| Rank | Abbreviation | Meaning |
|---|
| ***** | SPACE RATIO. | See passenger space ratio.
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| **** | SPACE AVAILABLE. | Term used to refer to any remaining seating or lodging sold at the last minute, generally at a discount.
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| **** | PASSENGER SPACE RATIO. | A statistical measure that compares the total public space of a cruise ship to the passenger capacity, resulting in the theoretical amount of public space allotted to each passenger. A high passenger
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| *** | SPACE TOURISM. | An emerging and very expensivetravel specialty involving sending passengers on suborbital flights that offer a brief experience of weightlessness and thrilling views of the earth below.
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| * | ADV SPACE RES | Advances in Space Research
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| * | PLANET SPACE SCI | Planetary and Space Science
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| * | TRANS JPN SOC AERONAUT SPACE SCI | Transactions of the Japan Society for Aeronautical and Space Sciences
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| * | REV GEOPHYS SPACE PHYS | Reviews of Geophysics and Space Physics
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| * | GEOPHYS SPACE PHYS | Geophysics and Space Physics
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| * | SPACE | Sidereal Polar Axis Celestial Equipment
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| * | SPACE | Spatial and Chemical Shift-Enclosed Excitation
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