Living Off the Ice on Europa
Living off the Ice on Europa

by Peter Kokh, 1997, 1998, 2001 Lunar Reclamation Society

Material in this paper previously published in Moon Miners' Manifesto

Welcome to New Atlantis, Europa -- At the 2nd [of 3] iteration of the Lunar Reclamation Society's Europa Workshop, one of the things talked about was the natural (or artificial) possibility of pockets of trapped volcanic gas (CO2?, 15 ATM?, 50 F?) in concavities in the underside of the ice crust, guesstimated at 1-5 km thick, but possibly thinner here and there. Such a harbor could be an interesting place to have a sub marine base. Add artificial light, a pressure dome and ...

Europa: Living off the Ice

Europa: Just the Facts

Welcome to New Atlantis

Braving Jupiter's Radiation Belts

Magnesium: Workhorse Metal on Europa

 

Living "off the Ice" on Europa

by Peter Kokh

We had previously suggested that Europa's ocean would be free of those salts common in Earth's oceans that derive from sedimentary erosion of the continents. We'd also predicted that carbon dioxide from ocean bottom volcanoes along with other soluble volcanic and hydrothermal vent exhalations would characterize the water. We even suggested (in an email letter) that CO2 in excess of what could be dissolved would build up in pockets under the ice [cf. MMM # 110, NOV '97, pp. 1, 8-10] and could be the principal method of triggering fissures that would spew this special brine out onto the surface. Salts are left when the water evaporates.

FIRST FINDINGS

Galileo finds Brine Salts on Ice Surface
Europa's Ocean Seems to be Carbonated

In its extended Europa mission, Galileo, has now found two of these telltale salts on the ice crust with its Near Infrared Mapping Spectrometer (NIMS). Various compounds absorb and reflect sunlight differently, and thus leave distinctive signatures.

So far, the Galileo NIMS has detected the signatures of Natron [hydrous sodium carbonate] and Epsom salts [hydrated magnesium sulfate] traces in several dark line areas of Europa. Traces of these salts have been found at several dark line areas, indicating a global ocean that is fairly homogenized.

The hope that Europa's Ocean [we've suggested it be named "The Rhadamanthic" after Rhadamanthes, mythical son of Europa sired by Jupiter] might harbor life is stimulated by the relatively recent discovery of rich oases of ocean bottom life on Earth around the hydrothermal vents found along the ocean bottom volcanic ridges that cause ocean floor spreading and continental drift. There has been no direct evidence of any kind that such theoretically possible vents are a feature of the sea bottom of the Rhadamanthic. But the presence of a saturation abundance of dissolved carbon dioxide (seltzer or soda water) makes this a very believable scenario, indeed hard to explain otherwise. And this makes the hope that we will find primeval life in the Rhadamanthic more realistic, less romantic. Detection of the signaltures of nitrate and phosphates would turn this hope of finding life into a strong expectation.

The interaction of Jupiter's giant magnetic field with the deep salty global currents of the Rhadamanthic may also give rise to a magnetic field island around Europa that could moderate the harsh radioactive climate previously expected. It's strength is yet to be measured, and its existence confirmed.

SEA SALT BONANZA?

Natron and Epsom Salts?!? Carbon, Sodium, Magnesium, Sulfur? What's that? This does not seem a lot upon which to base a "life-off-the-ice" effort at partial industrial self-sufficiency for a prospective human community engaged in continued exploration and research on this very fascinating world. Yet these six elements (not to forget hydrogen and oxygen in the water) form more of a "critical mass" of chemical feedstocks than one might suspect at first thought.

Moreover, these are just the first findings. Hopefully, we will find other elements present on Europa's surface in the form of evaporated sea salts.

EARTH SEA SALT INGREDIENTS FOR COMPARISON

To whet our imaginations, here's the scoop on Terrestrial Seawater (based on salinity of 35g/kg):

Some 3.5% of terrestrial seawater consists of dissolved substances in which 40 elements (other than hydrogen and oxygen) are represented. Of this, 82.86% is Sodium Chloride, NaCl, common table salt.

In the other 17.14% of seawater are sulfates, magnesium, bicarbonates (all detected on Europa), but also calcium, potassium, strontium, fluoride, boron, bromide, silicon, nitrogen and phosphorus. (underlined elements essential for life, along with many lesser micronutrients.)

We also find salts of the other engineering metals: iron, aluminum, titanium; these common alloy ingredients: zinc, copper, nickel, manganese, cobalt, vanadium, tin, chromium; these precious metals: gold, silver, lead; other halogens: iodine and barium; miscellaneous elements: mercury, bismuth, tungsten, antimony, thorium. beryllium,, arsenic, uranium.

Can we expect to find all of these in Europan seawater? Hopefully some of them. Detection by Galileo or follow-on probes of the major nutrients vital for life as calcium, potassium, nitrogen, and phosphorus would be encouraging. But on Earth, salts find their way into the ocean by two routes: erosion runoff from the continents, and submarine emissions from sea-bottom volcanoes and hydrothermal vents. Only the latter processes operate on Europa - maybe.

PLANNING FUTURE EUROPA MISSIONS

Scientists are even now excitedly preoccupied brainstorming future missions to Europa that will:

We suggest prioritizing the orbital detection of evaporated brine salts on Europa's ice surface - as this would give us three important things:

an earlier read on the likelyhood of life in the ocean. If we find nitrates and phosphates, the outlook for life will be greatly improved.

a clear preview of the geological processes that have been operating on Europa's sea floor, like volcanism and hydrothermal deep sea vents, etc.

a more complete list, especially if we have some idea on relative abundances, of the building blocks available for self-supporting industry for a substantial human presence engaged in a much more thorough scientific exploration of Europan geology, oceanography, and biology.

It is a happy confluence that what those of us interested in expansion of the human envelope to Europa need to find to flesh out our brainstorm further, will also cast a brilliant first light on the questions most interesting to both the planetary geologists and the exo-biologists. A Europa Brine Salt Mapper (or mapping instrumentation on the first Europa orbiter) is a no-brainer win-win for all.

GOING WITH WHAT WE KNOW NOW

What we have on the table already, thanks to Galileo's recent finds, gives us a situation similar to that awaiting those who would "Live Off The Clouds" in aerostats just below Venus' cloud deck. From the carbon dioxide (carbonates on Europa) we can make spun graphite products and, perhaps, Diamondite.

Add to the mix the hydrogen and oxygen from water (or water vapor) and sulfur, plus nitrogen, chlorine, and fluroine (the last three, so far, only on Venus) and we have the building blocks for hydrocarbons and organic synthetics: plastics (& fibers)

And, on Venus at least, where we have found hydrochloric and hydrofluoric acid cloud droplets:

Even if, on Europa, we do not find nitrates (that would kill the chances of finding life forms on Europa) or chlorine (despite the gigatonnage in our own oceans) or fluorine, that would still leaves a tidy repertoire of feedstocks for fuels and manufacturing plastics, fibers, resins and more.

If indeed the halide elements found in the Veneran clouds are not to be found in Europan brine salts, there is one big consolation. Europan pioneers will have a supply of at least one useful engineering metal: magnesium, and at least one potential ceramic: magnesium oxide. See the article that follows.

Get the chemical engineers busy and design minimal capital equipment (lowest shipping weight) factories to produce graphite, a varity of basic fuels, plastics, fibers, and resin-composites, as well as magnesium castings and sheet metal and magnesia ceramics. That would enable Europan pioneers to go a long way to meet their basic needs for shelter, furnishings, food production, transportation and recreation. Sounds like a World Seed to me.

If Galileo or follow up probes detect nitrogen, phosphorous, potassium, calcium, chlorine, fluorine - why then we can be really optimistic. Nor need we be rosy eyed to expect to find at least some of these.

ENTREPRENEURIAL "SPIN-UP" HOMEWORK

In the meantime, there is plenty of occasion and spin up entrepreneurial opportunity to experi-ment with stretching the applications of the above materials to cover uses ordinarily filled by other materials. On Earth we ordinarily concentrate on developing a new material just for those applications at which it will excel, or at least compete on price. Uses where a material will come in second best are rarely pursued. The result is that most materials are more versatile in potential application than we imagine. Has anyone experimented with fabricating items other than window panes and eye wear lenses out of Lexan™ polycarbonate? Has anyone tried to form curved shapes of the stuff by laminating thin flexible sheets? How far can graphite be pressed? When there are few metal alternatives, cost may not matter. The neglected homework list goes on and on.

The essence of the frontier is a readiness to reinvent everything to meet an unfamiliar set of challenges with less than the usual list of resources - and finding a way to thrive anew - therein giving glory to whatever Creative Energies are responsible for our existence. Europa, and Venus are challenges we must accept, or we do ourselves and our creation less than full justice. It is a matter of being true to ourselves, hidden talents and all.

HOW DO WE DO WE HARVEST THIS BOUNTY?

Those elements we do find on the surface in the form of precipitated salts can be concentrated by bacterial cultures. "Bioprocessing" would use a number of bioengineered bacteria that concentrate available elements differentially grown in nutrient vat cultures, their bodies then harvested for a bene-ficiated, concentrated product, or for life nutrients, added to the food supply in one form or another, either indirectly via hydroponic solutions, or directly as dietary supplements.

We are optimistic about detecting nitrate salt signatures, and guardedly so about phosphates, potassium salts, and calcium. We are even more guarded about chances of detecting dissolved silica, minute traces of which are efficiently absorbed by diatoms and sponges. Indeed, trying to grow such creatures may be the only way to both detect and harvest available silica. A source of Silica means true glass, concrete, ceramics, and more. Such early era experimental aquaculture will be a top priority in efforts at further industrial diversification.

To be kept in mind, of course, is that there is no providential logic that guarantees that elements will be available in abundances proportionate to the relative quantities we would like to have. That is why we have to go to the Moon for Helium-3, for example. It is why we have trade between nations and regions differently endowed. It is why those pioneers thrive who are resourceful enough to "make do" with what they find and who learn how to make happy substi-tutions, and why those pioneers fail who do not do so.

EUROPAN FRONTIER LIFESTYLES

Lets muse a bit about the lifestyles of the resourceful and industrious on Europa's frontier.

More than a one town world!

"New Woods Hole" in a thin but stable ice crust area at the site of the elevator exploration shaft to the ocean below - equipped with water-locks, of course

"New Oceanside" station at the elevator terminus on the underside of the ice crust, possibly afloat in an honest-to-goodness-air-pressurized cave pocket excavated in the bottom of the ice crust handy to the shaft terminus.

"Cornu Copia" situated in the midst of the richest brine salt evaporate fields in a dark line area, chief industrial settlement and population center

"Europaport" at the most favorable site for arrivals and departures from Europa orbit and from elsewhere in the Jovian system and beyond

Giving Europan landscapes the human touch:

Ice regeneration, melting rough ice and then allowing to refreeze flat and clear, perhaps under vapor escape retarding polyethylene film might be a useful side industry. One can imagine ice skating and ice dancing rinks, not just in the open vacuum but in pressurized shelters - or at least in man-made ice caves filled with diffracted blue light (those who have visited ice caves on Earth, perhaps the ones up Washington's Mt. Ranier, will know what we mean!)

Man-made surface ice caves could also best house a growing ice sculpture collection. Since such sculptures would not melt, even were they to be exposed to full Europa-strength sunlight, their production would invite more carefully cultivated skills and more serious talent, than that already respectable craft we see on display in our northern cities during winter festivals.

And why not Europan hockey? Again either in pressure suits under the stars or in bluelight ice caves, or indoors without air masks.

Regenerated snow could transform higher pressure ridges and ice fault scarps into ski hills, with magnesium ski jumps added for excitement.

Man-carved or molded ice "ramada" sheds would house tank farms for volatiles, warehouse various incoming goods awaiting delivery or manufactured items awaiting export, and in general for storage and routine "out-vac" tasks in a "lee" environment that shields from radiation and micrometeorite.

Ice tunnels could carry surface highways through pressure ridges. Roadway surfaces at the cryogenic temperatures out on Europa's surface would not be as slippery, no thin layer of lubricating water molecules would develop. But the surface could be micro-ridged to improve traction.

Better yet, magnesium-rails could support hovering MagLev coaches also made of magnesium, whisking people and goods between settlements.

Someday, if abundance is no problem and public largess for the arts is high, we might even see man-sculpted magnesium "nunataks" (exposed moun-tain peaks) rising out of the ice sheet paralleling some tourist-trafficked MagLev route between major settlements. Those who have had the fortune to fly over southern Greenland will get the picture. These could be of thin sheet stock on this windless moon.

Pleasant cityscapes

One can imagine Lexan™-thermopaned geo-desic domes and vaults covering public spaces. Covered with transparent regenerated ice, they would offer radiation free softly blued sunlight - no need for sunglasses at this distance from the Sun where it shines with only a 25th the brilliance we are accus-tomed to in the Inner System "bright space" areas.

To avoid the china-syndrome-like problem of warm habitat structures inexorably melting their way into and through the ice crust, hard/soft styro-foam foundation sandwiches over smooth regenerated ice could provide an adequate thermal barrier. Whereon the Moon, regolith serves as both radiation and thermal shielding, on Europa this job might be left to ice and styrofoam or other foams respectively.

At least some waste heat from habitat space might be used to pre-melt brine crusted ice for use in the various processing industries

Change of scenery get-aways

The floating habitats in under-the-ice gas pockets that we first suggested in MMM #110, pp. 1 and 8-10, will be built as working outposts. But rooms and suites in a hotel module expansion unit would not likely go unrented. It would provide quite a change of scenery, even the chance to go outdoors with a medium weight jacket if the atmosphere pressurizing the pocket were a breathable oxygen/ nitrogen (or helium) mix. At such a complex, even swiming in the ocean itself is not out of the question.

As relatively smooth as Europa is - highest and lowest elevations do not differ by more than a thousand meters, 3,000 feet over the entire Africa-sized globe, there are areas where the ice is especially fractured and jumbled in a chaotic way. Such a terrain might not be the easiest place to put an amusement park - or and "Old Frontier" type movie set - but mix the possibilities with imagina-tion and you get an explosive mix.

And somewhere, both on the Jove-facing side and the averted side will be places aplenty for private ice wilderness retreats, licensed retreat houses, even monasteries.

Fuels and Power for all this?

As on Mars and Venus, the elements neces-sary to produce methane for combusting with bottled oxygen are there. This can take care of non-railed surface transport and other uses.

At Jupiter's (i.e. Io's, Europa's, Ganymede's, and Callisto's) distance from the Sun solar power seems at first totally unrealistic. Some would tap the enormous power differentials in Jupiter's radiation belts for power, but that seems a more far distant prospect than another more familiar energy scheme, which to my knowledge, been totally overlooked. It would not be without its engineering challenges.

We speak of OTEC (Ocean Thermal Energy Conversion), i.e. tapping the considerable heat differences between Europan surface industry waste-heated water reservoirs and cold ocean waters - through the ice - using magnesium heat exchanger pipes if necessary to dam the shaft to prevent cata-strophic blow-outs.

On Earth, at depths of approximately 1,000 m (3,300 ft) in certain areas of the ocean, such as the Gulf Stream, temperature differences are 15-22 C (27-40 F) exist. On Europa we are talking about a similar vertical distance scale and a similar, if not greater temperature range.

Warm surface water is drawn into an evaporator where, under low pressure, some of this water flashed into low-pressure steam and used in a steam turbine. Exhaust steam passes into a condenser, at a still lower pressure, and is condensed by cold water brought up from the ocean depths, producing power. Vast quantities of water must be handled, and the component parts of the plant must be very large. For a 100,000-kW plant, the pipe bringing up the cold water might have a diameter of 30 m (100 ft). Maintaining the structural integrity of such a large pipe against the ice pressures working to collapse it might be no small design challenge. It would help efficiency, at the expense of greater complexity of working parts, to use ammonia, isobutane, or propane as the working fluid to be boiled by the warm surface water in order to power the turbine.

We have yet to work the engineering bugs out of an Earth-based OTEC system. Not a few have given up the challenge. But it will perhaps be the better part of a century before we are ready to add Europa to the list of human worlds. By then the economics of energy supply on Earth may have dictated that solu-tions to daunting engineering problems be found. The translation to a Europa system would then be easier.

Yet, while OTEC may be possible in theory, it would require a sizable installation that may be way too ambitious for a populace of a few thousands. Perhaps, even given the 25-fold diminution of the strength of sunshine at this distance out, solar power should not be dismissed. Everything else equal, that means that per design power output, a collector needs to be only five times larger side for side. Given improvements in efficiency and the use of concentra-ting mirrors, that should be no problem at all for surface based installations, as unworkable a solution it may be for weight-limited space craft in transit.

Europa's day/night cycle is 3.55 standard Earth days (85.2 hours) long, the same as its orbital period around Jupiter with which it is rotationally locked (as are most natural satellites). This period is less than an eighth as long as the Moon's dayspan/ nightspan cycle or sunth, and thus it will be that much easier to store up power for Europa's much briefer night period (42.6 hrs long). If fuel cells are used, it will be important to redesign them to use locally made components as much as possible.

REALITY CHECKS

Because the ions that are present in terres-trial seawater exist in minute amounts, more than 200 m (about 660 ft) of salt water must evaporate to precipitate mineral deposits 1 m (3 ft) thick. But on Earth the area of surface water available for evapora-tion has been relatively great. On Europa, such thick deposits are most unlikely as the total surface area of liquid water exposed to evaporation at one time on average has been comparatively minuscule.

Salt harvesting on Europa would entail mobile equipment roaming far afield from scattered primary processing stations. This should not discourage the scenario above. We are talking about some few thou-sands of pioneers at best, not billions as on Earth

Just as important as industry will be food production and biosphere maintenance. Discovery of nitrate and phosphate salts will be encouraging. Not finding them will discourage any "Live Off the Ice" efforts. Calcium deposits on Earth are biogenic, that is derived from shells and bone of living creatures. If we find the signature of calcium that means it most likely that relatively advanced lifeforms evolved in the ocean. For industry, concrete could be possible if we find aluminosilicates too. Expect not!

Will we find meteorite strewn fields exposed on the glacial surface of Europa as we have in our own Antarctic? They could be a source of silicates and metals to round out local industry. Given the nature of the processes that have brought buried meteorites to the glacier surface and left them exposed on Earth, processes which certainly will have no counterpart on Europa, that is most unlikely. Most meteorites on Europa, if they migrate at all, are likely to work their way through the ice to fall to the ocean floor.

Can the industries we outlined be realized on a scale small enough to serve that market? That is a question for the chemical engineers and low-capacity modular factory engineers to decide. What will it pay to produce on Europa from local chemical feedstocks given this small market? Could Europans export any surplus products and value added manufactures to neighbor outposts on Ganymede and Callisto where such surface brine salts are much less likely? If so, the potential market becomes as large as the human population of the entire Jovian mini-system.

"MUS / CLE" FOR EUROPA & STOWAWAY IMPORTS

Some parts of our scenario above will prove to be easier to implement than others. The nature of pioneering is learning to live with a different suite of resources than that to which one is accustomed. On Earth we are used to having it all. On Europa, we will have to make do with a much smaller list. We will have had to do likewise on the Moon - only the lunar list and the Europan list are going to be quite radically different from one another. In both cases, the defficiencies will determine and color the local material culture, and set the stage for vigorous trade. Both the lunar and Europan frontiers will create demands that will inevitably open up new supply markets. Europa's needs will reinforce other reasons to establish human communities elsewhere in the Jovian system where needed materials are to be found. And where supply must be sought further afield, from the asteroids, from Mars, from the Moon, even from Earth itself, the economic equation will force three things:

CONCLUSION

Here we sit on Earth, not yet returned to the Moon, farther than we'd like to be from launching the first human expedition to Mars. Yet we find ourselves talking about human futures on a much more distant if not less intriguing world - Europa. The ships that could take us there are not yet on the drawing boards - 3rd generation nuclear craft. We won't build the first generation prototype for some years to come. But dreams have power. After all, we are the "Ad Astra" people. We dare dream of being star folk. And as Europa-like worlds may be far more common than Earth-like ones, learning what we can do on Europa is clearly on our critical path to the Stars!

We have sketched quite an ambitious picture of what it might be like to live on Europa someday, grounded on too small a number of chemical tidbits. It may read to some that we would attempt to make a meat and potatoes meal out of mere seasonings stuffs. But many a delicious meal has been conjured up by chefs of outcast populations from ingredients looked down upon as garbage by the have-it-alls. It is a matter of attitude. To adapt an old saying for inclu-sion in the Space Pioneer's Bible, "Attitude, if not everything, beats the hell out of whatever's second!".

Dream with us. <MMM>

Europa: Living off the Ice

Europa: Just the Facts

Welcome to New Atlantis

Braving Jupiter's Radiation Belts

Magnesium: Workhorse Metal on Europa

top


 

Europa: Facts of Interest

and calculations by Peter Kokh, 1998

Just the Facts:

SIZING UP EUROPA: Europa is 3126 km (1942 mi) in diameter and its ice crust surface is 11.8 million square miles in area. That is some 81% of the Moon's surface, virtually the same area as Africa, and about 26% more surface than North America.

Europa contains lots of water and ice whereas the Moon is all rock and thus it is only 91% as dense as the Moon and has just 82% of the Moon's gravity level, or less than 1/7th (13.5%) the gravity of Earth. Anyone used to lunar gravity would be comfortable on Europa as well as on Io, Ganymede, Callisto, or Titan (111%, 87%, 75%, and 84% lunar gravity respectively) [* To get the relative gravity, multiply the ratio in diameters by the ratio in densities].

EUROPA WEATHER FORECAST: Europa (& Jupiter) are on average 5.2 times Earth's distance from the Sun and so get only 1/27th as much light and heat from the Sun (inverse square of the distance). That's still more than 15,000 times as bright as the full moon on Earth - plenty of light to see what you are doing! The Sun would have an apparent diameter of only 6.1 minutes of arc compared to the 31.8 minute disk we see on Earth. The intensity of the light would be the same - there would be just less of it. Looking away from the Sun, you wouldn't need sunglasses. But helmet visors would still need to offer protection against glare. The surface temperature at noon is likely to be some 200 below zero Fahrenheit.

EUROPA'S CALENDAR: Europa orbits Jupiter once every 3.55 Earth days. By happy coincidence, two such periods are just over one week, 7.1 days or 7 d, 2 hr, 24 min. So if Europan pioneers wanted to keep the hour, minute, and second for the convenience of scientific calculation, they could use digital clocks which would reset after 24:20:34 h/m/s instead of 23:59:59. Each Europan clock day would be only 20 min. 34 sec. longer than the 24 hr standard we enjoy. The beauty of this is that no matter where one makes camp on Europa, every 7th clock day, the lighting phases repeat exactly (sunrise, noon, sunset, etc.). That'd make planning ahead a snap for the pioneers. To make this digital timing solution work, there'd be but one common time zone for the whole globe.

Typical weekly dayspan/nightspan lighting pattern. The day and night spans are each 42.6 hrs long.

There would be 51.44 Europan Weeks (EW) to a standard Earth year, and 610 EW per Jovian year.

EUROPA'S SKY SHOW: The black airless skies of Europa host one of the most brilliant shows in the Solar System. But to take in the entire "Dance of the Worlds" one has to have a seat on the 50-yard line so to speak, i.e. along the Jovian nearside/farside limb. A polar perch (N or S) offers the best views, with all choreography at, and parallel to, the crisp horizon.

Europa orbits Jupiter at a distance of 671,000 km or 417,000 miles out (75% more than the Moon's average distance from Earth). But Jupiter is 11 times the diameter of Earth, so it will appear 6+ times as wide as Earth's 2 globe seen from the Moon. Jupiter will be a brilliant multi-hued ball in the sky some 12 across, filling 40 times as much sky as Full Earth from the Moon, 550 times as much sky as Full Moon from Earth. But at Europa's poles only its northern or southern hemisphere would be above the horizon.

For about 2 3/4 hours every 3.55 day orbit, Jupiter's bulk eclipses the Sun (as seen from Jovian nearside only) as Europa orbits swiftly through Jupiter's shadow cone at 30,750 mph (13.74 kps). The local dayspan time (morning, midday, afternoon, etc.) of the eclipses depends on the E-W longitude.

At their closest approach, Io (on the same side of Jupiter as Europa), Ganymede and Callisto (both to far side) present respectable disks with naked eye details. At their farthest (when they are on the other side of Jupiter from Europa)

While the Moon is always appears about the same size as seen from Earth, Europa's sibling moons revolve not about it, but about Jupiter, and that takes them to quite some distance when they are on the opposite side of Jupiter, as shown above. Of course, they will be eclipsed by Jupiter for short periods.

The best views of Jupiter and Io are 10 or more into the nearside from the limb and poles. And the best views of Ganymede and Callisto will be from at least a few degrees into farside. The limbs, and especially the poles, are the only and best points (respectively) to see them all, and the best points for a Europan Jovian System Observatory complex.

Closest approaches of Io to Europa occur every 3.53 days; of Ganymede to Europa every 7.04 days; of Callisto to Europa every 4.51 days. Their phases (new, crescent, half, full etc.) will vary. These "synodic periods" are the same as the intervals between launch/arrival windows to and from these sibling moons. The Jovian mini-system will be an interesting place to relocate!

Other Europa Quick-Look Statistics

Europa is the smoothest object in the solar system with a mostly flat surface, nothing exceeding 1 km in height. The surface of Europa is also very bright, about 5 times brighter than our Moon.

There are two types of ice crust terrains. One type is mottled, brown or gray in color and consists mainly small hills. The other type of terrain consists of large smooth plains criss-crossed with a large number of cracks, some curved and some straight. Some of these cracks extends for thousands of kilometers. The cracked surface appears remarkably similar to that of the Arctic Ocean on Earth. The ice / water crust may be no thicker than 150 km. There are very few large craters observed on Europa, indicating a young surface, no more than 30 million years old.

Europa's inner core is suspected to be iron-sulfur, similar to that of Io. Since Europa has a lower density than Io (3.01 gm/cm/3), the size of the inner core is expected to be smaller than Io's. <MMM>

Europa: Living off the Ice

Europa: Just the Facts

Welcome to New Atlantis

Braving Jupiter's Radiation Belts

Magnesium: Workhorse Metal on Europa

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Welcome to New Atlantis:
A Report on the Europa II Workshop

First Contact IV Science Fiction Convention, Milwaukee, September 27, 1997

by Peter Kokh, Mark Kaehny, Doug Armstrong, and Ken Burnside

Mission Control™ Workshops are an educational activity of the Lunar Reclamation Society, Inc.

Forward

The widespread interpretation of the Voyager photographs of Jupiter's 2nd innermost great moon Europa, is that here we have a world with a global ice crust floating on top of a global ocean of considerable depth, covering a rocky crust-mantle-core. Current best guesstimates, reargued from scratch from recent Galileo mission photographs, are amazingly close to those offered a decade or more ago by astronomy "bad boy" John Hoagland. The ice crust is on the order of 1-5 km thick, the ocean beneath it could be a 100 mi. or 60 km deep, likely holding almost twice as much water as all the oceans of Earth. While we have not had on scene the instruments necessary to make direct measurements, it'd be surprising, if this picture is "way off".

Tidal stresses caused by Europa's not quite circular orbit around Jupiter evidently supplies the heat to keep this ocean liquid. In ancient mythology, Rhadamanthus was the son of Europa by Jupiter. So The Rhadamanthic seems an ideally appropriate choice as a name for this hidden global ocean. Water and vacuum do not socialize. But ice and vacuum get along quite well. A thick enough self-derived icy "firmament" can contain an ocean just as effectively as does Earth's thick atmosphere.

The conditions for the formation and maintenance of Europa-like moon worlds seem rather easy to meet in the vicinity of gas giant planets. And gas giants should be quite commonplace throughout the galaxy. It will matter little if the Jove-like primary of the candidate moon does not orbit a sun-like star. The upshot is that there may be far more "Europids" in the galaxy than planets more like "Earth". What we are able to do at / with Europa, may provide the major theme of any human thrust to the stars.

[see MMM # 36 JUN '90, pp. "Oceanids", P. Kokh]

What do we, and don't we know about Europa? Maximum elevation differences in the surface are on the order of 100 meters, 300 feet, making Europa flatter than Florida, globe-wide. But ice, even very cold ice, is plastic, so we can argue from the analogy of icebergs that the surface profile is matched by an exaggerated unevenness of the ice crust undersurface. And where we have low spots on the surface, there the ice is correspondingly thicker, being matched with an exaggerated concavity on the underside.

We don't know the amount of impurities in the ice nor of salinity in the ocean. The mechanism that led to Earth's "briny deeps" was /is continual runoff from above ocean continents into the oceans via the river systems. This mechanism does not operate on Europa. There could be some level of salinity, however, if there are, or have been in the past, undersea volcanoes or deep vent ridges. Some of the material from eruptions could percolate into the water and go into suspension or solution. Volcanism is also the only possible source of dissolved gases (e.g. carbon dioxide) in the water.

But we don't know if there is, or ever has been geological activity in this undersea crust. We don't know if it has mountains and undersea continents and basins - or is relatively flat. We don't know a lot. No mission to Europa is now in the works, although a number of missions have been brainstormed to some degree. One cheap and elegant mission proposal would "sample" the chemical content of the ice crust by a simple flyby mission. Upon nearing Jupiter, the probe would aim a "shot" at Europa calculated to splash representative material into space. The probe would then "catch" some of this sample in an aerogel shield as it flew through the splashout cloud. On board instruments would analyze the "catch" and send the information back to Earth by radio.

Our Workshop series aims to ferret out ideas for robotic and follow-up manned missions to Europa, both to its ice crust and through the crust into its Rhadamanthic Ocean.

PRECURSOR ROBOTIC MISSION(S)

At the recent Europa II workshop, as we lacked a critical mass of participants to break up into sub groups, we decided to concentrate on manned mission possibilities. This is perhaps a good thing, because we quickly realized that for a manned assault to be successful a number of questions would already have had to have been decided by robotic missions. So the manned mission is the dog that wags the robotic tail, and any brainstorming of robotic missions without consideration of the needs of follow up manned efforts would be so much irrelevant ivory tower scientific curiosity scratching. Let us hope we will soon graduate to "prospecting mode" following the lead of Lunar Prospector.

Using as a criterion what we'll have to know to mount a human expedition to Europa's ocean, the horseblinders of individual scientific investigators specializing in this or that mini scientific cubbyhole will be off. We won't spend lot's of money learning irrelevant things. What do we need to know? Here are some tasks that need to be done by orbiters and surface missions or rovers.

Robotic Portion of Manned Mission

The following submarine robotic investigations can be carried out either before or in conjunction with a manned landing / submarine expedition. In the former case, a tethered sub-ice mother probe could send out a number of robotic submarine mini-probes reporting back by sonar to the mother probe. These could either have independent active propulsion or, leaving results to chance, be allowed to drift on whatever ocean currents there are.

A Manned Mission: Assumptions

Jupiter space, inwards of Callisto, is filled with deadly radiation, that is, Io, Europa, and Ganymede, along with the lesser inner satellites (Amalthea and company) orbit the gas giant primary within its vastly stronger more deadly version of Earth's Van Allen Belts. The success of the Galileo mission shows we know how to tackle the problem on the level of short duration robotic missions.

For human expeditions, the challenge is much greater and cannot be underestimated. There are those who have concluded man will never venture inwards from Callisto, the Mercury-sized outermost of Jupiter's mighty four, the Galilean moons known since 1610 and seen by countless millions in small amateur telescopes, even in good binoculars.

Providing material shielding against this radiation would add prohibitive amounts of mass to the manifest. For the purposes of our mission, we assume that it takes place in an era in which the engineering challenges of providing electromagnetic shielding have been mastered.

After a short debate, we assumed that we could land safely on the ice surface without sinking into a pool of fresh water melted by the descent rocket motors. We could use a bevy of smaller scattered rockets (an aerospike configuration?) or simply cut the motors just before touchdown.

On the ice crust surface, where on site material is available, a simple hanger can be erected to cover the base operations site. This could be done in modular fashion, by deploying an inflatable to be covered with shredded ice, which is then solidified into a self-sustaining igloo arch by microwaves. The inflatable form can then be deflated and moved along the axis to shape the next section, and so on. The surface base modules, any fuel storage tanks, vehicles, and other equipment regularly manned or tended can be regularly housed under this hanger.

Ice-shielded surface base hanger: elevation (L), plan (R).

Through the Ice Crust, Into the Ocean

At the prior (Duckon) workshop, we had discussed thermal melting of a shaft through the ice, using a vertical cabin cylinder of minimum cross-section with a heated (lower) prow cap. This vehicle might be about 10 feet or 3 meters in diameter or whatever the practical minimum. It could have spherical gimbaled rooms that would be stacked one atop the other for the descent and fore and aft of one another horizontally for submarine excursion once through the ice. If a cable winch was employed, it would be best to have the winch reel aboard the descending submarine. That way neither continued descent nor communications would be interrupted if the melted water or slush slurry in the shaft above refroze, seizing the cable.

In the second (First Contact) workshop, we wondered if it might not be more efficient to equip our vertically deployed submarine vehicle with a drill head to create a shaft somewhat wider than the vehicle to allow the crushed ice slurry to pass alongside to the rear (above) the descent vehicle. We did not do any math at this time to have a basis for comparing the melt vs. drill methods for energy efficiency and progress speed. We were simply identifying concepts to put them on the table.

How Long Will it Take to Melt Thru Europa's Ice Crust into its Ocean?

http://www.phys.cmu.edu/~clark/icepic.html -- Russel Clark

Roaming Free in the Rhadamanthic Ocean

We imagined that upon breaking through to liquid ocean water, the sub would keep descending vertically, reeling out extra communications cable, until it was below the lowest downward protrusions of the ice crust in the area [see illustration, below]. At this point, an antenna would be affixed to the cable, and the cable cut below this point.

The submarine would then be free to roam through the Rhadamanthic, maintaining communications with the surface base by radio or sonar to the antenna suspended below the descent shaft. Joining the antenna at cable's end would be a beacon, to guide the submarine back to the point in the ice crust underside directly below the surface base.

We did not discuss means of ascent, but did wonder if the water/ice slurry in the shaft would not have refrozen in the meantime. In this eventuality, a new parallel escape shaft may have to be bored upwards when the crew's mission was done.

We briefly considered how the shaft might be kept open [percolated bubbles?) to allow routine travel between surface base camp and cable's end, a luxury feature that will probably wait for a second or later follow up manned mission. The writer (PK) personally thinks the ice is to plastic, the cold too intrusive - the hole would quickly freeze solid.

The Submarine Mission

The intra-oceanic mission has already been outlined. It consists of undertaking the deployment of swimming, floating, and ocean bottom probes and science stations (see "Robotic Portion of Manned Mission" above). If an "easier" portion of this science chore list has already been done as part of an especially ambitious precursor robotic mission agenda, then the mission is to continue the work.

Inevitably, findings will pose new questions and if the manned vehicle is equipped to shed light on them, its mission may be expanded accordingly.

Duration of the Manned Mission
Size and Disposition of Personnel

The duration of the overall combined manned mission to Europa, and the division of crew between surface base and submarine vessel, should be figured backwards from the amount of work to be done and the location from which it is to be conducted. Simple as that. We determine the list of tasks to be accomplished, any necessary sequencing, any necessary time-sharing of equipment, and factor in the man-hours, travel time, and crew talents needed in redundancy, toss in a healthy percentage of unassigned time (repairs, recreation, etc. - and then we can sit down and size up the mission. Europa is too far to go not to do the whole job that needs to be done on the first visit. This undertaking will surely dwarf the crew, equipment manifests, and costs of the first Martian Expedition.

Now Just What If? Air, Down Below?

The writer (PK) had wondered if their might be ongoing volcanic outgasing from points along the ten million square miles of Europa's ocean bottom. If so, the likeliest major component would be carbon dioxide, CO2. If so, the ocean would become ever more carbonated (for as long as the volcanism continued) until a saturation point was reached. Beyond that point, free gas might build up in some / all of the concavities of the underside of the ice crust. The gas pressure would have to counterbalance the weight (in Europa's 1/7th Earth standard gravity) of the ice above. Possibly, form time to time the gas pressure would rupture the ice along weak fault lines and escape into space. Could this be at least a secondary source of ice crust fracturing?

There are a lot of ifs here, and the speculation that follows is far less "anchored" than I'd like it to be. Readers are encouraged to give their input, whether constructive or showstopping, and on that basis we'll decide whether continuing brainstorming along the lines that follow should be part of the final workshop in this series, at ISDC '98 next May.

Mentioning all this to my workshop mates, it excited their imaginations, sending them into overdrive. Are such "air" pockets over lagoon like calm ocean surfaces common? How big can they get in area (air-exposed water surface) and volume (air)? How oppressive will be the air pressure? Something that divers on Earth have managed in pressure-equalized sea floor habitats? If there are no naturally occurring gas pocket/lagoons, can we create them by elec-trolosis of the ice? How stable would they be in either case? And in such high pressures, might not the freezing point be on the balmy side? in the 50's?

There is a tradeoff: higher temperatures come with greater pressures. lower with less. We can live with 32 so minimum depth below surface = minimum thickness of ice overburden = lowest atmospheric pressures = the best situation, all else (size/surface/ volume) being equal.

Pitch dark, they could be lit. We could put together a floating outpost in such a pocket, even equipping it with a pressurized dome so the staff could look out on the "cavern" roof and the "lagoon". We could use water heat pumps to maintain interior comfortable conditions through diurnal and seasonal changes, effecting "weather-like" cycles. In these lagoons, we might do high CO2 agriculture on floating platforms, growing some food on the spot. Maybe mini OTEC installations could supply ample power.

Proximity to ocean floor thermal vents could be strategically important. Two possibilities: (1) gas saturation is homogeneous - there might be a real "sea level" above which there are always gas pockets. But what happens if one is breached and vented? (2) if there are pronounced oceanic convection cells, gas saturation may vary accordingly, and "sea" levels may be local or nonexistent.

What is the global distribution of such coves? Are there any clusters of fair sized anchorages? Are there gas pockets large enough to host sizable floating settlements? Cities? If so, such clusters might be where a Europan civilization to be should make its beachhead. Individual outposts could be named after classical harbors of old: New Syracuse, New Carthage, New Tyre, New Alexandria, New Atlantis, and so on.

A big whoa! Are their enough dissolved metal salts in the Rhadamanthic to allow for advanced extraction processing of building and manufacturing materials so that this Europan adventure might become an overture to a very unique Europan settlement and civilization? And if there are deep ocean floor hot vents such as host oases of Earth life not dependent on chlorophyll or sunshine, then aqua culture is possible. If they exist but are lifeless, they could be seeded with specimens from Earth.

How would one transit between coves? By submarine, or by shafts to the surface and transfer to suborbital surface hoppers? When anchorages are close by one another or clustered, might man-made tunnels above "sea level" work?

Could Europa, rather than boring Callisto, become the major human population center of Jove Space, with active trade to the other Galilean moons? Maybe there are no such places, and all we have done is to provide science fiction writers with a new class of venues for their stories.

Europa: Living off the Ice

Europa: Just the Facts

Welcome to New Atlantis

Braving Jupite's Radiation Belts

Magnesium: Workhorse Metal on Europa

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Magnesium -- Workhorse Metal for Europa

by Peter Kokh

INTRODUCTION

Magnesium is the lightest of the engineering metals with a density of only 1.74 g/cm3. However, it is used as a structural metal in an alloyed form and most magnesium alloys have a density a bit higher.

Magnesium is a reactive metal and is usually found in nature as a carbonate or silicate oxide, often together with calcium. Because of its reactivity, production of the metal is very energy intensive.

World production of magnesium is small compared to the other structural metals such as steel and aluminium at only about 300,000 tons per year. Half of this is used directly in aluminium alloys to harden and strengthen them. [E.g. an aluminium can body has about 1.5% Mg, a can top about 4.5% Mg.]

PROPERTIES OF PURE MG (PARTIAL LIST)

ORES OF MAGNESIUM

Magnesium is the 6th most abundant element metal in Earth's crust, about 2.5% of its composition. However, its high chemical reactivity means that it is not found in the metallic state in nature.

Terrestrial sea water contains 0.13% Mg and some production facilities use this content for the production of the metal, after the precipitation of other sea salts to leave a magnesium-enriched brine. (Many known magnesium silicate minerals are pure enough to warrant processing to metallic magnesium.)

The annual tonnage of magnesium oxide or magnesia used to make refractory items far exceeds the annual production of magnesium metal.

MAGNESIA & REFRACTORY PRODUCTS

Magnesia[MgO]-Carbon brick is resin-bonded with a high proportion of fused grain magnesite [MgCO3]. It is used as refractory brick [maintaining shape and composition at extreme high temperatures] in furnaces and in other hyperthermal situations. A range of qualities is available by varying proportions of fused grain magnesite.

On Europa, where other ceramic options may be unavailable, fused magnesia might "make do" "well enough" for many other construction and manu-facturing uses. Magnesia could also be useful in making glass if we find silicon compounds anywhere on Europa (surface-accummulated meteorites?) But Europa-made polycarbonate (Lexan™) is a proven substitute for glass window panes and eyewear.

SAND OR DIE CAST METAL COMPONENTS

This is the area of strongest demand growth for magnesium, particularly in automotive and avia-tion markets driven by the legislated need to meet fuel economy standards. The aluminum industry has been more successful at achieving this substitution, due in part both to the better corrosion resistance of aluminum and the wider familiarity with its use.

However, in recent years magnesium has been gaining popularity as the chemical purity of the alloys has been improved, resulting in a significant increase in corrosion resistance. The excellent castability of the common magnesium-aluminium alloys now sees use in large structural components such as seat frames, steering wheels, support brackets and instrument panels can now be successfully cast, often replacing complex multi-piece steel stampings.

If we cannot make such corrosion resistant alloys on Europa, magnesium products could be reserved for external use in unpressurized environments or in structural sandwiches, bonded between unreactive layers of magnesia ceramic or plastic.

Vapor deposition of magnesium (e.g. on surfaces of fused magnesia brick or ceramic) is one of the ways available magnesium on Europa could be stretched further in producing pressurized shelters.

MAGNESIUM ALLOYS

Magnesium products are made of alloys. The addition of other elements can strengthen and harden the metal and/or alter its chemical reactivity.

The common magnesium alloys incorporate aluminum (3-9%), zinc (0.7-1%), and manganese (0.13-0.2%). Zirconium, silicon, and rare earth elements are also sometimes used. Of these, we might hold out the most hope for finding manganese in Europan sea water. Assuming that other common magnesium alloying ingredients are unavailable on Europa, more work needs to be done in magnesium metallurgy to come up with (a) serviceable alloy(s).

Magnesium alloy development is a strong area for research at this time, with a view to improving the corrosion resistance and high temperature creep resistance of castings. This ongoing R&D offers an ideal climate for exploration of other "make-do" uses of magnesium, to substitute "well-enough" if iron (steel) and aluminum prove unavailable on Europa.

The problem with increased use of magnesium on Earth is that demand for magnesium die cast components is growing at about 15% per year and is scheduled to outstrip supply of available primary metal by the end of the decade. This keeps the price of magnesium metal high and is a disincentive for research and experimentation for additional uses.

MAGNESIUM & FOOD PRODUCTION

Magnesium is an important nutrient for living tissues. Now we have to hope we find phosphate and nitrate salts on Europa as well. <MMM>

Europa: Living off the Ice

Europa: Just the Facts

Welcome to New Atlantis

Braving Jupiter's Radiation Belts

Magnesium: Workhorse Metal on Europa

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TO EUROPA VIA CALLISTO:
BRAVING JUPITER'S RADIATION BELTS

Callisto's Place in the Sun

By Peter Kokh

There would seem to be a major problem with the idea of planning human expeditions to Europa and the establishment of outposts there. Of the four great Galilean moons, only more distant Callisto lies safely beyond the reach of Jupiter's deadly radiation belts. This has led several writers to predict that humans would be able to land on Callisto alone, and not on Ganymede, Europa, or Io, all further in. The amount of protection we would need would be quite a bit greater than that routinely needed against cosmic rays and random solar flares in general.

Extra shielding in the traditional form of water, cargo, lead or other mass would entail an unwelcome fuel penalty just to take it along for use inwards of Callisto. Electromagnetic shielding is an alternative that seems to us a long ways from coming off the drawing boards. Further, the apparatus to generate the needed field might be no less massive.

CALLISTO JUNCTION - Taking on an "Ice Jacket"

Here's our trial balloon work-around. Ships form Earth, Moon, Mars, or Ceres could pull into orbit around Callisto first, there to be "jacketed" with "extra" water derived from Callisto's surface. Thus the first Jovian System installations would have to be established on Callisto and in Callisto orbit. Let's call them Callisto Springs and Callisto Junction respectively. From Callisto orbit, radiation super-hardened ships would then proceed to any of the inner moons. They would need extra fuel for lugging around this extra shielding weight only for this last 3-6 day* leg of the long journey from Earth, and for this they could also be refueled with liquid hydrogen and liquid oxygen produced from Callistan ice.

The "jacket" to be filled with Callistan water could be an integral part of the ship, brought along from Earth empty i.e. uninflated - e.g. a Kevlar bag cradling the crew compartment and any sensitive cargo. Eventually, such jackets could be manufactured on Callisto itself, using local hydrogen, carbon, oxygen, and nitrogen to produce the Kevlar fabric.

Prior to this, it is conceivable that the operation of getting Callistan water into Callisto orbit to a waiting transfer tank could be managed entirely by robotic means. This would make sense at the outset when traffic is just beginning and crewed ships from Earth are few and far between. The first crewed ship wouldn't leave the Inner System for Callisto Junction until a first precursor robotic mission had succeeded in storing water there.

As usual, solve one problem and you create another. Getting to a parking orbit around Callisto without plunging into the radiation belt area to shed momentum via a close Jupiter flyby (recall the "ballute" used in skimming the upper reaches of Jupiter's atmosphere in Arthur C. Clarke's movie 2010) will be tricky. We welcome your suggestions.

CALLISTO-EUROPA TRADE INTERDEPENDENCE

Callisto, too, has an ice crust, much thicker than Europa's and much dirtier with rocky material which means alumino-silicates, calcium, iron. Those things which a Europa colony (colony used here as a global complex of pioneer settlements) cannot produce for itself from the brine salts evaporated on its surface, a Callisto industry should be able to supply. Sourcing as much as possible within the Jovian system will be top priority, with all Jovian outposts striving for integral interdependence. The logistics of supply from Earth is simply too strained.

In exchange, Europa can supply Callisto with plastics, fibers, graphite items, magnesium products, Lexan, and fiber/resin composites, thus easing the burden on the Callistan settlements and allowing them to concentrate on glass, ceramics, alloys, etc.

THE DOPE ON CALLISTO

MEANWHILE, ON EUROPA'S "HOT" ICY SURFACE

Ice, probably regenerated (melted and then refrozen for fracture-free translucency), can be used to "canopy" highways and Maglev lines, providing shielding as well as the soft ambient blue light seen in ice caves on Earth. Regenerated ice could also be used to carapace surface vehicles individually. The clear ice would be used to shield geodesic domes and vaults made of Lexan thermopanes set in magnesium framing, to shield and brighten habitat spaces. No problem! Anything is threatening until dealing with it becomes second nature. That has been the experience of pioneers from time immemorial.

And no doubt, we will find both the motives and the means to deal with life on Ganymede - and even sulfurous Io - as well. <MMM>

Europa: Living off the Ice

Europa: Just the Facts

Welcome to New Atlantis

Braving Jupiter's Radiation Belts

Magnesium: Workhorse Metal on Europa

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