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Acute abdominal pain is a medical emergency which requires diagnostic facilities not available on board spacecraft. It could require emergency return from LEO or mission abort in cislunar missions. One of the causes of acute abdominal pain is renal stones.

https://pubmed.ncbi.nlm.nih.gov/26456109

Bone loss and renal stone risk are longstanding concerns for astronauts. Bone resorption brought on by spaceflight elevates urinary calcium and the risk of renal stone formation... Regardless of exercise, the risk of renal stone formation increases during spaceflight. A key factor in this increase was urine volume, which was lower during flight in all groups at all time points. Thus, the easiest way to mitigate renal stone risk is to increase fluid consumption.

Prolonged microgravity causes significant calcium loss in bones (10 times the rate seen in Earth-bound osteoporosis), thereby increasing the risk of kidney stones. https://www.nasa.gov/mission_pages/station/research/benefits/bone_loss.html

Between 1% and 15% of people globally are affected by kidney stones at some point. In 2015, they caused about 16,000 deaths worldwide… By far, the most common type of kidney stones worldwide contain calcium. https://en.wikipedia.org/wiki/Calcium_oxalate#Kidney_stones

Acute abdominal pain in an ISS crewmember would necessitate return to Earth, along with the other crew in that Soyuz/Crew Dragon crew group. The same event on a Lunar mission would cause a mission abort. On a Mars mission...?

Since the risk of kidney stones can be reduced by maintaining adequate urine volume, "which was lower during flight in all groups at all time points", does NASA routinely “police” astronaut urine production (monitor urine production and enforce fluid consumption)?

Woody
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    Might it be less messy to police fluid intake? – BrendanLuke15 Dec 14 '21 at 17:15
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    Space travel is not for the squeamish! Dilution of calcium salts is critical. As well as oral fluid intake, urine volume is affected by perspiration, respiratory loss and metabolic water production . Urine collection also allows measurement of salt concentrations and trace blood detection which can be the first diagnostic sign of stones. – Woody Dec 14 '21 at 17:34
  • AFAIK (source) there is no on orbit processing of urine, so that would be a pretty piss poor (forgive me, I couldn't resist) response time for predicting kidney stones. (i.e., your urine gets back to Earth the same-ish time you do...) – BrendanLuke15 Dec 14 '21 at 17:45
  • Urine volume can be measured in microgravity. Quantitative dipstick tests are available for everything from specific gravity, blood and chemistry to pregnancy. Dipstick urine testing has already arrived at the ISS https://blog.healthy.io/company-news/healthy-in-space – Woody Dec 14 '21 at 18:05
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    @BrendanLuke15 they process the urine on the US side of the ISS (or they did in 2014 when I got out of the game) https://space.stackexchange.com/q/49419/6944 https://space.stackexchange.com/a/26745/6944 https://space.stackexchange.com/a/45727/6944 – Organic Marble Dec 14 '21 at 18:20
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    @OrganicMarble good catch, I should have said analysis, like proposed in the question. – BrendanLuke15 Dec 14 '21 at 18:22
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    Woody can you define what you mean by "police"? Do you mean "monitor", or do you mean "enforce a certain amount of production per individual"? – Organic Marble Dec 14 '21 at 18:24
  • @Woody Link indicates dipstick testing is not @ ISS yet "Early next year, when the Ax-1 spaceflight docks at the International Space Station..." (Axiom mission hasn't launched yet) & supports my lack of in-situ (analysis) claim: " One factor complicating such research has been the need to capture urine in space, freeze it, and test it back on Earth..." – BrendanLuke15 Dec 14 '21 at 18:24
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    By "police" I mean "monitor and enforce" rather than just measure. Urine volume... "which was lower during flight in all groups at all time points" indicates that self-motivated fluid intake by astronauts is insufficient to compensate for increased calcium excretion. This increases the risk of preventable mission-threatening medical emergencies. – Woody Dec 14 '21 at 18:57
  • different but related: Does extended microgravity increase the rate of kidney stones in astronauts? Do these lead to medical complains/discomfort while still in space? – uhoh Dec 14 '21 at 20:16
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    @Woody, that "monitor and enforce" aspect should go into your question then, to make it clear what you're asking without reading into the comments... – AnoE Dec 15 '21 at 08:00
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    @BrendanLuke15 Well, "Today's coffee is tomorrow's coffee!", as Scott Manley couldn't help remind coffee aficionado Christina Birch; the successful introduction of the system was cause for an adequate toast in 2009. The astonishing thing for me is that before recycling they must have launched tons of drinking water in supply runs during a mission, only to discard it into space. A no-go for a Mars mission for sure. – Peter - Reinstate Monica Dec 15 '21 at 08:11
  • To continue this line of thought: On generation ships or other very long term missions the bodies of the deceased will most likely be recycled in one way or another as well, just as they are on spaceship Earth. Cixin Liu made a big drama of it in Trisolaris but in all reality it's not. – Peter - Reinstate Monica Dec 15 '21 at 08:27

1 Answers1

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For shuttle:

  • There was no enforcement of and no policy existed regarding urine production per crewmember.
  • Even if such a policy had been desirable, there was no way to monitor per-crewmember urine production.

The shuttle toilet (formally, "Waste Collection System (WCS)") had no telemetry associated with it. (See this answer for a WCS overview) The responsible flight control group EECOM had to infer when toilet ops were ongoing by monitoring other signatures in the orbiter systems:

  • AC current signatures from operation of the WCS fans
  • Change in pressure over time (dp/dt) of the cabin atmosphere for a toilet flush
  • Quantity changes in the waste water tank

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Source: Shuttle ECLSS Training Manual (annotations mine)

This answer does not apply to dedicated life science experiments such as those conducted during the Spacelab Life Sciences missions which may have monitored per-crewmember urine production using a Urine Monitoring System.

Organic Marble
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  • Individual 24 hour urine collections were performed on ISS 3-6,8, and 11-14 as part of the potassium citrate stone prevention study. https://ntrs.nasa.gov/api/citations/20070008213/downloads/20070008213.pdf Results showed markedly lower stone formation risk with higher 24hr urine volumes. – Woody Dec 14 '21 at 23:04
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    @Woody your comment appears irrelevant to this shuttle-focused answer. – Organic Marble Dec 14 '21 at 23:06
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    Since the shuttle no longer flies, the answer itself is irrelevant to the posted question. But the information in the answer is interesting so thank you for the contribution. – Woody Dec 14 '21 at 23:12