MESSAGE
| DATE | 2015-02-06 |
| FROM | Ruben Safir
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| SUBJECT | Subject: [NYLXS - HANGOUT] antartic Linux
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http://linuxgizmos.com/rov-dives-deep-in-antarctic-waters-with-linux-based-cams/
ROV dives deep in Antarctic waters with Linux-based cams
Feb 5, 2015 | Eric Brown
[Updated 7PM] — A “Deep-SCINI” submersible with Linux-based Elphel
cameras discovered surprisingly diverse life under the Antarctic ice
shelf — and rapidly melting ice.
Linux has once again been spotted in the frigid seas around Antarctica,
which is not so surprising considering that Tux, the penguin, enjoys a
nice cold bath. In November, we learned about Woods Hole Oceanographic
Institute’s expedition to measure the thickness of Antarctic sea ice
using a Linux-based SeaBED AUV
(autonomous underwater vehicle) from Seabed Technologies.
*Deep-SCINI at the Ross Ice Shelf drillsite*
(click image to enlarge)
Now, a National Science Foundation funded research team has made some
remarkable discoveries under the Antarctic ice using a submersible
called Deep-SCINI (Submersible Capable of under Ice Navigation and
Imaging). Developed at the University of Nebraska-Lincoln, Deep-SCINI
features an imaging system with three high-resolution, Elphel cameras
featuring open source Linux computers (see farther below).
*Deep-SCINI at the drillsite*
(click images to enlarge)
Unlike the SeaBED, the tubular, 2-meter long Deep-SCINI is not an AUV,
but rather a tethered, remotely operated vehicle (ROV). It took 45
minutes for the craft to cruise down through a 740-meter borehole
through Antarctica’s Ross Ice Shelf, which was drilled with a jet of hot
water. Deep-SCINI traveled deeper under the Antarctic ice than any
previous ROV expedition.
The ROV was then set loose in a 10-meter deep layer of freezing water
below the ice and above the sea floor known as the “grounding zone.”
Here, the researchers were “stunned” to discover Elphel-captured images
of fish and other aquatic animals living in the hostile, pitch black
environment, according to a Jan. 21 story in Scientific American
.
*Lead driller Dennis Duling at the Ross Ice Shelf drillsite melt tank*
(click image to enlarge)
A NASA ASTEP (Astrobiology Science & Technology for Exploring Planets)
grant helped fund Deep-SCINI through UNL’s ANDRILL (ANtarctic geologic
DRILLing) Science Management Office (SMO) under the leadership of
Executive Director Frank Rack. The research was organized under the
Whillans Ice Stream Subglacial Access Research Drilling (WISSARD)
project, and included Northern Illinois University, Montana State
University, and the University of California at Santa Cruz. UNL’s SMO
was subcontracted to design and build the hot water drill system and
provide Deep-SCINI for sub-ice deployments.
The drilling location is near the inward shore side of Antarctica’s
France-sized Ross Ice Shelf, some 850 kilometers from the “the nearest
place where the ocean is in contact with sunlight that allows tiny
plankton to grow and sustain a food chain,” says Scientific American.
*Ross Ice Shelf drillsite aerial view*
(click image to enlarge)
Researchers had expected to find only a few microbes with sluggish
metabolic rates. Yet, despite the fact that the freezing waters held
little in the way of microbial food, Deep-SCINI discovered 20 to 30
species of fish and dozens of red, shrimp-like crustaceans and other
unidentified marine invertebrates.
Several species have yet to be identified, and might be new discoveries.
The ROV scooped up samples for further study.
It’s unclear what the fish and other creatures are eating. Possibilities
include periodic waves of plankton, which were not in evidence during
the dive, or microbes eating mineral grains or feeding on ammonium or
methane seeps. Unlike the deep-sea ocean floor in more temperate
regions, there was no evidence of mud-dwelling, epi-benthic life
attached to the seafloor.
The search for life under the ice was ancillary to the main focus of the
NSF-funded expedition. The chief goal was to determine how quickly the
Ross Ice Shelf is melting and sliding into the ocean due to global
warming. The drilling location was chosen due to its proximity to the
Whillans Ice Stream, which feeds the ice shelf with new ice.
Deep-SCNI discovered a large number of pebbles on the seafloor, which
were presumed to have fallen from the underside of the ice sheet as it
melted. Because older, deeper sediments were found to be free of
pebbles, it suggested a recent acceleration of melting due to global
warming.
*Inside Deep-SCINI*
UNL announced the Deep-SCINI
last July, and on Jan. 21
,
reported on its involvement via ANDRILL in the WISSARD expedition. The
drilling expedition had been delayed a year, due to the U.S. government
shutdown in Oct. 2013.
*Bob Zook (left) and Justin Burnett working on Deep-SCINI components*
(click image to enlarge)
The Deep-SCINI ROV was invented by Bob Zook, an engineer recruited by
UNL’s ANDRILL office, as well as Justin Burnett, a UNL graduate student
in mechanical engineering. Zook, who confirmed the presence of Linux in
his craft’s cameras to LinuxGizmos in an email, told Scientific American
the ROV’s nearly flawless maiden “flight” was “a minor miracle.” He
added: “The rule of thumb down here is that any new technological thing
does not work for the first deployment.”
The ROV has yet to be fitted with a navigation system, so it was
maneuvered using “tricks,” says Scientific American. For example, the
above-ice operators would “fly” the craft from one large rock to
another, or reel in the tether a couple meters to tug the ROV from
behind and point it away from the hole. The tether incorporated ENOP
(Ethernet over Power) for communications.
The Deep-SCINI design follows an earlier Zook-designed SCINI
model that had been tested in Antarctic waters starting in 2007. The
original, 1.5-meter craft, which was limited to depths of 300 meters,
was responsible for discovering a new species of sea anemone that lives
in burrows in the underside of the Ross Ice Shelf.
The Deep-SCINI was designed to descend to 6,500 feet, or about two
kilometers. The nearly two-meter long ROV has a diameter of 23
centimeters and weighs 60 to 80 pounds.
*Deep-SCINI’s open source Elphel cams*
The Deep-SCNI uses open source Linux-based cameras from Elphel
,
which are popular among academic researchers. Whereas the original SCINI
craft
had two older Elphel 353 cameras, the
Deep-SCINI has three Elphel NC353L-369
cameras for upward, downward,
and forward-looking views.
*Elphel NC353L-369*
According to UNL’s Justin Burnett, each camera is fitted with
5-megapixel CMOS sensors inside a custom 3,000-psi tested pressure
housing measuring 7.0 x 2.5 inches. The cameras were chosen for their
openness, flexibility, large feature set, and support team. “This is a
very flexible open source hardware and software IP camera,” he added.
The cameras are incorporated in Elphel’s Eyesis4Pi
panoramic and stereophotogrammetric
camera. A similar Elphel panoramic was originally mounted on Google
Streetview cars before being replaced with an in-house design.
The Elphel NC353L-369 features an accessory board that integrates
CompactFlash storage and configurable USB ports, one of which was used
by ANDRILL to control a focus motor. It also provides pulse
synchronization control for capturing multiple images simultaneously
across a network. The NC353L-369 can record video or images to the CF
card or an external SATA drive. A serial port provides access to the
root console, which Rack said simplifies firmware development.
While, the Elphel camera is primarily used for video, the Deep-SCINI
implementation focused on still images. “We actually stream images
rather than video at variable frame rates from the device, depending on
exposure and lighting conditions,” said Burnett. “The camera performs on
board JPEG compression fast enough so that we are able to fly the
vehicle smoothly, We are able to keep total delay under 200ms while
still keeping bandwidth usage low.”
Custom viewing software lets the researchers adjust the amount of
exposure, color compression, and binning to increase framerate. “It also
allows us to take instantaneous full resolution images with a
keystroke,” he said. “We have custom firmware written to interface with
our vehicle piloting software as well, such that vehicle telemetry data
is actually stored in the image exif data, greatly streamlining post
processing.”
According to Scientific American, the camera lenses were reinforced with
pressure-resistant sapphire crystal, as well as a streamlined body of
aluminum rods and “syntactic foam comprising millions of tiny, hollow
glass beads.”
In addition to the cameras, Deep-SCINI integrates five maneuvering
thrusters, lights, a CT (conductivity-temperature) sensor, a syringe
sampler for collecting water samples, and a gripper for picking up
objects. A drop weight held in the gripper kept the vehicle oriented
vertically while traveling through the borehole. An instrumented “clump
weight” isolated the deployment winch and fiber optic junction box from
the ROV’s tether.
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