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Q113 (CDS-II/2011) Science & Technology › Space & Defence Technology › Space exploration missions Answer Verified

It has been observed that astronauts lose substantial quantity of calcium through urine during space flight. This is due to

Result
Your answer: —  Â·  Correct: B
Explanation

Astronauts experience significant calcium loss through urine during spaceflight primarily due to microgravity. In a weightless environment, the skeletal system is 'unloaded' as it no longer needs to support the body's weight against Earth's gravity [t2][t4]. This lack of mechanical stress leads to bone demineralization, where calcium leaves the bones and enters the bloodstream [t2]. Consequently, the kidneys filter this excess calcium, resulting in hypercalciuria (increased urinary calcium excretion) and an elevated risk of renal stones [t1][t2]. Research from missions like Skylab and Mir confirms that urinary calcium levels can increase by 60-70% within days of entering microgravity [t2]. While other factors like diet and lighting play minor roles, the removal of the gravity vector is the fundamental cause of this physiological shift [t2][t5].

Sources

  1. [1] https://ntrs.nasa.gov/api/citations/20100030546/downloads/20100030546.pdf
  2. [2] https://www.nature.com/articles/s41526-022-00194-8
  3. [3] https://www.ncbi.nlm.nih.gov/books/NBK217835/
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