Search results
Results From The WOW.Com Content Network
Planetary habitability in the Solar System is the study that searches the possible existence of past or present extraterrestrial life in those celestial bodies. As exoplanets are too far away and can only be studied by indirect means, the celestial bodies in the Solar System allow for a much more detailed study: direct telescope observation, space probes, rovers and even human spaceflight.
While Earth is the only place in the Universe known to harbor life, [10] [11] estimates of habitable zones around other stars, [12] [13] along with the discovery of thousands of exoplanets and new insights into the extreme habitats on Earth where organisms known as extremophiles live, suggest that there may be many more habitable places in the ...
Surface planetary habitability is thought to require an orbit at the right distance from the host star for liquid surface water to be present, in addition to various geophysical and geodynamical aspects, atmospheric density, radiation type and intensity, and the host star's plasma environment. [2]
Optimistic habitable zone (OHZ): a zone where liquid surface water could have been on a planet at some time in its past history. This zone would be larger than the HZ. Mars is an example of a planet in the OHZ.: it is just beyond the HZ today, but had liquid water for a short time span before the Mars carbonate catastrophe, some 4 billion years ...
The immediate needs for breathable air and drinkable water are addressed by a life support system, a group of devices that allow human beings to survive in outer space. [15] The life support system supplies air, water and food. It must also maintain temperature and pressure within acceptable limits and deal with the body's waste products ...
Direct human presence in space was achieved with Yuri Gagarin flying a space capsule in 1961 for one orbit around Earth for the first time. While direct human presence in open space, by exiting a spacecraft in a spacesuit, a so-called extravehicular activity, has been achieved since the first person to do so, Alexei Leonov, in 1965.
This model fits the pattern of pulses of highly developed life appearing, diversifying and going extinct with astonishing rapidity through the Cambrian and Ordovician periods, and also explains the extraordinary genetic variety which appeared over this period." [31] This theory, however, is a fringe one, and is seen as being unlikely. [32]
For organ dose calculations, NASA uses the model of Billings et al. [23] to represent the self-shielding of the human body in a water-equivalent mass approximation. Consideration of the orientation of the human body relative to vehicle shielding should be made if it is known, especially for SPEs [ 24 ]