Tag Archives: lunar space elevator

The Big Five Characteristics

In previous posts the rationale for space settlement was discussed, as well as how the next generation of space stations can attract people in order to be successful.  This post will discuss the characteristics the next generation of space stations must have in order to advance the causes of space settlement and developing a human-centric LEO economy.

The next generation of space stations must:

  1. Be truly permanent
  2. Rotate to provide artificial gravity
  3. Support a larger population
  4. Produce
  5. Be flexible

Let’s take these one by one:

1. Be truly permanent – the next generation of space stations, or next gen, must be designed to be repaired and upgraded in space.  Components should be modular and subsystems should be able to be swapped out and upgraded as needs require.  Structural members should be composed of materials that can be repaired using in-space resources.  In short, the next gen should be thought of less as a vessel with a finite life but more like a settlement or a building that can be repaired, upgraded and changed over time.

2. Rotate to provide artificial gravity – the next gen of space stations must have gravity in order to provide a comfortable quality of life and thus persuade the average person to live in space.  While artificial gravity has been a mainstay of science fiction for decades, and is assumed to be possible using centripedal acceleration via rotating structures in space, it has never been attempted in real life.  The next gen must incorporate some level of artificial gravity in order to prove the concept so it can be refined for later, full-scale space settlements like Kalpana One.

3. Support a larger population – in keeping with the idea that the next gen of space stations are settlements, and not vessels, we ought to call the people living, visiting and working there a ‘population’ as opposed to a ‘crew.’  Furthermore, the next gen must be able to support a larger population in order to prove that a large number of people can live and thrive in space.  The challenges and opportunities of having dozens of people in space are far greater than having less than ten people in ISS.  Thus, the next generation of space stations should be designed to support a population of at least 100 people.

The next generation space station will support a crew population of at least 100 people.

4. Produce – the next gen of space stations must demonstrate, on a commercial-scale, the ability to extract useful products from raw materials obtained in space, refine those products into salable goods or services and then assemble them into other, more complex items.  For instance, extracting water from captured comets (perhaps delivered to the station by Planetary Resources) and manufacturing liquid oxygen to refuel a government mission to Mars. Or, later on, extracting silicon from lunar regolith (perhaps delivered by Liftport via a lunar space elevator) to produce solar panels to install into a satellite that is docked with the station. Whatever the method, it will be necessary to show that space manufacturing is feasible to advance the cause of space settlement.  It will be necessary to use local materials to construct full-scale space settlements because the tonnage required is too high to boost everything up from Earth. The nextgen must prove that local materials can be refined into usable goods, and it must do so at a profit in order to be sustainable.

5. Be flexible – finally, the next gen of space stations must be able to accommodate a variety of different users and uses within the same facility (as much as is feasible).  Again, in keeping with the idea that this is settlement, and not a single-use vessel, it must be able to accommodate recreation, manufacturing, military, R&D, etc. And, it must be flexible enough to be rearranged internally to accommodate as-yet-unforeseen users and needs.

Part 4 of 4: the pros & cons of Capturing an Asteroid to deliver raw materials to orbit

The first three posts in this series have discussed the advantages and disadvantages to using rockets, mass drivers or the “PR method” to deliver raw materials to orbit.  This post will describe the pros and cons of using a lunar space elevator to achieve that goal.

First, what is a lunar space elevator?  The best, most succinct answer to that question can be found on Wikipedia:

A lunar space elevator is a proposed cable running from the surface of the Moon into space.

It would…be constructed with its center of gravity in a stationary position above the surface of the Moon, providing a controlled means to transport people and/or materials between the surface and lunar orbit.

Here are a few videos of how the system may be built and how it might work (h/t LiftPort).  Bottom line: the lunar space elevator will allow a continuous flow of lunar regolith to be delivered to orbit for a very low price per pound.

Bottom line: a lunar space elevator will regularly deliver thousands of tons of raw materials to orbit for very little money.

That is, if it works.

Let’s start with the good news:

  • Highly efficient – once in place, delivers lots of material with low operating costs (lunar ground ops, ribbon maintenance, interorbital transport, etc.) relative to other systems
  • Easy access to large supply
  • more technologically achievable than an Earth space elevator

And now the challenges:

  • deployment/maintenance on target totally unknown, orbital debris/micrometeorites/radiation destroying/degrading the ribbon
  • slow rate of lift – probably not able to carry people
  • the giggle factor
  • pr issues surrounding excavating the moon i.e. “scarring the surface of the moon”

Part 3 of 4: The pros & cons of Capturing an Asteroid to deliver raw materials to orbit

The first two posts in this series have focused on the pros and cons of using rockets and mass drivers to collect raw materials in orbit. This post will discuss the merits of capturing an asteroid using what I’m calling the Planetary Resources (PR) method. As far as I can tell, PR will capture whole asteroids (small ones) and somehow drag them back to more convenient orbits closer to Earth for processing (as opposed to strip-mining them or processing the ore on-site).

How PR will (probably) capture asteroids. Credit: Planetary Resources

Let’s start with the advantages:

  • Easier transportation to destination – The more accurate way to state this is that it takes less of a change in velocity (delta-v) to move asteroids around the Earth-Moon system than it does to haul materials up from the Moon or Earth. This is because asteroids are already at the top of the cislunar gravity well. In other words, one should expend less fuel moving a typical asteroid from its orbit into, say, geosynchronous orbit, than one would on moving an equivalent mass from the lunar surface to geosynchronous orbit.

This is a HUGE advantage. Perhaps an Earth-bound analogy will drive home the point. Consider two mines on Earth. In one, the ore is laying on the surface and just has to be picked up and trucked to the processing facility. This is the PR method – snagging an asteroid and sliding it to where it needs to go. Now, consider another mine where the ore is buried deep underground. First one digs up the ore and hauls it to the surface and then it has to be trucked to the processing facility. Obviously it’s a lot more work to move all that heavy stuff around but this is what happens when ore is collected from the Earth or the Moon and then transported into orbit. By eliminating the need to haul the material up out of a gravity well, Planetary Resources has a great advantage over the other methods.

  • Provides massive infusions of raw material – Thousands of tons of material will be delivered immediately upon the arrival of a near-earth asteroid at the destination. No other technology known today has the capacity to deliver thousands of tons in one delivery. Rockets can, at most, deliver tens of tons of material. Space elevators and mass drivers provide a continuous trickle of material that, over time, can add up to thousands (even millions) of tons –but it requires patience.  If you need a lot of space rocks and you need them right away, asteroid capture may be the way to go.
  • Provides goodies – Asteroids could more easily provide resources that are not known to exist in great quantities on the Moon and are difficult to haul up from Earth e.g. rare platinum group metals, volatiles or even hydrocarbons.

But what about those disadvantages:

  • Lots of unknowns – No one has ever captured, or barely even landed on an asteroid. Pristine asteroidal material has never been examined on Earth. The composition of different classes of asteroids is essentially unknown and manipulating asteroids is, at this point, a best guess. Can a rubble pile asteroid be de-spun without it falling apart? Can a volatile-rich asteroid be “bagged” without all the water and oxygen boiling off and popping the containment unit? Mastering the capture and processing of asteroids will take many years, as well as the coordination of the swarms of robots it will take to accomplish these tasks. It may be decades before these techniques are commercially viable, especially when compared to the more familiar technologies required to exploit lunar resources.

“A mine is just a hole in the ground owned by a liar”

– Mark Twain

  • Long delays between deliveries – While a mass driver or space elevator provides a steady continuous trickle of material to orbit, asteroid capture provides huge shipments once every two or three years. This time lag will  complicate processing as facilities will have to be designed to store or digest a huge amount of material when the asteroid arrives but will then lay fallow while they wait for the next shipment. It could lead to inefficiencies.
  • Potential public relations problem – I’m not going to spill too much e-ink on this topic but it is possible that the same Luddites who oppose nuclear-powered space probes could oppose and potentially derail or delay asteroid mining because they fear “killer space rocks” being positioned closer to the Earth. Even though putting them into a more convenient orbit makes it easier for them to be deflected and diverted should something go wrong.

So, lots of pros and cons for this item. Stay tuned for the final installment regarding lunar space elevators.

 

Part 2 of 4: The pros & cons of using Mass Drivers to deliver raw materials to orbit

In a previous post I described the pros and cons of using rockets to deliver raw materials to orbit. And, in the post before that, I explained that this part of a series of posts discussing the best ways to amass raw materials in orbit needed for space development. In this post, I will discuss the pros and cons of using mass drivers to accumulate a resource base in Earth orbit.

The biggest advantage to using mass drivers is that they are very efficient. That is, once they are set up and functioning well, no fuel is required to launch payloads into orbit. In theory, the mass driver can launch hundreds of times its own weight using only electricity.

Furthermore, extensive research has been completed on mass drivers, and their earthbound cousin, the railgun. The Space Studies Institute and Gerard K. O’Neill himself built a small mass driver in the 1970s basically proving that this idea will work. And today, the US Navy is working on an electromagnetic railgun to fire artillery shells which is basically a mass driver.

Gerard K. O’Neill and his team with a working mass driver prototype in the 1970s. Courtesy: SSI

In practice, however, one cannot be sure that a mass driver will function as promised. It is, after all, a machine and machines require maintenance and upkeep. I am skeptical that mass drivers can function anywhere near their peak performance without a human presence on the moon to maintain them.

Which brings us to the biggest disadvantage to using mass drivers: they require a massive upfront investment in infrastructure. This infrastructure includes not only the kilometer-scale mass drivers but also megawatt-scale power systems (probably nuclear due to the long lunar nights – which means additional headaches), loading machinery, canister processing machinery and all the subsystems needed to make this structure work. Essentially, one must build a minor lunar base in order to construct, and possibly operate, a mass driver on the moon*.

So, bottom line, mass drivers are extremely efficient, but require a massive upfront investment in order to work.

*The fact that a mass driver may require a lunar base could be construed as either a positive or a negative, depending on one’s point of view. Positive because, hey, who doesn’t like moon bases, right? Negative because moon bases are expensive and, in this case, would simply be an overhead cost as we establish our raw material delivery system.

Part I: The pros and cons of Rockets for delivering orbital raw materials

In a previous post I described the four new options for amassing raw materials in orbit for the purpose of space development. They are: using rockets to lift stuff up from Earth, using mass drivers on the moon to shoot regolith into orbit, capturing asteroids a la Planetary Resources, and constructing a lunar space elevator a la LiftPort to transfer lunar ore into orbit. In this post I will describe the basic advantages and disadvantages of each method.

The goal here is to determine the fastest and most cost-efficient method for collecting hundreds of tons of raw material in Earth orbit. Hundreds of tons – if not thousands – are necessary to manufacture the large structures necessary to develop space i.e. to build a self-sustainable and self-replicating civilization in orbit. Let’s talk pros and cons one by one:

I. Rockets – There are several big benefits to using rockets:

  1. Proven technology with a deep market: rockets are proven and there are lots of vendors to choose from. It’s the “devil we know” versus the other technologies which are all unproven.
  2. Direct to orbit: rockets are the only option available to boost items directly from the Earth’s surface. This, in theory, allows one to boost finished structures to orbit, skipping the raw material/manufacturing stage. This is both a blessing and a curse: while having some finished products in orbit will be useful (Bigelow modules and 3d printers immediately come to mind), especially in the early stages of space development, ultimately the goal is to build an indigenous manufacturing base in orbit, not just boost everything up from Earth. Also, rockets are the only way to get people into orbit!

However, the major drawback to using rockets is, of course, their expense. Rockets are ultimately too expensive to boost anything except the highest value cargo. This is reef that every space development has foundered on since the beginning of the space age.

Future posts will discuss mass drivers, asteroid capture and lunar space elevators.

An Expanding Menu: Rockets, Mass Drivers, Asteroid Capture and Space Elevators

Since the halcyon days of Gerard K. O’Neill and his grand visions of massive solar power satellites and palatial space colonies, space cadets the world over have pondered the best way to collect the raw materials necessary to construct such structures in orbit. Many, including myself, deferred to Mr. O’Neill’s assertion that the lunar mass driver is the best mechanism to amass a raw material base in orbit. Indeed, there is something elegant in the idea of combining thousands of tiny cargos to form one large resource pile, as opposed to the brute force concept of launching one gargantuan payload at great expense. On the one hand, space enthusiasts have the familiar image of an explosive rocket breaking the surly bonds of Earth (and occasionally failing) in order to put a complete payload into orbit. But O’Neill offered a new, more tranquil vision: rows of silent, miles-long electromagnetic catapults safely and efficiently zooming thousands of tiny payloads into orbit over many months.

Mass Drivers….

Nice day for a lunar picnic next to the serene mass driver. Courtesy of the Lunar Institute. Credit: Pat Rawlings.

….Versus Rockets.

Hot dog! Look at that mother go! Yipppee! I just wish it weren’t so risky and inefficient…

But how times have changed. Today we have two additional visions. The first involves Planetary Resources and asteroid capture. The second involves LiftPort and the lunar space elevator.

As the readers of this blog know, Planetary Resources is a well-funded and well-staffed outfit based in Seattle, WA. They hope to develop new technology and methods to eventually capture and mine near-earth asteroids. LiftPort, the space elevator company, is also based in Seattle, WA and is slightly less well-funded and well-staffed than Planetary Resources. However, I would argue that LiftPort’s ideas and vision generate just as much enthusiasm as do the ideas of Planetary Resources. Furthermore, LiftPort has already failed and resurrected itself AND has successfully crowd-sourced innovation in the past. These two factors alone (perseverance in the face of failure and the ability to manage far-flung groups of researchers) indicate that LiftPort has the potential for success*. In fact, one could argue that Planetary Resources, with its venture capital and in-house engineering staff, represents the old style (1990s) of aerospace innovation while LiftPort, with its open(er)-source development plan and bootstrapping culture represents a new way, or at least a different way, of generating innovation.  

LiftPort, after an ignominious bankruptcy in 2007, is back from the dead, having just raised almost $80,000 over $110,000 of R&D funding in less than a month on, of all places, Kickstarter.

But let’s get to brass tacks – which method is the best way to support space development: rockets, mass drivers, capturing asteroids or lunar space elevators? In future posts I will discuss how each of these options have benefits and drawbacks to amassing raw materials in orbit. UPDATE: Part 1 of 4 (Rockets) is linked above.

*Full disclosure: I used to work for LiftPort. I quit in 2004, thinking at the time that the company was doomed. In  2007, I was proven right. But now, in 2012, I’m not too sure. LiftPort is scrappy and their vision is mesmerizing. Even if they don’t build a space elevator, they might generate enough IP and interest to get bought up by Google X Labs or some other group of yuppie-genius billionaires who will then carry the LiftPort vision to fruition.