| December 16, 2002 -
The high altitude winds still haven't stabilized, but it looks like they
are getting a little better. Looking at the two Pathfinder Balloons (
click on the "Track the ATIC experiment" link to the right), the
trajectories are not steady in a pattern going round and round. Rather
the winds still seem to be disorganized and that causes the balloons to
move in unpredictable directions. If ATIC were to have launched into
this, we could not be certain where it would go or where we might have
to go to recover it. Much of Antarctica is still too remote to mount a
recovery operation. We are expecting a low pressure system to move in
with high winds and possibly snow late Thursday, Friday, and into
Saturday. Expect clearing on Sunday, so ATIC has a 'tentative' for
launch on Sunday (12/21) depending on the actual weather. This gives the
high altitude winds another four days to stabilize. We may well not make
it on Sunday, but the subsequent several days may stay clear and we will
try to sneak an ATIC launch in, if at all possible, early in the week.
In preparation, however, we had our final Flight Readiness Review on
Saturday (12/12) during which we went over the equipment to be used
(balloons, parachute, transmitters, safety circuits, terminate and chute
cut-away packages) and reviewed the status of ATIC and its flight plan.
We agreed to not use ballast for drive up during ascent and to turn the
auto-ballast system off. We are carrying only 200 pounds of ballast and
want to save it for any emergency that might arise (hopefully none, but
ballooning is still risky business). In addition, we completed a
detailed Recovery Plan for the ATIC Instrument and have gone over it
with our Raytheon contact as well as with the NSBF crew. Joachim and
Sasha have both completed Snowcraft training and are certified to go on
recovery. If space permits, we have requested that both
participate in the disassembly / recovery operations. We have isolated
the tools to be taken on recovery and with approval of Phil (the RSPC
liason and recovery lead) will be packing them up. Phil plans to bring a
small generator, so we will be able to use corded tools rather than the
cordless ones, whose batteries do not last very long. Any further
detailed planning will have to wait until we see the balloon trajectory
and have an idea where it will come down.
We continued to monitor the slow leak in the shell and now have a long
baseline (see the ATIC pictures link). The sealing we saw after the high
pressure run seems to have survived and the leak rate remains at 16
mb/day. This is just about one liter per hour. The total amount of gas
within the gondola is just over 6000 liters. So, we can fly a long time
and not worry about this tiny leak.
Finally, we recently accomplished a communication check using a TDRSS
satellite to link ATIC to the Payload Operations Control Center (POCC)
in Palestine, TX and from there to LSU and to the ATIC team at Williams
Field, McMurdo over the internet. We have been allocated some space in
the Crary Laboratory building in town and have installed a NIDS system
there. We were able to monitor the TDRSS data and to send commands from
both of the McMurdo sites. Having this ability in town will save on the
need to transport people to and from Willy Field during the flight, when
long-term monitoring is needed. |
Doug Granger, John Wefel and Joachim Isbert
interpreting the latest pressure vessel leak rate measurement
Track
the ATIC experiment
|
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