Protection From Hostile External Environment
- Radiation: Some very large space habitat designs could be effectively shielded from cosmic rays by their structure and air. Smaller habitats could be shielded by stationary (nonrotating) bags of rock. Sunlight could be admitted indirectly via mirrors in radiation-proof louvres, which would function in the same manner as a periscope.
- For instance, 4 metric tons per square meter of surface area could reduce radiation dosage to several mSv or less annually, below the rate of some populated high natural background areas on Earth. Alternative concepts based on active shielding are untested yet and more complex than such passive mass shielding, but usage of magnetic and/or electric fields to deflect particles could potentially greatly reduce mass requirements.
- If a space habitat is located at L4 or L5, then its orbit will take it outside of the protection of the Earth's magnetosphere for approximately two-thirds of the time (as happens with the Moon), putting residents at risk of proton exposure from the solar wind.
- See Health threat from cosmic rays
- Heat rejection: The colony is in a vacuum, and therefore resembles a giant thermos bottle. The sunlight to radiated energy ratio can be reduced and controlled with large venetian blinds. Habitats also need a radiator to eliminate heat from absorbed sunlight and organisms. Very small habitats might have a central vane that rotates with the colony. In this design, convection would raise hot air "up" (toward the center), and cool air would fall down into the outer habitat. Some other designs would distribute coolants, such as chilled water from a central radiator.
- Foreign objects: The habitat would need to withstand potential impacts from space debris, meteoroids, dust, etc.
Radar will sweep the space around each habitat mapping the trajectory of debris and other man-made objects and allowing corrective actions to be taken to protect the habitat. Meteoroid strikes would pose a risk to a space habitat much stronger than they do to the Earth, unless there should be developed a method to avert them, because a space habitat does not possess a sheltering atmosphere.
Read more about this topic: Space Habitat
Famous quotes containing the words protection, hostile, external and/or environment:
“No: until I want the protection of Massachusetts to be extended to me in some distant Southern port, where my liberty is endangered, or until I am bent solely on building up an estate at home by peaceful enterprise, I can afford to refuse allegiance to Massachusetts, and her right to my property and life. It costs me less in every sense to incur the penalty of disobedience to the State than it would to obey. I should feel as if I were worth less in that case.”
—Henry David Thoreau (1817–1862)
“We feign pity when we want to demonstrate our ascendancy over feelings of hostility: but usually in vain. Whenever we notice this, there is an accompanying surge in those hostile sensations.”
—Friedrich Nietzsche (1844–1900)
“A tempest cracked on the theatre. Quickly,
The wind beat in the roof and half the walls.
The ruin stood still in an external world.
It had been real. It was something overseas
That I remembered, something that I remembered
Overseas, that stood in an external world.”
—Wallace Stevens (1879–1955)
“For those parents from lower-class and minority communities ... [who] have had minimal experience in negotiating dominant, external institutions or have had negative and hostile contact with social service agencies, their initial approaches to the school are often overwhelming and difficult. Not only does the school feel like an alien environment with incomprehensible norms and structures, but the families often do not feel entitled to make demands or force disagreements.”
—Sara Lawrence Lightfoot (20th century)