NASA scrubs launch of climate research satellite

A United Launch Alliance Delta 2 rocket carrying a NASA climate research satellite was grounded Thursday by high winds above the Vandenberg Air Force Base launch site northwest of Los Angeles.

There were no technical problems with the rocket and its satellite payload and NASA managers told the launch team to recycle the countdown for a second attempt Friday at 9:20 a.m. EST (GMT-5; 6:20 a.m. local time), the opening of a three-minute window. Forecasters are predicting good weather.

Conditions appeared ideal at Space Launch Complex 2 on Thursday, but weather balloons indicated a sharp wind shear 34,000 feet above the pad. NASA and ULA continued the countdown in hopes conditions would improve, but subsequent balloons showed no significant change and managers ordered a 24-hour delay.

The Soil Moisture Active Passive -- SMAP -- satellite perched atop the Delta 2 is the centerpiece of a $916 million program to map water, frozen and liquid, in the top few inches of soil around the world to help researchers improve near-term weather forecasts, better understand the causes and impacts of droughts, floods and other natural disasters and to improve long-range climate change projections.

Using a rotating 19.7-foot-wide mesh antenna to map out a 620-mile-wide swath as it orbits Earth's poles, the 2,000-pound satellite will use a powerful radiometer to "see" the moisture, liquid and frozen, in the top few inches of soil and a radar to improve the resolution, or scale, of the measurements.

The result will be a global map of soil moisture updated every two to three days, allowing near-real-time analysis of weather and sudden environmental changes around the world. It also will shed light on long-range changes to the planet's climate, helping scientists better understand the the role of ground moisture in the water, energy and carbon cycles that are critical to life.

"The fraction of water that's in soil is actually tiny, it's much less than 1 percent," said Dara Entekhabi, leader of the SMAP science team at the Massachusetts Institute of Technology. "About 97 percent of the water in the globe is locked up in the oceans and the rest is in the cryosphere, the ice.

"But that small percentage that's in the soil is rather important and very active, because it's what's interacting with the terrestrial biosphere, with the vegetation, it's what determines how much runoff occurs due to incident precipitation, how much fresh water there is in the rivers and lakes. It's a tiny amount, but a very important amount."

Case in point: the ongoing California drought. SMAP data will help scientists get a better understanding of the processes that contribute to such phenomena on a global scale.

"The measurements that SMAP makes will be direct measurements of the indicator of agricultural drought, which is the deficit in soil moisture," Entekhabi said. "So it will produce a high resolution ... map of the drought. But droughts are initiated, forced and maintained by much larger-scale processes, things such as the interaction between the oceans and the atmosphere over land and over continental regions, land and the atmosphere.

"So it's not just mapping the local California region, but seeing how the continent as a whole reinforce and feed back onto the climate system in order to make these things last beyond (short-duration) weather scales."

SMAP will join 18 other operational NASA satellite and ground-based programs designed to study Earth's environment in unprecedented detail.

SMAP will focus "on the water that lives and moves through the soil," said Christine Bonniksen, NASA's program executive at agency headquarters in Washington. "With the launch of this project, decision makers will be better able to understand the water cycle and how soil moisture fits into that."

SMAP's radiometer will act somewhat like a camera, Entekhabi said, using L-band microwaves to "see" in daylight and darkness, penetrating clouds, vegetation and the top few inches of soil to measure water volume. The satellite's L-band radar, while less sensitive, will provide higher resolution.

SMAP is unique in that "it has returns in two very distinct areas," Entekhabi said. "One of them is in fundamental understanding of how the environment works, It's addressing some fundamental Earth science question. The second is in the arena of applications. SMAP provides data that affect our everyday lives in terms of dealing with some really serious natural hazards."

In terms of Earth science, he said soil moisture links the planet's water, energy and carbon cycles. "If it wasn't for the soil moisture variable, these three processes over land would vary independently, but they don't. They work in concert like gears in a clock, they are linked together through the soil moisture variable."

Understanding the details of those interactions will help scientists improve short- and long-term forecasting.

"As water evaporates from soil water to vapor in the atmosphere, it feeds the water cycle," Entekhabi said. "It takes energy to vaporize water, and water vaporizing cools the surface and maintains the temperature much like humans have evolved sweating to regulate body temperature. The same thing happens with Earth system. And as plants transpire and pick up biomass through absorbing carbon dioxide from the atmosphere and releasing water vapor, they are engaged in the water and energy cycles as well.

"So these three cycles are intimately linked through the water variable. Through measurements SMAP can make, we can test and improve models that we use for atmospheric weather prediction and climate change projections."