Expedition Six Prepares for STS-114
Expedition Six Commander Ken Bowersox, Flight Engineer Nikolai Budarin
and NASA ISS Science Officer Don Pettit completed a busy workweek Friday.
The day's activities included work with science investigations and
preparations for the arrival of STS-114. 

Budarin conducted the third run of the Russian plasma crystal experiment.
Pettit set up equipment for the renal stone experiment. The experiment is
studying potassium citrate as a possible remedy to the formation of
kidney stones
 
   
Renal Stone Risk During Space Flight: Assessment
and Countermeasure Validation (Renal Stone) 
Principal Investigator: Peggy A. Whitson, NASA Johnson Space Center,
Houston, TX 

 
  Increment 3 Onward 
Experiment delivered by STS-105 for mission 7A.1 and will continue for
approximately 40 months. 
Renal Stone Flight Schedule (JPG image)  
Renal stones (also known as kidney stones) form out of minerals that are
washed out of the circulatory system by the kidneys. The patient must
wait until the stone moves, painfully, through the urinary tract on its
own (from the kidney, through the ureter, to the bladder, which expels it
from the body) or seek medical help to either have the stone broken up or
surgically removed—all difficult options for an astronaut in orbit. 
 
Significance 
The development of a renal stone in an astronaut could have serious
impacts to mission objectives and crew health. This experiment is
designed to test potassium citrate as a possible countermeasure to the
increased risk of renal stones during varying lengths of space flight.
Both long-duration and short-duration crew members will be tested through
urine collection before, during, and after the flight. This increased
risk may be linked to bone mass loss, also a result of microgravity.
Investigating a possible countermeasure, crew members will take either
potassium citrate or a placebo in this double blind experiment. Potassium
citrate is a proven Earth-based therapy, but has not yet been tried in
space. Twenty subjects on the Shuttle and ISS will be involved in this
study. Through food, fluid, and exercise monitoring, other influences on
urine mineral components will be accounted. This experiment will also
combine data from ground-based and previous Shuttle missions with data
taken from the specific 20 subjects to look at the effect of hydration as
another countermeasure. 

Previous Missions 
Similar experiments have flown on several Shuttle flights, including
Shuttle/Mir. 

Outreach Web Sites 
NASA Fact Sheet: Renal Stone Risk During Space Flight 
SPORTs Page: Renal Stone Risk During Spaceflight 
Critical Path Roadmap (Human Exploration and Development of Space)