Thursday, June 13, 2013

HABITATS CAN ORBIT

Habitat for Humanity is a great organization which provides affordable shelter for those of us who can least afford it.

It is a noble cause and deserves our enthusiastic support.

However, the real habitats for humanity will come
when humanity puts approaching asteroids to much better use than as themes for action movies.

Some asteroids will be refashioned as habitats
for sizable human populations.



Habitats will orbit about Solar System objects:
Earth, other planets, moons of Earth and other planets, Sol itself, and even large asteroids.

They will provide comfortable abodes for many people
as well as many types of production facilities.




Dr. Gerald O'Neill postulated the first habitat
to orbit the Earth at the Earth-Moon Lagrange 5 (L5) point.

Perhaps O'Neill's "Island One" might orbit Earth at L5, and his much larger Island Three might orbit Sol at either 60 ahead or 60behind Earth in its Solar orbit (Earth-Sol L4 and L5).
 
Extracts from "High Frontier..."
HabitatLinear Vel.Diam.PeriodCircum.
Island 147 m/seci457.2 mii30 sec1,436 m
Island 2  94 m/seciii1,800 m60 seciv5,655 m
Island 3v179 m/secvi6,437.4 m vii113 sec20,224 m

v= (g*d/2)d (given)T = C / vC = π d
Above table references extracted values from O'Neill's book
i. (pg 97) "Island 1 Diameter = 1,500 ft" = 457.2 m
ii.. (pg 59) "Island 1 Rotation Period = 31 sec" 
iii.. (pg 93) "Island 2 Diameter = 1,800 meters"
iv.. (pg 93) "Island 2 Circum = 4 miles" = 6.44 km
v. (pg 38) "Island 3 Linear Velocity = 400 mph"=179 m/s
vi. (pg 38) "Island 3 Diameter =  4 miles "=  6,438m
vii. (pg 38) "Island 3 Rotation Period = 120 sec"
The High Frontier: Human Colonies in Space was written in 1976 by Dr. Gerald O'Neill, a brilliant scientist who had previously achieved fame as the inventor of the storage tube for particle accelerators. His book describes a habitat, a large hollow, cylinder which rotates around its longitudinal axis to produce centrifugal force. A carefully selected angular velocity would create centrifugal "g-force" such that occupants inside the outer hull would experience "equivalence", same gravity experience as if static on Earth's surface.
Acceleration from Centrifugal Force
Following table adjusts some O'Neill values.
Hab.RadiusRad. Vel.Circum.PeriodAng. Vel.
rvCTω
Isl-1225 m47.1 m/s1,414m30s12°/s
Isl-2900 m94.2 m/s5,655m60s6°/s
Isl-33,600m188.5m/s22,619m120s3°/s

Given(g×r)2 π rC

v
v

r
×180°

π
π g = v2/r = 9.80665 m/sec2;  thus,
v = √(r×9.80665m/sec2)
Habitats can be "parked" in convenient orbits around large bodies such as the Sun, the Earth, other planets, even moons such as Luna (Earth's moon), Europa (a Jovian moon), Titan (Saturn's largest). 
Thought Experiment (TE) presumes it's possible to park a habitat adjacent a Near Earth Asteroid (NEA) and fly in close formation. While traveling same orbit as NEA, habitat's human crew could harvest construction materials and volatile ices.  If NEA periodically crosses planetary orbits (such as Earth and Mars), it could possibly become a "cycler", a habitat which routinely rendezvouses with certain planets.
Habitat Sizes. O'Neill described three habitats: Islands One, Two and Three which differ in size; different sizes give these habitats different deployment capabilities.  Length of cylinder does not directly cause angular velocity, the main factor affecting habitat's g-force.  However, length does correlate with habitat's mass; thus, to angular momentum.  Thus, more length leads to more habitat mass which leads to more force needed to attain required spin for desired centrifugal force to simulate gravity.
 ASTEROIDS AS ABODES




ASTEROID PROVIDES AVAILABLE MASS
A typical asteroid's considerable mass might provide:
  • Shielding to protect payload from radiation hazards.
  • Raw materials for construction.
  • Fuel to change orbits and/or change orbital position
  • Material for terraforming soil.
  • Oxygen for life support.
  • Life sustaining water; many asteroids have hydrated clays or even ice.



Radiation Hazards
can prove fatal to unprotected humans throughout the Solar System .
  • High energy cosmic rays require constant shielding; they are an ever present health threat in deep space.  Over long periods (years to decades), their cumulative effects become even more dangerous . 
  • Occasional high energy Galactic Cosmic Rays (GCRs) produce secondary radiation,  an even greater hazard.  To plan for worse case, habitat designers must include much more shielding then needed for normal conditions to ensure adequate protection for the infrequent high energy GCRs.
  • Regions of trapped solar wind particles produce very high radiation which dramatically increase during magnetic storms near certain planets.
  • Solar Proton Events (SPEs) are bursts of energetic protons accelerated by the Sun. Though  infrequent, they produce extremely high radiation levels. Without thick shielding, SPEs can cause acute radiation poisoning and death.
  • Coronal mass ejections from the Sun are highly dangerous; they quickly prove fatal to humans unless protected by massive shielding.
Since the worst case impacts are so great, prudent risk management calls for radiation shields which "over protect" most of the time.  Launching this mass from Earth would be prohibitively expensive, but an asteroid host would have abundant mass for this purpose.
Asteroids as Destinations
Main Asteroid Belt (between orbits of Mars and Jupiter) contains many thousands of objects. Some are very large; too large to transform into habitats.  However, these larger asteroids would make excellent way-stations and would provide much needed resources. EXAMPLES:
The largest Asteroid Belt Object, Ceres,
is actually a planetoid; thus, it is spherical. .
It probably has a rocky core
covered by an icy mantle.
Another large asteroid, Vesta,
has a reflective surface
with a much different composition;
 perhaps a nickel-iron core,
olivine mantle, and basaltic crust.






Yet another, Hygiea, 
seems to be entirely
carbonaceous chondrite.
Sylvia is a large collection 
of smaller asteroids, 
perhaps once a solid object
now broken up
due to disruptive impacts.
Typical Asteroid.  Typical asteroid is much smaller than Ceres and irregular in shape.  Eons of collisions have reduced most asteroids to collections of dust, pebbles and boulders which fly in close formation throughout their orbit. This loose agglomeration  has benefits; it'll be much easier to extract the desired elements. Composition  A typical asteroid will likely prove to be a good source of building material. In addition to basic basalt,  it contains carbonaceous chondrite, nickel, iron, and many other minerals.

Available Sunlight.

Dr. O'Neill discussed co-locating large mirrors with Earth orbiting habitats.
These mirrors could direct large quantities of sunlight to the habitats for ample power.
Perhaps, very large mirrors can provide Solar power to habitats throughout the Asteroid Belt and beyond.

Asteroids as Greenhouses
Many asteroids contain ices: water, methane, ammonia, carbon dioxide and others.
If a small, ten meter asteroid were completely enclosed by an transparent, inflatable sphere; then, a few simple resources (1/4 carbon dioxide,1/3 oxygen, 1/3 water vapor) at only 1% Earth  atmosphere (i.e., .01 air pressure at sea level) would suffice to grow some kinds of plants.
Of course, this type of air differs from Earth air which is 80% Nitrogen.  Thus, add Nitrogen for Earth like atmosphere.

Near Earth Asteroids (NEAs)
NEAs are typical asteroids which cross Earth's Solar orbit. While tiny compared to Ceres, a typical NEA has sufficient mass for a human habitat.
It is large enough to provide plenty of resources, but small enough to provide an easy landing pad and even easier launch site.
NEAs are often considered potential hazards because of the remote possibility they might impact the Earth; INSTEAD, they should be considered as mining opportunities; even better, consider them for future abodes.
Water Throughout the Solar System
Human habitats will need lots of water for lots of reasons.  Possible water sources include the following:
1) Earth's oceans will be the most likely source of water for first few habitats. Perhaps water can travel via space elevators to Geo-Synchronous Orbit (GSO).  From GSO, process payloads of seawater for eventual use by space bound humans. This method would be slow and expensive, but it's a start.
2) Nearby Comets.  For space travel, water from space is much cheaper than water from oceans. A preeminent source of space borne water is the numerous comets throughout the Solar System. As stray comets come to within vicinity of Earth, capture them and use their contents.
3) Collected Comets. Both Earth water and occasional near Earth objects have rigid limitations. Therefore, first interplanetary missions should concentrate on detecting and collecting comets throughout the Solar System. Asteroid Belt Objects (ABOs) will likely have considerable quantities of water and other ices.
4) Kuiper Comets. Eventually, missions to Kuiper Belt will routinely harvest comets. Even further out, missions will harvest bountiful comets from reported billions in the Oort Cloud.

Habitats can deploy in the following ways.
1. First habitats will most likely orbit Earth,
-----a. Geosynchronous orbit
-----b. Earth-Moon Lagrange points.
-----c. perhaps even orbiting Luna.
2. As habitats grow larger, they will disperse, first in Terran orbit around Sol. Such habitats will eventually house millions of humans, possibly at the Sol-Earth Lagrange points.
----L4 habitat would lead Earth in its orbit by 60° (Perhaps name it, Alpha (α))
----L5 would lag Earth by 60° (Maybe name it, Omega (Ω)).
3. Eventually, habitats could orbit moons of the Gas Giants or even establish their own Solar orbits (perhaps to mine asteroids).  Some habitats will be "towed" by smaller craft with powerful propulsion systems and then deployed into orbits at other planets.
New Economy. As interplanetary vessels prowl the Solar System and collect materials, they will bring them not to Terra Firma (Earth) where they might prove hazardous to the Mother Planet, but to Alpha and Omega to be easily processed.

Habitats Alpha and Omega will buy these materials from the interplanetary vessels; thus, detecting and collecting plantesimals will prove to be lucrative.

Alpha/Omega will process these materials to add considerable value to them and then sell them to other habitats while these habitats are departing Earth to their destination further out in the Solar System or perhaps another stellar system.
Thus, living on Alpha/Omega will also prove lucrative. 
Business Plan Development ... "13 REVENUE GENERATING ACTIVITIES"  Rescue Vehicles, Aldrin Earth – Mars Cycler. vehicles, Asteroid Retrieval and Processing. Vehicles, Telepossession Probes and Landers. www.lpi.usra.edu/meetings/roundtable2006/pdf/westfall.pdf
Some Useful Links

Humans will construct and inhabit many different habitats;
orbiting habitats (orbiters) will orbit other Solar objects;
cycling habitats (cyclers) will use transfer orbits to periodically return to Earth;
some migrating habitats (migrators) will even cruise to the stars.
SLIDESHOW




VOLUME 0: ELEVATIONAL
VOLUME I: ASTEROIDAL
VOLUME II: INTERPLANETARY
VOLUME III: INTERSTELLAR




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