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ANITA-lite: The Background Survey

ANITA-lite: The Background Survey. Jim Beatty Penn State. Context. A simple ‘Pathfinder’ program has been under consideration for some time to map the polar winds using small inexpensive payloads Iridium plus GPS ‘Antarctic sondes’

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ANITA-lite: The Background Survey

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  1. ANITA-lite:The Background Survey Jim Beatty Penn State ANITA Collaboration Meeting UC-Irvine November 24-25, 2002

  2. Context • A simple ‘Pathfinder’ program has been under consideration for some time to map the polar winds using small inexpensive payloads • Iridium plus GPS ‘Antarctic sondes’ • Vernon Jones suggested this platform as a possible way of squeezing in an Antarctic RF background survey for ANITA without being in the regular LDB queue. • A possible opportunity for this flight exists in the ’03/’04 season. • Low impact is important because of the NASA/NSF situation regarding support of the Antarctic balloon program. ANITA Collaboration Meeting UC-Irvine November 24-25, 2002

  3. Suggested Objectives • Measure impulsive background and noise floor over as much of the flight path as feasible. • Set an upper limit on neutrino signals based on survey. • Test key elements of the ANITA payload where practical under the constraints of the small payload. ANITA Collaboration Meeting UC-Irvine November 24-25, 2002

  4. Constraints • Operational impact of the payload on Antarctic program needs to be minimized • Crew of 1 or 2. • Minimal logistical support. • As small as feasible, but simplicity is paramount. • We need to accommodate the Pathfinder requirements (GPS + Iridium). ANITA Collaboration Meeting UC-Irvine November 24-25, 2002

  5. Payload Elements • Antennas and mounts • Electronics package • Options • Modified sealed shipping container • Existing small pressure vessel • Simple vessel manufactured from tube stock • Similar to sounding rocket • Use makeup gas to guard against slow leaks • Solar panels • Suspension system ANITA Collaboration Meeting UC-Irvine November 24-25, 2002

  6. Particle Astrophysics Digitizer • Acquiris V-series Digitizers (DC 241 2 channel ($12990), DC 271 4 channel ($14990)) • 1 channel at 4 GSPS,2 channels at 2 GSPS,4 channels at 1 GSPS (271 only) • Same underlying devices except for front end options. • 40 W per board ANITA Collaboration Meeting UC-Irvine November 24-25, 2002

  7. Observing Strategy • We need to select our observing strategy given power constraints. There is a trade among: • Number of simultaneous channels observed • Bandwidth of observation • Power consumption • Duty cycle (but need to avoid thermal cycling!) ANITA Collaboration Meeting UC-Irvine November 24-25, 2002

  8. Flight Computer and Software • Compact PCI computer, chosen for power consumption, digitizer interface, and ruggedness. • Use RTLinux or VxWorks (drivers) • Simplified first-pass ANITA software. • Autonomous observational cycle, with limited parameter choice from the ground. ANITA Collaboration Meeting UC-Irvine November 24-25, 2002

  9. Communications and Telemetry • Impact is minimized if we use Iridium • 2400 baud ‘dial-in’ service • Shared with WFF/NSBF primary user on a ‘pass-through’ basis? ANITA Collaboration Meeting UC-Irvine November 24-25, 2002

  10. Data Recovery • We can get some data back over Iridium. What would we want during flight? (2400 baud max., ‘dial in’) • With standard SIP we can get 6 kbps if not too close to pole, but this increases program impact significantly. • Most data will need to be recorded and recovered. ANITA Collaboration Meeting UC-Irvine November 24-25, 2002

  11. Payload Attitude Determination • Sun sensor to determine azimuth • Designs exist in the literature • Differential GPS system possible if ready in time and within power budget. ANITA Collaboration Meeting UC-Irvine November 24-25, 2002

  12. Thermal Design • Normal practice is to bias the payload cold by adjusting radiative coupling (using white paint), and rely on internal power dissipation and heaters to bring up temperature. • Payload should be safely within operating range with instrument on and heaters off. • Insulation is used to damp temperature swings. • Heaters must be adequate to reach minimum operating conditions in a worst case situation ANITA Collaboration Meeting UC-Irvine November 24-25, 2002

  13. Solar Power Systems • Most payloads have used systems from Meer Industries (Jim Billups) • Boomerang • Higregs • ATIC • Tracer • Flare Genesis • We should take advantage of this! Hiregs (after) ANITA Collaboration Meeting UC-Irvine November 24-25, 2002

  14. Solar Array Sizing • Typical output is 140 W/m2 for production cells. (Markvart) • Allowing for conversion and storage inefficiencies, expect 100 W/m2. • Typical commercial panels weigh 1 lb. per 5 W, or 25 lbs./m2 • Pointing or an omnidirectional design is required. • For a ‘lampshade’ omnidirectional array, this corresponds to about 4 m2 of panel per 100W continuous power. • Rotator weighs 200 lbs., so the lampshade wins unless NSBF needs the rotator themselves. ANITA Collaboration Meeting UC-Irvine November 24-25, 2002

  15. Actions Needed • Official Flight Request to NSBF/WFF • Meeting with Dave Gregory to set payload parameters and hash out design • Decisions on open design issues, and a worked out design based on agreed constraints. ANITA Collaboration Meeting UC-Irvine November 24-25, 2002

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