K. Liewer ANITA-Irvine CA 11/25/02 Gondola and Power Systems K. Liewer

K. Liewer - 1 ANITA-Irvine CA 11/25/02 Gondola ‘design’ introduction This material represents the state of the gondola design at the time of the original proposal (October ‘01) The shape accommodates the instrument field of view requirements No serious structural analysis done Missing –crash pad design/attachment –multipath analysis –handling interfaces

K. Liewer - 2 ANITA-Irvine CA 11/25/02 ANITA ballooncraft

K. Liewer - 3 ANITA-Irvine CA 11/25/02 Gondola diagram PV array

K. Liewer - 4 ANITA-Irvine CA 11/25/02 Gondola design 3 sections –upper antenna ring –electronics –lower antenna ring Sections have aluminum rings forming the interfaces to the other sections –frame is welded to the rings –sections bolt together Assumed aluminum tubing for the frame –1.90” OD x 1.50” ID – T6 –should withstand 10 G landing

K. Liewer - 5 ANITA-Irvine CA 11/25/02 Mass estimate Mass limit is 1814 Kg (4000 lb) –margin is only 5% –margin does include 20% reserve Review committee believed accounting is not correct and the reserve is really ~40% –mass limit may only have to include the science package

K. Liewer - 6 ANITA-Irvine CA 11/25/02 Gondola concerns No design exists for the crash pad locations –difficult to keep out of the beam Extremely difficult to prevent a significant fraction of the antennas from being destroyed on landing –antennas may be cheap to manufacture using honeycomb panels with flexible pcb sheets as the electrical elements (assuming the log periodic zig-zag design)

K. Liewer - 7 ANITA-Irvine CA 11/25/02 Power Subsystem Approximately 1000 W of power are required from the PV panels –Difficulties are limited area –to keep panels out of the antenna beams heat rejection –limited radiation area batteries are designed to supply 24 hrs of power only –used from time of disconnect from ground source until PV panels are operating –provides power if primary power is temporarily lost (balloon rotation) –provides for some data taking if there is a total primary power failure –Li/thionl chloride batteries baselined 58 kg

K. Liewer - 8 ANITA-Irvine CA 11/25/02 Power budget

K. Liewer - 9 ANITA-Irvine CA 11/25/02 Photovoltaic array requirements Need W maximum panel size is 5.1 m 2 PV output –Triple junction cells : 1240 W Ge:GaAs:InGaP cost : $950 K with solar concentrator –Si : 770 W cost : $6K Assumes PV array is at 60-70º C –less than  str. available to radiate heat into 2  is the gondola, ~  is the ice –additional radiators can lower the temperature to < 50º C –couple to radiators via heat pipes (tricky) pumped water –requires ~ 20 W

K. Liewer - 10 ANITA-Irvine CA 11/25/02 Power subsystem concerns Easiest solution (triple or double junction cells) is very expensive cheaper solution requires 40% more area –no place to put it cooling is required –not routinely done (if ever)