Envisat’s night eye supports icebound ship rescue in Antarctica
A German supply vessel and its crew are stuck in Antarctica until
October after severe winds and ice fields 7 metres high forced
an Argentinian rescue ship to retreat. A radar image from ESA’s
Envisat is helping the icebreaker plot its route to safety.
The German vessel ‘Magdalena Oldendorff’, with a skeleton crew
of 17, has been trapped in ice since 11 June. The Argentine
icebreaker, ‘Almirante Irizar’ was dispatched from Buenos Aires
last month and has been trying to lead them to safety since 19
July. Finally on Tuesday 30 July, in temperatures of -32 degrees
C and rapidly closing ice, they had to abandon the attempt.
Before leaving, the icebreaker helped the Magdelena Oldendorff
to a safe position in the Bay of Muskegbukta and transferred
enough supplies for the crew to survive the winter.
The German Federal Maritime and Hydrographic Agency asked ESA
to provide Envisat radar images to support the rescue efforts.
During the winter months the hours of daylight are very limited.
There are only two hours when visibility is sufficient for
helicopter reconnaissance missions. But Envisat’s Advanced
Synthetic Aperture Radar (ASAR) can view an area 400 km wide
with unprecedented accuracy during the polar night.
The German agency passed the Envisat data on to the US National
Ice Center, Washington, DC, and to the Argentine Navy, which
sent it on directly to the Argentine icebreaker to assist in
plotting the best possible route through the weakest points in
the ice.
Captain Manuel Picasso of Argentina’s Naval Glaciological
Center, Hydrographic Service sent his personal thanks for the
ASAR data to the ESA team.
Klaus Struebing of the German maritime agency explained the
relevance of the data. "Satellite images are a most useful tool
for ice services to provide ice information to their users. The
data are mostly used by trained interpreters and the extracted
info transferred to ice charts. For trained captains and ice
pilots the image itself is the best information — if it can
be read properly. The modern radar tools such as RadarSat, SAR
on ERS and now ASAR on Envisat are extremely useful because
the can provide data undependently from day-time and cloud
cover."
Obtaining this image proved quite a challenge, as Envisat
Mission Manager Henri Laur explains. "There are two small areas
in the world where we cannot recover ASAR data with the onboard
recorders, and the ship was precisely within one of those
areas", said Laur. "This required manual intervention by the
ESA team, briefly interrupting acquisition of data from other
Envisat instruments."
Most of the 79 Russian scientists and 28 crew aboard the
Magdalena Oldendorff were rescued in late June by helicopters
from a South African research vessel, but the 17-man skeleton
crew remained so as not to abandon the Magdalena. The
Magdalena’s Master Ivan Dikiy says: "Regardless of our waiting
position the mood is good onboard. To support this sweets,
cigarettes and sometimes a beer will be provided to the crew."
In October, when the Magdalena Oldendorf is ready to make its
escape, ESA will acquire another Envisat image of the area and
provide it to the German Maritime Agency. The data will be
used to analyse ice melt and the location of larger bergs in
the area to assist in the departure of the ship.
Related articles
* Why is ASAR useful for assisting polar operations?
http://www.esa.int/export/esaCP/ESATE976K3D_index_0.html
* ESA keeps vigil on the Antarctic ice pack
http://www.esa.int/export/esaCP/ESA6CV66K3D_index_0.html
* Envisat’s MERIS captures image of Hurricane Elida
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* What puts the "Advanced" in Envisat’s Advanced Synthetic
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Related Links
* Envisat Results
* Earth Observation Programme
http://www.esa.int/export/esaSA/earth.html
* Federal Maritime and Hydrographic Agency of Germany
IMAGE CAPTIONS:
[Image 1:
http://www.esa.int/export/esaCP/ESAOC976K3D_index_1.html]
Icebreaker Almirante Irízar moving northwards northwards with
German vessel Magdalena Oldendorff close behind (28 July).
Worsening conditions forced the rescue attempt to be called off.
Having left the Magdalena Oldendorff in a safe location in the
Bay of Muskegbuta the icebreaker is trying to break through the
Antarctic ice-belt headed for Buenos Aires. Envisat ASAR data
has been supplied to the icebreaker to assist in plotting the
safest course though weaker points in the ice. Credits: Argentine
Navy
[Image 2:
http://www.esa.int/export/esaCP/ESAOC976K3D_index_1.html#subhead1]
This image was acquired by Envisat’s Advanced Aperture Radar
(ASAR) on 31 July 2002, in support of rescue efforts in Antarctica.
The ASAR wide swath image shows a 400 km stretch of the Antarctic
Coast in Queen Maud Land. At this time of year, a belt of sea ice
up to 1100 km wide surrounds the Antarctic Continent and its ice
shelves and gives the sea in this image a textured grey appearance.
At the time of this acquisition, the supply ship Magdalena
Oldendorff was sheltering in a bay known as Muskegbukta on the
Eastern side of the Jutulstraumen Ice Tongue. Her location is
visible on the very edge of this scene (marked in blue). The
icebreaker Almirante Irizar’s course through the ice-infested
waters is shown as a series of GPS location measurements, one
of which was made within minutes of the acquisition (shown in
yellow). She will continue to skirt the ice shelf until reaching
safer waters in the vicinity of the Astrid Rise (longitude 12E,
off the image) in order to make her return to Buenos Aires. The
Mühlig-Hofmann Mountains are visible in the bottom left corner.
Glaciers flowing from the mountains feed the Fimbul Ice Shelf,
visible as a bright white swath bordering the South Atlantic
Ocean.
Technical Information:
Instrument: Advanced Syntetic Aperture Radar (ASAR)
Mode: Wide Swath
Date of Acquisition: 31 July 2002
Orbit number: 2177
Orbit direction: Ascending
Polarisation: H-H Resolution: 150 metres
Credits: ESA 2002
[Image 3:
http://www.esa.int/export/esaCP/ESAOC976K3D_index_1.html#subhead2]
Close-up of Envisat ASAR image acquired on 31 July 2002, in
support of a rescue mission in Antarctica. The area of the
Jutulstraumen Ice Tongue is shown in this close-up image (100
km wide) focusing on the positions of the ships at the time of
acquisition. The Magdalena Oldendorff is at anchor in a bay
called Muskegbukta, and the icebreaker Almirante Irizar is
making her way back to Argentina.
In this ASAR image, thick sea ice appears with a textured grey
signature in contrast to the bright ice shelf. It is evident
that the two neSons are separated by a narrow belt of clearer
water, which is facilitating the icebreaker’s eastward passage.
The whole area is littered with hazardous icebergs, visible as
bright specks against the darker background.
Technical Information:
Instrument: Advanced Synthetic Aperture Radar (ASAR)
Mode: Wide Swath
Acquisition date: 31 July 2002
Orbit number: 2177
Orbit direction: Ascending
Polarisation: H-H
Resolution: 150 metres
Credits: ESA 2002
[Image 4:
http://www.esa.int/export/esaCP/ESAOC976K3D_index_1.html#subhead3]
The ice-bound German-owned Magdalena Oldendorff is seen from a
South African Air Force Oryx helicopter Thursday June 27, 2002
near the Novolazarevskaya station in the northeast Antarctica.
Scientists and crew members were rescued off the vessel by the
SA Agulhas which arrived back in Cape Town Wednesday July 10,
2002. Credits: AP Photo-Edwuan Teich
