The launch of the Soil Moisture Active Passive (SMAP) observatory is planned for Jan. 29 aboard a Delta II rocket set to blast off from Space Launch Complex-2. The window extends from 6:20 to 6:23 a.m.
The observatory is designed to provide the most accurate, highest-resolution global measurements of moisture in soil ever made from space. It also will detect whether the ground is frozen or thawed, NASA officials said.
“This information will improve our knowledge of water, climate over land, as well as water-related hazards,” said Christine Bonniksen, SMAP program executive with NASA’s Earth Science Division.
SMAP joins 18 other spacecraft, many of which were launched from Vandenberg, in studying what scientists call “Earth’s vital signs.”
Soil collects rainfall before the water enters rivers and evaporates back into the atmosphere, she noted.
“As a result soil moisture impacts many areas of human interest, including flood, drought, disease control and weather,” she said.
The application of SMAP data about the amount of water in the top 2 inches of soil around the globe will allow scientists to create refined maps warning of natural dangers.
“There are some natural hazards, which actually very much relate to the surface soil moisture and soil moisture measurements made by SMAP,” said Dara Entekhabi, SMAP science team lead from the Massachusetts Institute of Technology.
One example is a county-by-county flash flood guidance map issued routinely by the National Weather Service. The map shows the deficit in soil moisture, which includes the capacity of the dirt to hold water minus the actual soil moisture. Forecasters use the map in conjunction with rainfall predictions to determine areas where precipitation exceeds the soil moisture deficit.
Those maps now use estimates, but SMAP will collect direct measurements and allow for creation of better maps.
Likewise, SMAP will allow for the creation of better drought monitor maps.
The United States has too few ground stations to create precise county-by-county maps, so forecasters instead use models based on historical data.
NASA officials said the mission’s cost — including satellite, launch and three years of operation — is $916 million.
The satellite arrived at Vandenberg in mid-October to undergo pre-launch processing. Next week, the craft will take a road trip to the launch pad for installation on the rocket.
This launch initially was planned for early November, but was delayed to allow more tests on key components of the craft.
SMAP has two instruments: A radar to provide high-resolution images and a radiometer to capture high-accuracy data.
“When you put these together, it’s very similar to looking through both lenses on a pair of bifocals at the same time,” Bonnikson said. “As a result, we will have a highly accurate global map of soil moisture for our scientists to use.”
A unique feature of this craft is the large spinning antenna that sits at the end of a long arm stowed for launch and set to be deployed two weeks after reaching space. Once the arm is extended, the antenna then must be unfurled in stages before it will begin spinning. By the time it’s fully deployed, the reflector antenna will have a 20-foot diameter.
The design will allow for the collection of science data about soil moisture in swaths 1,000 kilometers, or 612 miles, wide. This means the observatory will be able to map the entire planet every two to three days.
“It’s a very efficient mapping system,” said Kent Kellogg, SMAP project manager with NASA’s Jet Propulsion Laboratory in Pasadena.
This mission is a joint project between JPL and Goddard Space Flight Center in Greenbelt, Md.
SMAP is the last of five NASA Earth science missions scheduled for launch within a 12-month period.