As a response to the Vestal Lunar LEO & Lunar Tourism Concept Challenge, brief comments on hygiene issues in the Vestal Lunar System (VLS), which are important for offering clients a comfortable tour, will be made below. The comments involve three parts, including (1) toilet design, (2) spatial arrangement of toilet and shower, as well as (3) waste treatment. The relevant parts in the slide deck are page 11-13.
1. Toilet design:
1.1 Toilet Needs: Two types of toilets are needed in VLS, one for the Upper or Lower Deck and another one for the Spin Gravity Ring. A complete solution should be able to support a crew of 8 users for 30 days, a maximum estimate based on the Vestal Lunar Concept, while controlling odor, accommodating different types of waste (urine, feces, vomit, diarrhea, menses), and different gender users (female and male). The NASA's Lunar Loo Challenge, supported by the Artemis program for seeking new designs for a toilet that will work both in microgravity and lunar gravity, was held last year and may provide an option or clue for the need in the Upper or Lower Deck on VLS. However, a design for a toilet that can work well in the Spin Gravity Ring may remain unavailable.
1.2 NASA's Lunar Loo Challenge:
1.2.a. Requirements: Please refer to https://www.herox.com/LunarLoo/guidelines
for the requirements described in the challenge guidelines.
1.2.b. Result: Three official winners and two additional honorable mentions were selected. Please refer to https://www.herox.com/LunarLoo/update/3543
for the challenge result.
1.2.c. Disputes: In comments on the challenge result made by several participants, controversy arose as to whether the selected winning designs fully met the requirements. On the other hand, it is obvious that the degree of automation of these designs may be too low for the need of tourism. Please refer to the discussion under the following threads:
1.2.d. Other options: Some participants of the NASA’s challenge also provide their own designs other than the winners’ and honorable mentions’. Please refer to the following URLs.
1.3 Toilet for the Spin Gravity Ring:
1.3.a. Reclined toilet: In the Spin Gravity Ring, seats are reclined to minimize gravity force difference between feet and head (page 12). A toilet that can work well in it is expected to be reclined, too, for the same purpose. Therefore, the design will be very different from current layouts we ever see.
1.3.b. Development schedule: For being able to start incorporating the new toilet into a proven HLS Starship in 2027, the design of a new toilet for the Spin Gravity Ring should start soon.
2. Spatial arrangement of toilet and shower: To provide redundancy in the events of equipment failure, the spatial arrangement of the toilet and the shower at a deck (the Upper or Lower Deck) or ring (the Spin Gravity Ring) structure may be optimized to allow them to share fresh water supply and waste water treatment capability. For example, if the self-contained water of a toilet system fails, the water used for the neighboring shower can be diverted to the toilet and vice versa. On the other hand, to save water resources, the gray water (page 12) produced by taking showers might be used to flush a toilet.
3. Waste treatment: A variety of waste will be produced by using a toilet and a shower, including urine, feces, vomit, diarrhea, menses and waste/gray water. As VLS will be deployed for long-term in orbitals, a water recycling system for treating the waste might be installed on it to reduce the needs of shipping water. While the waste can be removed from VLS by regular visits of Cargo Pods, such a system might be financially more advantageous in a long term, in terms of saving fuels.