1. RBSP SWG Meeting 1 3/5/2009 BARREL Update (Balloon Array for RBSP Relativistic Electron Losses) R. M. Millan and the BARREL Team

2. RBSP SWG Meeting 2 3/5/2009 BARREL project overview Two Antarctic science campaigns during RBSP mission –20 balloon launched each campaign in 2012 and 2013 –Launched successively to set up slowly drifting array –LDB flights => ~30 day campaign duration –>3000 hours of data in radiation belt region (L<7) –Launch sites: South African Antarctic Station (SANAE) and Halley Bay Phase B test flights –Piggyback flight in December 2008 –Test campaign from McMurdo in December 2009  BARREL is a multiple-balloon experiment designed to study relativistic electron precipitation.

3. RBSP SWG Meeting 3 3/5/2009 BARREL concept Launch Sites –SANAE IV –Halley Bay  BARREL uses an array of balloons to achieve its science objectives.

4. RBSP SWG Meeting 4 3/5/2009 Balloon observations of precipitation Bremsstrahlung X-rays are produced as precipitating electrons collide with atmospheric neutrals First observation of X-rays to MeV energies made in 1996 over Kiruna, Sweden. Nearly stationary balloon platform => complementary to spacecraft measurements (Foat et al., 1998) ~30 km ~70 km

5. RBSP SWG Meeting 5 3/5/2009 Kiruna REP Event (from Lorentzen, 1999) Riometer X-ray instrument

6. RBSP SWG Meeting 6 3/5/2009 RBSP/Balloon Conjunctions Baseline: two campaigns separated by one year –Measurements of BOTH microbursts and duskside precipitation during both camaigns.  Conjunctions with RBSP spacecraft in dusk and dawn sectors Dusk conjunctions in 2012 Dawn conjunctions in 2013 BARREL MLT Hours

7. RBSP SWG Meeting 7 3/5/2009 Large-scale spatial structure S2 S3 X-ray count rate Balloon locations ~800km separation Precipitation simultaneously observed by two balloons on January 21, 2005 L=3.5 L=4 L=6 18MLT6 MLT18 MLT 1840 UT L=4 L=6 18MLT6 MLT18 MLT 1845 UT

8. RBSP SWG Meeting 8 3/5/2009 SANAE Riometer MINIS Balloons

9. RBSP SWG Meeting 9 3/5/2009 BARREL project overview Two Antarctic science campaigns during RBSP mission –20 balloon launched each campaign in 2012 and 2013 –Launched successively to set up slowly drifting array –LDB flights => ~30 day campaign duration –>3000 hours of data in radiation belt region (L<7) –Launch sites: South African Antarctic Station (SANAE) and Halley Bay Phase B test flights –Piggyback flight in December 2008 –Test campaign from McMurdo in December 2009

10. RBSP SWG Meeting 10 3/5/2009 2009 Piggyback Test Flight

11. RBSP SWG Meeting 11 3/5/2009 2008/2009 Piggyback Test Flight Launch: McMurdo, Dec. 28, 2008 Duration: 54 days Altitude: 34 km (112 kft) Photo Courtesy D. Gregory NASA BPO

12. RBSP SWG Meeting 12 3/5/2009 Summary Plot: X-ray Count Rate

13. RBSP SWG Meeting 13 3/5/2009 Summary Plot: X-ray Count Rate Relativistic Precipitation

14. RBSP SWG Meeting 14 3/5/2009 ~10-100 keV Precipitation Event X-ray Count Rate 9:00 UT

15. RBSP SWG Meeting 15 3/5/2009 BARREL Location THEMIS spacecraft at 9:00 UT TIPSOD

16. RBSP SWG Meeting 16 3/5/2009 THEMIS AE Index SST electrons Electric Field THEMIS Data on Jan. 3, 2009

17. RBSP SWG Meeting 17 3/5/2009 Feb 14-15, 2009 X-ray Spectrum Counts/s Energy (keV)

18. RBSP SWG Meeting 18 3/5/2009 WHAT’S NEXT? Two Antarctic science campaigns during RBSP mission –20 balloon launched each campaign in 2012 and 2013 –Launched successively to set up slowly drifting array –LDB flights => ~30 day campaign duration –>3000 hours of data in radiation belt region (L<7) –Launch sites: South African Antarctic Station (SANAE) and Halley Bay Phase B test flights –Piggyback flight in December 2008 –Test campaign from McMurdo in December 2009

19. RBSP SWG Meeting 19 3/5/2009 2009/2010 Test Campaign Prospective BARREL Configurations Prospective BARREL Configurations Currently building hardware for 6 payloads. Integration at Dartmouth starts at end of this month Thermal Vac and test launch in Palestine, TX summer 2009 Deploy to Antarctica November 2009

20. RBSP SWG Meeting 20 3/5/2009 Objectives of BARREL with RBSP Directly test models of wave-particle interactions. –Conjunctions between balloons and RBSP spacecraft => measurements of parameters needed to model interaction –Comparison of predicted and observed precipitating flux and energy distribution Large-scale spatial structure and total loss rate estimates. –What are the most useful data products or methods for displaying data?

21. RBSP SWG Meeting 21 3/5/2009 Cold plasma50 cm -3, 1 eV Magnetic Field170 nT Composition85% H, 10% He, 5% O Hot Protons: Density ----- Energy ----- T perp /T // ---- 1 cm -3 12 keV 1.47 Input parameters for WHAMP during the Jan. 19, 2000 precipitation event. Parameters are mean values taken from LANL MPA, except magnetic field taken from IGRF and plasma composition which was taken from Meredith et al., (2003). WHAMP calculation of the wave frequency for three branches of EMIC waves ω /omegai k k ω imaginary /omegai Modeling EMIC Wave Growth

22. RBSP SWG Meeting 22 3/5/2009 Barrel Primary Science Teams University of Washington NaI Scintillator Flight Computer UC Berkeley-SSL Power System Mission Assurance SE oversight GSFC + Balloon Program Office Programmatic, Management oversight CSBF MIP Launch Training UC Santa Cruz Magnetometer Ground Station Dartmouth College PI-Institution Systems Engineering Engineering Data Integration & Test

23. RBSP SWG Meeting 23 3/5/2009

24. RBSP SWG Meeting 24 3/5/2009 Example of Balloon Observation Precipitation observed on January 19, 2000 during a relativistic electron depletion observed by GOES satellites (from Millan et al., 2007b) Duskside precipitation observed by balloons during catastrophic depletions of radiation belt electrons.

25. RBSP SWG Meeting 25 3/5/2009 Microburst precipitation Dawnside Microbursts –Short ~100 ms bursts of precipitation –Low energy microbursts discovered by balloons –Relativistic (>1 MeV) microbursts Studied extensively by SAMPEX satellite May drain the radiation belts in a day or less But never observed by balloons! 30 s MAXIS Observations of ~100 keV microburst precipitation