Category Archives: ELEO Space Settlement

Revised ELEO Space Hotel Concept: Solar panels, active thermal

In light of feedback received from Joe Strout I’ve revised the power and thermal management system for the ELEO Space Hotel / “proto”-settlement. Specifically, I’ve right-sized the power generation and attached the solar panels/radiators  to an axial truss, rather than integrating them into the rotating truss ring as before.

I learned that if we use a power/thermal management system with performance similar to the ISS power/thermal system, the ELEO hotel needs a LOT of solar panels!! Specifically over 20 square kilometers of solar panels! So the station has become a giant solar power station with a rotating ring attached.

I tripled the mass of the ELEO hotel PV solar system to 117,000 kg because, frankly, the calculated mass seemed too low (39,000 kg).

Here is the summary for the radiators

I also considered manufacturing. Warning! The handwaving picks up here so if brainstorming bothers you, I suggest you stop reading now.  Constructive comments of any kind are always welcome.

The 3D printer factory can theoretically manufacture a panel 5m wide by 5m long. Let’s assume the panel (both solar and radiator) is less than half a meter deep. Breaking up our massive solar array into panels that can be manufactured in such a space means 1,792 panels need to be printed. Doing the same calculation for the radiator panels means 240 panels need to be printed. Assuming one panel printed per day (very ambitious!!!) it would take over five and a half years to print every panel.  This sounds bad at first but, as the reader will see in the next post, we are assuming a station lifetime of 20 years. Full power/thermal capacity might not be needed until, say, year 10 of operation, or even later.

ELEO Space Hotel Concept

In this post a crude model of a space hotel/proto-ELEO space settlement is presented. Rough mass and cost estimates are included in the table at the end of the post.

This is for brain storming purposes only, not a final design. Thoughtful feedback is always welcomed.

In this first image we see an overview of the space hotel, located in 500 km ELEO. The summary statistic are in the image.

  • Dark blue panels = solar arrays
  • Sky blue boxy modules = 3d printed habs
  • Golden cylindrical modules = a different type of 3d printed hab
  • Red boxes = service modules
  • Purple boxes on ring = elevator ‘docks’
  • Purple boxes on spokes = pressurized elevators going back and forth between hub and ring
  • Purple central module = rotating hub
  • Hollow gray cylinder at top = 3D printer factory w solar panel ‘skirt’
  • Green boxy module = docking module with barely-visible robotic arms attached

Mass estimates are based on comparable ISS hardware. For example, to calculate the mass of the truss ring (the ring to which all modules are attached along the circumference) I researched the mass of the S0 truss (14000 kg for 13.4 meters in length resulting in 1045 kg per meter of length).  Then I calculated the length (circumference) of the truss ring and multiplied that by 1045 kg to get the total mass of the truss ring. I used similar comparisons for all components, solar panels compared to ISS Solar Array Wing, gold colored modules compared to Bigelow BA330 modules, etc.

All mass estimates have an extra 10 percent margin.

Here we see a view from ‘below’ the station.  The brown panels are radiators/thermal management system components.

FYI Gravity estimates calculated using SpinCalc.

Note the station is modular and is not finished in this image. Population capacity in the pictured configuration is estimated to be 40. Total capacity once all modules are added around the rim is estimated to be 100, as indicated in the picture.

A closer view of the hub. The robotic arm can relocate (“walk”) itself around the station, like the robot arm on the ISS today.

And here are the rough mass estimates. Note I assume gun launcher technology is available to send feedstock to orbit and that 3D printer technology has advanced to the point that all the mass of the rotating parts of the station can be built in orbit. It is more likely that advanced components (electronics, etc.) will have to be boosted up from earth. However, it is fair to assume that the most massive parts of the station (structural, pressure hull, electrical and thermal components) can be built using advanced 3d printers because these massive parts are relatively simple (unlike an integrated circuit, for example).

A Possible ELEO Space Settlement Roadmap?

What follows is a simplified path to developing small space settlements in equatorial low earth orbit (ELEO): a space settlement roadmap.

Specifically, what is laid out here is the path to building a hotel/facility/large space station (call it what you will) that could, theoretically, be converted into a settlement where people permanently live.  It’s not the ideal settlement, as it will still be a bit cramped, but it could work.

The reader may want to read previous posts here, here and here to obtain some helpful background information.

New scientific research, new launch technology and new commercial developments are overturning long-held beliefs about orbital space settlements.  Space settlements no longer have to be massive kilometer-long structures requiring asteroid mines or moon bases to construct.  They need not cost trillions of dollars and mass billions of tons.  And they don’t have to be located at the Earth-Moon Lagrange points.

Instead, the aforementioned developments indicate that space settlements can be much smaller: roughly comparable in size to the International Space Station (in terms of length of structure, not volume).  Such small settlements could feasibly be built using materials boosted up from Earth.   And they could be fabricated and assembled using additive manufacturing and telerobotic techniques that are being developed in space right now.

Bottom line, a small orbital space settlement – literally a village in space – could conceivably be built in the next ten years, assuming certain key technologies are successfully developed.  Let’s see how (in very broad brushes. Warning, lots of hand-waving here, this is for brainstorming purposes only):

Step 1: Build and launch a cubesat probe to ELEO to characterize and confirm the radiation environment.

Step 2: Establish a 3D printer business at the ISS to manufacture cubesat components. Customer: small sat mega constellation operators. Note: Made In Space is already basically doing this, except with NASA as customer, not sat operators. Ways to minimize need for astronauts to do the work: design and deploy a telerobotic rig inside the space station to operate the 3D printer remotely from earth. Feedstock can be delivered remotely as well, via the soon-to-be installed Nanoracks airlock.  If this 3D printer/teleoperated rig is too big or in the way, rent space out in the essentially unused and uncrewed BEAM module (although access/logistics to/from this module may be tricky).

Step 3:  Develop a larger, more capable 3D printer/telerobotic rig for use outside the station in vacuum. Again, Made In Space is already working on this. Provide more and better services for the satellite operators.

Step 4: With revenues from the ISS-based fabrication facility, raise funds to 3D print and telerobotically assemble a scale model of the key components of the eventual first settlement. Make a proof of concept for rotating ring-hubs, elevators, airlocks, etc. Maybe even fluid management parts e.g. active thermal management system. Test printing and assembling more complex parts like solar panels.

Step 5: Attempt and then successfully 3D print and assemble an inter-orbital transfer vehicle to transport vehicles from ISS to ELEO 500km. Fueled with propellant gun-launched to ISS orbit from Earth (same as how 3D printer feedstock gets to ISS). This could be a more robust and long-lived version of ULA’s ACES vehicle.

Now the hand-waving really picks up:

Step 6: Leverage existing revenue streams, raise funds to 3D print and assemble the hub and support bus of the hotel (future posts will show a graphic of the hotel/settlement being described here). Transfer this so 500 km ELEO using the dedicated inter orbital vehicle manufactured in step 5.

Step 7: Using the 3d printer factory in the hotel/settlement hub, 3D print the remainder of the structure: the minimum viable product necessary to begin crewed operations in 500 km ELEO. The hotel/settlement is modular and can be expanded as needed up to its design capacity of 70 persons.

Subsequent posts will describe the geometry of the hotel/settlement described above as well as an innovative funding mechanism to pay for steps 1 through 4 (by which time hopefully the facility is raising enough revenue to leverage in order to obtain the really big money needed for steps 5 and 6).


Precursors to ELEO Space Settlement

Space settlement precursors are activities that really ought to be perfected before space settlement is attempted.

For instance, short suborbital space tourist jaunts will create demand for longer orbital space tourist trips.  Longer orbital trips will create demand for destinations in space: orbital hotels.  And a space hotel is not that much different from what a space settlement will look like.  A space hotel will require all the same characteristics a space settlement will need: high reliability, comfort and security for the dozens or hundreds of people aboard. So, before we have space settlements, we need to build space hotels.  And before we build space hotels, we need reliable human transportation to orbit.  The beginnings of which are being built now in the form of suborbital space tourism providers (e.g. Virgin Galactic and Blue Origin).

Space tourism, satellite servicing and 3D printing are three examples of space settlement precursor activities.

Satellite servicing is another precursor activity, one that is likely to start in the early 2020s (link, link). Moving fluids and gases around in microgravity and perfecting long-range telerobotics will be essential to constructing and managing a space hotel and, eventually,  a space settlement.  And, luckily for settlement and space manufacturing, it appears a golden age of satellite construction is about to begin with numerous companies planning multi-hundred (or thousand) satellite constellations in the next five years.  All many of those satellites will be designed to receive servicing, repair and replacement.  Perhaps the facilities to provide some of those services can be located in orbit?  The lessons learned at a satellite repair facility will be useful in constructing and maintaining space settlements.

Additive manufacturing is another space settlement precursor.  Ideally a large portion of a space hotel or space settlement will be 3D printed on orbit using feedstock delivered very cheaply to orbit by gun-launcher systems or, maybe, super-huge (and super cheap) rockets like SpaceX’s ITS.  This construction strategy will allow for more flexible settlement geometries: the modules won’t be constrained by the dimensions of a rocket fairing.  An added bonus: 3D printing can theoretically be adjusted to accept feedstock derived from asteroidal or lunar resources in the future.  So it’s an investment that can be amortized over the very long-term and used throughout cislunar space, and beyond.  Luckily, at least one company, Made In Space, is already working on putting 3d printers in the vacuum of space at the ISS. 

There are likely more precursors. Can you think of a few? Please make suggestions in the comments.

Bleeding Edge Developments in Space Launch

One of the least known and most exciting developments in the past year is the resurrection of the idea of using giant tubes or guns to launch cargo into space. This is not a new idea.  Jules Verne proposed the idea in 1856 in his novel From the Earth to the Moon.  It’s still highly suspect and implausible.  The commonly accepted knowledge about gun launchers is that its very hard to pack enough punch into a gun to get a payload to orbit without the gun blowing up in the process. And even if you could build a big enough and stable enough gun, the acceleration would destroy the payload inside the projectile.

But This Orbital Life is aware of at least two very well-capitalized and highly-credentialed companies working on this idea: 8 Rivers Capital and Green Launch. There are unsubstantiated rumors of other companies as well, although I was unable to find any proof online.

There is increased commercial interest in developing ground-based tube-launcher technologies.

There is increased interest in this field because of the skyrocketing demand for small satellite launches to orbit. If gun launchers can be perfected (a big if), they could theoretically launch small payloads to orbit every few minutes rather than every few weeks or months. And they could arguably do it much cheaper than conventional rockets, which are finicky, complex vehicles full of expensive rockets and electronics.

But we’re not interested in launching satellites to space. The value of gun launcher technology to space settlement is that it could cheaply and regularly launch feedstock for additive manufacturing facilities in orbit. 3D printers need lots of plastic and aluminum to operate. Plastic and aluminum feedstock would not mind the high acceleration experienced during a gun launch. In fact, the projectile itself could theoretically be ground up and recycled into 3D printer feedstock. And 3D printing in space is a critical precursor to orbital space settlement.

The value of gun launcher technology is that it would be ideal for launching feedstock to additive manufacturing facilities in orbit.

In the next post I will discuss the concept of space settlement precursors.

New Developments in Space Settlement: ELEO Radiation, Rotation and More

Several developments in the past year improved the possibilities for orbital space settlement.

Al Globus, a friend of This Orbital Life, published a number of papers showing that equatorial low earth orbit (ELEO, at roughly 500 kilometers) may be an area of low radiation.  Far less radiation shielding may be needed for structures located there than for structures located in higher inclination orbits (like the International Space Station) or in other areas of cislunar space (like the Lagrange points).  Because less material is needed, small settlements could be built in ELEO without requiring in-situ resource utilization. No lunar bases or asteroid mining will be necessary. In other words, everything needed to build a town in space could feasibly be boosted up from Earth.

According to new research, everything required to build a settlement could feasibly be boosted up from Earth, without the need for in-situ resource utilization.

This is not the only game-changing development.  Al Globus, in separate research, shows that humans can likely tolerate far higher revolutions-per-minute in a rotating* space settlement.  Higher RPMs mean a settlement can be smaller, further reducing the amount of mass needed to build a viable (albeit very small) settlement.

In the next post, bleeding-edge launch developments will be discussed. And they have nothing to do with chemical rockets.

*This Orbital Life is of the opinion that space settlements must generate some level of artificial gravity in order to provide the type of lifestyle that would attract large numbers of people to live in space. Living in microgravity is uncomfortable and unhealthy.