(Just a quick note)
I'm new to blogging so when I first
thought of this topic I wrote a whole smorgasbord of things I wanted to discuss.
In and of itself, this was a good idea but trying to put all of that content
into a single blog entry - blech!
I'm going to try to complete the
other sections but do each section as a separate blog entry.
This will be section IV of my blog The Case for Space
How to pay our way
Really, this is a far more troublesome question than it first seems. Space has nearly unlimited quantities of raw resources (space, energy, minerals, and simple chemicals). However, it doesn't have infrastructure and getting into space in the first place is a huge problem. Here's a more extensive essay called "Why Build Orbital Space Colonies?" It covers both sides of the equation (the troubles and rewards).
So let me set up a couple of
scenarios:
1) Humans have a robust presence in
space with multiple habitats (on the Moon or in orbit). The colonists in those
places need water, air, fuel, building materials, power, and raw resources to
establish their own industries. They could get all of these things from the
Earth but at a shipping cost of $10,000/lb of concrete, they're not going to be
able to build a very big house!
2) If the infrastructure to produce
such things were already in place, it might be possible to toss the materials
up from the surface of the Moon for substantially less money (say $25-$50/lb)
or heck, just have the colonists live there.
The problem is that this is a
catch-22, the only time it makes sense to build a space habitat is if there's
extensive infrastructure. The only reason to build infrastructure is to support
extensive space habitats!
The solution to this is called "bootstrapping"
- lofting major components of infrastructure into place to kick start the
development of space infrastructure. However, right now there's very little
reason for doing this.
Materials
Realistically almost any material
you could want is available in space from hydrogen to diamonds. The questions
we should ask, "What resources can we get," "how much will it
cost to get them," and "for how much can we sell it?"
I've provide a link to a detailed
discussion of the Economic feasibility of mining asteroids. The
come to the same conclusions that I have, namely that the first target is
finding a source for volatiles to use as a propellant.
There's another argument for going
to space and that is for the first time ever, modern industrial humans will
start to run out of resource over the next few decades. From copper to
platinum and rare earth metals, humans will need to find these resources from
somewhere other than the Earth (the reality is the Earth has plenty of these
things but we can't get to them because they mostly reside in the core).
In orbital dynamics, the exchange
currency is called "delta V" and that means change in velocity. To
get from the Earth's surface into Low Earth Orbit (LEO), you need to
"spend" about 7.6 km/s delta V (meaning accelerate by 7.6 km/s - but
in most cases you won't actually be going 7.6 km/s when done because some of
that was sapped by climbing out of the Earth's gravity well!).
There's a great table that gives us
most of what we want at the Atomic
Rockets web site.
Here's another table that gives us
most of the rest of what we want Delta-v
budget
The closest destination from a delta
V expenditure perspective is the Moon for about 5.7 km/s. There are several
Near Earth Objects (NEOs) we can get too with only 4.0 km/s or so from LEO and,
based upon the total mission propellant requirements, represent the best source
of materials. Mars also is "close" requiring only 6.1 km/s but is a
lot higher if you include landing on Mars' surface (10.2 km/s BUT you do get
some free aero braking too). Mining the main asteroid belt would also be useful
and would require a much lower delta V than landing on Mars.
Each of these is a potential source
for space construction materials.
What sort of materials? Well it
depends upon where you go.
from LEO to
|
Outbound
|
Inbound
|
||
delta V (km/s)
|
delta V (km/s)
|
|||
Rocket
|
Aerobrake
|
Rocket
|
Aerobrake
|
|
NEA
|
4
|
0
|
0.8
|
3.2
|
Earth-Sun
|
4.15
|
0
|
0.05
|
4.1
|
L4/L5
|
||||
Moon
|
5.7
|
0
|
1.6
|
4.1
|
Mars
|
3.8
|
6.4
|
6.4
|
3.8
|
This table shows how much it
"costs" to get there and back. Note, without aero braking, the
propulsion costs are reciprocal (it costs as much to get back as it does to get
there). However, with aero braking it is becomes much cheaper to get materials
back to Earth from certain locations (especially the L4/L5 and NEA locations).
This strongly supports a mission
profile in which automated (these will have to be automated because we can't
afford to send people to this location at this time because it's too expensive
AND too dangerous) machines are sent out once to setup an automated facility
and then materials are sent back on the "cheap" return trajectory.
The problem of course is that machines eventually break. This probably means
developing sophisticated telepresence and a generalized set of work robots that
can repair the mining machines.
Once deployed, the mining station
may not require propellant to send materials back to Earth. Instead, we can use
technology like a coilgun (mentioned in my first entry) and power from a
nuclear power plant to launch refined materials back to the Earth. This technique requires no (or very little)
propellant.
This leads to another question, what
sort of materials should we send back?
I've researched large numbers of
"economics of asteroid mining" essays that quote the spot price for
iron and indicate that we'll just drop 1,000,000s of tons of pig iron on Earth
and someone is going to pay billions of dollars for that material.
This is wrong.
Operations in space are expensive. Returning
material to LEO or Earth is expensive too. If the value of our materials by
weight is lower than our costs, then will we lose money, no matter how much of
it we can return to the Earth!
Our profits will be calculated based
upon this formula $$ = weight * (value - costs). We can't make a profit off the
stuff that costs more to get to the Earth than we can get for the material once
it reaches the Earth. Furthermore, materials returned from space could never
compete with cheaply extracted materials form Earth (e.g.). This means we'll never make a profit selling
asteroid iron on Earth.
So any space project will only send
materials that are very valuable back to Earth (to pay off our investors). We
could make a profit by selling materials useful for space infrastructure in LEO
(water, silicon, construction metals, rocket fuel, and other materials).
Therefore, we send ONLY platinum group metals and rare earth elements back to
Earth. We send water, bulk construction materials, and various other elements as
needed.
Now when you shoot a gun (or mass
driver), the gun has recoil or kick. We'll use our mass driver to ship
materials but it will also provide thrust to the asteroid. The mass driver will
do more than just ship our product materials back to Earth; it will also be the
asteroid's engine. We might be able to use it as a cheaper way to get the
asteroid back to LEO too!
Using gravity assists and aero
braking we might be able to make each mass driver shot perform two functions
(sending back materials and nudging our asteroid towards Earth). This would
mean that many of our mass driver shots will not put tour buckets on direct
return courses, instead they'd be taking the long way back to Earth (via flybys
of other planets). This may not be worthwhile in the end since such shots would
require on-board guidance and propulsion systems to correct their courses.
An alternative would be to use our
mining slag as propellant to nudge the asteroid toward Earth and only send
buckets directly to Earth when they were full of valuable materials
(propellant, PGM, & REE).
In addition, here's another table
that shows what you can expect to find when you get there:
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Here's schematic of the Near Earth
Asteroid 433 Eros and the trajectory of the NEAR
spacecraft that rendezvoused with it:
Here's an image of the asteroid itself:
The first thing we will need to get
will be propellant - without that, there is no way we can build the rest of the
infrastructure.
Asteroids possess higher
concentrations of both Platinum and similar metals (called Platinum Group
Metals) and elements. An additional resource that would be valuable in space
but perhaps not worth sending back to Earth would be radioactive elements
(especially those suitable for fission reactors such as Uranium, Thorium,
Polonium, etc.).
This is a link to a website (called "Asteroids")
which discusses some of the major asteroid types: M - metallic, S - Stony, and
C - Carbonaceous.
I apologize for running out of steam
on this topic (asteroid resources). I have a whole lot more to say but I've
already written a lot. I intend to return to this topic in another blog when
I've finished writing those details (which are as of 10/1/10 still in draft
form).
Free pollution
This really isn't a valuable
resource in and of itself but this should be a very important point for those
concerned about the Earth's environment. Many of the industrial processes
necessary to sustain our technological society require a great deal of
pollution generating processes.
In some cases, these processes can
be moved into space and we can allow those pollutants to be swept away by the
solar wind.
This particular usage of space would
necessarily come after the development of a robust space infrastructure. The
ability to mine, process, and ship the required materials would be a definite
prerequisite to the ability to manufacture and finish products for shipping
back to Earth.
How much do we now pay for pollution
disposal and counter measures?
The US spends about
$4.2 billion on superfund site clean
ups per year.
$30 billion on the BP oil spill
$4 billion per year on nuclear
reactor waste disposal
Other areas which could benefit (but
I couldn't easily find numbers) include
Highly toxic chemical wastes
Organic wastes.
Any industry we can move off of the
Earth means we also remove their waste products from our biosphere. Any
reprocessing or recycling would recover chemicals valuable to the colony. The colony could dump pure waste without
worrying about contamination.
Clean energy
When we develop space infrastructure, this element will be
second only to mining the raw materials in importance. At first space
infrastructure would rely upon the use of nuclear power because of its very
high energy density. High impulse (aka good propulsive efficiency) plasma drives
(such as the Hall Effect thruster shown below) require a power
source capable of producing a great deal of power. Furthermore other processes
such as drilling, smelting, and launching materials back to Earth (via a
coilgun - see below) also require substantial amounts of power.
Hall Effect Thruster in operation
Schematic of a coilgun in operation
These power requirements would drive
the size of the solar panel arrays to be much too big (optimistically 5000 sq
meters per megawatt) to economically launch the structures from Earth in the
first missions. In addition, a fact most solar power optimist’s neglect is that
solar panels degrade over time. In space, this will happen much faster (due to
particles impinging upon and degrading any coating over the PV cells). Meaning
after a very short time a photovoltaic (PV) panel array sized to provide 1
megawatt of power will produce less. After many years, it will produce much less
than 1 megawatt.
Given that the panels cost $3.13 per
Watt and electricity on Earth costs $0.10 per kW/hour, then just to pay back
the costs of the panels would take 4 years. That excludes any space
transportation cost for the materials and its assembly!
On the flip side of that, space
based solar power may be an answer to the world's energy problems!
Large structures are not difficult
to make, the sun always shines in space, the sun will continue shining stably
for the next 4 billion years, and there's multiple mechanisms for harness solar
power in space that make it attractive for use in space.
PV panels cost a lot ($3.13 to
generate 1 watt) due to the cost of the very pure silicon it takes to make them
(unlike computer chips in which the major cost is the cost of constructing the
fabrication plan). Silicon is abundant on both the Earth and in space; the
trick is in refining it to ultra-high purity. After constructing an
infrastructure for building these panels, space refining has two significant advantages
over Earth refining, weightlessness, and a very hard vacuum.
Space power satellites would transfer their
energy to Earth by using microwave beaming. Such a concept would permit us to
produce our power in space and beam the power to Earth - with the hope of
eliminating the need for messy power plants on Earth. In fact, once they were
in place, they would require minimal upkeep. However, their upkeep would
include the replacement of individual cells or perhaps entire stations over
time to accommodate the degradation of the cells over time.
However, such a concept would
require two things: large quantities of raw materials from space mining
operations and receiving stations on Earth for the microwaves beamed from
geosynchronous orbit. The microwave receiving stations on Earth would need to
be ten miles in diameter (but farming and other activities could continue
underneath the thin-wired antenna structure that would not block much light).
Would we be willing to sacrifice so much land for "clean energy"?
Would people concerned about anthropogenic global warming support such a
project with their political backing?
I don't know the answers to those
questions, I can only point out that it is FAR cheaper to produce our energy on
Earth using fossil fuels and nuclear power than it would be to generate it in
space.
Tourism
Tourism will never be a major driver
in the development of space. However, if the development of space
infrastructure becomes a marginal activity, just barely making economic sense,
then space tourism could certainly tip the balance into making it more
economically viable.
For instance, it costs approximately
$10,000 per pound to launch mass into low earth orbit (LEO). If the typical man
weighs 200 pounds and he needs 100 pounds of support (oxygen, water, and food)
then it would cost about $3,000,000 to send that person into space. The
Russians would charge $20,000,000 or more for this same trip. Even after adding
in costs like training, this could easily be a profitable venture.
Of course, the number of people who
can afford the cost of this trip to space is limited, but it is an income
stream.
Science
Science doesn't really provide a
strong profit motive. However, some science can only be done in space. Any
organization able to provide economical access to space will also be able to
perform this science at a much lower cost.
A case in point is president Obama's
decision to cancel all manned space activities by the US. Now NASA will need to
purchase manned space flight from the Russians anytime we wish to have a manned
presence in space. If a company could provide cheaper access to space, then the
US would purchase those launches from the more economical space launch company.
This could amount to hundreds of millions of dollars per year.
Just like space tourism, this will
not provide a primary motivation for creating space infrastructure but it could
provide an added opportunity for making money.
Colonization
The most successful of English
colonies were called Joint Stock Companies. The basic concept was/is
investors (and some colonists) invested their own money into the venture.
Stockowners were given the right to participate in the decision making process.
They were also entitled to a share in the profits of the colony.
Another means of investing in the
company would be similar to the concept of bonds. Essentially the owner of
these bonds (called debentures), were entitled to a set rate of return
regardless of whether the colony earned a profit or not. On the other hand, the
owners of the debentures were not entitled to any share of the profits.
This mechanism of financing space
colonies gives the colonists an element of self-rule, a motive to make the
venture profitable, a share in those profits, and a means of generating the
capital necessary to start the venture.
In my opinion the two main obstacles
would be risk (the colonists would be risking their lives) and the costs. I
think both of these obstacles link directly back to infrastructure or its lack.
Without an established and reliable means to provide supply essentials (air,
water, food, power, safe shelter, and fuel); delaying the colony's supplies would
doom colonists to a swift death. In some ways this is similar to what the
English colonists faced when coming to the new world but those colonists never
faced death by oxygen starvation, lack of water, or similar necessities (many
did starve or die of exposure).
In conclusion, I think the
colonization of this type could be a great way to finance the expansion into
space of human colonies BUT that this can only occur after the initial creation
of infrastructure to supply those colonies with essentials.
Survival
Someday, another whopper asteroid will
smack the Earth. Within the next couple of hundred years, multiple meteors
large enough to take out a city will hit the Earth. Over the next couple of
10,000 years, an asteroid large enough to take out a country will hit the Earth.
Over the next 100,000,000 years, an asteroid large enough to wipe out every
human on the Earth will hit us.
Scientists are certain that these
things will happen. We just don't know
when.
Someday, the super volcano that is
Yellowstone Park will erupt again. In
fact, it is now over-due for an eruption. When that happens most of North
American will become uninhabitable. In fact, this region produces 1/2 of all of
the grain produced in the entire world - so this will cause mass starvation
across the world too. Not to mention the effects of all of the dust an ash the
volcano will throw into the air.
This is very likely to happen, but we
don't know when.
In about 1-2 billion years the Earth
will run out of water - more precisely, most of the water will work its way
into crustal rocks and not get re-liberated by plate tectonics. In fact, the
global quantity of surface water has slowly been declining over the history of
the Earth. Eventually we'll run out. When that happens, there will be nothing
to trap and sequester carbon dioxide.
This will put the Earth into a run-away greenhouse effect that will
mimic that of Venus.
If the water crisis doesn't get us
first, the gradual warming of the Sun will (the Sun has already heated up by
25% since it first started shining). Over about the same 1-2 billion year
period the Sun will warm the atmosphere enough that some atmospheric water will
achieve escape velocity and leave the Earth (more precisely the water molecules
will get high enough to become dissociated by UV light and its hydrogen will
escape).
These last two are a certainty and
we even know about when they'll happen.
Sooner (as exemplified by the former
example) or later (as exemplified by the latter) all humans left on the Earth
will die. Without any colonization of space, humanity will die with them. With
the colonization of space, some of humanity will survive AND if we see the threat
early enough, some of those on the planet will have a hope of escaping.
I'm a firm believer in not keeping
all of our eggs in one basket on this regard.
Go back to my earlier discussions on
The Case for Space
Go to my next discussion called The Case for Space V: Lightcraft
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