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TENACIOUS: Tomographic ENA Comprehensive Ion+Optical University Satellite

TENACIOUS: Tomographic ENA Comprehensive Ion+Optical University Satellite. Robert Sheldon, UAH , T.Fritz, H.Spence, J.Sullivan, J.Vickers, D.Cotton, M.Alothman, BU Oct 29, 1998. Tomographic ENA?!.

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TENACIOUS: Tomographic ENA Comprehensive Ion+Optical University Satellite

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  1. TENACIOUS: Tomographic ENA Comprehensive Ion+Optical University Satellite Robert Sheldon, UAH, T.Fritz, H.Spence, J.Sullivan, J.Vickers, D.Cotton, M.Alothman, BU Oct 29, 1998

  2. Tomographic ENA?! Is this just another fundamental physics globally imaging tomographic ENA multiscale constellation new millenium mission? Well,yes, except for the constellation part. ENAs are a new tool that is ALREADY changing the way we understand the M’sph. Tomography is the next logical step. Tomography is the next necessary step Tomography is the next practical step.

  3. January 10-11, 1997

  4. TENA FAQ Doesn’t tomography require constellations? Not if the image rotates rapidly = LEO Doesn’t a rotating image blur? Not if the countrate is high, exposures short = LEO Isn’t the ENA flux rather small? Not if one is very close to the source region = LEO Isn’t the brightest ENA source at the equator? No, it’s just more photogenic, LEO is brighter.

  5. Fluxtube Tomography Parallel Pot. Fluxtube ENA obs. Tenacious

  6. Global view of equatorial plane Line-of-sight projected on a plane Exposures ~minutes Optically thin Pixelsize ~ Re Observer ~ stationary ISEE, GEOTAIL, POLAR, IMAGE, TWINS Regional view of both equatorial plane +LEO Projections on a fluxtube Exposures ~seconds Optically thin h>600km Pixelsize ~10-100 km Observer moving TIROS, ASTRID, SAC/B, POLAR* Comparison between orbits: HEO LEO

  7. Logical Step? POLAR (and all other) ENA images to date, though global, have been 2-D and therefore, model-dependent. Tomography removes certain ambiguities. Tomography enriches the observations with an analysis algorithm giving a big return on a small investment. Tomography complements existing imagers by making their data more complete.

  8. Equatorial Ring Current 6>L>3, 90>PA>60 Substorms (!) 7>L>5 Plasmasheet intrusions (nose events) Calculate J|| from DivJ Global perp potentials Precipitating R.C. 8>L>3, 30>PA>0 Substorms 10>L>5 Ionosphere intrusions (conics, etc) Direct J|| into ionosph Field-aligned potentials High-latitude auroral ion precipitation Low-altitude flux tube mappings Comparison of ENA Physics HEO LEO

  9. Necessary Step? ENA images are powerful data tools absolute Dst (and ASY) correction real asymmetric ring current imaged substorm initiation region resolved global electric potential imaged BUT current ENA images: are projections onto a plane (2-D) require deconvolution of [H] can only see r<7 Re because of [H] from HEO (global) can’t resolve footpoints

  10. ENA Projection Geometry

  11. Parallel Potential Imaging • In black(bright) aurora, ions are accelerated downward(upward) • They lose(gain) energy with altitude • When they charge-exchange with [H], they are “tagged” by energy & direction • We can finally image the parallel potentials within a flux tube, possibly from 450 - 8000 km. • Auroral images to complement FAST

  12. M-I Coupling • “Constellation”, as we envision it, will give the 5<R<20 magnetic field geometry with N>100 satellites. (Look under MMM at //buspace.bu.edu/EPG/rsheldon) • BUT the ionosphere mapping needs to connect r=100km to r=20,000 km. This is where multipoles & errors are largest! • If TENA can map from 450km-8000km, it can complete the fluxline mapping & greatly reduce the B-field mapping error

  13. Auroral Imaging withNOAA-TIROS/MEPED

  14. TIROS AL Correlation

  15. Practical Step? Many ENA imagers have been built, some purposely, several flown, and a few have returned data. Tomographic imagers have been built (algorithms proven, etc.), some have almost flown. TENACIOUS combines the proven heritage of the POLAR ENA imager with the TERRIERS tomographic imager => TENA

  16. TERRIERS+IPS Same bus Same optics Same price Swap spec

  17. Conclusions Using existing technologies, we can complete the ENA picture with a LEO Tomographic ENA imager. The possibility exists for resolving the auroral acceleration region, mapping flux tubes, observing the RC injections---filling in the missing link between the Magnetosphere and Ionosphere. All for about the price of a UNEX

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