Europa drill on BBC website

For an update on one version of the plan to explore Europa, check out
the article at http://news.bbc.co.uk/2/hi/science/nature/3548139.stm

Plan to melt through Europa's ice

By Paul Rincon
BBC News Online science staff

Europa may hold a warm water ocean underneath its ice crust

Researchers are testing technology that could allow a lander to melt
through the ice crust of Jupiter's moon Europa to reach the water
ocean beneath. Space scientists want to send a craft to the Jovian
moon because its ocean might, in theory, harbour life.

Once through the 10-30km ice sheet, the probe could take a sample of
water, to analyse it for microbial life.

But significant engineering challenges remain before the German
Aerospace Centre lander could be sent to Europa.

"The idea is to land on Europa and somehow get through the ice," the
centre's Dr Stephan Ulamec told BBC News Online.

"One needs some kind of melting probe which can melt through the ice
and carry out investigation in the liquid ocean expected underneath."

The prototype being tested by Dr Ulamec is a 225cm-long hollow
aluminium cylinder with a copper melting head powered by an electrical
cable.

More details, and discussion of Lake Validivostok in the rest of the
article. Answers some of our recent questions.

/dps

Niko Holm wrote:
Personally I think that melting the ice is not that effective, as
the water would just re-freeze like stated in the article. The best
way would be to either cut it out with a wide drill or somehow
vapourise the water and deliver it up a pipe to the surface to let
it refreeze... I know there would be a whole lot of other things to
take into account...

Like the possibility of a blow-out I suspect that would put a
serious damper on the entire mission. By definition, there will be a
non-trivial pressure differential between the ocean presumed under the
ice and the vacuum of space, so water will start flowing-up the hole,
perhaps with non-trivial momentum...

I think the article mentioned something about trying to use ELF (?)
for radio comms - presumeably that would be back to a lander on the
surface that would relay signals to Earth. But ELF is really really
slow right?

Presuming one cannot trail a few wires as one goes (the aforementioned
issue of the ice shifting and breaking the wires), not knowing a thing
about the physics, I'm still curious to know if it would be possible
to "make" a wire/antenna in the ice as the water froze behind the
probe on its way down, by doping the water with something.
Presumeably to allow higher bitrate comms bewteen the probe and the
lander on the surface.

rick jones
--
Process shall set you free from the need for rational thought.
these opinions are mine, all mine; HP might not want them anyway...
feel free to post, OR email to raj in cup.hp.com but NOT BOTH...

(dave schneider) writes:

For an update on one version of the plan to explore Europa,
check out the article at
http://news.bbc.co.uk/2/hi/science/nature/3548139.stm

[quote]
Plan to melt through Europa's ice

Researchers are testing technology that could allow a lander to
melt through the ice crust of Jupiter's moon Europa to reach the
water ocean beneath. Space scientists want to send a craft to
the Jovian moon because its ocean might, in theory, harbour
life.

Once through the 10-30km ice sheet, the probe could take a
sample of water, to analyse it for microbial life.

This kind of mission can probably only be done with a nuclear power
source.

The article seems to identify two methods of getting information back:

1. ELF radio transmissions as used by submarines. This requires
fairly long wire antennas, probably hundreds of meters on both
sides of the comms link.

2. Touch and return. Once through the ice do all the sampling and
investigating, then drop a ballast to make the probe buoyant and
let it melt back to the surface again. Once back at the surface
it can transmit its data and potentially transfer samples for
return to earth.

It may also be possible to:

3. Trail a thin, tough, twisted pair cable like the ones used in
wire-guided missiles. The cable would unspool from the back of
the probe and provide a high speed data link to a relay left at
the surface.

1) and 3) allow a degree of in-situ control from Earth.

3) can provide continuous data.

1) may need a heated antenna to provide continuous data.

2) seems the simplest but if something goes wrong we will never
know what and why. Maybe this option would work well with a bunch
of small probes dropped at various locations.

Travel time through 30km of ice at 3m/h would be 416 days, so a
return trip could take over 2 years -- hmm, sounds a bit too long
to be without comms. Maybe one could boost the melting speed?

--
Manfred Bartz
----------------------------------------------------------------
A strong conviction that something must be done is the parent of
many bad measures. -- Daniel Webster

Rick Jones wrote in message ...
Like the possibility of a blow-out I suspect that would put a
serious damper on the entire mission. By definition, there will be a
non-trivial pressure differential between the ocean presumed under the
ice and the vacuum of space, so water will start flowing-up the hole,
perhaps with non-trivial momentum...

Not really. To a rough approximation, the pressure at the
top of the ocean will be equal to the weight of the column
of ice above it (per area). Since the melt-water will have
the same weight (being the same material), and will almost
certainly refreeze above the probe as it burrows down, this
should be a non-issue.

Christopher M. Jones wrote:
(dave schneider) wrote in message . com...
The prototype being tested by Dr Ulamec is a 225cm-long hollow
aluminium cylinder with a copper melting head powered by an electrical
cable.

Sounds like less of a prototype than a mockup. Almost
certainly, a Europa driller/diver will need to be powered
by an RTG. The idea of powering it by solar panels on
the surface is really a non-starter. First you cut down
their performance near-Earth by a factor of 25 due to
Jupiter's distance from the Sun, then you cut down by
maybe 50% or more, likely more, due to odd sun angles from
lying flat on the surface, then you cut down yet again by
about 50% due to night time on Europa every day. Then,
to compensate for this you have to make the PV arrays
extra large and you have to add a wonking battery to the
craft.

Not to mention the hideous, hideous radiation enviroment
that will destroy your solar cells rapidly.

(Christopher M. Jones) wrote in message . com...
(dave schneider) wrote in message . com...
The prototype being tested by Dr Ulamec is a 225cm-long hollow
aluminium cylinder with a copper melting head powered by an electrical
cable.

Sounds like less of a prototype than a mockup. Almost
certainly, a Europa driller/diver will need to be powered
by an RTG. The idea of powering it by solar panels on
the surface is really a non-starter. First you cut down
their performance near-Earth by a factor of 25 due to
Jupiter's distance from the Sun, then you cut down by
maybe 50% or more, likely more, due to odd sun angles from
lying flat on the surface, then you cut down yet again by
about 50% due to night time on Europa every day. Then,
to compensate for this you have to make the PV arrays
extra large and you have to add a wonking battery to the
craft.

Any spacecraft visiting Europa in the near future is
going to be RTG powered. As a bonus, RTGs produce tons
of waste heat which would be usable for just this sort of
thing.


Instead of relaying the data to the surface for transmission to Earth,
how about skipping the surface relay completely?

Imagine that JIMO releases a surface probe to the surface of Europa.
This probe is in fact the aforementionned submersible. It comes with
it's own RTG, low gain antennas, and typical extraterrestrial ocean
explorer's microlab kit.

It goes to the surface under it's own power, and then releases itself
from the powered lander, and goes down by melting the ice slowly. It
might take a year, or two... Once in a liquid environment, it conducts
it's mission, and once completed, it dumps ballast (might even be some
of the instruments for a liquid environnement), floats back up, and
then melts back up, while providing it's own upward movement with
scoops, or somekind of caterpillar like movement. Maybe conceive the
probe to have a lower-than-ice density once it has dumped it's
ballast.

Once back on the surface, it transmit back it's finding to JIMO for
relay at good bitrate, or very very low (Galileo-type) bitrate if a
Bad Day occured in Jovian space meanwhile.

Sure you loose interactivity. But you get your data back without
having to haul 10-20 km of cable along.

Manfred Bartz wrote in message ...
(dave schneider) writes:

For an update on one version of the plan to explore Europa,
check out the article at
http://news.bbc.co.uk/2/hi/science/nature/3548139.stm

[quote]
Plan to melt through Europa's ice

Researchers are testing technology that could allow a lander to
melt through the ice crust of Jupiter's moon Europa to reach the
water ocean beneath. Space scientists want to send a craft to
the Jovian moon because its ocean might, in theory, harbour
life.

Once through the 10-30km ice sheet, the probe could take a
sample of water, to analyse it for microbial life.

This kind of mission can probably only be done with a nuclear power
source.

The article seems to identify two methods of getting information back:

1. ELF radio transmissions as used by submarines. This requires
fairly long wire antennas, probably hundreds of meters on both
sides of the comms link.

2. Touch and return. Once through the ice do all the sampling and
investigating, then drop a ballast to make the probe buoyant and
let it melt back to the surface again. Once back at the surface
it can transmit its data and potentially transfer samples for
return to earth.

It may also be possible to:

3. Trail a thin, tough, twisted pair cable like the ones used in
wire-guided missiles. The cable would unspool from the back of
the probe and provide a high speed data link to a relay left at
the surface.

1) and 3) allow a degree of in-situ control from Earth.

3) can provide continuous data.

1) may need a heated antenna to provide continuous data.

2) seems the simplest but if something goes wrong we will never
know what and why. Maybe this option would work well with a bunch
of small probes dropped at various locations.

Travel time through 30km of ice at 3m/h would be 416 days, so a
return trip could take over 2 years -- hmm, sounds a bit too long
to be without comms. Maybe one could boost the melting speed?

In my youth, I was involved with getting data from very deep (18000')
oil and gas wells via armored cable and quickly found many of the
problems with such a method. Anything that can go wrong will and in
this case you have no way to solve the problems. The hole would
crtainly freeze above the probe making it VERY difficult to keep
dragging the cable downward (assuming the cable spool is on the
surface). If the cable spool is on the probe, ANY ice movement above
the probe would exert tremendous tensile stress on the cable.
Instead, I suggest a variation on a technique that has been used in
the oil and gas industry, ultrasonic pulsations carrying data. In oil
and gas, the pulses are transmitted up through the drilling mud. In
this case, they would have to be transmitted through the ice. The
data would have to be encoded to remove it from significant background
noise.
The ELF method is a non starter as the data transmission rates are
waaaaaaay to low. When used for transmission to deep submarines, the
transmission rates were no more than a few characters/sec. Do the
calculations and you see the problems.
If you opted to return the probe to surface by lowering its density to
less than that of the water, it would naturally rise up through the
ice as it melted a pool of water around itself.

(Remy Villeneuve) wrote in message om...
Instead of relaying the data to the surface for transmission to Earth,
how about skipping the surface relay completely?

Imagine that JIMO releases a surface probe to the surface of Europa.
This probe is in fact the aforementionned submersible. It comes with
it's own RTG, low gain antennas, and typical extraterrestrial ocean
explorer's microlab kit.

It goes to the surface under it's own power, and then releases itself
from the powered lander, and goes down by melting the ice slowly. It
might take a year, or two... Once in a liquid environment, it conducts
it's mission, and once completed, it dumps ballast (might even be some
of the instruments for a liquid environnement), floats back up, and
then melts back up, while providing it's own upward movement with
scoops, or somekind of caterpillar like movement. Maybe conceive the
probe to have a lower-than-ice density once it has dumped it's
ballast.

Once back on the surface, it transmit back it's finding to JIMO for
relay at good bitrate, or very very low (Galileo-type) bitrate if a
Bad Day occured in Jovian space meanwhile.

Sure you loose interactivity. But you get your data back without
having to haul 10-20 km of cable along.

That's not a valid trade off. It would be preferable if
this were merely a back up option, with a cable or other
high-throughput low-latency communications path as the
primary system. Personally I don't think a cable would
be as vulnerable as some people make out. More so, we
have ice on Earth, we can, and should, test this sort of
thing before we make a decision. Luckily, I think we are.

Anyway, with a probe of this sort there's no possible way
it could run well without a human in the loop. An ocean
is big and a robot is not going to have the smarts any
time soon to study and traverse it to find out the most
interesting spots.

(Christopher M. Jones) wrote:
(dave schneider) wrote:
The prototype being tested by Dr Ulamec is a 225cm-long hollow
aluminium cylinder with a copper melting head powered by an electrical
cable.

Sounds like less of a prototype than a mockup. Almost
certainly, a Europa driller/diver will need to be powered
by an RTG. The idea of powering it by solar panels on
the surface is really a non-starter.

IIRC, the article acknowledges that.

It is just one item on their To Do list. (Said list may not fit on my
Visor Edge).


In reply to another comment in this thread, is ELF really too slow
when you're talking about a mission lasting over a year (See Herr
Bartz calculations)? I like the ultrasound data channel better, but
we're not talking about being in a rush.

Of course, once through the ice, there may be a ton of data being
collected in a short time, but playback could be quite leisurely given
the other durations of the mission.

/dps

(Christopher M. Jones) :

That's not a valid trade off. It would be preferable if
this were merely a back up option, with a cable or other
high-throughput low-latency communications path as the
primary system. Personally I don't think a cable would
be as vulnerable as some people make out. More so, we
have ice on Earth, we can, and should, test this sort of
thing before we make a decision. Luckily, I think we are.

Anyway, with a probe of this sort there's no possible way
it could run well without a human in the loop. An ocean
is big and a robot is not going to have the smarts any
time soon to study and traverse it to find out the most
interesting spots.

You know this sounds like a perfect probe to design and test on that
ultra-salty lake that is buried under a couple kilometers of ice. One
problem they stated was that they don't want to simply drill down to it
because they could introduce extra items into the lake thru the hole. A
melting probe could be make pre-cleaned and would seal it's hole behind
itself, and if it brings back a sample the surface recovery mode could also
be tested.

Earl Colby Pottinger


--
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