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Spacecraft can be constructed out of hydrogen-rich plastics, rather than aluminium. [37] Mass and material shielding: Liquid hydrogen, often used as fuel, tends to give relatively good shielding, while producing relatively low levels of secondary radiation. Therefore, the fuel could be placed so as to act as a form of shielding around the crew.
Space travelers have spent by 2007 over 29,000 person-days (or a cumulative total of over 77 years) in space including over 100 person-days of spacewalks. [51] Usual durations for individuals to inhabit space on long-duration stays are six months, [52] with the longest stays on record being at about a year.
Space medicine is a developing medical practice that studies the health of astronauts living in outer space. The main purpose of this academic pursuit is to discover how well and for how long people can survive the extreme conditions in space, and how fast they can re-adapt to the Earth's environment after returning from space.
The warm neutral medium produces most of the 21-cm line emission from hydrogen detected by radio telescopes, although atomic hydrogen in the cold neutral medium also contributes, both in emission and by absorption of photons from background warm gas ('H I self-absorption', HISA). While not important for cooling, the 21-cm line is easily ...
Astronautical hygiene evaluates, and mitigates, hazards and health risks to those working in low-gravity environments. [1] The discipline of astronautical hygiene includes such topics as the use and maintenance of life support systems, the risks of the extravehicular activity, the risks of exposure to chemicals or radiation, the characterization of hazards, human factor issues, and the ...
Space colonization has been in a broad sense referred to as space settlement, space humanization or space habitation. [16] Space colonization in a narrow sense refers to space settlements, as envisioned by Gerard K. O'Neill. [17] It is characterized by elements such as: settlement and exploitation, [18] as well as territorial claim. [19]
The Bussard ramjet is a theoretical method of spacecraft propulsion for interstellar travel.A fast moving spacecraft scoops up hydrogen from the interstellar medium using an enormous funnel-shaped magnetic field (ranging from kilometers to many thousands of kilometers in diameter); the hydrogen is compressed until thermonuclear fusion occurs, which provides thrust to counter the drag created ...
(H is the chemical symbol for hydrogen, and "I" is the Roman numeral. It is customary in astronomy to use the Roman numeral I for neutral atoms, II for singly-ionized—HII is H + in other sciences—III for doubly-ionized, e.g. OIII is O ++ , etc. [ 1 ] ) These regions do not emit detectable visible light (except in spectral lines from ...