1. Space Colonization Terra-forming
ASTR 1420
Lecture 26
Not in the Textbook

2. Space Colonization
Space colonization in this lecture is a narrow sense : colonization by human and in the Solar System only (say within next few millennia).
Also known as space settlement, space habitation, etc.
Space colonization = self-sufficient human habitation outside Earth
on planets
on satellites
In free space
outside the Solar System eventually

3. Reasons why some humans will live in Space
Survival of our species
$$$ : solar power satellites, asteroid mining, space manufacturing, etc.
Resources : sufficient supply of rare materials
lessen the burden on the Earth
spread our beauty(?) to the Universe
Insulin crystal growth in space (left) versus on Earth (right)
Movie (Moon): Sam Blackwell  "Sam Bell (Sam Rockwell) is nearing the end of his contract with Lunar. He’s been a faithful employee for 3 long years. His home has been Selene, a moon base where he has spent his days alone, mining Helium 3. The precious gas holds the key to reversing the Earth’s energy crisis.
He3: a light, non-radioactive isotope of helium with two protons and one neutron. It is rare on Earth, and is sought for use in nuclear fusion research. The abundance of helium-3 is thought to be greater on the Moon (embedded in the upper layer of regolith by the solar wind over billions of years)
“The long-term survival of the human race is at risk as long as it is confined to a single planet. Sooner or later, disasters such as an asteroid collision or nuclear war could wipe us all out. But once we spread out into space and establish independent colonies, our future should be safe.” Stephen Hawking

4. Space solar power station (immediate feature)
Advantages of space:
No atmosphere!
No day-night limitation!
No weather!
~40 times efficient!
A space-based solar power station will use an array of mirrors to concentrate the sun’s rays on photovoltaic cells. The electricity produced is converted into a powerful microwave beam directed at an antenna on Earth, where it is converted back into electricity and fed to the grid.

5. Space Solar Power Station
Solar energy is abundant in the space (no night, no cloud, no atmosphere).
Energy (watts/m2) = 1366 / d2, (d is distance in AU)
In developed countries, energy usage ~ 1000 watts/person
Export created energy back to Earth

6. Things to be considered for space habitats
mass per person
radiation shielding
minimum size
leakage rates
cost
schedule

7. Materials and Energy
using material from Earth is very expensive due to larger gravity of Earth.
Also, large-scale projects will impact the Earth community
Use materials from Moon, Mars, large asteroids
however, these objects lack volatiles (Hydrogen and Nitrogen).
Jupiter’s Trojan asteroids have high content of water ice and other volatiles.
Mars and Moon colonies may need to use nuclear energy
waste heats?  requires a large radiator!

8. Transportation and Communication
expect millions of shuttle launches..  requires cheaper and less pollutant transportation devices.
hypersonic spaceplane, space elevator, mass driver, etc.
all other rocket technologies we studied last lecture!
Communication
for more distant colonies (e.g., Mars), a real time communication is impractical due to the light travel time (7 – 44 minutes lag).
or voice mails…
mass driver = electromagnetic catapult

9. Minimum population size
To prevent inbreeding  reduced fertility, genetic disorders, infant mortality, malfunctioning immune system, etc.
In 2002, anthropologist, John H. Moore.
population of would allow normal reproduction for 60—80 generations (~2,000 population for a long-term survival).
“50/500” rule: conservation biologists, 50 is the minimum to prevent an unacceptable rate of inbreeding, 500 is required to main overall genetic variability.

10. Life support We need air, water, food, mild temperature, and gravity.
In space, closed ecological systems must recycle (or import) resources
Nuclear submarine : carry out missions for months without resurfacing
although they recycle oxygen, it is not “closed” system.
they extract oxygen from sea water and dump CO2 outside.
Genetic engineering, terrahumanism, cyborg
to be more compatible with the environment?
Radiation protection:
against harmful cosmic rays and solar wind.
Either we need 5—10 tons of blocking (absorbing) material per square meter of surface habitat area. Or we can make the hull-metal electric to protect against charged particles.
Two experiments; 1991 and 1994

11. Biosphere 2 Biosphere 2 in Arizona
a small, complex, manmade biosphere supported
8 people for 1+ years!
after 1 year, oxygen had to be replenished.
savana & ocean
coastal fog desert
Size of 2.5 football field. $200 million dollars
crew quarters

12. Bernal Sphere
a type of space habitat intended as a long-term home for permanent residents, first proposed in 1929 by John Desmond Bernal (Irish Scientist).

13. O’Neil’s habitat Good locations are L4 & L5 points.
While teaching undergraduate physics at Princeton University, O'Neill had students design large structures in space, with the intent to show that living in space could be desirable. Several of the architectures were able to provide areas large enough to be suitable for human habitation. This cooperative result inspired the idea of the cylinder and was first published by O'Neill in a September 1974 article of Physics Today.
The UL image is one of O’Neil’s three designs called “Island Three”: two very large, counter-rotating cylinders, each 5 miles (8 km) in diameter and 20 miles (32 km) long

14. Other variants
Toroidal and Spherical colonies. Bernal Spheres.

15. Objections
Even if the technology becomes available, and the costs of deploying a program relatively low, and the likelihood of success relatively high, only a small number of people would directly benefit from a colony (either enthusiastic colonists or high risk commercial interests), leaving most of financial burden on the public.
Humans are treated as assets
If the main reason is “insurance” against the annihilation of human, then why people on Earth need to pay for something useful only after their deaths?

16. Counter arguments argument of need
“population growth and limited resources on Earth”
By 2040, population will be 10 billion!
argument of cost
IRAQ+Afghanistan war = $813 billion + $632 = about $1.445 trillion
argument of benefits
despite the high cost of initial investment…
space colonies can provides precious metals, gem stones, power, etc.
US government spent $580 billion in social security, $560 billion on medicare while $16 billion for the NASA budget.

17. Space mining
the smallest Earth-crossing asteroid 3554 Amun (see orbit) is a mile-wide (2 km) lump of iron, nickel, cobalt, platinum, and other metals; it contains 30 times as much metal as Humans have mined throughout history, although it is only the smallest of dozens of known metallic asteroids and worth perhaps USD $20 trillion if mined slowly to meet demand at 2001 market prices.

18. Terraforming

19. Terraforming
process of deliberately modifying atmosphere, temperature, surface topography, or ecology of celestial objects to fit our purposes = planetary engineering

20. Terraforming Mars Two things: atmosphere and heating
Once it is terraformed to be similar to Earth, will it be able to sustain the condition over geological timescales (10s Myrs)?
Small size is the main issue…
Re-heating the core of Mars is considered an impractical solution
the slow loss of atmosphere could possibly be counteracted with ongoing low-level artificial terraforming activities.

21. How? Bring one of ice moons of Jupiter or Saturn
Put several, large solar mirrors to direct light to the Martian surface (to increase T)
Magnetic field!!!
 induce an impact with ~1,000 km object to melt the whole thing which will re-liquefy the core

23. Terraforming Venus
removing most of the planet's dense 9 MPa carbon dioxide atmosphere
reducing the planet's 450 °C (850 K) surface temperature
Addition of O2
Reduce the length of day(?) : 117 Earth days

24. Terraforming Venus How? Solar shade at L1
reflector on the ground or in the atmosphere
use of genetically engineered bacteria (CO2  other organics)
induce an impact with km asteroid (to eliminate atmosphere)

25. Europa a good potential candidate for terraforming
One advantage to Europa is the presence of liquid water
Difficulties
huge radiation (in the middle of Jupiter’s radiation belt)
require the building of massive radiation deflectors, which is currently impractical
satellite is covered in ice and would have to be heated
need for oxygen  electrolysis of ocean water
On Europa, a human would die from the radiation within ten minutes on the surface

26. Chapter/sections covered in this lecture : Not from the textbook
In summary…
Important Concepts
Important Terms
Space habitat
Pros and cons of space habitats
Space mining
Various designs
Terraforming Mars, Venus, etc.
Terraforming
Chapter/sections covered in this lecture : Not from the textbook