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Category: engineering – Page 276

http://news.yahoo.com/nowhere-japans-growing-plutonium-stockpile-064038796.html

A half century after being developed, nuclear pulse propulsion remains the only practical system of interplanetary travel. What is required to launch a bomb propelled mission to the outer solar system? Well, first you need.…..bombs.

There is no shortage of bomb material on planet Earth. The problem is lack of a vehicle that can get this material to the nearest place a nuclear mission can be launched; the Moon. For over a quarter of a century a launch vehicle capable of sending significant payloads (and people) to the Moon has been lacking. The Space Transportation System, aka the space shuttle, was a dead end as far as exploration due to the lack of funding for a Sidemount cargo version.

Now we wait on the SLS.

http://www.sciencedaily.com/releases/2012/12/121228100748.htm

Only this human rated Heavy Lift Vehicle (HLV) with a powerful escape tower will be suitable for transporting survivable packaged fissionables to the Moon. It is not only the fissionables that are required; hundreds of tons of water from lunar ice deposits are necessary to fill the radiation shield for any such Human Space Flight Beyond Earth Lunar Orbit (HSF-BELO).

Eventually lunar resources can be used to actually construct atomic spaceships and also the thorium reactors necessary to power colonies in the outer system. It is the establishment of a beam propulsion infrastructure that will finally open up the solar system to large scale development. This will require a massive infrastructure on the Moon. Such a base will serve as insurance against an extinction level event wiping out our species. As such it deserves a full measure of DOD funding. Like that trillion dollars that is going to be spent on the F-35 stealth fighter over the next half century.

Only monthly Heavy Lift Vehicle launches of payloads to the Moon can be considered as a beginning to a true space program- where Apollo left off. There is no cheap and there is no flexible path.

OK, why do we need a different technology to achieve commercial viability (as in mass space tourism) for either interplanetary or interstellar travel?

In many of my previous posts I had shown that all the currently proposed technologies or technologies to be, are either phenomenally expensive (on the order of several multiples of World GDP), bordering on the impossible or just plain conjecture. This is very unfortunate, as I was hoping that some of the proposals would at least appear realistic, but no joy. I feel very sorry for those who are funding these projects. For a refresher I have posted an updated version of the Interstellar Challenge Matrix (ICM) here which documents 5 of the 11 inconsistencies in modern physics. I give permission to my readers to use this material for non-commercial or academic uses.

I recently completed the 12-year study into the theoretical & technological feasibility of gravity modification published under the title An Introduction to Gravity Modification, 2nd Edition. For the very first time we now have a scientific definition for gravity modification:

Gravity modification is defined as the modification of the strength and/or direction of the gravitational acceleration without the use of mass as the primary source of this modification, in local space time. It consists of field modulation and field vectoring. Field modulation is the ability to attenuate or amplify a force field. Field vectoring is the ability to change the direction of this force field.

Note that this definition specifically states “without the use of mass”, for obvious reasons – for example it does not make sense to carry around the mass of a planet to propel 7 astronauts, does it?

By this definition alone, we have eliminated all three status quo theories – general relativity, quantum gravity and string theories. Therefore, the urgent need to construct a new theory that will facilitate the development of gravity modification technologies.

And further, by this definition we know the additional requirements of such a new theory. The theory should show us, firstly, how to attenuate or amplify the gravitational field strength, and secondly, how to change the direction of this force field – all without using mass.

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Benjamin T Solomon is the author & principal investigator of the 12-year study into the theoretical & technological feasibility of gravitation modification, titled An Introduction to Gravity Modification, to achieve interstellar travel in our lifetimes. For more information visit iSETI LLC, Interstellar Space Exploration Technology Initiative.

Solomon is inviting all serious participants to his LinkedIn Group Interstellar Travel & Gravity Modification.

Last month a colleague of mine and I visited with Dennis Heap, Executive Director of the National Front Range Airport, at Watkins, CO, the location of the future Spaceport Colorado, and Colorado’s contribution to getting into space. Here is Part 4.

In Part 4, I dwell more into the economic concepts necessary for a spaceports’ long term success. The single most important concept one has to understand with any type of port, airport, seaport and spaceports is the concept of the hinterland economy. The hinterland economy is the surrounding local economy that the port services, either by population demographics, commercial & industrial base or transportation hub per its geographic location.

The Sweden-America model, like Westport Malaysia requires that a hinterland economy will eventually be built close to the port. Westport’s then Vice-Chairman of the Board, Gnanalingam (we called him ‘G’) whom I reported to, had the foresight, the influence and the connections within the Malaysian public sector, to encourage the infrastructure development within Pulah Indah and the neighboring locations.

The hinterland is critical to the success of the port. Therefore the key to a port’s success is the clarification of the term ‘local’ in the definition of the concept of the hinterland. When I joined Westport in 1995, a hinterland was defined as within approximately a 15 mile (24 km) radius of the port. In my opinion that was too small a segment of the economy to facilitate the success of Westport. That definition did not match up with Westport’s ambition to be a world class seaport and transshipment hub that could give PSA (Port Authority of Singapore, then largest container port in the world) a run for its money.

So I changed the definition.

I changed the definition of ‘local’ to 7-hours. Any warehouse, manufacturing site or distribution center within a 7-hour drive of Westport was now Westport’s hinterland. And because Westport was in the middle of Peninsula Malaysia, that ‘7-hours’ translated into the whole of Peninsula Malaysia, from the border with Thailand in the North to all the way down South to Singapore. This increased Westport’s hinterland from 350 sq miles (900 sq km) to 51,000 sq miles (132,000 sq km).

Of course that ‘7-hours’ would not have meant much if Malaysia had not built an interstate system of roads. That is why the public sector involvement in the economy is so vital to an economy’s success; in a manner that says, how can we give back to our tax payers?

And coming back to our original topic, that is the beauty of Spaceport Colorado. It is tucked in close to Denver International Airport (DIA) and the city of Denver. Spaceport Colorado’s hinterland is the whole of the Continental United States. First through the passenger traffic via DIA and second tapping into the high end winter tourists market at Aspen, Vail & Beaver Creek ski resorts.

Spaceport Colorado will be an immense success.

—————————————————————————————————

Benjamin T Solomon is the author & principal investigator of the 12-year study into the theoretical & technological feasibility of gravitation modification, titled An Introduction to Gravity Modification, to achieve interstellar travel in our lifetimes. For more information visit iSETI LLC, Interstellar Space Exploration Technology Initiative.

Solomon is inviting all serious participants to his LinkedIn Group Interstellar Travel & Gravity Modification.

Last month a colleague of mine and I visited with Dennis Heap, Executive Director of the National Front Range Airport, at Watkins, CO, the location of the future Spaceport Colorado, and Colorado’s contribution to getting into space. Here is Part 3.

In my last post I had mentioned that there were 2 business models for spaceports. I’ll name the first Sweden-America model after spaceports Sweden & America. The second, I’ll name Colorado-Singapore model after (yet to be) spaceports Colorado & Singapore.

The Sweden-America model basic premise is that spaceport ought to be built in remote locations, and then a hinterland economy is eventually built around the spaceport. This approach was originally driven by safety concerns and the need for a rocket range or vacant land for launching rockets to crash back to.

The basic premise of the Colorado-Singapore model is that launch vehicles are safe and that spaceports ought to be built close to centers of commerce and intermodal transportation networks. That is, spaceports are to be built in an existing hinterland economy.

Spaceport Colorado is therefore tucked in close to Denver International Airport and the city of Denver. Spaceport Singapore is to be built within Changi Aiport (ranked #2 out of 388 airports in the world). Changi Airport is located on the Eastern end of the island of Singapore, with Malaysia to the North.

Note that in the case of Spaceport Singapore, the Singapore Strait to the South and East of Changi form a natural rocket range. While Spaceport Colorado has 3,000 acres (less 900 acres for the spaceport) of vacant land to develop additional revenue generating and revenue supporting facilities.

There has been debate about which is the better business model. Both models are correct. Having been Head of Corporate Planning in the early days at Westport, Malaysia, I can assure you that the key is to match your capex with revenue generation. Today the Goggle map of Westport, shows a well-developed island of Pulah Indah. When I worked there in 1995–96 the whole island was virgin and civil engineering firms were draining the swampland.

That is, if there is enough drive, ambition, and cooperation between the private and public sectors a whole island can be transformed from swampland to a world class shipping hub, commercial, industrial & residential zones in a decade. The same is true for spaceports, and for that matter, American cities.

The problem with Spaceport America is that the public sector is not willing to do enough to ensure its success. At least not what it took to ensure Westport’s long term success. New Mexico take a look at Westport and see what you will be missing 10 years from now.

I have to run now. More in the next post.

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Benjamin T Solomon is the author & principal investigator of the 12-year study into the theoretical & technological feasibility of gravitation modification, titled An Introduction to Gravity Modification, to achieve interstellar travel in our lifetimes. For more information visit iSETI LLC, Interstellar Space Exploration Technology Initiative.

Solomon is inviting all serious participants to his LinkedIn Group Interstellar Travel & Gravity Modification.

Last month a colleague of mine and I visited with Dennis Heap, Executive Director of the National Front Range Airport, at Watkins, CO, the location of the future Spaceport Colorado, and Colorado’s contribution to getting into space. Here is Part 2.

What is a spaceport?

Wikipedia gives a very broad definition of a spaceport, that anything and everything that is used to launch vehicles into orbit, space and interplanetary missions are now termed spaceports. ICBM sites are termed launch sites. There is, however, a distinction between a military site and a commercial site. In the aviation world a military site is termed an ‘airbase’ while a commercial civilian site is termed an ‘airport’. Similarly in the marine world the respective terms are ‘naval base’ and ‘seaport’. In that vein there are ‘spacebases’ and ‘spaceports’. So bear in mind that not everything that is labeled a ‘spaceport’ is one.

As far as I can remember the term ‘spaceport’ caught the public’s imagination only recently with the advent of Spaceport America at Las Cruces, NM. So let’s clarify. A spaceport is port for launching vehicles into suborbital, orbital and interplanetary space whose primary mission is to support and manage commercial activities, not military, not government sponsored launches. And therefore, in the United States there are only 10 existing or proposed spaceports. They are (1)Mid-Atlantic Regional Spaceport, Wallops Island, VA (2)Cecil Field Spaceport, Jacksonville, FL (3)Spaceport Florida, Cape Canaveral (4)Spaceport Oklahoma, Burns Flat, OK (5)Spaceport America, Las Cruces, NM (6)Mojave Air and Spaceport, Mojave, CA (7) California Spaceport, Vandenberg Air Force Base, Lompac, CA (8)Kodiak Launch Complex, Kodiak Island, AK, (9) Spaceport Colorado, Watkins, CO and (10)Spaceport Hawaii, HI.

Map of US Spaceports as of Aug 26, 2011, Courtesy of US Department of Transportation.

The proposed spaceports outside of the United States that interest me are Spaceport Sweden, Spaceport Singapore, and Ras Al Khaimah Spaceport, UAE. Spaceport Sweden is the only one of the three that shows some form of life. The other two appear to be dormant with no signs of life. If one were to compare business concepts, Spaceport Sweden is closer to Spaceport America and Spaceport Singapore is similar to Spaceport Colorado.

Spaceports, real people doing real things to get into space.

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Benjamin T Solomon is the author & principal investigator of the 12-year study into the theoretical & technological feasibility of gravitation modification, titled An Introduction to Gravity Modification, to achieve interstellar travel in our lifetimes. For more information visit iSETI LLC, Interstellar Space Exploration Technology Initiative.

Solomon is inviting all serious participants to his LinkedIn Group Interstellar Travel & Gravity Modification.

Last month a colleague of mine and I visited with Dennis Heap, Executive Director of the National Front Range Airport, at Watkins, CO, the location of the future Spaceport Colorado, and Colorado’s contribution to getting into space.

On April 19, 2012, Gov. John Hickenlooper signed a bill that limited a spaceflight entity’s liability for spaceflight participants and paved the way for Spaceport Colorado’s development. The Front Range Airport Authority situated on 3,900 acres will allocate 900 acres towards the development and construction of Spaceport Colorado and ancillary facilities. The next steps are the completion of an environmental assessment, and feasibility and marketing study. This is expected to be completed by end of 2013.

In the 1995–96 I was Head of Corporate Planning at Westport, a $1 billion seaport infrastructure project in Malaysia, where I created and deployed the 7-hour port strategy, streamlined financial controls, container handling and container tariffs, reducing incoming (wharf to gate) dwell time to zero hours compared to the then world’s largest container port, Port Authority of Singapore’s (PSA) 18-hours. Westport was able to grow substantially, to the point where, in 2011, Westport handled 6.4 million TEUs compared to PSA’s 29.9 million TEUs. (TEU = Twenty-foot Equivalent Units or half a container)

So it caught my attention when Dennis Heap said Spaceport Colorado will be 33 miles (53 km) east of the city of Denver and about 6 miles (10 km) south of Denver International Airport (DIA).

DIA is the 5th busiest airport in the US, and the 11th busiest airport in the world. It is located centrally in the continental United States. Read more about DIA here. The plan is to build a rail link between DIA and the Spaceport.

Denver is the second largest city after Phoenix, AZ, in the Mountain States (Arizona, Colorado, Idaho, Montana, Nevada, New Mexico, Utah, & Wyoming). It is the 23rd most populous city in the United States. Read more about Denver here.

After our visit with Dennis Heap, I took some photos of the Front Range Airport.

This photo above is of the view of the left side of the runway. In this photo you can see a white smudge just above the fourth plane (from the right). That white smudge is the Denver International Airport. The blue and white streak above ground on the horizon (left to middle of photo) is the majestic snowcapped Rocky Mountains. The city of Denver would be 33 miles (53 km) left or west of the Front Range Airport.

You can see from this picture that the Front Range Airport is a general aviation airport. That white smudge above the first plane (from the left) is the Denver International Airport. Note the clear blue skies. Colorado is the sunniest state in the US with more sunny days than even Hawaii.

This photo above was of the view to the right of the runway. Terminal building and offices are on the right of this photo. And if I have my bearing right, when built, Spaceport Colorado will be visible on the horizon.

I must congratulate Dennis Heap, Front Range Airport, and the many people, county and state officials and private companies who made this a reality. Public and private sectors cooperating to make things happen today. Real people doing real things to get into space sooner rather than later.

—————————————————————————————————

Benjamin T Solomon is the author & principal investigator of the 12-year study into the theoretical & technological feasibility of gravitation modification, titled An Introduction to Gravity Modification, to achieve interstellar travel in our lifetimes. For more information visit iSETI LLC, Interstellar Space Exploration Technology Initiative.

Solomon is inviting all serious participants to his LinkedIn Group Interstellar Travel & Gravity Modification.

To achieve interstellar travel, the Kline Directive instructs us to be bold, to explore what others have not, to seek what others will not, to change what others dare not. To extend the boundaries of our knowledge, to advocate new methods, techniques and research, to sponsor change not status quo, on 5 fronts, Legal Standing, Safety Awareness, Economic Viability, Theoretical-Empirical Relationships, and Technological Feasibility.

In a previous post on Technological Feasibility I had stated that a quick and dirty model shows that we could achieve velocity of light c by 2151 or the late 2150s. See table below.

Year Velocity (m/s) % of c
2200 8,419,759,324 2808.5%
2152 314,296,410 104.8%
2150 274,057,112 91.4%
2125 49,443,793 16.5%
2118 30,610,299 10.2%
2111 18,950,618 6.3%
2100 8,920,362 3.0%
2075 1,609,360 0.5%
2050 290,351 0.1%
2025 52,384 0.0%

That is, at the current rate of technological innovation we could as a civilization reach light speed in about 140 years. More importantly we could not even reach anywhere near that within the next 100 years. Our capability would be 6.3% of c.

The Lorentz-Fitzgerald transformation informs us light speed would require an infinite amount of energy (i.e. more than there is in the Universe!), thereby highlighting the weaknesses in these types of technological forecasting methods. But these models still serve a purpose. They provide some guidance as to what is possible and when. The operative word is guidance.

Rephrasing is required. Is the technological light speed horizon of the 2150s too far out? If you are as impatient as I am the answer is ‘yes’. It would not be in the spirit of the Kline Directive to accept a 2150s horizon. 2150s is for people with no imagination, people who have resigned to the inevitable snail’s progress of physics. Further, we now know the inevitable impossibility using our contemporary physics because of the 5 major errors.

Completing the Interstellar Challenge Matrix (ICH) gives:

PDF version available here.

What are we left with? We have to find new directions, new models, new mathematical constructions, that address all 5 errors. And in the spirit of the Kline Directive, there needs to be a better method of sifting through academic papers “ … to provide reasonability in guidance and correctness in answers to our questions in the sciences …”

What do we do for starters? Here are my initial recommendations are:

1. The physics community has to refocus on mathematical construction hypotheses.

2. More experimental physicist leading combined teams of experimental and theoretical physicist.

3. Prioritize research funding by Engineering Feasible Theories, 100-Year Theories, and only then Millennium Theories.

I started this series of blog posts in order to achieve interstellar travel sooner rather than later, but we as a community are heading in the wrong direction. It won’t work to build bigger carriages. It won’t work add more horses, as some would suggest. That would be like flogging a dead horse. We have to do something radically different. That is why the Kline Directive matters.

I have made the assumption that technological feasibility is a necessary step. Yes it is, given our lack of technological capability to reach the stars in a realistic and finite time frame. Technology feasibility very quickly leads back to the next question of commercial viability, the second step.

Future feasible technologies will iterate between technological feasibility and commercial viability until we can reach the stars in a manner we don’t have to ask the question, whom do we select to leave Earth?

Until then we are not ready!

Previous post in the Kline Directive series.

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Benjamin T Solomon is the author & principal investigator of the 12-year study into the theoretical & technological feasibility of gravitation modification, titled An Introduction to Gravity Modification, to achieve interstellar travel in our lifetimes. For more information visit iSETI LLC, Interstellar Space Exploration Technology Initiative.

Solomon is inviting all serious participants to his LinkedIn Group Interstellar Travel & Gravity Modification.

To achieve interstellar travel, the Kline Directive instructs us to be bold, to explore what others have not, to seek what others will not, to change what others dare not. To extend the boundaries of our knowledge, to advocate new methods, techniques and research, to sponsor change not status quo, on 5 fronts, Legal Standing, Safety Awareness, Economic Viability, Theoretical-Empirical Relationships, and Technological Feasibility.

My apologies to my readers for this long break since my last post of Nov 19, 2012. I write the quarterly economic report for a Colorado bank’s Board of Directors. Based on my quarterly reports to the Board, I gave a talk Are We Good Stewards? on the US Economy to about 35 business executives at a TiE Rockies’ Business for Breakfast event. This talk was originally scheduled for Dec 14, but had moved forward to Nov 30 because the original speaker could not make the time commitment for that day. There was a lot to prepare, and I am very glad to say that it was very well received. For my readers who are interested here is the link to a pdf copy of my slides to Are We Good Stewards?

Now back to interstellar physics and the Kline Directive. Let’s recap.

In my last four posts (2c), (2d), (2e) & (2f) I had identified four major errors taught in contemporary physics. First, to be consistent (2c) with Lorentz-Fitzgerald and Special Theory of Relativity, elementary particles contract as their energy increases. This is antithetical to string theories and explains why string theories are becoming more and more complex without discovering new empirically verifiable fundamental laws of Nature.

Second, (2d) again to be consistent with Lorentz-Fitzgerald and Special Theory of Relativity, a photon’s wave function cannot have length. It must infinitesimally thin, zero length. Therefore, this wave function necessarily has to be a part of the photon’s disturbance of spacetime that is non-moving. Just like a moving garden rake under a rug creates the appearance that the bulge or wave function like envelope is moving.

Third, that exotic matter, negative mass in particular, converts the General Theory of Relativity into perpetual motion physics (sacrilege!) and therefore cannot exist in Nature. Fourth, that the baking bread model (2e) of the Universe is incorrect as our observations of the Milky Way necessarily point to the baking bread model not being ‘isoacentric’.

Einstein (2f) had used the Universe as an expanding 4-dimensional surface of a sphere (E4DSS) in one of his talks to explain how the number of galaxies looks the same in every direction we look. If Einstein is correct then time travel theories are not, as an expanding surface would necessarily require that the 4-dimensional Universe that we know, does not exists inside the expanding sphere, and therefore we cannot return to a past. And, we cannot head to a future because that surface has not happened. Therefore, first, the law of conservation of mass-energy holds as nothing is mysteriously added by timelines. And second, causality paradoxes cannot occur in Nature. Note there is a distinction between temporal reversibility and time travel.

In this E4DSS model, wormholes would not cause time travel but connect us to other parts of the Universe by creating tunnels from one part of the surface to another by going inside the sphere and tunneling to a different part of the sphere. So the real problem for theoretical physics is how does one create wormholes without using exotic matter?

Previous post in the Kline Directive series.

Next post in the Kline Directive series.

—————————————————————————————————

Benjamin T Solomon is the author & principal investigator of the 12-year study into the theoretical & technological feasibility of gravitation modification, titled An Introduction to Gravity Modification, to achieve interstellar travel in our lifetimes. For more information visit iSETI LLC, Interstellar Space Exploration Technology Initiative.

Solomon is inviting all serious participants to his LinkedIn Group Interstellar Travel & Gravity Modification.

In a previous post I explored the feasibility of an industrial base on planet Mercury — an option which on first glance had seemed implausible but on getting down to the detail could be considered quite reasonable. Here I go the other direction — outward to the first of the gas giants — and the Galilean moons of Jupiter.

From a scientific point of view it makes a lot of sense to set up a base in this region as it provides the nearest possible base to home that could start to explore the dynamics and weather systems of gaseous planets — which are quite common in our Universe — and how such planets impact on their moons — as potential locations for off-earth colonies and industrial bases. It bears consideration that only two other moons in our outer solar system are of requisite size to have a gravitational field similar or greater to that of our Moon — namely Saturn’s Titan and Neptune’s Triton — so the Galilean moons demand attention.

The first difficulty to consider is the intense radiation from Jupiter, which is far stronger than the Earth’s Van Allen radiation belts. Although proper shielding normally protects living organisms and electronic instrumentation, that from Jupiter is whipped up from magnetic fields 20,000 stronger than Earth’s, so shielding would become difficult. It has been considered that such radiation would be the greatest threat to any craft closing within 300,000 km of the planet. At 420,000 km from Jupiter, Io is the closest of the Galilean satellites. With over 400 active volcanoes, from which plumes of sulphur and sulphur dioxide regularly rise as high as 400 km above its surface, it is considered the most geologically active object in the solar system. The activity could be viewed as a source of heat/energy.

Unlike most satellites, it is composed of silicate rock with a molten iron or iron sulphide core, and despite extensive mountain ranges, the majority of its surface is characterized by extensive plains coated with sulphur and sulphur dioxide frost. One can perhaps disregard its extremely thin sulphur dioxide atmosphere as an inconvenience, though is in too close proximity to Jupiter and its extensive magnetosphere even for occasional mining expeditions from the other moons. In this regard one would have to rule out Io and any resources there completely from consideration for such as base. Onto the other options…

At 670,000 km from Jupiter, the intriguing ice-world of Europa is a much more interesting proposition. Under the ice surface it has a layer of Water Ocean surrounding the planet thought to be 100 km thick. One of the first dilemmas of setting up a base on Europa would be not to contaminate any primitive life that may already have a foothold there. Often considered a strong candidate for extra-terrestrial microbial-type life, if life was found there it could render Europa off-limits for colonisation on the grounds of ethics due to the possible contamination/destruction of a delicate ecosystem. Discounting this concern — with an unlimited supply of water — and by extraction, unlimited oxygen and hydrogen also — we have the most important ingredient to support a colony at our disposal here.

The main drawback for Europa — other than high radiation levels from proximity to Jupiter — could be the inability to mine other materials — though these could be attained from other nearby moons, and of course the extreme cold surface temperature — at approx. 100K.

Further out at just over 1,000,000 km we have Ganymede, the most massive of the Galilean moons, and hence with the strongest gravitational field. Composed of silicate rock and water ice in roughly equal proportions, it also is theorised to have a saltwater ocean far below its surface due to salts (magnesium sulphate and sodium sulphate) shown in results from the Galileo spacecraft, which also detected signs of carbon dioxide and organic compounds.

Ganymede is also thought to have a thin oxygen atmosphere, including ozone and perhaps also an ionosphere — although all again in trace amounts, and a weak magnetosphere. Whilst the atmosphere could be considered negligible in terms of the needs for a colony, it is still far more suited as an industrial base than Europa — as not only has it an ample supply of water/ice, it also has abundant resources in silicates and irons for mining and construction.

And last — but by no means least — we have Callisto — furthest out at almost 2,000,000 km, also composed of equal amounts of rocks and ices, it is different from the other Galilean satellites in that as it does not form a part of the orbital resonance that affects the three inner Galilean satellites, and therefore does not experience appreciable tidal heating. Despite this it enjoys a mean surface temperature of 135K and up to a maximum 165K – still very cold – but not as cold as the other Galilean satellites. Like Ganymede, it also has an extremely thin atmosphere, in this case composed mainly of carbon dioxide and molecular oxygen and may have a subsurface of liquid water — the likelihood of which has raised suggestions in the past that it could harbour life. Callisto has long been considered the most suitable place for a human base for future exploration of the Jupiter system since it is furthest from the intense radiation of Jupiter (http://www.nasa-academy.org/soffen/travelgrant/bethke.pdf). HOPE — Human Outer Planet Exploration — as in the above linked 2003 NASA presentation explores some of the objectives and requirements for such a pilot mission, where Callisto was selected — not surprisingly — as the most appropriate mission destination.

HOPE surface operation concepts where vehicle and robot system concepts were explored to achieving a successful first phase, and the division of tasks between crew and robotics, including the exploration of all these satellites, and it concluded a roundtrip crewed mission between 2–5 years is feasible — with significant advancement in propulsion technologies.