Spacesuit Compatibility Requirement

tahanson43206 · 2024-09-07 07:22:07

Recently (fall of 2024) it was revealed that Boeing Corporation had developed/created space suits that are incompatible with ones created and operated by SpaceX.

This might not have seemed a problem to the Boeing employees working on the project, but it became obvious when the Boeing Starliner crew discovered their suits were incompatible with SpaceX when the Boeing Starliner failed, and NASA decided to return the Boeing astronauts to Earth in a SpaceX capsule.

Compatibility between systems produced by different vendors is a defining characteristic of modern civilization. Such compatibility does not happen by accident. It occurs because there an agency of government that is responsible for setting and enforcing standards.

Often (if not always) standards are first created by a vendor, and the government agency evaluates various proposals and settles on one that is then defined as ** the ** standard.

It is past time for a government agency to set standards for safety equipment used on US based spacecraft.

Not all equipment can be given standards this early in spaceflight, but the docking mechanism for the ISS is standardized, and that achievement sets a benchmark for other critical subsystems, such as hose connection to oxygen supply, or electrical connection from a spacesuit to a spacecraft.

This topic is available for NewMars members who might be willing to investigate to see what connections for spacesuits to spacecraft are in use today in various countries.

Ultimately a consensus will occur, but how that will happen is unclear at this point.

It is possible that permanent incompatibility will occur, such as right and left hand driving depending upon which colonial power had influence at a particular time, or 120 VAC vs 240 VAC.

(th)

tahanson43206 · 2024-09-07 07:32:10

This post is reserved for an index to posts that may be contributed by NewMars members over time.

(th)

SpaceNut · 2024-09-07 07:56:35

First reported in 8-24-24 in my post Boeing has been quite silent on what it is that makes it not compatible.

GW, indicated that there was a suit that would fit the smaller woman of the crew onboard but so far there is none for Butch.

While it may be power it could also be other connection issues where the chosen fittings are the issue and not what its connecting too.

tahanson43206 · 2024-09-07 08:06:18

For SpaceNut re #3

Thank you for supporting this new topic! Please see if you can find more details about the incompatibility.

The only ones I can think of are oxygen and power, but there may be a need for a water connection and even ? a waste connection?

Communications with other members of the crew and the spacecraft would seem a requirement.

All connections need to be standardized across nations if possible, as soon as possible.

Aircraft would have gone through a similar shakeout process.

(th)

SpaceNut · 2024-09-07 08:44:49

Space x suits

Russian suits

Boeing suits

tahanson43206 · 2024-09-07 12:08:25

For SpaceNut re #4

Thanks for the three space suit designs that are currently flying (ie, in orbit). (The Chinese have their own design but I doubt we'll get information)

For all ... I'd like to see the specifications for the two major connections for each of the three non-Chinese designs...

1) The oxygen connector
2) The communications connector

These can be augmented if there are other connections.

For example: Power, water, waste

(th)

RobertDyck · 2024-09-10 05:21:03

Things that might be relevant:
Suit pressure, gas mix, cooling system, glove compatibility with switches and touch screen, does the suit fit in a seat, when suit is inflated can the astronaut operate controls?

Mercury suits had poor joints. They were adapted from air force pressure suits for pilots operating high altitude aircraft. The suit was designed so you can't stand when the suit is inflated. Just sit in the seat, feet on control peddles, arms forward to operate controls. Gloves were not designed to open fingers flat when inflated, just curl around the joystick. Suit joint mobility was improved with successive suit designs, but Mercury suits were an emergency measure in case the capsule lost pressure. It wasn't designed for a space walk, certainly not for the Moon, just remain seated and operate controls.

SpaceX Dragon capsules are unique: they have a touch screen instead of physical switches. Their suit glove fingerss have a coating that works with the touch screen. There's a "stick" you can buy at dollar stores that is a thin steel tube with a rubber end. The soft rubber end is compatible with smartphone and tablet touch screens so you can use them while outdoors in winter and wearing winter gloves. SpaceX gloves have that rubber on glove fingertips. Does Boeing gloves?

Apollo had toggle switches with metal rails on either side. If an astronaut floated and bumped his back into the control panel, the little rails would ensure he didn't activate every switch on the panel. A finger must fit between the metal rails to operate a toggle switch. If glove fingers when inflated are too thick, they won't be able to operate switches. I believe Boeing Starliner has similar toggle switches.

Space Shuttle astronauts wore orange ACES suits during ascent and descent for later missions. ACES suits do not have a liquid cooling system. Apollo A7L and A7L-B suits did. White EMU suits also do. But ACES was for emergency use in case of cabin decompression only, not for space walks, so no cooling system.

I haven't been able to find details of either SpaceX or Boeing's suit. NASA suits have details available.

RobertDyck · 2024-09-10 11:17:00

From SpaceX website

Quick Disconnect
A single connection point between the suit and vehicle provides the life support system for the astronauts: avionics for communications, cooling systems, and pressurization of the suit, all via an easy-to-use plug-in.

Texas Tech University Libraries: Development of the Crew Dragon ECLSS

C. Space Suit Interfaces
Crew Dragon uses open loop, air-cooled, SpaceX-developed intravehicular pressure suits (Figure 5). The suit provides each crewmember with environmental protection, occupant protection, and emergency pressurization during contingency events, and is designed to remain as invisible as possible to the crew during nominal operations. The suit is a fully integrated garment that includes permanently attached boots, gloves, and a helmet. An umbilical is connected to each suit which distributes recirculated cabin air for suit cooling, delivers nitrox or oxygen for suit leak checks and contingency operations, and contains an electrical interface for pressure sensing and communications when the crew is suited.
The suit fluid module which feeds the umbilical is a small valve tray mounted inside the seat structure shell containing the main components of the suit fluid management system: a solenoid isolation valve with manual override, a regulator, flow control orifice, suit air check valve, and buddy breathe quick disconnect. The buddy breathe functionality permits a crewmember in a seat with a malfunctioning solenoid valve or regulator to receive gas from an adjacent seat.

Boeing: Spacesuit

Lightweight, leather gloves are enabled for tablets and touchscreens.

So the only issue I see is the connector. Boeing suits don't use cabin air for suit cooling, but that has to be sealed off anyway when cabin decompresses. An adapter should be possible.

RobertDyck · 2024-09-11 09:38:36

YKK - manufacturer of zippers: YKK partners with David Clark Company to produce Boeing’s New Crew Space Transportation (CST)-100 Starliner Spacesuit

The Starliner spacesuit utilizes YKK’s PROSEAL® watertight and airtight zipper for the suit’s main entry and for its hood-like soft helmet. The PROSEAL® zipper is an integral part of the survival function of the suit and is capable of holding pressure in excess of 4 psi.

SpaceNews: SpaceX reveals EVA suit design as Polaris Dawn mission approaches

comments...
SpaceX website lists 5.6 psi as the suit internal pressure or about 1.3psi higher than an EMU.
...
Watching Scott Manley latest vid, who bothered to watch the X press conference, unlike me. The Dragon cabin will have its pressure lowered to 5.1psi., which is the suit pressure. For comparison NASA EMU suits are at 4.3 psi.

SpaceX: Human Spaceflight
scroll down to "The Suits", then click "EXTRAVEHICULAR ACTIVITY (EVA)". Then click the circle over the right arm.

DUAL CAPABILITY
Used for both intravehicular and extravehicular activities, redundant helmet seals, lockouts on latching mechanisms, and added internal valves for fault tolerant pressure control ensure suit robustness and safety when operating at 5.1 psia during the EVA.

If the chair life support connector for a SpaceX Dragon is designed to provide 5.1 psi oxygen when the cabin is decompressed, but zippers for the Boeing suit are only rated to 4.0 psi, then there's a problem. No point wearing a spacesuit if it won't work in event of cabin decompression.

tahanson43206 · 2024-09-11 10:31:41

For RobertDyck re Post #9

Thanks for these additional details about these two existing suit designs.

Your observation about the 4.1 psi vs 5.1 psi pressures caught my eye... I don't know the answer to this, but wonder if the Boeing Suit can maintain it's own pressure? In other words, if the cabin supply is 5.1, and the suit limit is 4.1, can the suit limit pressure to 4.1? That would seem like a good idea, but perhaps Boeing planned for the external supply to handle delivered pressure.

Update: You hinted at the possibility of an adapter for the Boeing suits. Such an adapter might include the pressure metering function.

(th)

RobertDyck · 2024-09-11 12:05:37

I wonder. A Portable Support System (PLSS) supplies oxygen to the helmet, return air to a lithium hydroxide canister. Human lungs do not extract all oxygen so there's significant O2 in exhaled breath. Activated carbon absorbs bad smells such as bad breath. Slowly human metabolism will convert carbohydrates + O2 into CO2 + water. Body fat + O2 also becomes CO2 + water. Number of molecules of CO2 exhaled equals O2 inhaled, so breathing doesn't change pressure. As lithium hydroxide absorbs CO2, pressure is reduced. That is topped up by bottled O2 via a pressure regulator.

An adapter could use a regulator to convert 5.1 psi to 4.0 psi. But return air would require a pressure pump to convert back. That's the issue.

Caveat: the SpaceX website lists pressure for their EVA suit. I assume their IVA suit operates at the same pressure.

tahanson43206 · 2024-09-11 13:16:16

Thank you for the explanation of the situation in Post #11

Just thinking out loud as you work your way through this, it occurs to me that dumping waste air to vacuum might be a solution, if the return air line does not accept the lower pressure.

In the scenario we are discussing, the cabin lost pressure, and all humans are drawing upon the capsule supply. The scrubbing function is not very useful in an emergency, so just dumping to vacuum seems to me to be a reasonable action to take.

This discussion reminds me to check to see how the Polaris Dawn crew are doing. There should be some news by now.

(th)

RobertDyck · 2024-09-11 19:35:00

A study site called BYJU: Gasses: We Breathe In and Breathe Out

If you breathe 100% oxygen, that still means 80% of the oxygen you inhale, will be exhaled. So if you vent exhaled air, that means your oxygen supply will only last 20% as long. Recirculating breathing air results in your oxygen supply lasting 5 times as long. I think you want to do that. So recirculated breathing air from spacesuits must be captured and sent through a CO2 scrubber, even when the capsule cabin has vacuum.

Oh! These numbers apply if using a breathing mask, like a fighter jet pilot's breathing mask. With flap valves so inhaled air comes from one hose, exhaled air goes out another. This image shows exhaled air vented to one side. If a spacesuit helmet does not separate inhaled from exhaled air, then you vent even more oxygen. That results in losing your oxygen supply even faster. I don't see a breathing mask in either the SpaceX or Boeing helmet design.

tahanson43206 · 2024-09-12 05:57:19

For RobertDyck re #13

Thank you for the helpful graphs, and for the image of an aircraft breathing apparatus.

As a reminder for our present readers, but mostly for future ones who will be drawn to the topic, RobertDyck is addressing a situation that has not yet occurred, but which might occur if we have another need to carry passengers with space suits from another vendor in a SpaceX capsule.

RobertDyck has shown us that the air pressure in a SpaceX capsule is 5.1 psi, and that the space suit by Boeing has an internal burst pressure of 4.1 psi.

The issue to be addressed is how the Boeing suit might be fitted with an adapter to allow it to serve reliably if cabin pressure is lost in the SpaceX capsule.

****
For RobertDyck ... The chart you have provided seems (to me at least) to show that it would be beneficial to exhaust only CO2, while retaining the unused Oxygen for the next breath.

If the Boeing suit is fitted with it's own recirculation subsystem (such as a back pack might provide) then that device might be held in reserve in case the cabin pressure is lost.

****
Regarding the SpaceX capsule ... I have no way of knowing how the SpaceX capsule is designed, beyond the information you have provided, but I'm wondering if the subsystem that provides air via hoses to passengers is separate from the one that provides cabin pressure. If cabin pressure is lost the cabin pressure subsystem might try to maintain pressure and thus lose oxygen to the vacuum. I wonder if the existing design considers such emergency conditions?

One thing this topic can provide (if we continue to build it up as we've been doing) is a short course on how to design breathing apparatus for spaceflight.

Links to resources about specific designs would be welcome and helpful, as has been shown in several posts in this series.

(th)

RobertDyck · 2024-09-12 11:12:16

That's brilliant! Yes, that's the solution. An adapter for a Boeing spacesuit would include a lithium hydroxide canister to absorb CO2. Since neither the SpaceX nor Boeing suits have the breathing mask depicted, a fan would be required to circulate air in the Boeing suit. The fan would be powered by the connector to the SpaceX seat.

So: one connector to SpaceX seat. Two hoses to Boeing suit, one inlet, one outlet. Do not vent anything to space. A pressure regulator would reduce pressure from the SpaceX connector to Boeing suit pressure. As astronaut metabolism consumes O2, he/she will produce CO2. As that CO2 is absorbed by the LiOH canister, it will reduce pressure in the suit. But the pressure regulator will release O2 into the suit to top up pressure to required level. The whole PLSS would be the size of a large coffee thermos. A clip could attach it to the SpaceX seat, leaving it dangling under the right side of the seat. Since the SpaceX connector on the seat is located at the astronaut's right thigh.

To answer your question, yes a design feature includes valves to shut off air supply to the capsule in case of decompression. That's used for EVA as well as emergency operation. The SpaceX suit has valves in the seat, while the SpaceX EVA suit has additional valves.

RobertDyck · 2024-09-12 11:39:01

Brief PowerPoint on spacesuit design: spacesuits

RobertDyck · 2024-09-12 11:55:15

I don't have an image of the lithium hydroxide canister for a SpaceX EVA suit or NASA's EMU suit, but here is one for an Apollo spacesuit. It gives you an idea of the size for a single astronaut. All that's needed for an adapter is a cylinder to contain this canister, and the cylinder can have very thin walls. A fan at one end so about 2" (5cm) lid at one end. One Boeing hose attaches to the lid, a hose to the SpaceX seat also attached to the lid, the other Boeing hose attaches to the other end of the cylinder. Pressure regulator either built into the connector for the SpaceX seat, or the cylinder lid.

None of the other features of the PLSS are required, because much is done by the SpaceX seat. The water cooling system isn't needed because both SpaceX and Boeing IVA suits use air cooling. And an IVA suit would only be pressured in case of emergency decompression of the capsule. The only time that has happened is during atmospheric entry, so the suit would be used for several minutes, not hours. The LiOH canister would have an 8 hour capacity, but highly unlikely to be used that long.

kbd512 · 2024-09-12 12:17:24

The new technology used by NASA for CO2 removal is known as an "amine swingbed", and the acronym is "CAMRAS" (Carbon-dioxide And Moisture Removal Amine Swingbed). This particular type of CO2 scrubber is regenerative, meaning it cycles on and off, somewhat like a motor vehicle's catalytic converter. It both collects and then releases the filtered / collected CO2 on a regular cycle, and is electrical / electro-thermo-chemically powered. A heating element heats the amine swingbed up to a higher temperature to release the captured CO2. It has an "air save" and a "water save" feature. This tech was developed for the Orion space capsule as well as the new generations of space suits.

The amine swingbed material consists of granules of very high surface area catalyst that captures and releases the CO2. The air save feature vents CO2 while retaining most of the O2, but I cannot recall how it works. The water save feature uses condensation to condense the water out and prevent it from being rejected into the vacuum of space, which is what Orion and the PLSS does with the collected CO2. The PLSS version of the amine swingbed is known as the "RCA" (Rapid Cycle Amine swingbed) assembly. They're at least up to Version 3.0 right now, the 3rd major and 4th or 5th minor iteration of the technology.

The document below is from 2015:
Rapid Cycle Amine 3.0 System Development

Edit:
As the document above indicates, the latest version, or at least the version from 9 years ago, consumes a constant 2W of electrical power from the life support system's power supply, with a peak consumption of 10W to 12W during regeneration. If the entire suit only uses a constant 10W of electrical power (blower motors for air circulation, CO2 and moisture scrubber / removal, communications, thermal regulation), then a 1kg Lithium-ion battery would last for 25 hours. 10W is also well within the realm of feasibility for a Carbon-based nuclear decay batteries that last for decades. If it's possible to strip the Carbon from the O2 and to truly "close the loop" for personal life support, then you could conceivably wear a suit, in an emergency, for greatly extended periods of time measured in days rather than hours. If you were temporarily stranded, you would not run out of life support capacity for days rather than hours. You'd still need water replenishment with a MCP suit because you sweat through the suit, but we're moving closer and closer to NASA's goal of having a "personal spacecraft" that's more independent of larger vehicles.

Edit #2:
Development of Carbon Dioxide Removal Systems for NASA's Deep Space Human Exploration Missions 2017-2018

Last edited by kbd512 (2024-09-12 12:39:32)

kbd512 · 2024-09-12 12:45:03

They're currently working on this little gem:

Power Generation and Storage - Cryogenic Flux Capacitor (KSC-TOPS-62)

A Device for Solid-State Storage and On-Demand Distribution of Cryogenic Fluid Commodities
Overview
NASA Kennedy Space Center seeks partners interested in the commercial application of the Cryogenic Flux Capacitor (CFC). This new technology capitalizes on the energy storage capacity of liquefied gasses. By exploiting a unique attribute of nano-porous materials, aerogel in this case, fluid commodities such as oxygen, hydrogen, methane, etc. can be stored in a molecular surface-adsorbed state. This cryogenic fluid can be stored at low to moderate pressure densities, on par with liquid, and then quickly converted to a gas, when the need arises. This solution reduces both safety-related logistics issues and the limitations of complex storage systems. Currently, high pressured gasses are stored in vessels with heavy thick walls that require constant pressurization and complex storage systems to limit boil-off. These systems are not well suited to overly dynamic situations where the tank orientation can change suddenly. NASA's CFC address all of the aforementioned issues, simplifying current operations and opening the possibilities for new applications and new markets from cryogenic liquid.
The Technology
Storage and transfer of fluid commodities such as oxygen, hydrogen, natural gas, nitrogen, argon, etc. is an absolute necessity in virtually every industry on Earth. These fluids are typically contained in one of two ways; as low pressure, cryogenic liquids, or as a high pressure gases. Energy storage is not useful unless the energy can be practically obtained ("un-stored") as needed. Here the goal is to store as many fluid molecules as possible in the smallest, lightest weight volume possible; and to supply ("un-store") those molecules on demand as needed in the end-use application. The CFC concept addresses this dual storage/usage problem with an elegant charging/discharging design approach. The CFC's packaging is ingeniously designed, tightly packing aerogel composite materials within a container allows for a greater amount of storage media to be packed densely and strategically. An integrated conductive membrane also acts as a highly effective heat exchanger that easily distributes heat through the entire container to discharge the CFC quickly, it can also be interfaced to a cooling source for convenient system charging; this feature also allows the fluid to easily saturate the container for fast charging. Additionally, the unit can be charged either with cryogenic liquid or from an ambient temperature gas supply, depending on the desired manner of refrigeration. Finally, the heater integration system offers two promising methods, both of which have been fabricated and tested, to evenly distribute heat throughout the entire core, both axially and radially. NASA engineers also applied the CFC to a Cryogenic Oxygen Storage Module to store oxygen in solid-state form and deliver it as a gas to an end-use environmental control and/or life support system. The Module can scrub out nuisance or containment gases such as carbon dioxide and/or water vapor in conjunction with supplying oxygen, forming a synergistic system when used in a closed-loop application. The combination of these capabilities to work simultaneously may allow for reduced system volume, mass, complexity, and cost of a breathing device.

kbd512 · 2024-09-12 12:56:49

For use on the lunar surface and Mars, we'll need:

Mechanical and Fluid Systems - Debris-Tolerant Valve (MFS-TOPS-100)

For Use in Environments with Substantial Dust or other Contaminants
Overview
Innovators at NASA's Marshall Space Flight Center (MSFC) have developed a Debris-Tolerant Valve designed for use in machines/environments with a large quantity of airborne dust or other contaminants. The invention was created for an atmospheric revitalization system on the International Space Station. On the ISS, the use of dried pelletized media in the system caused a problem with the collection of contaminants in the existing selector valve, requiring persistent valve maintenance and replacement. NASA's Debris-Tolerant Valve was offered as a solution and is currently being developed for use in future NASA missions. The new valve implements a novel design that has been extensively tested and offers substantial benefits including extended lifetime of internal valve parts, ease of maintenance, and low-cost manufacturability. Applications for the Debris-Tolerant Valve include use in aerospace or industrial processes.
The Technology
NASA's Debris-Tolerant Valve is designed for use in machines/environments with a large quantity of airborne dust or other contaminants. Valves subjected to airborne contaminants tend to have limited lifetime due to damaged seals, bearings, and other internal components. The Debris-Tolerant Valve design addresses this problem with four core improvements over existing commercial valves that are typically used in dusty or debris-laden processes: (1) a new cylinder design that substantially decreases dust collection within the valve; (2) a rotational valve design that minimizes grinding and packing experienced by the standard ball valve; (3) the use of elastomeric seals rather than the Teflon-based seals used in existing valves which are prone to scratching and subsequent leakage; and (4) a bleed port for fluid intake that allows pressure to build slowly in the valve and eliminates the stirring of dust commonly caused by rapid inflow of air in existing valves. The operational lifetime of NASA's Debris-Tolerant Valve exceeds the lifetime of a standard commercial valve and the existing selector valve used on the ISS by 12X and 6X, respectively. NASA's valve design has fewer parts than existing valves and could be disassembled without tools, enabling easier servicing and maintenance. The Debris-Tolerant Valve is only about one-seventh (1/7) the cost of the existing ISS selector valve.

RobertDyck · 2024-09-12 17:22:28

kbd512: "amine swingbed" is system we discussed on this forum years ago. Analysis showed an issue: which is heavier, silver oxide granules or the batteries needed to power the swing bed? I said silver oxide because it's compact and 100% regenerable. That means CO2 can be baked out. Currently EMU suits use silver oxide sheet metal to adsorb CO2. When Shuttle flew, including when Shuttle serviced ISS, EMU suits used lithium hydroxide. They were upgraded to silver oxide because LiOH is not regenerable, while Ag2O is. Silver oxide is heavier, but over the span of a mission to Mars, a small number of regenerable cartridges have lower total mass than a large number of expendable ones. ISS uses a toaster oven to bake out the CO2. I have a paper from 1997 about using a microwave oven to regenerate silver oxide. It uses granules instead of sheet metal, which is necessary due to management of the microwaves. So comparing silver oxide granules vs an amine swingbed with lithium ion batteries seemed to result in the granules being lower mass for an 8 hour EVA. One reason is the overhead mass of the swingbed, which requires an oven to bake out the CO2. It's not just the amine. The extended duration orbiter pallet for the Shuttle used amine paste painted on styrofoam beads aka peas. The problem with that is too much heat will melt the styrofoam. The pallet for Shuttle solved this by keeping temperature relatively low when baking out CO2, but that results in greater time to bake out. If you want a swingbed to be practical for a spacesuit, you want to keep it small. Keeping it small means rapid cycle. That means you need to increase temperature when baking out. So you need a substrate that isn't going to melt. What did they use for the substrate for the amine?

When you compare lithium hydroxide to an amine swingbed plus lithium ion batteries, the result is dramatically in favour of lithium hydroxide. Again that is only true for single use, not repeated use. However, this discussion thread is about compatibility of IntraVehicular Activity (IVA) suits. Those suits are a safety measure for a capsule entering Earth orbit. Suit helmets will only be closed during the 20 minute (approximate) time to go from Low Earth Orbit to the surface. So we're talking about a suit for emergency use with a life support system that is single use, and expected duration less than one hour.

SpaceNut · 2024-09-12 17:40:30

Stranded NASA Astronauts Are Ditching Boeing Spacesuits For SpaceX Gear: Here's Why

There are significant differences between the Boeing CST-100 Starliner and the SpaceX Dragon, so the Starliner IVA spacesuit and the SpaceX IVA spacesuit are wildly different as well.
For a start, the Boeing CST-100 Starliner lands on solid ground using three parachutes and airbags. The SpaceX Dragon, on the other hand, lands under four main parachutes in the ocean, using two drogue parachutes to slow its descent. The Boeing CST-100 Starliner has a diameter of 15 feet and a length of 16.5 feet. The SpaceX Dragon, meanwhile, is 26.7 feet long and 13 feet wide. As NASA explained in a statement to USA Today, "suits for different providers are not designed to be compatible outside of their own spacecraft, as each suit design must match its respective system."
According to program manager for NASA's Commercial Crew Program Steve Stich, it has always been NASA's goal to "have two dissimilar systems." That is because having an alternative system is key in the event of a failure, like the one we witnessed with the Starliner.

kbd512 · 2024-09-13 08:03:16

RobertDyck,

The CAMRAS and RCA CO2 scrubbers use zeolites, which primarily consist of Aluminum or Silicon and Oxygen. They melt near 1,700C. Silver oxide melts near 280C to form pure Silver. The Silver oxide is likely more compact, but the zeolite has greater temperature stability and surface area, so baking it at high temperature is less likely to be a problem. Silver is a great conductor of electricity, but Tungsten heating elements are more durable. Which one has greater bio compatibility is more of your area of expertise than mine. I suspect it's Silver. I'm not partial to one over the other. I'm merely stating that we have the tech, it's gone through multiple years of testing in space aboard ISS, and it works so well it's now a permanent part of the ISS life support suite.

For the portable RCA system, peak power usage is 12 Watts and average / constant power use is 2 Watts. LiOH is almost certainly lower mass and lower power because it only requires a blower motor. RCA is intended for extended duration usage measured in years (the zeolite catalyst). We now have Carbon-based nuclear batteries in commercial production. Those last for decades. Given the much lower total and peak power required for this new generation of long-duration and nearly-closed-loop life support systems, the equipment contained within the PLSS backpack is approaching the point where an astronaut could conceivably be in their suit for several days if that's what it took to survive.

I'm not asserting that they should deliberately do something like that, I'm stating that on the surface of the moon or Mars, a long duration suit that can first separate CO2 and then regenerate O2 from CO2 might be a really good idea for crew survival. Let's say you're out tooling around in a dune buggy type rover while prospecting for metal ore deposits, perhaps a hundred miles away from real protection. You receive an emergency radio call stating that a solar flare is headed your way. Unfortunately for you and your partner, you don't have enough time to make it all the way back to a real shelter. You have a dune buggy, shovels, extra water, and extra O2. If you sit on your duff in the rover, then you get fried by the massive burst of radiation. If you dig underneath your rover, then you're protected up top, to the extent you can be, by the mass of your rover's battery. You're protected on all sides by digging a shallow foxhole to hang out in for a day or two while that solar flare passes.

If your suit has been designed to provide several days of life support because electrical power and O2 recycling are not an issue, then you survive your ordeal and live to fight another day. It's the same concept behind digging in to survive an artillery or air strike. If you could feasibly escape, then you'd choose to be almost anywhere else but there. If you can't, then hanging out in a foxhole for awhile is better than the alternative. If we have the equipment required to do that, then we may as well use it.

The long duration nature of the life support equipment also allows for greater risk taking without the likelihood that the risk outweighs the reward. I'm not saying that you should dig yourself into a hole, merely because your equipment is good enough to get you out of a bad spot. I am asserting that if we can make this work, then we absolutely should design our equipment that way. As always, superior judgement prevents the need to demonstrate superior skill. Lapses in judgement will inevitably happen. I'd rather we get our crew back so we can question their decision making at a later date, in a more benign setting.

As far as IVA vs EVA suits go, I think we should pursue a single suit design that serves both purposes. There's little harm to having a more capable suit and PLSS, especially when the suit and PLSS designs in question have nominal weight and volume claims. Every capsule should have EVA suits, just in case they're needed, in much the same way that all capsules already have redundant power generation, navigation and flight control computers, thrusters, and propellant reserves, even when most of the time they're not needed. This is forward-looking, rather than backwards. We didn't typically include such suits in the past because our tech wasn't good enough to make the solution fit the size and weight constraints of the capsules. Now our tech is much better and our capsules have much more interior volume. Our rockets have greater lift capability.

RobertDyck · 2024-09-14 19:54:43

Interesting. Very interesting. If compact high power nuclear batteries exist, that solves several problems. One scenario I wrote about was a geologist leaving on a multi-day prospecting trip. A dome tent with built-in air mattress floor. Bring the suit PLSS into the tent for life support. I thought an electrical connector could power the PLSS from the rover, and the river could carry extra O2 bottles.

But an amine swing-bed with a MOXIE. Hmm. MOXIE must generate a lot of heat.

kbd512 · 2024-09-15 11:10:40

RobertDyck,

If Carbon-14 proves impractical, Nickel-63 provides about 5.7W/kg. Strontium-90 provides 460W/kg, with surface temperatures between 700C and 800C. That falls squarely within the range of temperatures sCO2 power turbines operate at. At 50% thermal efficiency, providing 25W of electrical power requires 109g of Sr-90. A heat sink plate covering the rear of the life support pack would be warm to the touch, but it wouldn't burn you. 50W / 288in^2 is only 0.1736W/in^2. Sunlight at high noon is 0.6452W/in^2.

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Spacesuit Compatibility Requirement

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Re: Spacesuit Compatibility Requirement

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Re: Spacesuit Compatibility Requirement

#4 2024-09-07 08:06:18

Re: Spacesuit Compatibility Requirement

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Re: Spacesuit Compatibility Requirement

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Re: Spacesuit Compatibility Requirement

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Re: Spacesuit Compatibility Requirement

#8 2024-09-10 11:17:00

Re: Spacesuit Compatibility Requirement

#9 2024-09-11 09:38:36

Re: Spacesuit Compatibility Requirement

#10 2024-09-11 10:31:41

Re: Spacesuit Compatibility Requirement

#11 2024-09-11 12:05:37

Re: Spacesuit Compatibility Requirement

#12 2024-09-11 13:16:16

Re: Spacesuit Compatibility Requirement

#13 2024-09-11 19:35:00

Re: Spacesuit Compatibility Requirement

#14 2024-09-12 05:57:19

Re: Spacesuit Compatibility Requirement

#15 2024-09-12 11:12:16

Re: Spacesuit Compatibility Requirement

#16 2024-09-12 11:39:01

Re: Spacesuit Compatibility Requirement

#17 2024-09-12 11:55:15

Re: Spacesuit Compatibility Requirement

#18 2024-09-12 12:17:24

Re: Spacesuit Compatibility Requirement

#19 2024-09-12 12:45:03

Re: Spacesuit Compatibility Requirement

#20 2024-09-12 12:56:49

Re: Spacesuit Compatibility Requirement

#21 2024-09-12 17:22:28

Re: Spacesuit Compatibility Requirement

#22 2024-09-12 17:40:30

Re: Spacesuit Compatibility Requirement

#23 2024-09-13 08:03:16

Re: Spacesuit Compatibility Requirement

#24 2024-09-14 19:54:43

Re: Spacesuit Compatibility Requirement

#25 2024-09-15 11:10:40

Re: Spacesuit Compatibility Requirement

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