You can notice some shift in the display of the ship localization, probably due to the unspecified manually registered data setting sent by the QM2 AIS transceiver (XY offset of the AIS GPS antenna position compared to the ship geometry) : see reference point. The width for display is the waterline beam (41 m) and not the one at the bridge level (45 m). Length: 1,132 ft (345.03 m) Beam :135 ft (41 m) waterline VS 147.5 ft (45.0 m) extreme (bridge wings) so a difference of width of 4 m, around 8% of the Joubert lock width. Ship dimensions and AIS GPS antenna reference point should be obtained from AIS Class A within a 1 minute (in worst cases it might be up to 6 minutes by AIS IEC 61993 Ed2 standard). It is recommended to use the ‘Conning Station’ position at the midship line, Conning Station reference point (CRP) is the main reference point and GPS data recalculates to the specified Conning Station Position.
Les Glénans 2017 with the GeoGarage platform (SHOM nautical chart)
Les Glénans in 1958 This year, the Glénans sailing school celebrates its 70th anniversary. This association created during the post-WWII period by two members of the Resistance Hélène and Philippe Viannay participated in the democratization of the practice of sailing. Over the years, the school has expanded to include five venues for training courses and new materials (catamaran, kitesurfing, windsurfing ...). But the celebrity of the Glénans has also been forged on its slogan "school of sailing, school of sea, school of life".
The seabed drill rig (MeBo) was developed at the MARUM in order to be able to obtain cores of up to 50 m in length from loose sediments and solid rock.
The 10-ton-weight machine is placed on the seabed and works in water depths of up to 2000 m. The film shots show - uncommented - tests of different components of the system in the MARUM technology hall, preparations for the suspension of MeBo on board FS METEOR, the drilling of sediment cores on the seabed and - after the return on board - the removal of the drill cores.
A tangle of tubes, cables, and actuators - Mebo looks as though it could
morph at any moment into one of those Transformer robots from the
movies.
The 10-tonne machine is in fact a seabed drilling system, and a very sophisticated one at that.
Deployed
over the side of any large ship but driven remotely from onboard, it's
opening up new opportunities to take sediment samples from the ocean
floor. MeBo was developed at the MARUM research facility in Bremen, Germany, and has not long returned from a pathfinding expedition to the West Antarctic.
In
the iceberg-infested waters of the Amundsen Sea Embayment (ASE), it
obtained the very first cores to be drilled from just in front of some
of the mightiest glaciers on Earth.
Chief among these are Pine
Island Glacier and Thwaites Glacier, colossal streams of ice that drain
the White Continent and which are now spilling mass into the ocean at an alarming rate.
There's concern that deep, warm water is undercutting the glaciers, possibly tipping them into an unstoppable retreat.
And that has global implications for significant sea-level rise.
It was MeBo's job to help investigate whether this really could be happening.
"Meeresboden-Bohrgerät" is German for "seafloor drill rig"
It's lowered to the seabed with a specially designed cable
This also delivers power, and carries commands and video
An operator drives MeBo remotely from the deployment ship
System has a magazine of pipes to lengthen the drill string
Mebo can penetrate mud and rock to a depth of up to 80m
The goal was to retrieve seafloor sediments that would reveal the
behaviour of the West Antarctic Ice Sheet (WAIS) in previous warm
phases.
To read the future in the past.
"Has the West Antarctic Ice Sheet collapsed before? Is that the
scenario we should expect in the next couple of hundred years?" pondered
project leader Karsten Gohl from the Alfred Wegener Institute (AWI).
"Perhaps
in some of these warm periods it has only partially collapsed, just a
few portions of it. Or maybe the WAIS was hardly affected in those
times. We hope we can understand this better by collecting samples
because basically the sediments are a climate archive."
As
glaciers grind their way off the continent they crush and bulldoze rock
and drop it offshore.
This material - the range of particles and their
shapes, the way they are sorted, etc - codes the activity of the
glaciers in the region.
Layers deposited during periods when the
WAIS was extensive will contrast with those from times when glaciers
were absent or significantly withdrawn.
"If you find ice-rafted debris (stones dropped by icebergs), for
example, you can be sure there was ice on land and that the ice had
advanced to the coast," explained Claus-Dieter Hillenbrand from the British Antarctic Survey (BAS).
"But
also new developments - especially what's known as geochemical
provenance - have emerged in the last 10 years that mean it's even
possible now to compare this material with rocks on land to pin down the
actual sources in the hinterland."
Helpfully, nature also
date-stamps the sediments by incorporating the remains of single-celled
organisms (foraminifera and diatoms) from the ocean.
The distinct
species that lived through different epochs act as a fossil
chronometer.
Back in Bremen: The cores have undergone CT scanning and have now been split open
MeBo's drill cores are now back in Bremen.
A week ago, the
cylindrical liners containing some 60m of ocean-floor material were
being X-rayed at a local hospital to precisely determine their internal
structure.
And in the past few days, the task began of splitting the
cores to allow their contents to be fully analysed.
The
scientists who travelled to the Amundsen Sea with MeBo, on Germany's
Polarstern research ship, already have some clues to what the cores will
contain.
They got a sneak preview in the rock and mud that was visible
at the ends of the drill pipe segments when they were brought back up
from below.
From the 11 locations MeBo sampled, it's very likely
there are sediments that record the very deep past - from the Late
Cretaceous, some 70 million years ago when dinosaurs still roamed the
Earth and the landmass that is now Antarctica was green.
Ice challenge: The drill system can only be lowered when big bergs are absent
courtesy of T. Ronge, AWI
Coming forward in time, it's probable also there are records from the
Oligocene (34-23 million years ago) and the Miocene (23-5 million years
ago) which should document some key events in Antarctica's history when
a burgeoning ice sheet in the East of the continent was supplemented by
one in the West.
"We haven't got a continuous sequence; we have
spot samples from these different times," explained Dr Gohl.
"But with
these sediments we hope we can establish the onset of glaciation in
Antarctica, and then get records from the time in the Miocene where in
other areas of the Antarctic it's known there was the main glacial
advance that has persisted to today."
With luck there are
additional sediments distributed in the last few hundred thousand years,
when WAIS glaciers would have advanced and retreated through the recent
cycle of "ice ages".
courtesy of T. Ronge, AWI
What many scientists would dearly love to see is a rich record from
the Pliocene, from a time three million years ago when carbon dioxide
levels in Earth's atmosphere were very similar to what they are today
(400 molecules of CO2 in every million molecules of dry air).
WAIS
behaviour at this time could represent the best analogue for what is
about to happen to the ice sheet in the near future.
But this
desire may have to wait to be satisfied by a second expedition with a
dedicated drill ship, the Joides Resolution.
The JR can bore hundreds of
metres into the seabed, increasing the chances of capturing an
unabridged view of the past. A firm booking has been made for 2019.
For
now, researchers must work with the initial snapshot provided by MeBo.
BAS team-member Bob Larter: "This is the first time we've had any real
constraint on the West Antarctic Ice Sheet, because although there's
been a number of drilling exercises in the Ross Sea, it's hard from that
location to know for sure whether the glacial signal is coming from the
East or the West. Whereas if you drill in the Amundsen Sea, you know it's a record of the WAIS."
The
results of the various lab analyses now under way are eagerly awaited
and will be reported in a slew of scientific papers.
For MeBo, the
expedition has demonstrated once again what an agile system it is.
"This type of drilling will become more common, not just in science but also in industry," predicted Marum's Tim Freudenthal.
"There
are several applications in the oil and mining industries, and offshore
wind farms - they need geotechnical investigation of the seabed. For
all these types of investigation, the big drilling vessels can often be
too powerful. The seabed drilling systems like MeBo offer a very good
alternative."
An update on the Amundsen Sea Embayment expedition was presented to the recent General Assembly of the European Geosciences Union (EGU).
Satellites will function like a mesh network and deliver gigabit speeds.
In May this year, SpaceX said its planned constellation of 4,425 broadband
satellites will launch from the Falcon 9 rocket beginning in 2019 and
continue launching in phases until reaching full capacity in 2024.
SpaceX gave the Senate Commerce Committee an update on its satellite plans during a broadband infrastructure hearing this morning via testimony by
VP of satellite government affairs Patricia Cooper.
Satellite Internet
access traditionally suffers from high latency, relatively slow speeds,
and strict data caps.
But as we reported in November, SpaceX says it intends to solve these problems with custom-designed satellites launched into low-Earth orbits.
SpaceX mentioned 2019 as a possible launch date in an application
filed with the Federal Communications Commission in November and offered
a more specific launch timeline today.
Cooper told senators:
"Later this year, SpaceX will begin the process of testing the satellites themselves, launching one prototype before the end of the year and another during the early months of 2018. Following successful demonstration of the technology, SpaceX intends to begin the operational satellite launch campaign in 2019. The remaining satellites in the constellation will be launched in phases through 2024, when the system will reach full capacity with the Ka- and Ku-Band satellites. SpaceX intends to launch the system onboard our Falcon 9 rocket, leveraging significant launch cost savings afforded by the first stage reusability now demonstrated with the vehicle."
Washington-based company Vulcan Aerospace announced that its Stratolaunch Systems, an air-launch platform for rockets, is close to completion.
The 4,425 satellites will "operat[e] in 83 orbital planes (at
altitudes ranging from 1,110km to 1,325km)," and "require associated
ground control facilities, gateway Earth stations, and end-user Earth
stations," Cooper said.
By contrast, the existing HughesNet satellite
network has an altitude of about 35,400km, making for a much longer round-trip time than ground-based networks.
SpaceX has also proposed an additional 7,500 satellites operating
even closer to the ground, saying that this will boost capacity and
reduce latency in heavily populated areas.
But Cooper offered no
specific timeline for this part of the project.
There were an estimated 1,459 operating satellites orbiting
Earth at the end of 2016, and the 4,425 satellites in SpaceX's planned
initial launch would be three times that many.
Other companies are also
considering large satellite launches, raising concerns about potential
collisions and a worsening "space junk problem," an MIT Technology Reviewarticle noted last month.
SpaceX today urged the government to relax regulations related to
satellite launches and to include satellite technology in any future
broadband infrastructure legislation and funding.
Network design
SpaceX's satellites will essentially operate as a mesh network and
"allocate broadband resources in real time, placing capacity where it is
most needed and directing energy away from areas where it might cause
interference to other systems, either in space or on the ground," Cooper
said.
Satellites will beam directly to gateway stations and terminals
at customers' homes, a strategy that will greatly reduce the amount of
infrastructure needed on the ground, particularly in rural and remote
areas, she said.
"In other words, the common challenges associated with siting,
digging trenches, laying fiber, and dealing with property rights are
materially alleviated through a space-based broadband network," she
said.
Customer terminals will be the size of a laptop.
While speeds should
hit a gigabit per second, SpaceX said it "intends to market different
packages of data at different price points, accommodating a variety of
consumer demands."
Current satellite ISPs have latencies of 600ms or
more, according to FCC measurements,
but SpaceX has said its own system will have latencies between 25 and
35ms.
That's better than DSL and similar to several of today's major
cable and fiber systems, according to FCC measurements.
The measurements show that the Altice-owned Optimum and Verizon FiOS
had latencies of just over 10ms, better than what SpaceX is expecting to
achieve.
SpaceX promised that its satellite technology won't become stale after
launch.
The company's "satellite manufacturing cost profile and in-house
launch capability" will allow it to continually update the system's
technology to meet changing customer needs, Cooper said.
SHOM largest scale raster chart (6797 1:15 000 in overzoom) issued from the GeoGarage platform
SHOM ENC largest scale chart (FR567970 1:12000) issued from the GeoGarage platform
