Earth Orbiting Observatory Launch Rescheduled for Saturday

The SMAP satellite will provide information for weather forecasters, flood monitoring, climate change research and drought management

The launch of a satellite that will help scientists study the moisture in Earth's soil, which could help guide decisions about water resources, weather forecasts and drought, was postponed until Saturday at California's Vandenberg Air Force Base.

The Soil Moisture Active Passive satellite launch was initially scheduled for a 6:20 a.m. PT Friday launch, but mission control scrubbed the launch due to upper level winds just minutes ahead of planned lift-off. The launch was re-scheduled for Friday morning, but delayed again due to minor repairs to the rocket.

The launch is scheduled for Saturday at 6:20 a.m.

The satellite is expected to provide the most useful soil moisture maps ever created, providing more accurate and timely information for weather forecasters, flood monitoring, climate change research and drought management, especially significant in California where a three-year dry spell has left the state's water reservoirs at critically low levels.

The satellite arrived at Vandenberg AFB, just northwest of Santa Barbara, from Jet Propulsion Laboratory in Pasadena in October.

"Water is vital for all life on Earth, and the water present in soil is a small but critically important part of Earth's water cycle," said Kent Kellogg, SMAP project manager at Jet Propulsion Laboratory. "The delivery of NASA's SMAP spacecraft to Vandenberg Air Force Base marks a final step to bring these unique and valuable measurements to the global science community."

After rocketing into space, the satellite will fly at an altitude of 426 miles and provide a global map of soil moisture every two to three days for the next three years. The topsoil observations are more frequent and accurate than anything previously provided to researchers.

"This mission could not be more timely in my view," said Kellogg.

The mission required JPL to build the largest rotating antenna that could be stowed in the satellite’s 1-by-4-foot compartment — about the size of a kitchen trash can. The antenna dish and unfurls to a diameter of nearly 20 feet after spinning out of the compartment like a lasso on an extending support arm.

"We call it the spinning lasso," said Wendy Edelstein, the SMAP instrument manager. "The antenna caused us a lot of angst, no doubt about it.

"We test, and we test, and we test some more. We have a very stable and robust system now."

Once fully deployed, the satellite will orbit Earth every 98.5 minutes, allowing it to map the globe every two to three days.

The satellite's radar system transmits signal to Earth that penetrate its soil and bounce back. Any changes in the electrical properties of the signals indicate changes in soil moisture. It is one of "the most sophisticated signal-processing" systems every developed, according to NASA.

The deployment process has been pre-tested from start to finish 18 times, Kellogg said.

The satellite is capable of telling scientists a lot about the condition of Earth's soil, including its freeze-thaw state. Determining whether soil if frozen or thawed helps researchers better plan for natural hazards.

Soil moisture is already closely tracked in developed agricultural regions, but in vast areas remains unknown.

The launch marks a milestone for NASA’s Earth science missions, which essentially monitor the planet’s vital signs. The satellite is the last of five program mission launches during a 12-month period.

The NASA mission will cost $916 million, according to the space agency. The observatory was assembled at NASA's Southern California Jet Propulsion Laboratory.

The next launch at Vandenberg AFB, a Jason 3 satellite aboard a Falcon 9 vehicle, is scheduled for March 31. A launch scheduled for April 13 will blast a classified payload for the U.S. National Reconnaissance Office.

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