four feet (30 by 120 centimeters) to fit inside the rocket’s fairing for launch, and it weighs only 128 pounds (about 58 kilograms).

 For more information about SMAP, see:

 Source: Alan Buis, Carol Rasmussen (JPL, NASA)