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

2. = Particle Astrophysics 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.

3. = Particle Astrophysics 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.

4. = Particle Astrophysics 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).

5. = Particle Astrophysics 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

6. = Particle Astrophysics ANITA Collaboration Meeting UC-Irvine November 24-25, 2002 6 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 Particle Astrophysics

7. = 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!)

8. = Particle Astrophysics 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.

9. = Particle Astrophysics 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?

10. = Particle Astrophysics 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.

11. = Particle Astrophysics 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.

12. = Particle Astrophysics 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

13. = Particle Astrophysics 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)

14. = Particle Astrophysics ANITA Collaboration Meeting UC-Irvine November 24-25, 2002 14 Solar Array Sizing Typical output is 140 W/m 2 for production cells. (Markvart) Allowing for conversion and storage inefficiencies, expect 100 W/m 2. Typical commercial panels weigh 1 lb. per 5 W, or 25 lbs./m 2 Pointing or an omnidirectional design is required. For a ‘lampshade’ omnidirectional array, this corresponds to about 4 m 2 of panel per 100W continuous power. Rotator weighs 200 lbs., so the lampshade wins unless NSBF needs the rotator themselves.

15. = Particle Astrophysics 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.