Dec 20, 16 / Cap 19, 00 21:12 UTC

Optimal station distance  

Presuming the station will orbit earth, what would be the best distance from the earth's surface for building and maintaining the station? Would it be interesting at some point to make changes at that distance with some frequency, in addition to orbit corrections?

Dec 20, 16 / Cap 19, 00 21:49 UTC

I think that the station has to be placed into an orbit far from the atmosphere drag, in order to avoid (or reduce to the minimum) any kind of orbit correction with RCS or engines; for example, the ISS is orbiting the Earth around 400 km of altitude and it needs to correct its orbit periodically due to the light atmosphere drag that acts on the station.

My suggestion is to place Asgardia's space station into a geostationary orbit over the terrestrial base where the launch of the crews and supplies take place. In this case, it will be very easy to mantain the communication between the space station and the Earth base because we won't need any relay-satellites constellation; also, having the space station as a "fixed" point into the space (from a Earth's POV), will make the launch of supply and crewed vessels less complicated (regarding space maneuvers and rendevous).

  Last edited by:  Andrea Titti (Asgardian)  on Dec 20, 16 / Cap 19, 00 22:15 UTC, Total number of edits: 1 time

Dec 20, 16 / Cap 19, 00 22:13 UTC

In my mind there would be a construction "yard" in LEO, maybe 350-500km. There components would be assembled to modules or entire sections which would then be boosted much higher to where the station would be. I'm thinking the final Apogee would be from 10,000km-35,786km(geostationary). Smaller components and supplies can be flown directly to the station and heavier or multipart items can be sent to the constructions site first and then using a simpler/more economic propulsion system gradually raised to the station.

I have done no calculations and have no background but that's how I do it in Kerbal Space Program :)

Dec 20, 16 / Cap 19, 00 23:46 UTC

I feel like Earth-Moon L1 would be the best option for our station. This lagrange point can serve as a halfway point between Earth and the Moon, allowing not only us but others to possible colonize the moon and make easier supply runs. Not to mention that people who want to "visit" a moon colony would almost "have" to stop at our base 1st, serving as a possible area of revenue (docking fees, refueling fees, cargo fees).

Dec 21, 16 / Cap 20, 00 00:25 UTC

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  Updated  on Jun 15, 17 / Can 26, 01 17:01 UTC, Total number of edits: 1 time
Reason: "This user no longer wishes to be associated with a tin pot banana republic"

Dec 21, 16 / Cap 20, 00 02:44 UTC

This is a tricky one and depends heavily on what perspective you are taking on "optimal".

Anything orbiting the earth at a distance of less than about 100,000 km enjoys at least a degree of protection from stellar and interstellar radiation courtesy of the Van Allen belts generated by the Earth's magnetic field. If my recollection (and maths) is correct, the Earth-Moon L1 point lies outside of this protected zone. This doesn't mean it is impossible to live there, but radiation levels would have to be monitored constantly and any station would have to be shielded (or at the very least have shielded "bunkers"). Shielding is heavy and with current technology, extra weight equal extra cost.

However, it is a swings and roundabouts situation. LEO offers cheaper construction and radiation protection, but you have the need to correct orbits (also costly) and the maintenance issues associated with damage from space junk impacts. Remember, a small fleck of paint travelling at 8km/s can have more kinetic energy than a projectile fired from a Barret 50 cal!

  Updated  on Dec 21, 16 / Cap 20, 00 02:45 UTC, Total number of edits: 1 time

Dec 21, 16 / Cap 20, 00 04:05 UTC

Orbits between 400 and 1000 km have drag makeup requirements far less than what is needed in going to remote orbits beyond the radiation belts. Both structure and radiation shielding in those more remote orbits are extremely expensive. In the nearer orbits, only micrometeoroid / debris shielding is needed, which is low mass, low cost, and a straightforward engineering issue. Such shielding has been tested and employed for decades. What is optimal depends on what the requirements are and what the available budget might be. Real projects begin with statements of requirements and constraints, not jumping immediately to design solutions when one does not even know what he should be designing for. Is this about a station like ISS, or a temporary experimental station, or a permanent habitat that people will live in for decades, even their entire lives? Scarbs: I am skeptical of your statement about relative kinetic energy. Can you provide numbers?

  Last edited by:  Jerome Wright (Asgardian)  on Dec 21, 16 / Cap 20, 00 04:08 UTC, Total number of edits: 1 time

Dec 21, 16 / Cap 20, 00 08:40 UTC

Sure - a 1 gram fleck of paint travelling at 7km per second (average LEO speed), using the kinetic energy formula KE = 0.5mv^2 -

0.5 * 0.001kg x 7000m/s^2 = 24.5kJ

The Barret 50 cal (or M107 as it is known in the US now), has a rated muzzle energy of 15.5kJ -

Obviously, the further out you go, the lower the orbital speeds, the less kinetic energy objects have. Velocity is the key determinant of kinetic energy - the faster you go, the bigger dent you make!

Dec 21, 16 / Cap 20, 00 13:43 UTC

Scarbs: thanks for the numbers. A low-mass, high-speed particle has a different impact response, a condition taken advantage of by micrometeoroid / debris shielding design. That fleck of paint will vaporize upon hitting the shield because the resulting thermal energy is delivered to both the shield and the particle, which is sufficient to vaporize the low-mass particle before it could reach the pressure hull, while I have no doubt that a 50 cal will penetrate the shield and pressure hull as found on something like ISS because there is not enough thermal energy to destroy the more massive bullet. Wikipedia has a good article at 'Whipple shield'.

Dec 21, 16 / Cap 20, 00 19:43 UTC

I'm personally in agreement with Bjorn Schrammel, in as much as a "contruction yard" would make most sense first. I'd suggest a little lower in orbit, however. Only by about 100,000 meters. This is also done without math etc, and purely by similar projects in KSP.

If you're not wasting resources lifting from surface, and instead mining, refining and producing materials in space, then construction of enhanced density radiation sheilding isn't so much of an issue, and modular station components can be launched further up to about the 350,000 mark and assembled on site. Constant adjustment of velocity will be a minor thing with something like a Q-thruster system deployed.

To assume a permenantly inhabited, long term residental station, I disagree with the L1 placement. Mostly because that's a single point of failure. Sensibly, there'd be a collection of stations, evenly distributed aorund the orbital path. Each station vastly able to exceed it's citizen's draw, it will be able to act as a nearby "lifeboat" destinaiton in case of some critical failure that causes abandonment, splitting a stations occupants to those either side...

And velocity is the key determinant of kinetic energy, but however, it's relative velocity. Where you are in regards to orbital distance doesn't matter half as much as the direction the projectile is comming from, and the speed it's doing in relation to you.

Dec 22, 16 / Cap 21, 00 02:19 UTC

JLWright - point taken on the shielding options for the hull. Whipple shields are a good option, but there are two issues: 1. I think Asgardians wouldn't take too kindly to living in a dark sealed can. Any orbital habitat will almost certainly have a variety of external surfaces (eg. solar panels, communications arrays, viewports ,etc). Not all surfaces would respond in the same manner to an impact like the Whipple shield would. These collisions wouldn't be an uncommon occurrence in LEO - NASA recorded 1,951 impacts from orbital debris on the space shuttle's windows and radiators from mission STS-50 to mission STS-114. 2. Not all orbital debris are 1 gram flecks of paint. There are some big pieces of junk whizzing around in LEO. These higher mass debris pieces will transfer significantly more of it's kinetic energy on impact than lower mass debris pieces.

EyeR - point also taken about relative velocity, but this is a double edged sword. Worst case, a LEO orbital debris impact can occur with a relative velocity of approximately 14km/s. Doubling velocity results in a four fold increase in kinetic energy.

The moral of the story is that with every orbital insertion and every collision that happens in LEO, the amount or orbital debris increases - as does the risk of any activity conducted in LEO. In deciding a location / construction method for any long term habitat, this risk will have to be weighed up against the risks / costs of alternatives.

Dec 22, 16 / Cap 21, 00 02:54 UTC

Ultimately, If there's operations to remove the LEO debris field, then it's a problem that will get lesser with time, and eventually no longer become an issue. Certainly all the larger masses will be eaten up as fodder for other things...

Dec 22, 16 / Cap 21, 00 03:07 UTC

Scarbs - You are right about the impacts, that is why I would put a facility at about twice the distance of ISS: up to about 700-800 km to help minimize the problem. Repair and replace tasks would be common. The bigger objects would show up on radar and other detectors. The facility should have really good radars to do its own tracking to support evasion or interception. Going above the radiation belts to enjoy greater cosmic radiation is not a problem-free approach. The cost of placing the facility there with radiation shielding is huge. For the time being, I think staying below the radiation belts is the best way to start. Whatever is placed there is inherently moveable, which could be done if it is necessary to take everything farther out. I like starting with the lower cost approach and adapt as necessary.

Dec 22, 16 / Cap 21, 00 07:10 UTC

I read all the above and concur with most points made. Micrometeors and debris woukd pose a problem at LEO, but this may have to be a bullet we have to bite at first. The shielding required above the Van Allen belts is extensively heavy and would cost a lot to get there. I propose a station in a lower orbit, doubke to triple the altitude of the ISS as suggested above. At first... Having an existing infrastructure (mining, construction, manufacturing, and assembly) in soace would be immensely helpful and, in my opinion, should be one of Asgardia's first space objectives to achieve. Building the stations would be far cheaper and things could be added later at lower costs, such as more extensive shielding.

Dec 22, 16 / Cap 21, 00 07:34 UTC


I feel like Earth-Moon L1 would be the best option for our station. This lagrange point can serve as a halfway point between Earth and the Moon, allowing not only us but others to possible colonize the moon and make easier supply runs. Not to mention that people who want to "visit" a moon colony would almost "have" to stop at our base 1st, serving as a possible area of revenue (docking fees, refueling fees, cargo fees).

I agree. For what concerns shielding if we concentrate on mining the construction materials from NEOs instead of sending them from Earth we would cut the costs a lot and have much less problems (sending stuff in orbit rather than gathering it directly from space is crazy in my opinion)