Imagine

 Imagine - a very wonderful topic

Imagine, if you will, when we reach out for the planets in our own system and perhaps the stars, how will we go about it? One cannot resist but to think about the space station and spaceship, the United States Spacecraft Discovery One, depicted by Stanley Kubrick from the story by Arthur C. Clark, 2001 – A Space Odyssey. The question is, how would we justify its cost? Where would the resources come from to build such a thing? What’s its return on investment? I would be willing to bet that these questions came up when building ocean going sailing ships and planning trips to prove the world is a sphere. Perhaps similar questions came about when Shackleton was planning to go to the Antarctic pole. It’s time to dream again. Do you remember the spinning wheel space station from that movie?

Justification and Return on Investment

What is the cost of loosing humans on Earth? You know it can happen many ways. We could eliminate ourselves through war or our own stupidity, we could get hit by a rock from space large enough to destroy everything we’ve built. So, the justification would be risk management and the return on investment would be our own survival. How could one even estimate the financial value of that?

What is Required

So that we can explore our solar system and perhaps venture beyond our average sized star we will need to build large spacecraft, very large. Imagine having to travel for years and even decades, perhaps generations, to make it to the stars. We will require spaceships with pseudo gravity, farms large enough to grow all the required food, an extremely long-lasting power source, machine shops, mining abilities, well basically a self-contained planet of sorts. We can’t launch something like that all-in-one piece from Mother Earth. We need a way to assemble the pieces in orbit. Perhaps even mine the resources required from space, from asteroids like Psyche.

Cooperation is another requirement. A project as huge as this, and one that is for all humans, would work best if all, or most, humans were involved in the development. We are all stakeholders in our exploration, our continued survival and we all can share the benefits of that effort. After all it is us who will benefit. We are all one species.

How

Now imagine an orbiting space station for assembling these interplanetary and interstellar space vehicles. These vehicles would be too large to launch all in one so we would have a space station where they are assembled in orbit. That space station, itself, would need to be launched in many pieces and assembled in orbit as was the international space station but it would need to be larger than the ISS, much, much larger.

It would require an energy source that could maintain it indefinitely such as solar and nuclear. In addition to assembling spacecraft, would be used for research and development of many varied studies as well as serving and maintaining the existing space fleet.

For pseudo gravity It would need to have it spin so that centrifugal force would give the people staying there a place to feel a force like gravity. Gravity makes so many things much easier.

Instead of being in a low earth orbit it may be better to have it stationed in geosynchronous orbit or far enough way so that if an accident happened there would be time to respond so that it would not crash down on the earth causing damage, it could be guided out of its fall. Something this size would most certainly not completely burn up upon re-entry.

Mining Ships

The solar system is full of asteroids that have valuable minerals in them. To access these valuable resources, we would need ships to mine and haul the material. Remember 16 Psyche? It was at 1.6 astronomical units of the earth in December of 2020 during its opposition, it orbits the sun between Mars and Jupiter about every 5 years. NASA will send a craft out to explore it with an expected launch of 2022, that has now been delayed due to development difficulties, arriving hopefully in 2026.

At 226 kilometers wide it holds more resources than we can dream of using. Perhaps they could partially process the material as well. These ships would most likely be robotic but perhaps not. Either way they would require unloading of their haul and regular maintenance. The space station could perform both these tasks.

With automation, even now at its current level, it is possible to imagine a feasible iron smelter in space powered by the sun with robotic spacecraft feeding ore from gathered asteroids. I would expect other metals to be available also.

Interplanetary Exploration

We’ve dreamed for a long time of exploring the other planets and their satellites and so far, we’ve made it to our moon and robotically explored Mars and even flown past Pluto with the New Horizons (by the way it is in the Kuiper Belt). Jupiter’s natural satellites hold a possible promise for humans to establish a foothold in, such as Europa.

It is slightly smaller than Earth's Moon and, according to analysis from the flyby data of the Galileo mission, Europa is primarily made of silicate rock and has a water-ice crust and probably has an iron–nickel core. It has a very thin atmosphere, composed primarily of oxygen. Its surface is striated by cracks and streaks, but craters are relatively few. This smoothness of the surface has led to the possibility that a water ocean exists beneath the surface, where there could conceivably be extraterrestrial life. It is thought that heat from tidal flexing from its orbit about Jupiter causes the ocean to remain liquid and drives ice movement like plate tectonics.

Interplanetary space travel for humans would require spaceships with much more space than we`ve ever built as the trips would last years. People require space to move around in, space to grow food in, live and work. The vessels would require their own energy source such as solar power but would also use a long-term nuclear reactor. When traveling the outer reaches of the solar system and beyond solar power would become useless so nuclear would be a requirement. Whatever their energy system they require multiple backups to reduce the chance of catastrophic failures. Multiple systems are much safer so that if there is a failure, partial or entire, then the other system would be able to supply the required energy to not only complete the mission but return the astronauts’ safely to earth orbit again.

Missions would last for decades so it is imperative to have ships that can support many people and do it comfortably. The systems would need to generate all the required food, energy, consumables and process all the waste, or better still, produce no waste. On board would require minor manufacturing of consumables, things like replacement parts, food, clothing, cleaning products and toiletry. Also, several technical people who would be capable of troubleshooting and repairing the equipment which runs the spaceship.

Industry in Space

To support this effort to build extremely large spaceships and to continue our growth as a space faring people we will need to develop industry off our planet. There are literally tons of materials out there just orbiting around our sun. Water probably being the most abundant. From water, not only can we satisfy our thirst, but we can also make hydrogen fuel, acquire the oxygen need to breath and to act as an oxidizer for our fuels. Electrolysis is the way to produce both hydrogen and oxygen. In orbit around the sun, we will have a constant source of energy pumped into our photovoltaics to produce all the hydrogen and oxygen we’ll ever need plus the electrical energy.

To build large structures, such as the ships to travel long interplanetary and interstellar trips, it would be best to mine the material required from the asteroids directly then refine and smelt in space. Now smelting in a gravity well, the metal trickles down the rock after heating it beyond the melting point of the metal but in space, well we have no gravity. So how do we gather the metal? Perhaps spin it somehow while heating it. The metal is a higher density than the silicates and carbonates which it is often combined with, and we will need some way to extract it.

Some meteorites found on earth are high in metal content. Most "iron" meteorites are iron-nickel alloy with a bit of sulfide minerals. The alloys are 5 to 12 percent nickel, with traces of cobalt, chromium, gold, platinum, iridium, tungsten, and other elements that dissolved in the molten iron. Assuming this is representative of most asteroids, these could be easily separated through the smelting process, a solar driven smelting process. We erect a huge parabolic mirror in orbit with the earth, around the sun, and use it to smelt iron and other metals.

Processing Metals

Casting the metals is another problem in space though. Usually, metals are cast by pouring them into pigs or running them through a water-cooled mould in continuous casting operations, but this requires gravity. Perhaps pig moulds attached to the spinning container used to smelt the metal? All the other metals except Chromium have a higher density and so iron would float to the top if it didn’t bond in any way with the other metals. Below is a list of metals found in asteroids, their melting points and density.

Not only is there a lot of good stuff out there but we will need to think deeply about the methods of processing them.