After reading the exchanges here on the test project, I have to say that
virtually all of you are WAY too optimistic about our ability to do anything
that hasn't already been done, or won't be done very soon, vastly better by
NASA.
Then you didn't read my replies to Robert Bradbury. We don't care if NASA can do it better. We simply want to prove it can be done, that the public can participate, that ordinary people can do something besides read newspaper articles or write emails.
Preliminary tests have already been started, on a Norwegian glacier,
of the JPL Cryobot which uses warm-water jets (there was an asbtract on this
at an AGU meeting last year, which I'll track down).
Yes, I saw that article. I know that the Norwegians are fooling around with glacier science, etc. So what? This ain't Norway. Norway is not going to put a probe on Europa. America is, IF the public gets involved.
The JPL Cryobot team
is already actively testing a cryobot of exactly the sort we're talking
about for the proposed 2007 "Cryoscout" Mars Scout mission, which would melt
100 meters or so down through Mars' polar cap using a Cryobot powered
through a cable connected to the surface lander. This, as I say, would be
the very first tentative step towad the far more ambitious autonomous,
transponder-equipped, nuclear-heated full-scale Europa cryobot. In short,
our discussions so far remind me of that mountain hermit Alexander King
swore he'd met who single-handedly reinvented the typewriter in the 1930s.
Well, we all know that the QWERTY typewriter layout could have been vastly improved, had it been invented with people in mind, rather than the difficulties encountered with 1890s typewriter keys sticking.
Is it already done? About to be done better? Alright.
The Pluto survey is / was reachable as well. Funding got cut, and it's not going to happen. Why? Because not enough people out of the science community cared about it, or even knew about it to care about it.
We're not out to reinvent the wheel. We're out to build public support. We can't build it with a spate of emails, or a quiet little lab project somewhere. We need a loud, obnoxious experiment, done by a group of ordinary people using off the shelf parts.
Taking my analogy another step: I can tell you that in paleontology, at least, discoveries have to be made, and remade every 30 years or so. Why? Because some high level scientist comes up with a theory that squashes out the competing theories, those theories are shelved, and then rediscovered again 30 years later. Happens quite often in paleontology, largely because the field is so limited to a small group of interested people.
Spread the field out, increase the participation base, and space exploration MIGHT happen. Experiments might not be forgotten. Concepts might not get shelved... simply because there are too many people who remember that, way back in 2002, a group of space enthusiasts got together on a website, and came up with an ice submersible, without having to beg NASA for it, or rely on someone else's crib notes.
Also, some of the discussions about both energy sources and connecting
cables are straight out of the Twilight Zone. Robert Bradbury has provided
a needed reality check on the former.
Robert Bradbury hit plutonium again and again, which is not very realistic, in my view. For one thing, we don't have it. For another thing, we can't use it on Earth.
I do not accept that plutonium is the only way to cut through 500' of terrestial ice. I cannot accept that 40 scientists and technicians on this site cannot come up with an alternative, that gets the job done... perhaps not as efficiently, but that still accomplishes the task of cutting an 8" diameter hole in a block of ice, 500' long.
Nothing short of a nose made of some
extremely intense radioisotope can possibly provide a full-scale Europa
Cryobot with the power it needs --
We're not out to build a Europa scale probe. We're out to build a model, to demonstrate feasibility here on Earth, and to get public participation and generate enthusiasm for such a project, and thereby help ensure that the Europa exploration project doesn't get shelved in the budget cutting administration of 2015.
the JPL design calls for a meter-long
Cryobot which generates one full kilowatt of heat using Pu-238 in its nose
to melt down about 1 km every 6 months (also converting a small fraction of
that heat into its electrical power). Earlier designs called for several
kilowatts.
Well then, we've stumbled across the exact parameters we need. We're shooting for a 3' long, 8" diameter torpedo, with water jets, guided by radio control. Sounds simple enough. The hard part is not the project itself, it is public inertia.
To melt down through Europa's ice using any kind of chemical heat source,
you would need -- at a minimum -- hundreds of tons of chemicals.
We're not suggesting that the actual probe use chemicals. We know it will use plutonium. We're suggesting using chemicals as a stand-in for plutonium, for a terrestial bound model.
And as for
generating electricity by absorbing the energy of Jupiter's radiation belts:
the people at this website worked that one out in detail back in 1999.
Conclusion: if you have about 100,000 tons of radiation-absorbing material,
you might be able to do it... Jupiter's radiation belts are splendid for
poisoning electronics and people, but useless as a power source. And we
also looked into an inductive tether to use Europa's movement through
Jupiter's magnetic field to power the Cryobot heater. Conclusion: if it was
laid out for 50-100 km along the surface, it might work... Stick with
plutonium.
Yes, I remember those postings. I participated in them. I remember that we came to the conclusion that plutonium is the way to go. However, by March of 2001 (is this email still in the archives?) we were already discussing a working model to be tested on Earth. That was 1 1/2 years ago. Hundreds of emails later, here we are again. Hopefully, this time, we'll generate enough impetus to produce something physical.
As for a communications line: the problems remain. Even a very thin line
will be alarmingly heavy and bulky if the Cryobot has to carry a coil of it
20 km or so long -- and the volume of that big rear reel (perhaps as big as
the rest of the Cryobot put together) may be the harder problem, since it
also greatly increases the amount of heat the Cryobot needs to melt its way
down through the ice. And Europa's subsurface ice may flow sideways at an
angle of as much as 10 degrees or more per year, which means that the cable
must also be both extremely tough and extremely elastic -- which means, in
turn, that it must be structured like a helical phone cord to stretch, which
in turn will greatly increase its total thickness and weight. Again, stick
with transponders.
Yes, we all agreed, transponders are the way to go. That's why the model is proposed to drop 3-5 animal tracking transponders behind it, as the sole payload. We all know that wire won't work on Europa, and so we're going to try to avoid it here.
That's why we're shooting for batteries or chemicals for an onboard powersource -- so we don't rely on a 500' extension cord.
If NASA's model, with 1 Kw of power can cut through 20 kilometers of salt ice, our little model, with an onboard water heater can cut through 500' of gritty glacial ice. Results might be extrapolated for their far more efficient model. It doesn't matter if the extrapolation is not a direct correlation.
We all know that space is a publicity game. If in the public mind a model can cut through 500' of glacial ice with a crappy little water heater, then the public resistance will be dramatically lessened... even if a rowboat is not the Queen Mary, anyone can still see the potentials of the rowboat, and make a simple extrapolation.
So: is there anything we CAN do to assist with the Cryobot development
effort? Maybe. There are several needed technological tests that -- as far
as I know -- have not yet been adequately done, and which we can do (as
separate projects). JPL still needs to know just how far VLF radio signals
can pass through water ice, especially if it's contaminated with the various
other substances (salts, sulfuric acid, rock grit -- any of them maybe in
quite large amounts) proposed for Europa.
We might be able to do some work inside a lab on the multiple-water jet
system allowing a Cryobot to veer gradually to one side -- I'll review what
that recent IEEE paper has to say on this. (And, indeed, I'm mailing the
whole article to Bradbury so he can convert the damn thing into some kind of
a file that we all can read, which is extremely important -- it's by far
the most thorough summarization of the substantial Cryobot design and test
work already done.)
That's fine, but it still doesn't alter the underlying mission, which is not to duplicate technology, or beat NASA at its own game, but to make an ice submersible. It's the romance thing, all over again.
Without romance, there will be no space exploration. You can't get romance in a lab.
There's also the need to test the Cryobot's obstacle-detection equipment,
which will involve either low-frequency radar or sonar, which must detect
rocks and dense sediment pockets hundreds of meters below the Cryobot to
give it enough time to very gradually veer out of the way. As yet, I don't
think any firm decision has been reached on the best sensor technique and
frequency.
I don't believe we have the capacities to offer anything substantial in that regard. We don't have high-power radio transmitting and receiving devices, and we don't have the ability to alter the signal. We don't have a handy sheet of ice to place between the two.
This model will probably be blind. That's alright. We don't expect to recover it. That's one reason why we're shooting for a big block of old ice: lack of sediment, grit, and rocks.
Finally, there's another possibility, which might be the best of all for us.
As Gary McMurty has pointed out, there is considerable apprehension about
the problems a Europa Cryobot may have melting its way through Europa's ice
if it's extremely salty (and some theories suggest that much of Europa's ice
layer may be as much as 20-30% salt by weight!) Frank Carsey, in fact, has
personally told me that they're confident that a simple melting-head Cryobot
can penetrate Mars' ice, despite the large amount of dust in it, because the
meltwater produced whould be enough to wash the dust to the side. But he
says they're far less certain about the ability of a simple melting
Cryobot -- even with hot-water jets -- to wash its way successfully through
very briny Europan ice without a dense block of salt building up very
quickly in front of the Cryobot, and perhaps stopping it after only a couple
of meters of downward motion. A mechanical drill head may have to be added
to its tip to chew through the salt buildup -- but the tests on this have
yet to be run. (I think there was an abstract on this at the third "Europa
Focus group" meeting. Again, I'll look for it.) This is the sort of test
that a small independent group very well might be able to run.
I don't think we have the capacity to create a model with a rotary head. Too many working parts, too many opportunities for error.
Besides, the salt on Europa is still theoretical. On top of that, a rotary head, if used, is presumeably to cancel the effects of salt buildup -- the main motive power is still... hot water. That, we can do.
Any of these things are the sort of thing that an independent amateur group
really MIGHT be able to do genuinely useful independent studies on -- far
more productively to Cryobot development than any attempt to build our own
complete Cryobot and just duplicate what's already long since been done by
the government itself.
The government itself told us we would have colonies on Mars by the year 2000.
Besides: we are not a chapter of NASA. Any research we could do would be tossed aside, in favor of that done by a 6 figures a year team of NASA techs.
The best we can hope to do is stir up publicity, and generate substantial public interest. That's the cause celebre of the project, not research redundancy.
-- John Harlow Byrne
