Production Journal

Space Storms Interrupt GPS Signals

The irritating interruptions in global positioning system (GPS) signals you primarily see in the afternoon may be due to a problem that's over your head. Space storms in the ionosphere--at altitudes of 30 to 250 miles above the earth--often are at fault.

The

ionosphere is an electrically conducting series of layers of the Earth's atmosphere consisting of rarified gasses ionized by solar radiation. GPS satellite signals must travel through the ionosphere before reaching your receiver. That's generally not a problem until a hot gas called plasma builds up in the ionosphere.

Recent findings. As plasma from solar storms buffets the earth, an electric field is transmitted through Earth's ionosphere. This field propels plasma from the ionosphere into space. At northern latitudes, the affect of these storms might be observed in the form of Aurora Borealis, or northern lights.

Now, researchers from the National Aeronautics and Space Administration (NASA) and the National Science Foundation say these storms have another effect--they impede GPS navigation signals.

The NASA team used GPS signal disturbances to build a model of how these storms behave. "We are beginning to put together the full picture, which will ultimately let us predict space storms," says Tony Mannucci of NASA's Jet Propulsion Laboratory.

The ionosphere supports its own weather systems that can be mapped like hot and cold fronts. The plumes of ionized gas that result can cause GPS position errors by time-delaying the propagation of GPS signals. The turbulence they generate causes receivers to lose the signal through an effect known as scintillation, similar to the apparent twinkling of stars caused by atmospheric turbulence.

Off and on. "We also know these disturbances occur most often between noon and dusk and between mid to high latitudes," says Anthea Coster of the Haystack Observatory. "So now you know. Those afternoon GPS outages are real and not just a hallucination. The good news is they don't last very long. In 15 minutes or less, you'll be up and running again.

Tech Companies Shake Hands

Dow AgroSciences LLC and Monsanto Company are teaming up to bring farmers new technology and new product choices. In coming years you'll be able to plant products, such as Roundup Ready Corn 2 by Monsanto stacked with Herculex by Dow AgroSciences or WideStrike by Dow AgroSciences stacked with Roundup Ready Flex cotton by Monsanto. Such combinations wouldn't be possible without this agreement.

The two companies, which have a history of waging legal disputes against each other, also agreed to stop the bickering over who was first to invent synthetic Bt genes and the Cry1F gene.