AIDJEX Bulletin #40 - Polar Science Center - University of Washington

AIR DROPPABLE RAMS (ADRAMS) BUOY
W. P. Brown
Polar Research Laboratory, Inc.
123 Santa Barbara Street
Santa Barbara, California 93101
E. C. Kerut
NOAA Data Buoy Office
Mississippi Test Facility
Bay St. Louis, Mississippi 39520
Abstract
The ADRAMS buoy was developed to provide
remote tracking of drifting sea ice near the
Arctic coast. The air droppable feature was
employed to reduce the high cost of deployment
inherent to manual installation and to provide
access to, deployment areas and seasons of the
year not previously suitable. ADRAMS contains
a 401.2 MHz transmitter and suitable digital
encoding to allow it to be received by the
NIMBUS-6 satellite. This satellite contains a
random access measurement system (RAMS) package.
The RAMS system determines the position
of the ADRAMS buoys to an accuracy of better
than 5 €31 thru doppler measurements of the
received signal. The buoy is deployed via its
own parachute and is designed to survive and
properly orient its antenna on any type of
terrain. The 80 pound package contains enough
batteries for 7 to 8 months operation at surface
temperatures as low as -5OOC. Although
the original ADRAMS was designed for tracking
only, it has been modified to incorporate a
capability for sensor data telemetry. The RAMS
system in the NIMBUS-6 satellite accepts 32 bits
of data from each transmission. Nineteen ADRAMS
buoys have been deployed thus far; 17 in the
Arctic and 2 in the Antarctic. The air drops
have been 100% successful.
1. Introduction
The Bureau of Land Management, in conjunction
with the Arctic Ice Dynamics Joint Experiment
(AIDJEX) program, developed an urgent need for a
device to allow remote tracking of the Arctic
ice pack drifting near shore. This need resulted
from the expansion of oil activities on the
northern coast of Alaska and from problems encountered
during 1975 in attempting to ship
large amounts of material to the oil-rich Prudhoe
Bay area.
Because of the urgent nature of the program,
it was probable that the buoys would have to be
deployed,during the all-dark period of winter
in the Arctic and under adverse weather conditions.
Previously-developed Arctic data buoys
(~,2) were not suitable because their installation
required a crew to land on the ice, an
operation too hazardous for the dark of winter.
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Therefore, the concept was evolved for a small
buoy which could be deployed from an aircraft via
parachute. With the constraint of small size,
the obvious choke of a tracking scheme was the
NIMBUS-6 satellite Random Access Measurement
System (RAMS). This system is being used succese
fully in other buoy programs. The buoy was given
the acronym ADRAMS (Air Droppable RAMS). The
NOAA Data Buoy Office was selected to spearhead
this program because of its wide experience in
developing data buoys for the open ocean as well
as the Arctic.
A contractor, Polar Research Laboratory, of
Santa Barbara, California was selected to perform
the ADRAMS design, development, and fabrication.
2. Design Considerations
The following factors provided the major constraints
on the overall system design.
1.
2.
3.
4.
5.
6.
7.
8.
The fabrication of the first group of
buoys had to be complete within six months
of the program start to allow deployment
for the critical winter season. This
factor constrained the use of electronic
components, materials and energy sources
to those that were readily available.
The size of the buoy could not Cxceed the
dimensions of the parachute door on available
deployment aircraft.
The electronic subsystems and mechanical
structure had to withstand the landing
impact of a parachute landing on smooth
and rough ice.
The parachute had to be disconnected from
the buoy after landing to prevent the buoy
from being dragged across the ice by high
winds.
The rate of change of oscillator frequency
with temperature had to be minimized, wittr
out using power, to optimize tracking
accuracy.
The system was to have a minimum life of
six months.
The system was to withstand the
surface temperature extremes of
-5OOC.
ice pack
t10 to
The buoy hull had to be water t ght in the