ANITA Collaboration MeetingUC-Irvine November 24-25, 2002

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=Particle Astrophysics

ANITA-lite:The Background Survey

Jim BeattyPenn State

ANITA Collaboration MeetingUC-Irvine November 24-25, 2002

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=Particle Astrophysics

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 MeetingUC-Irvine November 24-25, 2002

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=Particle Astrophysics

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 MeetingUC-Irvine November 24-25, 2002

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=Particle Astrophysics

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 MeetingUC-Irvine November 24-25, 2002

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=Particle Astrophysics

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 MeetingUC-Irvine November 24-25, 2002

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=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

Particle Astrophysics

ANITA Collaboration MeetingUC-Irvine November 24-25, 2002

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=Particle Astrophysics

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 MeetingUC-Irvine November 24-25, 2002

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=Particle Astrophysics

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 MeetingUC-Irvine November 24-25, 2002

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=Particle Astrophysics

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 MeetingUC-Irvine November 24-25, 2002

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=Particle Astrophysics

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 MeetingUC-Irvine November 24-25, 2002

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=Particle Astrophysics

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 MeetingUC-Irvine November 24-25, 2002

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=Particle Astrophysics

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 MeetingUC-Irvine November 24-25, 2002

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=Particle Astrophysics

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 MeetingUC-Irvine November 24-25, 2002

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=Particle Astrophysics

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 MeetingUC-Irvine November 24-25, 2002

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=Particle Astrophysics

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.