Deep Water and Europa

by Paul Gilster on March 3, 2007

If humans ever do establish a presence on Europa, it will surely be somewhere under the ice. Assuming, that is, that the ice isn’t too thick, and to learn about that we have to await further study, and probably a Galilean moon orbiter of some kind that can observe Europa up close and for lengthy periods. But assuming the ice is more than a few meters thick, it should provide radiation screening, and getting down into that presumed Europan ocean is where we want to be in the search for life.

DEPTHX in the water

Of course, the first undersea explorations on the Jovian moon will have to be robotic, and here we can talk about technologies under development today. NASA has funded a self-contained robot submarine called the Deep Phreatic Thermal Explorer (DEPTHX) that operates with an unusual degree of autonomy, navigating with an array of 56 sonar sensors and an inertial guidance system. Now a series of tests in Mexico at a geothermal sinkhole, or cenote, called La Pilita have tested out key components, proving DEPTHX can manage unexplored three-dimensional spaces.

Image: DEPTHX in the water at Cenote la Pilita. Credit: David Wettergreen/CMU.

What’s ahead for the technology is a much more challenging task: to explore the Zacatón sinkhole in the Mexican state of Tamaulipas in May. La Pilita seems easy by comparison. It’s about 100 meters deep, filled with overhanging rock and interesting biology. The depth of the Zacatón site is unknown. But Bill Stone (Stone Aerospace), leader of (DEPTHX) mission, sees La Pilita as a powerful proof of concept:

“The fact that it ran untethered in a complicated, unexplored three-dimensional space is very impressive. That’s a fundamentally new capability never before demonstrated in autonomous underwater vehicles (AUVs).”

Even so, don’t underestimate the challenge at Zacatón. From a Pittsburgh Tribune-Review story on the technology:

Divers have explored Zacaton for decades, but a turning point came on April 6, 1994, when cave-diving pioneers Jim Bowden and Sheck Exley strapped on scuba tanks and tried to reach Zacaton’s elusive bottom. Bowden made it to a depth of 925 feet — a world record for deep-water diving since broken — but tragedy overshadowed his feat. Exley did not return to the surface.

Using software called SLAM (Simultaneous Localization and Mapping) developed at CMU, DEPTHX maneuvered close to rocky walls at La Pilita and was able to take core samples. With Zacatón on the horizon, the robot’s ability to determine its position within 15 centimeters using sonar seems reassuring. Will technologies like this one day explore a Europan sea? Perhaps, but they’ll be just one part of a much larger challenge depending on how deeply we need to drill to reach liquid water.

And if any of this work on autonomous exploration technologies sounds familiar, it may be because DEPTHX’s software is being developed by CMU’s David Wettergreen, who was project leader for the four-wheeled Zoë robot recently tested in Chile’s Atacama desert. Think of the Atacama as a Mars analogue, while Zacatón reflects — at least in some respects — our exploratory needs on Europa. Autonomy is the key, operating unassisted in the remotest environments, and this work may one day ensure that when we do get to Europa, we’re up to the challenge.

{ 16 comments }

X March 3, 2007 at 14:48

One thing I wonder about concerning a submersible on Europa is how it’s going to communicate with the surface and Earth. Wouldn’t that very deep ice and water essentially act to block radio communication and threaten to pinch apart any tether that connects the submersible to a relay craft sitting on the surface?

andy March 3, 2007 at 15:32

What would be really useful would be to plant seismometers at various locations on the Europan ice shell, which would provide the kind of geological monitoring needed to provide a good determination of the interior structure. Presumably tidal flexing of the ice shell would provide ample Europaquakes.

On second thoughts, that could provide a serious difficulty to anything trying to dig deep shafts through the ice… hmmm…

Kurt9 March 3, 2007 at 15:44

Why would anyone want to live under the ice on Europa? I see two possible futures for humanity in space. One, we develop some kind of FTL (or wormholes) and settle terra-compatible planets that we find in other star-systems. Two, if we don’t get an FTL or some other “cheap” method of going to the stars, we will be living in O’neill type space habitats or whatever improved versions of them we can make out of the nanotechnology we have at the time (Dyson Trees?).

I just don’t see any other plausible scenario for large scale human settlement in space.

Administrator March 3, 2007 at 16:09

Kurt, I’m talking about laboratories under the Europan surface, not large settlements. The sort of research stations we have in Antarctica, for example.

george scaglione March 9, 2007 at 9:39

kurt, if you happen to ever have the time i wish you would read some admittedly very very blue sky ideas i wrote up under the section of this site “a practical positron rocket” regarding how we might develop worm holes in the not to near future,admittedly.there are about 125 postings so far over there and this one is aprox # 123 or something.thank you my friend, respectfully george

ljk April 9, 2007 at 12:00

NASA Contemplates Future Trips To Europa And Neptune

Cameron Park CA (SPX) Apr 04, 2007

by Bruce Moomaw

By early 2006, the scientific advisory group chosen by NASA to plan its newest “strategic roadmap” for exploring the non-Martian Solar System had pretty much reached a consensus on the next three really big, “Flagship”-class missions that should be flown — the missions to Europa, Titan and Venus that I have already described.

They had also decided, however, that the fourth one should be one of two alternatives.

Full article here:

http://www.spacedaily.com/reports/NASA_Contemplates_Future_Trips_To_Europa_And_Neptune_999.html

ljk May 16, 2007 at 9:32

NASA Robot to Explore ‘Bottomless’ Pit

http://bcast1.imaginova.com/t?r=2&ctl=11A52:4A48D

Aquatic robot to carry out automated mission in watery pit this week.

ljk May 17, 2007 at 15:49

What it may look like under the ice of Europa one day:

http://www.starstryder.com/wp-content/uploads/2007/05/07depthxnightarm.jpg

ljk June 1, 2007 at 15:42

NASA DEPTHX Robot Completes Test Drive of Exploration Capabilities

http://www.spaceref.com/news/viewpr.nl.html?pid=22737

n late May, a NASA-funded robot successfully navigated one
of the world’s deepest sinkholes.

The mission could be a prelude to a future mission to Jupiter’s
moon Europa, believed to contain a liquid water ocean. The
Deep Phreatic Thermal Explorer (DEPTHX) is a 3,300-pound,
computerized, underwater vehicle that makes its own decisions.
With more than 100 sensors, 36 onboard computers, and 16
thrusters and actuators, it decides where to swim, which
samples to collect and how to get home.

ljk June 22, 2007 at 11:05

Voyage to the bottom of the Arctic Ocean

Robotics make exploration possible

By Colin Nickerson, Globe Staff | June 22, 2007

FALMOUTH — An international team of scientists is embarking on a search for life on the floor of the ocean at the roof of the world.

Led by researchers from the Woods Hole Oceanographic Institution — and equipped with unique robotic vehicles designed to explore mountain ranges miles beneath the polar ice cap — 30 geophysicists, biologists, engineers, chemists, and other deep-sea specialists will depart July 1 from a remote Norwegian archipelago, Svalbard, aboard a powerful icebreaker that will smash a path to exploration sites near the geographic North Pole.

The Arctic, its mysteries concealed beneath thick ice, is the smallest but least known of the world’s oceans.

“This is about exploring a portion of the earth that has been largely inaccessible to science,” said Robert Reves-Sohn, a geophysicist from the institution who will be chief scientist on the 40-day voyage.

“We’re looking for underseas habitats and creatures never seen before,” he said during a news conference yesterday.

Full article here:

http://www.boston.com/news/local/articles/2007/06/22/voyage_to_the_bottom_of_the_arctic_ocean/

ljk June 29, 2007 at 10:47

If there is life under Europa’s ice crust, this is what it may
be like:

http://lava.nationalgeographic.com/cgi-bin/pod/PhotoOfTheDay.cgi?day=13&month=5&year=07

ljk September 5, 2007 at 11:24

A Submarine for Europa

Many planetary scientists believe that Jupiter’s moon Europa is our solar system’s best contender to share Earth’s distinction of harboring life. Evidence gathered by the Voyager and Galileo spacecrafts suggests Europa contains a deep, possibly warm ocean of salty water under an outer shell of fissured ice. In a paper published in the July 2007 Journal of Aerospace Engineering a British mechanical engineer proposes sending a submarine to explore Europa’s oceans.

Carl T. F. Ross, a professor at the University of Portsmouth in England offers an abstract design of an underwater craft built of a metal matrix composite. He also provides suggestions for suitable power supplies, communication techniques and propulsion systems for such a vessel in his paper, “Conceptual Design of a Submarine to Explore Europa’s Oceans.”

Full article here:

http://www.universetoday.com/2007/08/29/a-submarine-for-europa/

ljk September 10, 2007 at 1:01

Essentially Immortal

“The implication of our research is that the large ice sheets of Antarctica, which make up 70 percent of the planet’s fresh water reserves, may represent active biomes, substantially expanding the known boundaries for life on Earth,” said Brent Christner.

by Staff Writers

Baton Rouge LO (SPX) Sep 10, 2007

Antarctica is home to the largest body of ice on Earth. Prior to approximately 10 years ago, no one thought that life could exist beneath the Antarctic ice sheets, which can be more than two miles thick in places, because conditions were believed to be too extreme. However, Brent Christner, assistant professor of biological sciences at LSU, has spent a great deal of time in one of the world’s most hostile environments conducting research that proves otherwise.

Christner’s discoveries of viable microbes in ancient ice cores and subglacial environments coupled with the realization that large quantities of liquid water exist beneath the Antarctic ice sheet have changed the way biologists view life in Antarctica.

“More than 150 lakes have been discovered underneath nearly two-and-a-half miles of ice in Antactica,” said Christner, “and most of these bodies of water have likely been covered by ice for at least 15 million years. The environmental conditions in the deep cold biosphere are unlike anything on the Earth’s surface and this represents one of the most extreme habitats for life on the planet.”

A timeframe of up to one million years is required for microbes in the atmosphere to be transported through the ice sheet and enter an Antarctic subglacial lake. Even though cells are preserved in the ice, the question of how the DNA of these organisms remains unscathed over such long periods of apparent metabolic inactivity still remains.

Full article here:

http://www.terradaily.com/reports/Essentially_Immortal_999.html

ljk February 29, 2008 at 9:16

The follow-up craft to DEPTHX, the Environmentally
Non-Disturbing Under-ice Robotic ANtarctiC Explorer,
or ENDURANCE:

http://www.stoneaerospace.com/products-pages/products-ENDURANCE.php

ENDURANCE Mission Description:

The principal AUV (Autonomous Underwater Vehicle)
mission at Lake Bonney is to serve as a tether-less
programmable mobile platform for an onboard suite of
science probes. The concept (upper right figure) is to
deploy a compact vehicle through a melt hole in the ice
surface of the lake and thence to have the vehicle execute
a pre-programmed 3D grid sampling trajectory in order to
populate a voxel model of the scan volume with the scalar
science data. Each layer of the grid is scanned in strips,
raster style, with a strip width, X, and length, L. In a
square search pattern samples will be taken in longitudinal
slices of width X and the length of any side would be n*X,
where n is the number of scan lines. This can be taken a step
further by rastering in the depth direction by an increment
Z between layers. A sample volume equal to X2Z would
represent 1 voxel. The present grid being considered for
the ENDURANCE project is 10 m (width) x 10 m (length) x
1 m (depth) for fine resolution sampling. The grid is geo-
referenced to the melt hole coordinates (using GPS), and
the sub-ice positions are determined using a multi-stage
sensor fusion approach. Each geo-referenced voxel is then
populated with fiber sensor data (fluorescence spectrometer;
Raman spectrometer; dissolved oxygen; temperature;
ambient light; Raman bottom probe); aqueous chemistry
(chloride and conductivity); and an optical image.

Data for any given mission are stored redundantly on flash
disk for later recovery and analysis on the surface. Planned
mission duration is 8 hours between vehicle battery changes
and maintenance and it is planned for at least one mission per
day to be conducted in the field. The navigation system is
designed to permit the vehicle to work autonomously.
However, for safety and recovery surety reasons, a
backup nav system will be used that will limit range of
up to 1,000 m from the melt hole.

chuck November 16, 2008 at 0:30

why drill when you can melt your way through? That’s really what I don’t understand. A nice little exothermic reaction could melt a pod straight through miles of ice. Shielding sensitive components from the heat could be as simple as a few layers of that wonderful comet catcher material nasa has developed.

chuck November 16, 2008 at 0:38

and as far as evolution is concerned on a satellite like Europa, that’s a fun speculative and imaginative thing to postulate. I’d love to know what sort of organics exist below the surface of the ice.

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