Future Opportunities in Geomagnetism and Electromagnetism: The Next Decade for Geopotential Field Research John LaBrecque NASA HQ Academic Workshop on Earth Sciences 2F, Institute of Earth Sciences, Academia Sinica, Taipei November 18-21, 2012

In 2005 NASA’s Solid Earth Science Working Group proposed a 20 year plan for Earth Observation (solidearth.jpl.nasa.gov). All components have been adopted by NASA with the exception of the Geomagnetic Constellation because significant programs were underway through international cooperation. This lapse has hurt the US geomagnetic community while advancing geomagnetism internationally.

Two Major Challenges for Geomagnetic Field Research Relevance in today’s Earth Science Climate Change Natural Hazards Hazards 2. Data Acquistion Cost Effectiveness Aliasing and Separation of signal sources

GRACE has managed to revive gravity field and geodetic science by meeting these challenges….Can we do this for Geomagnetics?

Two observatory quality geomagnetic Satellites in 1979 (Magsat) and Oersted in 1999 provided the first accurate high resolution information on the multi-decadal secular variation and a glimpse at the accuracy of the geomagnetic dynamo models. Technological advances in self-calibrating magnetometers and GNSS remote sensing positioning provide the possibility for a constellation of satellite based geomagnetic observatories for space weather and Earth System Science. However, the geomagnetic community must develop a strong scientific and societal justification for investments in geomagnetic field research.

Magsat- 1970’s High Tech

Oersted- 1990’s Simplicity and Effectiveness

Champ-2000’s Style and GRACE

These Satellites Revealed the Intermediate Wavelength Geomagnetic Field English: Lithospheric Magnetic Anomalies. A modeled image of Earth's magnetic field variations created as a result of science satellites like Magsat. nT = nanoteslas. The color bar indicates areas with positive and negative magnetic fields. Date May 17, 2004 - (date of web publication) Source http://www.nasa.gov/centers/goddard/news/topstory/2004/0517magnet.html Author Credit: Terrence Sabaka et al./NASA GSFC Identification of the Seafloor Spreading anomalies helped to validate the measurement utility of the Magsat satellite laying the ground work for future geomagnetic satellite missions.

Swarm- A Bracelet of GRACElets SWARM will allow us to write the sequel … Thirty years in the life of the Earth’s magnetic field

The Vector Helium magnetometer for Cost Effectiveness SWARM Will Introduce Three Important New Concepts to Geomagnetic Earth Observation Constellation of Earth Observing Geomagnetic Satellites for Reduction of Aliasing and measurement of field aligned currents. The introduction of new software for signal separation and cross calibration. The Vector Helium magnetometer for Cost Effectiveness

2005-2010 2010-2015 2015-2030

2005-2010 2010-2015 2015-2030 SWARM

Magnetospheric and Ionospheric Measurement Constellation The Last Decade- The Decade of Geopotential Field Research Developed new Geomagnetic Instrumentation, Programs, and Missions Magnetospheric and Ionospheric Measurement Constellation Three-Axis Coil System RF  network InGaAs Detector Laser Input Optics Internal 6 cm3 Helium Cell Miniature Self Calibrating Vector Magnetometer The miniature self calibrating magnetometer is intended for launch aboard microsatellites. Self calibration is achieved by nearly simultaneous scalar/vector measurements over various field directions during an orbit.

2005-2010 2010-2015 2015-2030

Swarm is a first step in the constellation approach but what is to follow SWARM? Geomagnetism must identify with goals that are relevant to society and which at the same time challenge and advance our knowledge of the environment. Gravity has reinvented itself through the paradigm of linking temporal gravity field variability to mass transport. New geomagnetic observations should be made on ground, airborne, and spaceborne platforms with focused attention to crustal stress change, ionospheric TIDS, ocean circulation, and separation of sources. Launch the Dense Geomagnetic Constellation by 2020 with the new suite of geomagnetic instrumentation including precision positioning and self calibrating atomic magnetometers and non magnetic star cameras while restraining mission creep.

Science Challenges for the Next Decade of Geopotential Field Research Can we constrain geodynamo models with observable phenomena Earth Surface Phenomena? Can we combine geomagnetism with temporal gravity fields to better measure ocean circulation? Can we utilize geomagnetic measurements to better understand crustal stress variability? Can we better parse sources of Geomagnetic variability through a better separation of sources both external and internal and the significant reduction of aliasing? Is constellation flight the answer? Can we achieve geomagnetic imaging of Traveling Ionospheric Disturbances (TID’s) or perhaps ocean tsunamis? Some resu

In Conclusion We must develop geomagnetic goals consistent with Environmental monitoring for Climate Change and Natural Hazards. We should formulate a Second Decade for Geopotential Field Research through the IAGA and IAG because important new opportunities do exist for both Gravity, Geomagnetism, and Electromagnetism. Technology is now available to build cost effective geomagnetic microsatellite constellations to improve temporal and spatial sampling of the geomagnetic spectrum. Mission creep must be avoided to make 1 nT, 3D vector geomagnetic measurements possible and cost effective. We must make core dynamo studies more relevant to societal interests through stronger linkage to planetary formation and geodetic observables