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MSI-SuperDARN Radars | Spacecraft Shielding | Ionospheric Convection | GICs | Publications


MSI-SuperDARN Radars       

Scientists at four institutions (Virginia Tech, Dartmouth College, the University of Alaska Fairbanks, and the Johns Hopkins University Applied Physics Laboratory) will build eight (8) SuperDARN-style HF radars at middle geomagnetic latitudes across the U.S. and in the Azores between 2009 and 2012. This collaborative effort was made possible by a generous grant from the National Science Foundation (NSF) through the Mid-Sized Infrastructure (MSI) program.

The MSI SuperDARN radars, together with existing mid-latitude SuperDARN radars, will provide unprecedented measurements of the drifting plasma with coverage that spans over 12 hours in local time and extends from ~50 degrees magnetic latitude all the way to the pole. The array of radars, coupled with the existing SuperDARN network, will provide exciting new measurements of ionospheric plasma irregularities in regions of the plasmaspheric boundary layer and during magnetic storms.

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Spacecraft Radiation Shielding              

Manned missions to planets such as Mars require extended missions that will expose astronauts to harmful radiation in the form of energetic particles from solar and galatic sources. Traditional methods for protecting spacecraft and occupants from these forms of radiation involve some configuration of a massive material shield to absorb the energy of incoming particles. For the high energy galactic cosmic rays (GCRs) that astronauts will be exposed to, these so-called passive shields are too massive to be practical and will likely produce showers of secondary radiation that could be more harmful than the GCRs themselves.

Active shields which rely on magnetic (or electric) fields to deflect energetic particles offer a potential solution to the problem. Designing a magnetic shield that is strong enough to deflect GCR particles but weak enough to not harm astronauts is a challenge. Investigating possible solutions involves a combination of electromagnetic theory, numerical analysis, engineering practicality, and an astronaut's sense of exploration.

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Ionospheric Electric Fields              

A combination of reconnection and viscous processes occurring at the magnetopause and in the magnetotail are responsible for creating large-scale electric fields. These fields map down geomagnetic field lines into the high-latitude ionosphere where they cause the plasma to 'E x B' drift. By measuring the motion of this ionospheric plasma it is, therefore, possible to infer a great deal about the magnetospheric processes that are responsible for the convection.

Scientists from all over the world are involved in a cooperative program which operate HF radars for the purpose of measuring the ionospheric plasma drift (or equivalently, the ionospheric electric field.)

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Geomagnetically Induced Currents (GICs)              

Large-scale currents flowing overhead in the ionosphere induce electric and magnetic fields on the surface of the Earth. So-called Geomagnetically Induced Currents (GICs) can in turn be induced in technologically networks located underneath these currents, such as railroads, power transmission lines, and pipelines. During electromagnetic storm periods caused by the Sun these GICs can be large, often exceeding several hundred Amperes, and cause catastrophic consequences to the system in which they flow.

Scientists at Dartmouth are attempting to predict the occurence of GICs using physics-based models of the global magnetosphere, ionosphere, and Earth conductivity together with input from a satellite located in the upstream solar wind. The electric (and magentic) field at the surface of the Earth over North America will be determined with 30-90 minutes warning, allowing an advance warning of GICs to be calculated for specific conducting networks.

More details can be found on the Darmtouth College GIC Page  

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Online Publications


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