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Thread: Callisto colonization -- some crazy ideas

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    Lightbulb Callisto colonization -- some crazy ideas

    There was a NASA proposal back in 2003 to eventually (2040s) send an expedition to Callisto, the outermost Galilean moon of Jupiter, and turn it into a major space base. Details on that in a bit.

    A Crazy Idea: Infinite Hydroelectric Power

    Callisto is thought to have a subsurface saltwater ocean below the 80-150 km thick crust. If this proves true, and if there are no worthwhile organisms inhabiting this underground worldwide sea, then:

    1. Cut a hole through the crust, which might be of low density as the whole world of Callisto is of a lower density than the other Galilean moons;

    2. Lower a huge hydroelectric turbine, with power cables and a mount to attach it to the underside of the crust;

    3. Turn it on.

    The subsurface ocean might be stirred constantly by a tidal-gravity-based combination of Callisto's orbit around Jupiter interacting with the gravity of the other Galilean satellites. It seems logical to place the hydroelectric plant along Callisto's equator or thereabouts to get the maximum effect from being in roughly the same orbital plane as the other satellites and of course Jupiter, taking advantage of age-old currents. I cannot believe the ocean there would be stagnant, but who knows.

    Problems

    1. The subsurface ocean is sure to be corrosive, so the hydroelectric turbine(s) will need constant replacement and repair.

    2. The turbine will produce a bit of drag on the subsurface ocean, which might affect the orbit of Callisto around Jupiter.

    3. The turbine(s) will certainly produce heat, slowly warming up the underground ocean with unknown effects.

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    Lightbulb

    Background on the 2003 proposal. This was a breath-taking overview of a human + robot expedition to Callisto. It was released as a PowerPoint slideshow, produced by the NASA Langley Research Center & Princeton University. The best way to get it is through the Wayback Machine.

    https://web.archive.org/web/20090327...nt/bethke.pdf/

    Revolutionary Concepts for Human Outer Planet Exploration (HOPE)
    by Pat Troutman & Kristen Bethke: February 3, 2003
    Presentation for STAIF-2003 Fission Propulsion Systems for Human Missions

    A bit of humor mixed with a dead-serious proposal to establish a temporary crewed base on Callisto, 2045+, a 5-year mission for 6 astronauts, age 35-45, and an assortment of AI robots. Several advanced propulsion systems are discussed. Assume 100°K operating environment on Callisto. Nuclear reactor for the base will be unshielded and dangerous to humans, so it will need to be isolated. Slideshow is heavily illustrated.

    QUOTES: "A crewed expedition is to be sent to the surface of Callisto to teleoperate the Europa submarine [assumes life was discovered in Europa's underground seas, and a robot sub is sent separately to Europa] and excavate Callisto surface samples.... The expedition will also establish a reusable surface base with an ISRU plant to support future Jovian system exploration."

    Callisto can be explored as the radiation levels there are far lower than for the other three Galilean satellites, where the radiation is fatal to humans.

    Pictures attached show the HOPE booklet cover, a selection of advanced spacecraft to get to Jupiter, and an artist's concept of the Callisto base.

    .
    Attached Images Attached Images
    Last edited by Roger E. Moore; 2019-Apr-17 at 02:11 PM. Reason: add pics

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    Quote Originally Posted by Roger E. Moore View Post
    There was a NASA proposal back in 2003 to eventually (2040s) send an expedition to Callisto, the outermost Galilean moon of Jupiter, and turn it into a major space base. Details on that in a bit.

    A Crazy Idea: Infinite Hydroelectric Power

    Callisto is thought to have a subsurface saltwater ocean below the 80-150 km thick crust. If this proves true, and if there are no worthwhile organisms inhabiting this underground worldwide sea, then:

    1. Cut a hole through the crust, which might be of low density as the whole world of Callisto is of a lower density than the other Galilean moons;

    2. Lower a huge hydroelectric turbine, with power cables and a mount to attach it to the underside of the crust;

    3. Turn it on.

    The subsurface ocean might be stirred constantly by a tidal-gravity-based combination of Callisto's orbit around Jupiter interacting with the gravity of the other Galilean satellites. It seems logical to place the hydroelectric plant along Callisto's equator or thereabouts to get the maximum effect from being in roughly the same orbital plane as the other satellites and of course Jupiter, taking advantage of age-old currents. I cannot believe the ocean there would be stagnant, but who knows.

    Problems

    1. The subsurface ocean is sure to be corrosive, so the hydroelectric turbine(s) will need constant replacement and repair.

    2. The turbine will produce a bit of drag on the subsurface ocean, which might affect the orbit of Callisto around Jupiter.

    3. The turbine(s) will certainly produce heat, slowly warming up the underground ocean with unknown effects.

    1: True, and the local pressure (my WAG is about 2,700 atm, a bit more than twice that at the bottom of the Earth's ocean) may be enough to affect chemistry and behavior of insulators. There would need to be test installations and material qualifications first.

    2: It would have to -- First Law says so -- but even a terawatt of turbines (producing perhaps 700 gigawatts; turbines are not 100% efficient) will take about 1.1 million years to reduce orbital velocity by one part in 10^5.

    3: Changes in the flow field from the turbines may be more important.
    Information about American English usage here and here. Floating point issues? Please read this before posting.

    How do things fly? This explains it all.

    Actually they can't: "Heavier-than-air flying machines are impossible." - Lord Kelvin, president, Royal Society, 1895.



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    A detailed method of reaching Callisto was also offered in 2003 in a short booklet put out by the NASA Glenn Research Center in Ohio.

    https://trajectory.grc.nasa.gov/abou...F-2003-177.pdf
    High Power MPD Nuclear Electric Propulsion (NEP) for Artificial Gravity HOPE Missions to Callisto (NASA/TM—2003-212349)
    by Melissa L. McGuire, Stanley K. Borowski, Lee M. Mason, and James Gilland (December 2003)

    QUOTES: "Why Callisto? The key requirements considered in selecting a worthy exploration destination beyond Mars were (1) the opportunities for conducting interesting science and (2) the availability of in-situ resources to support a human mission. The body chosen for the HOPE study was Callisto, the third largest satellite in the Solar System, and the outermost Galilean moon of Jupiter. Orbiting at a distance of ~1.9 million kilometers, Callisto is located beyond Jupiter’s main radiation belts making its local environment more conducive to human exploration. Callisto is an icy, rocky world with a surface gravity of ~0.127 g(Earth) and a composition consisting of water-ice and rock in a mixture ratio of 55:45. Besides having significant quantities of water-ice for propellant production, Callisto’s heavily cratered and ancient landscape (~4 billion years old) has a relatively low albedo indicating that significant quantities of non-ice materials and asteroid dust may reside on its surface."

    "The HOPE mission consists of sending a crew of six on an expedition to Callisto to establish an outpost and propellant production facility near the Asgard asteroid impact site, a region where the surface crust is potentially rich in water ice. An “all NEP” space transportation system architecture is examined in this paper. It uses a split mission approach involving separate multi-megawatt electric (MWe)-class cargo, tanker and piloted vehicles each propelled by hydrogen MPD thrusters. Fully automated cargo and tanker vehicles depart first to pre-deploy both orbital and surface assets at Callisto prior to the arrival of the crew onboard the artificial gravity Piloted Callisto Transfer Vehicle (PCTV). The NEP cargo vehicle delivers three different landers for crew ascent / descent, surface habitation and propellant production. The later carries an In-Situ Resource Utilization (ISRU) processing plant and several combination “bulldozer / rover” surface vehicles used to produce liquid oxygen (LOX) and hydrogen (LH2) propellant from the Callisto surface ice. This propellant is supplied to the reusable crew ascent / descent vehicle allowing crew rotation / re-supply sortie missions between the orbiting PCTV and the surface habitat every 30 days. A small, mobile nuclear surface Brayton power system, also carried on the ISRU lander, provides ~250 kWe to power the ISRU plant and surface habitat, and to recharge the fuel cell power systems of the surface vehicles. The NEP tanker delivers LH2 “return” propellant to Callisto orbit that is subsequently transferred to the PCTV for its trip back to Earth. The tanker remains in orbit where it will function as an orbital propellant depot and refinery once larger scale water extraction and propellant manufacturing operations begin on Callisto. The low thrust trajectory profiles of the cargo and tanker vehicles involve a slow spiral away from the Earth-Moon L1 Lagrange point, a direct heliocentric transfer to Jupiter and then a gradual spiral into Callisto orbit (Melbourne, 1965). Once these vehicles are on station and operating properly, the PCTV departs from L1 using a similar, though higher energy, trajectory to Callisto. After a surface exploration period lasting ~120 days, the “refueled” PCTV begins its spiral escape from Callisto on a direct return to Earth and an eventual capture back at L1."

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    Quote Originally Posted by swampyankee View Post
    3: Changes in the flow field from the turbines may be more important.
    I mulled over whether the turbines should be fixed in place or able to swivel, like the rotors on a wind-power generator or a farm's windmill pump, so the turbines could follow changes in the local currents of the underground sea.

    Someone must have thought of this idea before I did and worked it out better than I have here. I'm usually pretty late to the blue-sky party.

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    If you have some spare change, you could toss it toward getting a copy of this paper. No clue as to the contents, but relevant to everything above.

    https://aip.scitation.org/doi/abs/10.1063/1.1541373
    Revolutionary Concepts for Human Outer Planet Exploration (HOPE)
    by Patrick A. Troutman, Kristen Bethke, Fred Stillwagen, Darrell L. Caldwell, Jr., Ram Manvi, Chris Strickland, and Shawn A. Krizan

    Abstract: This paper summarizes the content of a NASA‐led study performed to identify revolutionary concepts and supporting technologies for Human Outer Planet Exploration (HOPE). Callisto, the fourth of Jupiter’s Galilean moons, was chosen as the destination for the HOPE study. Assumptions for the Callisto mission include a launch year of 2045 or later, a spacecraft capable of transporting humans to and from Callisto in less than five years, and a requirement to support three humans on the surface for a minimum of 30 days. Analyses performed in support of HOPE include identification of precursor science and technology demonstration missions and development of vehicle concepts for transporting crew and supplies. A complete surface architecture was developed to provide the human crew with a power system, a propellant production plant, a surface habitat, and supporting robotic systems. An operational concept was defined that provides a surface layout for these architecture components, a list of surface tasks, a 30‐day timeline, a daily schedule, and a plan for communication from the surface.

    REM: Paper hidden behind paywall ($30.00 US).

    http://cdsads.u-strasbg.fr/abs/2003AIPC..654..821T
    Abstract page for the above.

    ===

    Also unavailable on the internet is...

    http://cdsads.u-strasbg.fr/abs/2004cosp...35.1013N

    A trade study on radiation exposure for a crewed mission to the Jovian moon Callisto
    by Nealy, J. E.; Clowdsley, M. S.; Wilson, J. W.; de Angelis, G.; Anderson, B. M.; Krizan, S. A.; Troutman, P. A.; Stillwagon, F. H.; Adams, R. B.; Borowski, S. K.
    35th COSPAR Scientific Assembly. Held 18 - 25 July 2004, in Paris, France., p.1013 (2004)

    .
    Last edited by Roger E. Moore; 2019-Apr-17 at 02:57 PM.

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    Seems like you should add to the list of problems:

    Digging a hole at least 80 km down in the first place (the best we've managed on Earth is a little over 12 km, and that's a narrow drilled hole, not something you could fit a large turbine down).
    Conserve energy. Commute with the Hamiltonian.

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    Quote Originally Posted by Roger E. Moore View Post
    I mulled over whether the turbines should be fixed in place or able to swivel, like the rotors on a wind-power generator or a farm's windmill pump, so the turbines could follow changes in the local currents of the underground sea.

    Someone must have thought of this idea before I did and worked it out better than I have here. I'm usually pretty late to the blue-sky party.
    Use something like vertical axis wind turbines. They're not sensitive to flow direction perpendicular to their axis of rotation, although many are not self-starting.
    Information about American English usage here and here. Floating point issues? Please read this before posting.

    How do things fly? This explains it all.

    Actually they can't: "Heavier-than-air flying machines are impossible." - Lord Kelvin, president, Royal Society, 1895.



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    Five recent papers relevant to establishing a Callisto colony, covering radiation levels, orbiting spacecraft around Callisto (easily possible), and the underground ocean's characteristics.

    ===

    https://web.archive.org/web/20180504...oper_et_al.pdf
    Energetic Ion and Electron Irradiation of the Icy Galilean Satellites
    by Cooper, Johnson, Mauk, Garrett, & Gehrels (revised May 15, 2000)

    REM: Research paper based on Galileo spacecraft findings, not stored in arXiv.

    ===

    https://www.webcitation.org/5jwBSgPu...l/w08a.jup.txt
    2000 February 29, SPS 1020 (Introduction to Space Sciences), Planetary magnetospheres (continued)

    REM: This astronomy teacher's page also offers information on the radiation environment of the Galilean moons. Not sure if it is accurate, though.

    ===

    https://arxiv.org/abs/1810.03304
    Can Moons Have Moons?
    Juna A. Kollmeier, Sean N. Raymond (Submitted on 8 Oct 2018 (v1), last revised 21 Jan 2019 (this version, v2))

    ABSTRACT Each of the giant planets within the Solar System has large moons but none of these moons have their own moons (which we call submoons). By analogy with studies of moons around short-period exoplanets, we investigate the tidal-dynamical stability of submoons. We find that 10 km-scale submoons can only survive around large (1000 km-scale) moons on wide-separation orbits. Tidal dissipation destabilizes the orbits of submoons around moons that are small or too close to their host planet; this is the case for most of the Solar System's moons. A handful of known moons are, however, capable of hosting long-lived submoons: Saturn's moons Titan and Iapetus, Jupiter's moon Callisto, and Earth's Moon. Based on its inferred mass and orbital separation, the newly-discovered exomoon candidate Kepler-1625b-I can in principle host a large submoon, although its stability depends on a number of unknown parameters. We discuss the possible habitability of submoons and the potential for subsubmoons. The existence, or lack thereof, of submoons, may yield important constraints on satellite formation and evolution in planetary systems.

    ===

    https://arxiv.org/abs/1705.03999
    Geophysical tests for habitability in ice-covered ocean worlds
    Steven D. Vance, et al. (Submitted on 11 May 2017)

    ABSTRACT Geophysical measurements can reveal the structure of icy ocean worlds and cycling of volatiles. The associated density, temperature, sound speed, and electrical conductivity of such worlds thus characterizes their habitability. To explore the variability and correlation of these parameters, and to provide tools for planning and data analyses, we develop 1-D calculations of internal structure, which use available constraints on the thermodynamics of aqueous MgSO4, NaCl (as seawater), and NH3, water ices, and silicate content. Limits in available thermodynamic data narrow the parameter space that can be explored: insufficient coverage in pressure, temperature, and composition for end-member salinities of MgSO4 and NaCl, and for relevant water ices; and a dearth of suitable data for aqueous mixtures of Na-Mg-Cl-SO4-NH3. For Europa, ocean compositions that are oxidized and dominated by MgSO4, vs reduced (NaCl), illustrate these gaps, but also show the potential for diagnostic and measurable combinations of geophysical parameters. The low-density rocky core of Enceladus may comprise hydrated minerals, or anydrous minerals with high porosity comparable to Earth's upper mantle. Titan's ocean must be dense, but not necessarily saline, as previously noted, and may have little or no high-pressure ice at its base. Ganymede's silicious interior is deepest among all known ocean worlds, and may contain multiple phases of high-pressure ice, which will become buoyant if the ocean is sufficiently salty. Callisto's likely near-eutectic ocean cannot be adequately modeled using available data. Callisto may also lack high-pressure ices, but this cannot be confirmed due to uncertainty in its moment of inertia.

    ===

    https://www.hou.usra.edu/meetings/lpsc2018/pdf/1519.pdf (paper is very short, fast download)
    The Origin of Callisto's Valhalla Basin: First Results of SPH Impact Simulations and the Search for the Impactor's Origin
    by Winter, P. M.; Maindl, T. I.; Galiazzo, M. A.; Schäfer, C. M.
    49th Lunar and Planetary Science Conference 19-23 March, 2018, held at The Woodlands, Texas; LPI Contribution No. 2083, id.1519 (03/2018)

    QUOTES: We were able to get preliminary results on collisions with Callisto using a novelty GA-approach that allows to cover a much larger parameter space than previous methods. Based on collision velocity and impact angle distributions, we simulate “likely” impacts onto Callisto and are able to roughly reproduce the observed data of the Valhalla basin. We confirmed the necessity of a subsurface ocean for explaining the observed nature of that basin. In the future, we will study possible origins of the impactor that formed Valhalla more closely), considering asteroid families like the Centaurs as possible source.
    Last edited by Roger E. Moore; 2019-Apr-17 at 06:19 PM.

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    The turbine thing might work under Enceladus as well, since the subsurface ocean looks like it is being squeezed (and is therefore mobile) by orbital or tidal pressures, per the news article below on this moon's libration.

    http://www.astronomy.com/news/2015/0...moon-enceladus

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    Quote Originally Posted by Roger E. Moore View Post
    Revolutionary Concepts for Human Outer Planet Exploration (HOPE)
    by Patrick A. Troutman, Kristen Bethke, Fred Stillwagen, Darrell L. Caldwell, Jr., Ram Manvi, Chris Strickland, and Shawn A. Krizan

    Abstract: This paper summarizes the content of a NASA‐led study performed to identify revolutionary concepts and supporting technologies for Human Outer Planet Exploration (HOPE). Callisto, the fourth of Jupiter’s Galilean moons, was chosen as the destination for the HOPE study. Assumptions for the Callisto mission include a launch year of 2045 or later, a spacecraft capable of transporting humans to and from Callisto in less than five years, and a requirement to support three humans on the surface for a minimum of 30 days. Analyses performed in support of HOPE include identification of precursor science and technology demonstration missions and development of vehicle concepts for transporting crew and supplies. A complete surface architecture was developed to provide the human crew with a power system, a propellant production plant, a surface habitat, and supporting robotic systems. An operational concept was defined that provides a surface layout for these architecture components, a list of surface tasks, a 30‐day timeline, a daily schedule, and a plan for communication from the surface.

    REM: Paper hidden behind paywall ($30.00 US).
    Just found a copy of this paper online for free. Here's the url:

    https://ntrs.nasa.gov/archive/nasa/c...0030063128.pdf

    The internet wins again!

    The paper elaborates a bit on a proposal to have Callisto turned into an interplanetary refueling stop, with a processing facility creating LH2 and LOX out of the ices making up the world's surface. It also seems to imply that the base would not be permanently staffed, but would be used by passing spacecraft, assumedly in cooperation with whoever built and owns the base and outlying facilities.

    Curious now as to the delta-vee requirements to leave Callisto and escape from Jupiter's gravitational pull, so as to reach anywhere else in the Solar System. Also, whether it would be more cost-effective to put the base near the world's equator instead of away from it, or whether it would even matter.

    .
    Last edited by Roger E. Moore; 2019-Apr-17 at 07:45 PM. Reason: adds

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    Quote Originally Posted by swampyankee View Post
    Use something like vertical axis wind turbines. They're not sensitive to flow direction perpendicular to their axis of rotation, although many are not self-starting.
    And some can be collapsed down to fit through a narrow bore, and expanded on the other side.

    As for heat, the turbine would produce less than friction of the unimpeded water would. You're removing energy from the system, after all...the stuff you're powering will be producing heat instead. But this is going to be tiny compared to the other disruptions involved in putting a turbine into the ocean.

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    Most excellent.

    Was thinking myself that it would not hurt to plant the unshielded reactor in a pit of some kind, though the reactor might (depending on its radiation) melt the ice around it. Too expensive to ship lead there. Maybe building surface steam power using solar power (heating from large curved mirrors) would help. I dunno.

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    Perhaps Callisto has a lot of material to be mined and used by a colony. Also implies many craters on Callisto are from ex-moons of Jupiter.

    http://cdsads.u-strasbg.fr/abs/2013Icar..223..775B
    Black rain: The burial of the Galilean satellites in irregular satellite debris
    Bottke, William F.; Vokrouhlický, David; Nesvorný, David; Moore, Jeffrey M.
    Icarus, Volume 223, Issue 2, p. 775-795. (04/2013)

    Irregular satellites are dormant comet-like bodies that reside on distant prograde and retrograde orbits around the giant planets. They are likely to be captured objects. Dynamical modeling work indicates they may have been caught during a violent reshuffling of the giant planets ˜4 Gy ago (Ga) as described by the so-called Nice model. According to this scenario, giant planet migration scattered tens of Earth masses of comet-like bodies throughout the Solar System, with some comets finding themselves near giant planets experiencing mutual encounters. In these cases, gravitational perturbations between the giant planets were often sufficient to capture the comet-like bodies onto irregular satellite-like orbits via three-body reactions. Modeling work suggests these events led to the capture of on the order of ˜0.001 lunar masses of comet-like objects on isotropic orbits around the giant planets. Roughly half of the population was readily lost by interactions with the Kozai resonance. The remaining half found themselves on orbits consistent with the known irregular satellites. From there, the bodies experienced substantial collisional evolution, enough to grind themselves down to their current low-mass states. Here we explore the fate of the putative irregular satellite debris in the Jupiter system. Pulverized by collisions, we hypothesize that the carbonaceous chondrite-like material was beaten into small enough particles that it could be driven toward Jupiter by Poynting-Robertson (P-R) drag forces. Assuming its mass distribution was dominated by D > 50 mum particles, we find that >40% ended up striking the Galilean satellites. The majority were swept up by Callisto, with a factor of 3-4 and 20-30 fewer particles reaching Ganymede and Europa/Io, respectively. Collision evolution models indicate most of this material arrived about 4 Ga, but some is still arriving today. We predict that Callisto, Ganymede, Europa, and Io were buried about 4 Ga by ˜120-140 m, 25-30 m, 7-15 m, and 7-8 m of dark debris, respectively. The first two values are consistent with observations of the deepest dark lag deposits found on the most ancient terrains of Callisto and Ganymede. The rest of the debris was likely worked into the crusts of these worlds by geologic and impact processes. This suggests the debris is a plausible source of the dark lag material found in Europa's low-lying crevices. More speculatively, it is conceivable that the accreted dark particles were a significant source of organic material to Europa's subsurface ocean.

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    Two references of use to anyone also mulling over the exploration and settlement of Callisto. I think robots will end up settling it permanently, humans only now and then as necessary.

    https://nssdc.gsfc.nasa.gov/planetar...act_table.html
    REM: "Solar System Small Worlds Fact Sheet" table showing major statistics for the largest natural satellites in the Solar System, plus Mercury, Ceres, and Earth for comparison. It is interesting that these worlds have very similar gravities, leading one to speculate whether humans adapted to the gravity of the Moon early in the colonization of the Solar System might permanently settle those other worlds with similar gravities (Galilean moons, Titan, Triton, etc.).

    https://web.archive.org/web/20190403...age/Categories
    REM: How locations on Callisto (and other worlds here) are named. Callisto gets all the Far North names from the Vikings, Inuit, etc. I guess this means the first spacecraft to land on Callisto should be called Eric the Red after the guy who settled Greenland.

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    Raises the question of whether radio transmissions on Callisto could be reflected around that world by its ionosphere, saving the trouble of putting up orbiting communications spacecraft.

    http://cdsads.u-strasbg.fr/abs/2017JGRA..12211677H

    Induction signals from Callisto's ionosphere and their implications on a possible subsurface ocean
    Hartkorn, Oliver; Saur, Joachim (11/2017)
    Journal of Geophysical Research: Space Physics, Volume 122, Issue 11, pp. 11,677-11,697 (JGRA Homepage)

    We investigate whether induction within Callisto's electrically conductive ionosphere can explain observed magnetic fields which have previously been interpreted as evidence of induction in a saline, electrically conductive subsurface ocean. Callisto's ionosphere is subject to the flow of time-periodic magnetized plasma of Jupiter's magnetosphere, which induces electric fields and electric currents in Callisto's electrically conductive ionosphere. We develop a simple analytic model for a first quantitative understanding of the effects of induction in Callisto's ionosphere caused by the interaction with a time-variable magnetic field environment. With this model, we also investigate how the associated ionospheric currents close in the ambient magnetospheric plasma. Based on our model, we find that the anisotropic nature of Callisto's ionospheric conductivity generates an enhancement effect on ionospheric loop currents which are driven by the time-variable magnetic field. This effect is similar to the Cowling channel effect known from Earth's ionosphere. Subsequently, we numerically calculate the expected induced magnetic fields due to Jupiter's time-variable magnetic field in an anisotropic conductive ionosphere and compare our results with the Galileo C-3 and C-9 flybys. We find that induction within Callisto's ionosphere is responsible for a significant part of the observed magnetic fields. Ionospheric induction creates induced magnetic fields to some extent similar as expected from a subsurface water ocean. Depending on currently unknown properties such as Callisto's nightside ionosphere, the existence of layers of "dirty ice" and the details of the plasma interaction, a water ocean might be located much deeper than previously thought or might not exist at all.

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    A base on Callisto might prove useful in monitoring the progress of spacecraft performing a gravity-assisted maneuver around Jupiter, i.e. a slingshot maneuver, and using radar to detect nearby asteroids and debris in the paths of spacecraft.

    https://en.wikipedia.org/wiki/Gravity_assist

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    In addition, the thermal conductivity of gases at low temperatures is very low. A habitat or temporary shelter could be made with a double-hulled dome, the space between the domes filled with a gas that won't freeze out at Callisto's low surface temperature (whether during day or night, or eclipse).

    https://www.researchgate.net/post/Wh...uids_and_gases

    https://www.engineersedge.com/heat_t...vity-gases.htm

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    A pamphlet-sized article on colonizing the four largest Jovian moons. Interesting idea given on seeding the world with gene-engineered plants that can grow in the cold.

    https://environmental-safety.webs.co...aS_Journal.pdf
    Colonizing Jupiter’s Moons: An Assessment of Our Options and Alternatives
    Thomas B. Kerwick
    The Lifeboat Foundation / CEVA, Inc. (Winter 2012)

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    Wonder if it would be possible to gene-engineer mosses and lichens to live on Callisto and build up a thicker carbon dioxide atmosphere.

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    It might be good to follow the path of any potential impactor on the way to any ice moon--so that a probe can follow it and splash down before everything freezes over again.
    Last edited by publiusr; 2019-May-01 at 07:21 PM.

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    Quote Originally Posted by publiusr View Post
    It might be good to follow the path of any potential impator on the way to any ice moon--so that a probe can follow it and splash down before everything freezes over again.
    I like this!

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    Quote Originally Posted by Roger E. Moore View Post
    Wonder if it would be possible to gene-engineer mosses and lichens to live on Callisto and build up a thicker carbon dioxide atmosphere.
    Currently its atmosphere is little more than vacuum. Dyson Trees?
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by Noclevername View Post
    Currently its atmosphere is little more than vacuum. Dyson Trees?
    Mulling this over. I like it.

    Was also mulling over why bother to give the world an atmosphere. Short answer was, it helps astronauts see better by scattering light all around. Also makes the world seem a bit more Earthlike, helps psychologically. If no one is landing there, no need for atmosphere. Too cold to take off spacesuit, no way to make atmosphere nonpoisonous, but surely looking around at lit ground under a blue sky can't hurt. Works for Mars, right?

    Callisto sounds like a good place to set up observatories, but really, we've been doing great setting up observatories in space orbiting the Earth or Sun. Why bother putting them on a world unless a maintenance crew could fix it? The HST does its best work flying around Earth being serviced occasionally by spacecraft.

  25. #25
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    Quote Originally Posted by Roger E. Moore View Post

    Was also mulling over why bother to give the world an atmosphere. Short answer was, it helps astronauts see better by scattering light all around.
    Don't change the object, change the astronauts! Add a little thermal to their visible spectrum. (Or just put it in their suits' visors, whatever works best.)
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  26. #26
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    Quote Originally Posted by Noclevername View Post
    Don't change the object, change the astronauts! Add a little thermal to their visible spectrum. (Or just put it in their suits' visors, whatever works best.)
    I read about that a few years ago while writing a science-fiction/fantasy magazine article about infrared vision. The trouble is that the viewer's own body heat messes up the heat vision. Otherwise a fine idea. Maybe a little starlight vision would not hurt, though.

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    Quote Originally Posted by Roger E. Moore View Post
    I read about that a few years ago while writing a science-fiction/fantasy magazine article about infrared vision. The trouble is that the viewer's own body heat messes up the heat vision. Otherwise a fine idea.
    There's surely an engineering solution to that. A heat sensing membrane outside the eye? A separate organ for sensing? Cybernetics with a cooling system?
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  28. #28
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    Quote Originally Posted by Noclevername View Post
    There's surely an engineering solution to that. A heat sensing membrane outside the eye? A separate organ for sensing? Cybernetics with a cooling system?
    Was thinking about this. With heat-sensing vision, the surface of Callisto might be uniformly super-black, as hot objects radiate "light" (heat) but cold ones do not. Again, light-intensifying vision might be better.

    However, heat vision might be useful on Mars to spot other astronauts (who would emit a little heat through their suits), running motors, engine fluid spills, and anything else that's been heated up. This would be best used at night.

  29. #29
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    The article I wrote was "Sight in the Darkness", which used real-world infrared vision data. It can be found in this PDF.

    https://annarchive.com/files/Drmg211.pdf

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    It occurs to me, somewhat late, that the giant unsafe radiation-spilling nuclear reactor that NASA proposed sending along with the HOPE astronauts would be awesome at creating an atmosphere on Callisto. The heat from it would melt the ices around it. Throw an insulating blanket over the reactor, and the heat is directed straight down. If some of the radiation emitted is in alpha and beta particles, you'll have a new crater and maybe a shaft downward in no time. Hope there's nothing alive below the reactor in the underground ocean. Oh, right, will have to keep getting extension cords from Earth, too.

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