Xjyuk

This answer immediately sparked the question in my mind of how space suits manage water excretion from the person wearing them. I am aware that the astronauts had to wear diapers since one may need to pee during an hours long EVA. However this only manages the liquids exiting the person.

If during the course of a long and strenuous EVA astronauts lose several pounds of liquid to sweat and breathing, how does the EVA suit manage all this water? They may have a thermal management system to reduce sweating, but that doesn't solve the breathing issue. I can't imaging they let water/water vapor build up inside the suit, it would make the suit environment extremely uncomfortable.

The shuttle (and ISS) EMU (Extravehicular Mobility Unit) has a condensing heat exchanger as part of its ventilation loop. The condensate is stored, used for cooling, and the excess is drained after each EVA (Extravehicular Activity).

Reference: Shuttle Crew Operations Manual: https://www.nasa.gov/centers/johnson/pdf/390651main_shuttle_crew_operations_manual.pdf page 2.11-7

The water produced by perspiration and breathing is withdrawn from the oxygen supply by being condensed in the sublimator and is carried by the condensate circuit. The water is then sent to the water - storage tanks of the feedwater circuit and
added to their supply for eventual use in the sublimator. In this manner, the PLSS is able to maintain suit
cooling for a longer period than would be possible
with just the tank’s original water supply.

From Suited for Spacewalking https://www.nasa.gov/pdf/143159main_Suited_for_Spacewalking.pdf

PLSS = Portable Life Support System

I'm sure there are different techniques for different space suits, but here's an example of how it is done for the ISS suits:

The key to handling body heat and sweat is the Liquid Ventilation Garment, or LVC. This is essentially what looks like a full body thermal underwear, but it is lined with tubes that pass water through them. If you heat up, cold water is passed through the tubes, cooling you down. The idea is to keep you cool enough that you don't sweat much.

After the water is heated, it passes through a heat exchanger to cool it down again, then it's recirculated. If necessary, the water can be passed into a sublimator, where it passes though small holes into the vacuum of space, where it sublimates away, carrying heat with it.

If a person does still sweat, the LVC has a wicking layer that will absorb the sweat, and through some mechanism the sweat is collected and added back to the cooling water supply. The problem here is that as you work harder, the temperature of the water in the cooling tubes has to be lower to transport enough heat, which can make it feel cold. Add in a damp undergarment, and astronauts can feel very uncomfortable with this system. Also, you are losing a lot of water to space through the sublimator - maybe a kg of water for a four hour EVA. That's not only expensive, but it limits EVA time.

There is a new LVC being developed for the next gen of suits which will have porous micro-tubules stitched into it that can actually absorb the sweat, the transport it back to the cooling system for recycling. That will allow astronauts to use sweating as their natural heat control.

In the future, mechanical counterpressure suits that don't need to be pressurized will have semi-permeable materials that allow sweat to pass through and sublimate away all across the surface of the suit, which would allow for more passive cooling and a more natural feeling environment.

Link to a paper on the new generation of LVC garments being considered:

Multi-Functional Cooling Garment for Spacesuit Environmental Control

And a paper from 1969 describing the old system for cooling:

Regulation of Thermal Sweating in EVA Space Suits