1. 1 Third Workshop on Astroparticle Physics at Ooty 14 – 16 December, 2010 “Antarctic Balloon Flights” W. Vernon Jones Senior Scientist for Suborbital Research Science Mission Directorate NASA Headquarters w.vernon.jones@nasa.gov w.vernon.jones@nasa.gov 1-202-358-0885

2. 2 CREAM-I 12/16/04 – 1/27/05 42 days Five successful Flights: ~ 156 days cumulative exposure CREAM-IV 12/19/08 – 1/7/09 19 days 13 hrs CREAM-V 12/1/09 – 1/8/10 37 days 10 hrs CREAM-III 12/19/07-1/17/08 29 days CREAM-II 12/16/05-1/13/06 28 days CREAM-VI currently awaiting launch in Antarctica

3. 3 History of NASA Long-Duration Balloon (LDB) Flights 44 polar Long-Duration Balloon (LDB) flights have been conducted since the first successful launch in 1991 by the NASA - NSF Office of Polar Programs partnership 36 Antarctic flights (*) - 25 single circumpolar flights with durations of 8 - 20 days - 6 double circumpolar flights with durations of 20 - 32 days - 4 triple circumpolar flights with durations of 35 - 42 days - 1 super-pressure balloon test flight with duration of 54 days 2 flights from Fairbanks, Alaska to Canada over Russia with durations of 13 days 6 Flights from Kiruna, Sweden to Canada with durations of 4 - 6 days (*) 2 science payloads, BLAST & CREAM, 14 MCF SPB test flight, and 2 handheld balloons are planned for December 2010 launches.

4. 4 Congressionally Mandated NRC Suborbital Study “Revitalizing NASA’s Suborbital Program” Steven R. Bohlen et al. February 2010 Recommendations No. 1: “NASA should undertake the restoration of the suborbital program as a foundation for meeting its mission responsibilities, workforce requirements, instrumentation development needs, and anticipated capability requirements. To do so, NASA should reorder its priorities to increase funding for suborbital programs.” No. 4: “NASA should make essential investments in stabilizing and advancing the capabilities in each of the suborbital program elements, including the development of ultra-long-duration super-pressure balloons with the capability to carry 2 to 3 tons of payload to 130,000 feet, etc. The 2008 NASA Authorization bill from Congress required a National Research Council (NRC) study of the Suborbital Program.

5. 5 ASTRO 2010 Decadal Study Released August 13, 2010 Summary Page 1-9: The balloon and sounding rocket programs provide fast access to space for substantive scientific investigations and flight testing of new technology. The balloon program in particular is important for advancing detection of the cosmic microwave background and particles for the principal investigators of tomorrow’s major missions. A growth in the budget by $15 million per year is recommended. Summary Page 7-27: To increase the launch rate by about 25 percent, it is recommended that the R&A program be augmented by $5 million per year to accommodate the selection of additional balloon and rocket payloads. In addition, $10 million per year will be needed to support the additional launches and improvements in infrastructure. PAG Panel Report Page 8-28: For this panel’s purposes, it recommends that the development of technologies needed for ULDB be completed and a ULDB program of one or two flights per year be supported, including their payloads, possibly replacing some LDB flights. The panel estimates that the cost for this capability requires an augmentation to the balloon program of about $250 million over the next decade.

6. 6 Super-Pressure Balloon (SPB) Development Ultra-Long-Duration Balloon (ULDB) flights Successful SPB Test Flight 54 days 7 MCF At Float (12/28/08 – 2/20/09) Vented “Constant Pressure” balloons used in Antarctica are in equilibrium with the atmosphere, so the altitude changes with air temperature/pressure. Super-pressure “Constant Volume” balloons maintain altitude stability, so they would enable long-duration flights, even at mid-latitudes. CREAM-IV SPB ANITA-II

7. 7 Tentative Schedule for SPB Development The 7 MCF SPB test flight achieved a new NASA LDB Flight Duration Record. Its altitude and differential pressure remained steady, with no degradation / gas loss over time. - It could have flown indefinitely. A 14 MCF test balloon failed catastrophically during the 2009 Darjeeling WAPP. Another 14 MCF Super-Pressure balloon is currently awaiting launch in Antarctica. 7 MCF Balloon trajectory

8. 8 Particle Astrophysics & LDB/ULDB Particle Astrophysics topic Cosmic ray origin & acceleration Astrophysical neutrinos Dark matter Current & planned missions Potential ULDB Missions* ATIC CREAM BESS ANITA [ATIC] GAPS EeVA Super-TIGER ALL of these [DM-ULDB?] GAPS-ULDB [ANITA-UHECR] * ULDB defined as: Super-pressure balloon, >110,000 ft, >60 days aloft, any latitude, up to 2000 kg suspended mass CREST

9. 9 Non-Particle LDB/ULDB Astrophysics Missions Science topic Potential ULDB Missions Cosmic microwave BG Big Bang Cosmology X-ray &  -ray sources ARCADE EBEX SPIDER BLAST CMBR foreground sources Polarized emission, Nuclear lines GRAPE Science focus area NCT HALO Dark Energy AstrobiologyExoplanets Planet Scope BEST BENI PIPER

10. 10 ATIC: Advanced Thin Ionization Calorimeter John Wefel, Louisiana State University, PI Hydrogen to Nickel spectra 50 GeV to 100 TeV BGO calorimeter (320 crystals) to measure nuclear - electromagnetic cascades Silicon detector (4,480 pixels) to measure particle charge (in presence of backscatter) Multiple long-duration balloon flights needed to obtain the necessary exposure -ATIC-1 during 2000 - 2001 (14 days) -ATIC-2 during 2002 - 2003 (17 days) -ATIC-3 flight aborted December 2005 -ATIC-4 during 2007 - 2008 (19.5 days) ATIC Electron Spectrum

11. 11 Cosmic Ray Energetics And Mass (CREAM) Eun-Suk Seo, University of Maryland, PI Seo et al. Adv. in Space Res., 33 (10), 1777, 2004; Ahn et al., NIM A, 579, 1034, 2007 Transition Radiation Detector (TRD) and Tungsten Scintillating Fiber Calorimeter - In-flight cross-calibration of energy scales for Z > He Silicon detector to measure particle charge in presence of shower backscatter Flared, segmented carbon target with tracking scintillator hodoscopes Hodoscopes for particle tracking through the instrument CREAM uses two designs - With and without the TRD This exploded view shows the “With TRD” design The “Without TRD” design uses Cherenkov Camera

12. 12 CREAM: p & He spectra are not the same (Y. S. Yoon’s thesis work) CREAM-1  P = 2.66 ± 0.03  He = 2.57± 0.04 CREAM fluxes are significantly higher than the extrapolation of a single-power law fit to the low energy spectra Different types of sources or acceleration mechanisms? (e.g., Biermann, P. L. A&A 271, 649,1993)

13. 13 TeV spectra are harder than spectra <100 GeV/n AMS  P = 2.78 ± 0.009  He = 2.74 ± 0.01 CREAM-1  P = 2.66 ± 0.03  He = 2.57± 0.04

14. 14 Heavies look like He: The same valley?

15. 15 Not a single power law  < 200 GeV/n = 2.77 ± 0.03  > 200 GeV/n = 2.56 ± 0.04 Effect of a non-uniform distribution of sources? (Erlykin & Wolfendale A&A 350, L1,1999) Younger sources would dominate the high-energy spectra (Taillet et al. ApJ 609, 173, 2004) Effect of distributed acceleration by multiple remnants? (Medina-Tanco & Opher ApJ 411, 690, 1993) Superbubbles? (Butt & Bykov, ApJ 677, L21, 2008) Departure from a single power law caused by cosmic ray interactions with the shock? (e.g., Ellison et al. ApJ 540, 292, 2000) CREAM C-Fe He  CREAM = 2.57± 0.04  AMS = 2.74 ± 0.01

16. 16 CREAM Approved for Second Phase (5 yr) Expected Spectra based on past average LDB flight: Up to 150 Additional days; Total ~300 Days

17. 17 CREST: Cosmic Ray Electron-Synchrotron Telescope Jim Musser, U. Indiana, PI CREST identifies UHE electrons by observing the characteristic linear trail of synchrotron gamma rays generated as the electron passes through the Earth’s magnetic field - This results in effective detector area much larger than the physical instrument size CREST expected to fly as Antarctic LDB payload in the 2011-2012 season Upgrade of CREST for ULDB operation would be straightforward Expected result: 100-day CREST exposure CREST Detector – A 2 x 2 m array of 1600 1” diameter BF 2 crystals.

18. 18 Trans-Iron Galactic Element Recorder (TIGER) Bob Binns, Wash. U., St. Louis, PI TIGER was a 1 m 2 electronic instrument to measure the elemental composition of the rare galactic cosmic rays heavier than iron –Obtained best measurement to date of abundances of 31 Ga, 32 Ge, & 34 Se. Two balloon flights over Antarctica totaling 50 days at float –Dec. 2001 – Jan. 2002, 32 day flight; Dec. 2003 – Jan. 2004, 18 day flight TIGER data recovered, but instrument only partially recovered in Jan. 2006 A new instrument, Super-TIGER, was selected via ROSES-07

19. 19 Super-TIGER Instrument being developed ULDB Super-TIGER Instrument using Silicon Arrays instead of Scintillator for dE/dx LDB Super-TIGER ~ 8x increase in statistics over TIGER ULDB Super-TIGER Instrument: ~ 8x increase statistics over Super-TIGER –Excellent statistics for most nuclei through barium –Exploratory measurements through Pb Super Trans-Iron Galactic Element Recorder (SuperTIGER) Bob Binns, Wash. U., St. Louis, PI

20. 20 ANITA: Antarctic Impulsive transient Antenna Peter Gorham, U. Hawaii, PI Ultra High Energy Cosmic Rays guarantee an associated “GZK neutrino” flux –Hadrons interact with CMBR photons: p,n +        ANITA utilizes Askaryan effect: coherent radio Cherenkov from showers in ice (0.2-1GHz) Antarctic observations unique for balloons –110 kft altitude near optimal for neutrino energies of interest Synoptically observes ~1 M km 3 of ice Most sensitive method for 10 18-20 eV neutrinos GZK neutrinos ANITA-2 on ascent (2008)

21. 21 ANITA: Ultra-High Energy Particle Astrophysics: 1. UHE Cosmic rays (UHECRs) via geosynchrotron radio impulse detection ANITA now has highest-energy sample of radio-detected UHECRs Several important firsts in this new and rapidly developing UHECR field UHECR Event distribution: Direct (2), reflected (14) Geomagnetic correlation  Lorentz force on e+e- air shower UHECR pulse shape & spectrum: first broadband observation UHECR event sky map, 2-3 o resolution; No source correlations UHECR Event energy distribution: data (red, w/ std errors on mean), Monte Carlo (blue)  at or near GZK cutoff 2006-2007 flight results:

22. 22 ANITA: Ultra-High Energy Particle Astrophysics: 2. Ultra-High Energy Cosmogenic Neutrino Limits ANITA-2: 40 dual-pol ultra- wideband quad-ridged horns 30-day ‘08-09 flight: 2 Vpol (neutrino) candidates, 3 Hpol UHECR events 2 Candidates: clean and isolated; expected background <1 event ANITA-2 limits 2010: currently world’s best in UHE range; several mainstream cosmogenic neutrino models are now eliminated at >90%CL; several models predict 2-3 events! Impulse waveform Power spectrum Radio map ANITA-3 plans: Improve sensitivity by x3 with better hardware trigger, more antennas Optimize for both UHECRs & neutrinos ~350-500 UHECR events expected Try for up to 60 days of flight exposure, 5-10 neutrino events? 2008-2009 flight results:

23. 23 ANITA results in 2009 from 1 st & 2 nd flights ANITA-1 deeper blind analysis yields 16 candidates – but events are in “background” horizontal polarization (Hpol) channel –Trigger was blind to plane of polarization; neutrinos are predominantly Vert. pol. (Vpol) Events are consistent with ultra-high energy cosmic ray radio impulses – “geosynchrotron” emission – seen in reflection off the relatively smooth ice surface! To be certain: check the residual Vpol content of dominant Hpol events against known residual horizontal Bfield component vs. event location in Antarctica : strong correlation! 16 event overlay Vpol residual component vs. Geomagnetic model prediction Avg. profile S. Hoover UCLA

24. 24 Ultra-high Energy Neutrino Astrophysics At energies above 10 14-15 eV: Universe becomes opaque to photons beyond few tens of kpc Cosmic ray protons, nuclei are galactic up to ~10 18 eV, suffer GZK cutoff above that Neutrinos unabsorbed at all energies Sources exist to at least 3x10 20 eV Conclusion: UHE neutrinos are the only viable messenger beyond the local universe Neutrinos viable Throughout these regions

25. 25 Highly successful Japan/United States cooperative program since 1993 (11 flights). Measures cosmic-ray particles and antiparticles to study the early Universe and cosmic ray transport. Antiproton, proton, light element, and isotope spectra; antinucleus search Fully identifies particles by charge, mass, charge-sign and and energy Collecting power an order of magnitude larger than other balloon spectrometers. BESS-Polar flew 8.5 days in 2004 and 24.5 days in 2007-2008. Balloon-borne Experiment with a Superconducting Spectrometer (BESS) John W. Mitchell, GSFC, U.S. PI ; Akira Yamamoto, KEK, Japan PI Superconducting magnetic rigidity spectrometer: momentum Time-of-flight system (TOF): velocity and charge Silica-aerogel Cherenkov detector : background rejection BESS-Polar II Launch BESS-Polar II Trajectory

26. 26 BESS-Polar Search for Cosmic Origins Antiprotons Most antiprotons are secondary products from interactions of cosmic ray nuclei with ISM. “Primary” source, if any, may enhance antiproton flux. Hawking radiation from primordial black hole (PBH) evaporation may be detectable as increase in flux of antiprotons at energies below 1 GeV. Measurements most sensitive to a primary source near solar minimum activity. BESS-Polar extends measurements to lower energy and obtained ~20 times previous solar minimum statistics in 2007-08 flight: >8000 antiprotons in full BESS-Polar II dataset Instrument Performance Spectrometer - <130 mm resolution, maximum detectable rigidity 281 GV Outer TOF - 120 ps Middle TOF - 280-380 ps Aerogel Cherenkov - 11.3 pe, >6000 background rejection factor Data Acquisition - 2.5 kHz event rate, no onboard event selection, 82% live p p d t BESS-Polar II Particle ID BESS-Polar II antiproton spectrum – ¼ data BESS-Polar II antiproton/proton ratio – ¼ data >8000 antiprotons

27. 27 BESS-Polar / BESS Search for Cosmic Origins Antideuteron Secondary antideuterons are strongly suppressed. A single event would be primary! Suffer from antiproton background. First reported antideuteron upper limit from BESS 97+98+99+00 BESS-Polar I and II will increase sensitivity Unambiguous detection of a single antihelium would be conclusive evidence of primordial antimatter. No antihelium has been detected by any instrument. BESS-Polar II enhanced search sensitivity by factor of ~20. No antihelium candidates found in the -1 to -14 GV rigidity range. Upper limit of 9.4 x 10 -8 using BESS-Polar II data. Upper limit of 6.9 x 10 -8 using all BESS data. Antihelium |Z|=2 events Expanded negative rigidity range: no events <-14 GV

28. 28 Long Duration Balloon (LDB) flights employing conventional zero-pressure balloons have a proven history of scientific discovery, with many cited achievements. - Most High Priority projects are proposing multiple LDB missions. Super-pressure balloons are a major technological advance. - They offer an order of magnitude increase in flight capability. - They enable Ultra Long Duration Balloon (ULDB) flights (60-100 days). - They open areas of exploration closed to zero-pressure balloons, e.g. LDB flights at mid-latitudes. Modest cost impact to convert LDB payloads for ULDB. - Most LDB payloads can be upgraded for ULDB flights. - LDB and ULDB together form a science opportunity continuum. ULDB missions can be adapted quickly to new challenges. - They are ideally suited as a Small Explorer (SMEX) mission equivalent. - They offer significant science at fraction of the cost of a space mission. Concluding Remarks Natural Evolution to Super Pressure Ballooning

29. 29 Acknowledgements Executive oversight of the NASA Balloon Program is provided by the Astrophysics Division, Science Mission Directorate, NASA Headquarters Implementation of the Balloon Program is delegated to the Goddard Space Flight Center Wallops Flight Facility (WFF) at Wallops Island, Virginia http://www.wff.nasa.gov/balloonshttp://www.wff.nasa.gov/balloons Balloon flights are conducted by the Columbia Scientific Balloon Facility (CSBF) in Palestine, Texas http://www.csbf.nasa.gov/http://www.csbf.nasa.gov/ The CSBF is managed by the Physical Science Laboratory, New Mexico State University, under contract with WFF The balloons are manufactured by Raven Industries, Aerostar Division in Sulfur Springs, Texas The Antarctic LDB program would not be possible without the crucial contribution of the U.S. National Science Foundation Office of Polar Programs and Raytheon Polar Services Company