ScienceMag reports that NASA is about to launch the Soil Moisture Activity Probe (SMAP) satellite on January 29th.
One of the weirdest satellites we've seen in a while, the SMAP is designed to map the water content of soil globally with a resolution of 10 kilometers. It replaces a loose and spotty network of people sticking probes in the ground to measure moisture content.
Globally, soils hold a tiny fraction of the Earth’s water. But that moisture is nevertheless a crucial quantity in water, carbon and energy cycles: it determines how vulnerable regions are to drought and flood; how well plants grow and suck up atmospheric carbon; and how the Earth heats up and cools off -- a key driver for storms. Yet for the most part, soil moisture has been monitored by a sparse set of probes stuck in the ground. “The three biggest cycles in a climate model are being modeled with something that’s a complete fantasy,” says Dara Entekhabi, a hydrologist at the Massachusetts Institute of Technology in Cambridge.
The SMAP is a strange satellite to begin with. See JPL Animation. The instrument's three main parts are a radar, a radiometer and the largest rotating mesh antenna ever deployed in space. The huge rotating antenna dish is 19.7 feet (6 meters) in diameter, and it spins around the arm at about 14 revolutions per minute allow focusing the radar on wide swatches of land covering the globe every three days or less.
"The radiometer provides more accurate soil moisture but a coarse resolution of about 40 kilometers [25 miles] across," said JPL's Eni Njoku, a research scientist with SMAP. "With the radar, you can create very high resolution, but it's less accurate. The radar signals penetrates a few inches or more into the soil before they rebound. To get both an accurate and a high-resolution measurement, we process the two signals together."
JPL has a explanation of the technical challenges in building the crazy whirling dervish satellite, but also the problems inherent in signal processing radar and radiometer data, which are constrained by bandwidth limitations, signal interference, and the need to operate within certain radar frequencies that best detect water.
(Score: 2) by frojack on Thursday January 29 2015, @08:53PM
The launch team is setting up for a 24-hour turnaround for a launch attempt tomorrow morning. Launch time on Friday remains 9:20 a.m. EST.
http://blogs.nasa.gov/smap/ [nasa.gov]
No, you are mistaken. I've always had this sig.
(Score: 2) by mrchew1982 on Thursday January 29 2015, @11:21PM
Drove up from San Diego to see the launch with my five year old space geek, major disappointment that it was scrubbed... and no way to make it back tomorrow. Going to have to try for the Spacex launch in March!
(Score: 2) by frojack on Friday January 30 2015, @02:21AM
On line is always an option. Not the same tho....
No, you are mistaken. I've always had this sig.
(Score: 1) by FunkyLich on Thursday January 29 2015, @10:42PM
As it is something in space, I like that.
It is something that as it is in space it must look spacey, and it does. I like that too.
Those spacey gadgets and arms and that netlike thing, actually are not only for the sake of looking spacey, but they are antennas well studied and understood and built to detect signals at high precision and actually they have to be looking the way they do or signals would be weak and fuzzy. So I can't help but liking this too.
This technological oddshape in space serves to study this tiny insignificant amount of water that wants to use soil as a sponge. Where and when and how well it succeeds to do that is directly related to a lot of things that influence our lives in the cumulative way which is climate and weather. I think the ability to have this data as precise as possible is done through measurements and the ground probes. I see it as a very efficient way to get fast measurements to an area as big as the Earth itself. Weather and climate is a global phenomenon and it is best studied with global data. This is a good thing, I like this too.
So. I have something in space, it looks geeky and it is an art of electromagnetism physics, it studies Earth's personality and health in a devilish way (Let me see how wet you are! No? I got a Big Spinning Lasso!), the data it provides is a good thing... I like it.