anita-lite: the background survey
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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’ - PowerPoint PPT PresentationTRANSCRIPT
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.