|10-01-2011, 08:29 PM||#1|
(As I mention in my introductory post, I am not an engineer. It is rather an exercise in logistics / salvaging. Any kind of feedback and additional ideas would be appreciated ! )
A substantial part of the cost of launching objects into space is the energy required to lift mass into orbit.
Every time an obsolete satellite or an ISS resupply ship is de-orbited and subsequently desintegrates, value is destroyed.
These space objects are valuable sources of raw materials for future space projects, such as colonisation or exploitation of planets.
Any long-term installation on the Moon or Mars would require large amounts of copper, aluminium, plastics and other materials. Lunar or martian mining may not provide enough of these materials, especially in their refined form, in the early stages of colony construction. The lifting of these materials from Earth would be a financial burden, degrading the feasability of the projects.
Some materials are already present in orbit, in the form of satellites and space station equipment, either already obsolete (on graveyard orbit) or poised to become so eventually. Even human waste can be valuable in biological projects (gardening, farming).
Most space objects are using high-quality components such as electrical motors, that can be salvaged for further use.
Refurbishing and salvaging have been common solutions for mankind when ressources and energy were scarce ; it is only logical that it should be used in the context of extreme scarcity of space programs.
Following ideas are a personal view of such a salvaging program. Nothing has been calculated, be it on engineering or financial matters. The solutions *seem* reasonable enough in terms of cost and complexity.
The goal is not to build core components from scrap in orbit, but to provide raw materials, and possibly components such as wire and motors for non-critical duties.
The project takes the assumption that objects and materials orbiting Earth can be transferred to the moon at a low cost, using the same procedure as has been used for the PAS-22 communication satellite ( http://en.wikipedia.org/wiki/PAS-22 ).
1. Taking obsolete satellites to the moon
2. A second life for ressuply ships.
3. Solar furnace.
4. Waste centrifugal cannon
5. Design of spacecraft as an assembly of modules.
1. Taking obsolete satellites to the moon
The lifetime of satellites can be extended by using techniques like those of the Robotic Refueling Mission (RRM) (http://www.nasa.gov/mission_pages/st...ments/RRM.html ) : a robotic spacecraft installs a refueling port on the satellite, and refuels it to extend its useable lifetime. Eventually, components such as solar panels or batteries become « worn out », and the satellite would then be lifted into graveyard orbit with its remaining fuel.
On such a mission, the cost of refueling the satellite beyond what would be required for the operational lifetime would be acceptable : the mission would take place anyway, all that would be required would be to transport and transfer more propellant. The supplemental quantity of propellant would have to be sufficient to propell the satellite to the Moon.
Without any further modification, the satellite could be de-orbited onto the moon surface, using its remaining fuel to decelerate as much as possible, and to restrict its landing zone as much as possible. After a rather harsh landing, what remains of the satellite would be chiefly raw materials (aluminium, copper, plastics, some chemicals), to be scrapped and smelted by subsequent lunar missions.
For the price of lifting an additional quantity of fuel, more than its weight in valuable materials would have been transported to the moon.
Who is to pay for that extra fuel ?
Having transferred valuable materials to the moon is not an immediate benefit to anybody.
The benefit of it would come in secundary phases of the colonisation of the moon, when the base nucleus would have to be extended. It would be used to manufacture structural elements or components of heavy machinery.
The only immediate benefit would be the decongestion of Earth's orbit, and the reduction of risk due to space debris. As such, one could consider the transfer of obsolete satellites to the moon as an « environmental » cleansing, just as municipal garbage disposal. It could be included in the lifetime of the product from conception on.
For existing satellites, the graveyard orbit could be managed by an international agency : a « slot » on this orbit would have to be rented, making the extra fueling cost a viable alternative to the graveyard orbit. The « rent » money would be used to transfer older satellites to the moon. Present owners of graveyard satellites could « sell » their slot and thus finance a refueling of their space object.
2. A second life for ressuply ships.
ISS ressuply ships (Progress, ATV etc.) are usually filled with refuse from the Space Station, and de-orbited, consuming themselves on re-entry.
These spacecrafts have interesting features : their equipment is still operational (for instance, solar panels and batteries), they can be pressurized and used by humans.
They carry objects that are no longer of use on the ISS, but still useable as such or as source of parts. Some examples :
- Belts used to stash supplies could have other structural uses in a lunar colony
- Old computers can still function, be cannibalised for parts, or retrofitted with a few elements (flashcards replacing rotating hard disks for instance)
- Dirty clothes could be stored in vacuum-sealed bags (who are also discarded routinely), to prevent bacterial growth, and eventually washed on a moon colony decades later, saving up space and weight on lunar missions.
- Discarded experiments still have excellent components such as motors, or could even have a second life on the moon (analysing soil, microbes, colonial biology, monitoring radiation for instance). While not cutting edge, they would fill a niche, liberating and sparing more sophisticated equipment from routine duties.
Beyond these features, a ressuply ships and its content also represents tons of valuable materials by themselves, that can be smelted at the end of its lifetime.
These crafts are built in relatively large numbers and high frequency. Unlike satellites, they could be designed for a second life of service, with minimal alterations, such as :
- the possibility to be refueled
- additional connectors for electricity
- the possibility of remote controlled lunar landing.
A ressuply ship would leave the ISS loaded with discarded equipment, be placed on graveyard orbit until there is an opportunity to refuel (for instance, using residual capacity of refueling spacecraft), and then transport itself and its cargo to the moon.
Once it has landed, using its solar panels and battery, it could power rovers or be added to a local power network for microfactories etc. Once the base is built, its cargo could be cleaned, refurbished or recycled and the craft in itself would serve as a pressurized storage area. Even the fuel tank could be eventually cleaned and used for storage of industrial liquids.
3. Solar furnace.
What uses could satellites have if they could be spared from a brutal landing on the moon ?
At the end of its lifetime, a satellite's solar panels and batteries are not working anymore. Solar panels could nevertheless still be folded and oriented.
Given the very smooth surface of these panels, and assuming their surface is not warped, they could be coated with a reflective material that would turn them into mirrors.
The satellite would then have been turned into a heliostat (
Heliostat - Wikipedia, the free encyclopedia Heliostat - Wikipedia, the free encyclopedia
). Several of these could reflect enough sunlight onto a parabolic mirror (that would have to be built purposedly) to create a small solar furnace (
Solar furnace - Wikipedia, the free encyclopedia Solar furnace - Wikipedia, the free encyclopedia
This solar furnace could be used on the moon or in orbit. It would allow :
- the smelting of scrap metal
- with sufficient precision, limited industrial applications, akin to a « poor man's laser ».
- the melting of lunar soil to produce « glass » bricks, with which landing areas and even primitive shelters, cellars or tunnels could be built. A barrel vault (
Barrel vault - Wikipedia, the free encyclopedia Barrel vault - Wikipedia, the free encyclopedia
) made of bricks could carry the weight of a protective layer of soil, requiring only a light and cheap inflatable lifespace within.
The satellite could become a lunar heliostat with a delicate landing, and the addition of a pod and a wheel to orient it horizontally. The addition would take place at the same time as wires to the panels are cut and a derivation is installed. A battery feeds the satellite in energy, for its positioning and djustement, it also has ports to be plugged into the energy network.
4. Waste centrifugal cannon
Resupply ships and an orbital furnace could be combined for another feature. Human waste would be stored onboard the resupply ship in a special container, that could connect to a « brick / pellet » facility attached to the solar furnace.
This waste would then be heated to extract whatever gasses could escape, the gasses being stored as a propellant. The remaining solid mass would be shaped into small spheres of stable mass and size, (« pellets ») perhaps with the addition of a binding material (as an example, enough water to create frozen spheres), or if possible melted into shape. The idea is to use the available mass that is already in orbit.
Heavy colony elements that are meant to land on the moon could use a centrifugal cannon (an electrical motor using battery power) to fire these pellets to decelerate in the early phase.
It would save the cost of lifting the ergols that would otherwise be used to decelerate.
As a small bonus, the pellets could be retrieved at a later time to build up farm soil.
5.Design of spacecraft as an assembly of modules.
Of course, the salvage and reuse of parts would be made considerably easier if spacecraft were concieved from the start with these capabilities. An historical example of such a design was the Zeppelin LZ104 (
Zeppelin LZ104 - Wikipedia, the free encyclopedia Zeppelin LZ104 - Wikipedia, the free encyclopedia
), a WW1 ressuply airship that was meant to have as many dual-use components as possible.
Thank you for ready this far !
|10-01-2011, 09:32 PM||#2|
In the 1970's design studies, reflectors for solar ovens measured 7.4 X 10^5 m^2. I wonder how much smaller they could be made now?
|11-01-2011, 09:18 PM||#3|
While I think these are all great ideas, I sadly don't see them being implemented any time soon. The problem is that these ideas require a long term investment strategy - in a world addicted to short term gains.
In some cases, these ideas would increase the cost of launching the satellite in the first place, which no company concerned with quarterly profits will do.
Most of these ideas require an infrastructure be created. This means a very high expense that won't show any significant return for years. Politicians want to get re-elected every couple years, and CEOs need to show a profit THIS year. Consequently, short term profits often outweigh long term savings - no matter how much could be saved in the long run.
These are GREAT ideas, and I hope someone in power has the foresight and wisdom to implement them. Unfortunately, our corporate and political cultures haven't shown any real commitment to a long term future. I suspect nothing like this will happen until we start losing satellites to collisions with space junk because LEO is just too polluted.
|11-01-2011, 09:59 PM||#4|
SA 2010 Soccermaniac
One issue is that this all requires a very extensive industry in space. An industry that isn't going to magically exist to fulfill itself (in other words, it needs a purpose), and isn't likely to bootstrap itself into existence.
The other issue is that spacecraft are very high-tech, highly intensive, highly sensitive pieces of equipment. They need to be constructed and serviced in highly controlled, highly capable facilities. It is not a case of "smelt some metal, then hammer it into a satellite".
And it is not even limited to spacecraft, or similarly high-tech pieces of technology, but even surprisingly simple objects. Their problem is not that the material needed to make them needs to come from Earth, but that the labour and facilities and infrastructure needed to make them does not exist off of the Earth. It can be 'ported' to space, but not without difficulty.
The remains of violently deorbited satellites might well be more difficult to collect than your average lunar resources. And saving dirty clothes for a Moon colony decades later? I don't know, that sounds very... desperate to me.
I think the key to any 'space plan' is better launch vehicle infrastructure. Nothing should supplant the importance of this part of spaceflight. Being the first step into space, it is obviously immensely important.
Of course the Big Bad Question, is this: who pays for these lunar colonies? Who bothers? Why do they exist? What do they contribute to everyone else, what profit do they turn?
Yes, I know asking that question is 'pessimist' behaviour, and is questioning the 'Space Future' ideal. But it is a valid question. No moon colony is ever going to be built if people just stand around and say "sometime in the future, magic will happen and the Space Future will come true". The only way it can happen is if people try to find out how to make it happen, and come up with the reasons that really are good enough.
|11-01-2011, 10:32 PM||#6|
Joking apart, that made for a very interesting read, thank you very much!
|11-02-2011, 06:24 AM||#7|
As far as re-use and re-cycling goes, near term (read - next 50 years ) target is closed-cycle life-support. Consumables are much more important mass-wise than spacecraft or ground facility structures. This means having much better wastewater/urine purification techniques which don't require batch operations by crewmembers. This means improved throughput and reliability for Sabatier etc. reactors. This also means growing carrots and salad in space. As far as old clothes go, there is an urgent need to provide spacefarers with laundry services.
All in all, I think that logistically, consumables take precedence over cannibalizing spares from incompatible spacecraft and re-manufacturing/re-testing them in orbit. The only exception that may warrant further study is salvaging FPGAs from anything that floats in the space nearby, and doesn't require fuel waste to fetch it (a VERY narrow niche, I'd reckon).
As n0mad23 said, vacuum deposition techniques would be very welcome...
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