A Jovian Outpost: The Fifty Year Plan

by Paul Gilster on February 26, 2007

Long-term thinking is a continuing preoccupation in these precincts. For if we lack the ability now to mount human expeditions to the outer planets and to push probes into the Oort Cloud and beyond, the building of our mission concepts is still vital. We go experiment by experiment, paper by paper, creating a foundation for that future. Ad astra incrementis — you get to the stars one step at a time, and as you go up those steps, you realize that each one has taken you that much farther than the last.

It can be hard to make that case heard in a culture obsessed with consumerism and immediate satisfaction, but we can shape an argument for results in the long-term that may catch the most jaded eye. Ponder that we are on the verge of nanotechnology and computing capabilities that may resolve key issues of propulsion and instrumentation. By the end of the century, we may be sending intelligent robotic probes to destinations now thought impossible. If, that is, we take the needed steps now.

At Kyushu University in Japan, Tetsuo Yasaka and colleagues are developing a fifty-year plan for building an outpost on or near Callisto, one that would control laboratories on other Galilean satellites and send probes into the Jovian atmosphere. Primarily robotic, the outpost might include human crews under the Europan ice, where Jupiter’s intense radiation would pose far less of a threat. It would exploit the potential of this environment to produce propellants and study the ocean for life.

Yasaka’s thinking is to move beyond what isolated probes can do to create a permanent human presence that can be self-sustaining and aimed at systematized exploration of the entire Jovian system. Early priorities, after creating the central node at the Callisto L2 point, would be a geophysics laboratory on Io (robotic, to be sure) and the Europan sub-surface outpost, with a station on Ganymede to follow.

An idle daydream? Projects like this will always seem so without intelligent planning, but this exercise in long-term thinking, which may eventually bear fruit in one form or another, relies on a sound methodology. Ten major items of technological development are targeted, each to be undertaken in a five-year plan that could produce near-term benefits for spinoff to other space projects and industry.

The challenges of such a project are immense. To maximize payload and minimize travel time to Jupiter, aerobraking and aerocapture methods must be used. For power, nuclear energy seems to be the first candidate, but huge deployable solar arrays may be an option even though Jupiter’s orbit is at the outer limit of solar energy use. Intelligent robotics is also crucial, and here we look to machines that are supremely adaptable to their environment. The radiation hazard must be studied as well, identifying candidate technologies for dealing with it. And so far we are only in the first five-year phase of study.

Why put intensive effort into creating a fifty year plan for a series of missions that may never happen? This is how Tetsuo Yasaka explains the project, relying on collaborations between technology developers, government agencies and academia:

The project basically is, at present, a technology project that mainly contains items related to transportation, energy and environment driven technologies, that are identified as crucial to outer planet explorations. The explorations will not be carried out by the University alone. Planetary explorations will be carried out under government agency initiative, with close collaborations with academia. In case of the Jovian outpost, it will no doubt be an international project. Missions are likely proposed by academic community, which Kyushu University has strong alliance with.

You see why I bring this up. What I’m after here is a methodology that looks at goals that are not presently attainable, and sets up step-by-step methods to define and investigate the technologies that can reach those goals. This is something like the ‘horizon mission methodology’ that NASA sometimes employs to stimulate new thinking in its seminars and conferences. Present a problem that is at present impossible to solve. Then define the breakthroughs needed to make this future possible.

You wind up targeting the key gaps in our knowledge. You look at ideas on the edge and try to distinguish the viable ones from the far more numerous dead-ends. You aim at provoking discussion that leads to insight. And one day something flows from all this. I suspect Tetsuo Yasaka would be surprised if we end up with a Jovian outpost that looks like this one. But that there will be a human presence in Jupiter space — and by this I mean people or intelligent AI — seems overwhelmingly likely.

And when that happens, it will be because projects like this one at Kyushu University have started early, worked hard, and thought long-term. For more, see Yasaka, “Outpost in Jovian system—a stepwise long-term undertaking,” Acta Astronautica 59 (2006), pp. 638–643.


Drage February 27, 2007 at 3:46

Great blog! I came across your site a couple of days ago and I have recieved immense enjoyment reading the various entries.

RE Jovian Outpost:

Very interesting ideas by the Japanese and blog author.

I would further that with this long term planning we also need to start templatising space craft production, using models which we know work, and can be tailored in a modular fashion so as to produce modules for living, transport, sciences, storage etc

As space seems to be homogenous (unless you are stuck in an asteroid field) surely it makes sense that we develop a standard module, which in turn can be easily attached to other modules, be they for transport/propulsion systems, living quarters, storage or whatever.

An example of a system that can be copied again and again and we know works are the MERs. Those two rovers are exactly the same build and specification and they have both outperformed even the most optimistic predictions concerning battery life, energy conservation and mechanical robusticity. Obvioulsy we need other technologies for a permanent manned Jovian space station, but the Rovers produced on mass could become a tested and well understood army of planetary probes for the Jovian moons. Think of the science which would be sent back to earth if we had 6 of those Rovers simultaneously exploring various moons.

Personally im not impressed with NASAs plans so far for the Orion vehicle which apparently is about to be given the green light. It just looks like a more modern, bigger Apollo module and from what i understand will work in the same way as the Apollo missions. Does this demonstrate much progress form the 1960s? I dont think so.

Anyways…great site.

Adam February 27, 2007 at 4:00

The MERs aren’t optimised for the Jovian system since they’re solar-powered and not hardened against the Jovian proton barrage.

The forward planning is a welcome take on the issue, very much a methodology which should get more air-play in Space enthusiast circles.

Aerobraking isn’t effective at Jupiter, unlike all the other big planets. Its gravity well is steeper than what’s practical. I might do up an analysis and put it up at my blog. Been a while since I looked at it in depth.

Adam February 27, 2007 at 6:41

A quick note.

The advantage for aerobraking at Jupiter is nil for Hohmann transfer orbits, so direct braking at Callisto orbit makes the most sense. Travel time is ~ 1000 days.

A faster transfer (T~526 days) increases the advantage slightly, but the re-entry heating is more than 220% the heating from an Earth-Moon return – just to save a measly 2.4 km/s dV.

A parabolic transfer (T~404 days) saves 6.7 km/s, but the re-entry heating load is over 350% the Earth-Moon load.

So there’s a saving for fast orbits, but the mass penalty for extra aeroshell mass is probably going to eat up the gain. An aeroshell masses typically 15% of the mass being deccelerated – even more for higher energy re-entry like a Jovian aerobrake. So call it 20% extra fuel required for the boost out of Earth-space. Maybe no saving for a fast elliptical transfer, and just a saving for a parabolic transfer.

IMHO safer not to bother.

Administrator February 27, 2007 at 7:22

Drage, I appreciate the thought re modular production, which plays into the long-term scenario of creating a human presence in the outer Solar System. Re the Orion design, it’s quite a contrast from the 1960s-era Orion and the nuclear pulse notions that had people dreaming of Saturn by 1970! But we’ll see what we get out of it, even as we try to put the ideas in play for much more sophisticated vehicles (and longer missions) in the future.

Administrator February 27, 2007 at 7:23

Good thoughts on aerobraking, Adam, though you may get an argument on this from some quarters. In any case, it’s no open and shut case, and only one of various options that need more work. I see that Kyushu has it as a major topic for investigation in their first five-year study.

Drage February 27, 2007 at 9:48

Hi Guys

Adam: I didnt actually mean we should use the very same MERs for missions to the Jovian moons. I understand that new systems would need to be tested which fit the physics and other environmental variables pertaining to Jupiter and its environs. But perhaps once we build an EER (shall we say) which is tested on Europa (which seems the target most indicated by the scientific community), then if successful, as the MERs have been for Mars, they should be replicated as if we were churning out Ford Fiestas.

And of course, the follow on from that is we standardise a design for space travel/habitat that works and doesnt need to be re-dsigned for every mission to Jupiter, or the Jupiters space station modules.

Im not very good at maths so i wont comment on your aerobraking calculations :-) In fact i always wish my science or maths teachers had explained to me that the deep philosophical questions of our universe, and the relevant theories use maths as a language to prove or to disprove. I hope science and maths teachers these days are making those subjects interesting to young wanna be astronauts.

But from a popular science point of view, one of the problems i think we really need to overcome if we are serious about longterm manned missions, and space stations is the zero gravity problem. I really dont think any of this can happen until we can build space environments with psuedo gravity. We know that zero g is deadly for our immune systems over a long period of time, and of course we know about the muscle and bones wasting symptoms which are bad enough.

I dont buy the idea currently doing the rounds which is some sort of excercise vehicle which astronauts jump on once or twice a day in order to work the body in a 1 g enviroment.

This may sound simplistic but i think that is the big hold back at the moment. For instance a Jupiter space station with 1 g would make everything else, such as staying there and keeping healthy for years on end much easier to accomplish.

Please correct me if im wrong but from what i have read, we have the technology and designs for spaceships or craft in order to simluate gravity through a revolving cylinder type mechanism. I think its just we dont yet have the engineering and energy capacity to make it happen, as described in some of the plans. Surely that is not too far away considering the exponential rate of technological advance currently enjoyed by humanity.

Is this correct?

Drage February 27, 2007 at 9:53


I guess you are right about Orion being a stop gap until we produce better technology. I know im so impatient for all this to be happening now.

Ron S February 27, 2007 at 11:00

A question: Europa is tidally locked to Jupiter, so is the radiation hazard manageable by putting a rover on the ‘far side’? Direct radiation should be blocked, but perhaps it is still subject to magnetically-directed radiation that could reach far side.

andy February 27, 2007 at 11:53

Good idea to keep out of the radiation by going to Callisto. Any closer than that would require serious shielding. In any case, isn’t Callisto also supposed to have an underground ocean?

philw February 27, 2007 at 13:06

The radiation is not FROM Jupiter like the sun’s light shines on Earth. The moons surfaces are surrounded by belts of radiation that orbit Jupiter. Rovers will get toasted on the 1st 3 Gallilean moons.

Administrator February 27, 2007 at 16:41

Re Callisto’s possible ocean, this interesting quote: “”Until now, we thought Callisto was a dead and boring moon, just a hunk of rock and ice,” said Dr. Margaret Kivelson, space physics professor at the University of California at Los Angeles (UCLA) and principal investigator for Galileo’s magnetometer instrument, which measures magnetic fields around Jupiter and its moons. “The new data certainly suggest that something is hidden below Callisto’s surface, and that something may very well be a salty ocean.”


Adam February 28, 2007 at 2:22

Hi Drage

The main reason spin-gravity isn’t used seems to be simple inertia of an institutional kind.

Adam February 28, 2007 at 2:27

Oops… hit the ‘submit’ button too soon. Spin-gravity has been investigated numerous times and it doesn’t pose any real engineering issues, but no current planned mission makes it worthwhile – the ISS needs micro-g for some of its experiments and isn’t really designed for vigorous rotation, while all the proposed Moon-flights are too short for it to matter.

Flights to Mars can be done with travel times of 130-180 days, which we have plenty of biomedical data on thanks to the Russians. There’s no reason to research it further – if we’re going to Mars, for Mars’ sake. There’s a kind of unacknowledged myopia about the zero-g thing which is counter-productive.

Drage February 28, 2007 at 5:08


I have a bad feeling about a manned mission to Mars without the correct environment (including psuedo gravity) provided for the astronauts. Im not saying it cannot be done but im not so sure that the Russians experience of many months orbiting earth without gravity has given us the experience in order to expect the same results from what will be a v small craft with no gravity, losing sight of earth. At least in orbit around earth one may feel earth isnt too distant because one can see it without magnification. On a spacecraft to Mars there is no room for error and no-one can send a rescue mission in a timely fashion.

Apart from the physically unhealthy effects I am concerned about the mental aspects as well of which we dont know alot because we have never sent humans on a space mission that far, in that kind of isolation.

I just feel a 1 g gravity environment could take away some of the edge that will no doubt rear its head on a first manned mission to Mars.

Of course, i think we should do it in any case but without some sort of psuedo gravity we will need really strong characters. In fact i think NASA should do a small testrun. For instance perhaps a 60 day round journey for the crew and spacecraft would iron out some of the probs which will be faced by the crew in the Mars spacecraft. I dont see why they would attempt a Mars mission before we conduct a test run.

Hope im not sounding too pessimisitic (because im not) i just think these long journeys could present problems not yet experienced by lenghty stays orbiting earth.

Adam March 1, 2007 at 0:56

Hi Drage

Much of the problem of long-duration orbital stays has been boredom. And the old Salyut & Mir stations were really cramped. Nothing changes but the Earth in an LEO long-duration mission, whereas interplanetary flights have a lot more going on, and a definite destination that gets bigger all the time. The psychology is quite different, and spending 60 days going nowhere in a big loop just isn’t going to successfully emulate the difference.

Just a thought. Astronauts train pretty hard and are pretty rugged mentally – they won’t be just passengers, they’ll be going somewhere with things to do. With so much “free time” they should be given a large role in planning the stay on Mars, exploring as much as they can virtually (thanks to robotic precursors) before hitting the ground, so they’re ready for it mentally as well as procedurally and physically.

Stephen March 1, 2007 at 15:15

One could use spin gravity on the Moon or Mars. We have centrifuges on Earth.

Or would that work? According to my Palm Pilot, the Moon and Mars are planets, but the Earth isn’t listed as a planet.

Darnell Clayton March 1, 2007 at 22:18

Great post! Despite Callisto being a great place to establish a settlement, I was thinking that Ganymede might be a better choice because it not only has a magnetic field (which helps protect against radiation), but may be “a bit warmer” than Callisto.

Not to mention plenty of minerals and water ice for us to call this world home.

andy March 2, 2007 at 8:54

I wouldn’t have thought Ganymede’s rather weak magnetic field would offer much protection, and in any case the amount of radiation at Ganymede orbit is far greater than at Callisto, so I’d suspect the radiation environment at the surface of Ganymede is going to be worse than that at Callisto, despite the magnetic field.

How good is ice at absorbing radiation – how far down would you have to dig to shelter on an ice moon? Also, another question is how strong the surfaces of the ice moons are: would a base on the surface be stable (especially given that a base is going to have an internal temperature well above the sublimation point).

Administrator March 2, 2007 at 9:20

I don’t know the answer on radiation and ice, though I notice that at AAAS, Jere Lipps talked about a meter or two of ice as being a sufficient shield for some biological processes. That led him to speculate on near-surface environments like caves and even ice overhangs where organisms brought up from below by shifting ice might survive.

Tetsuo Yasaka March 16, 2007 at 1:28

Thanks to Paul for putting my paper on this unique site, and to many who showed interest on this topic. I do not have answers to many comments, but here is a quick note to Adam on Aerobreak. Actually there was a skepticism about its application to Jupiter, but it was found out that capture from Hohmann orbit is possible with a very narrow corridor of 100 km out of 714,000 km insertion altitude. A few percent of abrator mass gains 2km delta-V. The resulting orbit is a very long ellipsoid, which is much unstable. Errors of atmospheric model or even possible fluctuation of the atmospheric density may kill the advantage. We are now inclined rather to direct insertion to Callisto.

Last week, I was invited to present this work at “Space Exploration Symposium” hosted by JAXA. Many agency leaders were there including Michel Griffin and Jean-Jack Dordain. It was a pitty that those VIP’s were not in the room when I made presentation. They had a separate meeting at that moment. It was interesting, and this was what I expected, that government people were not much interested in this kind of very very long term project. They are interested in 25 years span at most. Those who showed interest most were Science Fiction writers!!

Adam March 16, 2007 at 7:37

Hi Tetsuo

That’s what I thought, though the advantage improves for non-Hohmann trajectories – which seem unlikely for a first mission. A 1,000 day Hohmann transfer is a long time to be in space soaking up cosmic-rays, so what kind of shielding is proposed to mitigate against that particular hazard?

Anything that can protect against 10 GeV cosmic-rays will easily give a vehicle access to moons deep in Jupiter’s radiation belts. Also I wonder if there’s not a low radiation region in the wake of the moons themselves? That might allow landers at Europa – Ganymede and Callisto should be accessible without elaborate shielding, according to the radiation figures Robert Zubrin quotes in “Entering Space”.

ljk September 21, 2009 at 8:49

Ganymede Enhanced

Credit: Galileo Project, DLR, JPL, NASA

Explanation: What does the largest moon in the Solar System look like? Ganymede, larger than even Mercury and Pluto, has a surface speckled with bright young craters overlying a mixture of older, darker, more cratered terrain laced with grooves and ridges. Like Earth’s Moon, Ganymede keeps the same face towards its central planet, in this case Jupiter.

In this historic and detailed image mosaic taken by the Galileo spacecraft that orbited Jupiter from 1995 to 2003, the colors of this planet-sized moon have been enhanced to increase surface contrasts. The violet shades extending from the top and bottom are likely due to frost particles in Ganymede’s polar regions.

Possible future missions to Jupiter are being proposed that can search Europa and Ganymede for deep oceans that may harbor elements thought important for supporting life.


Comments on this entry are closed.

{ 3 trackbacks }