Lifeboats for Space Travel based on Apollo Example

tahanson43206 · 2021-12-01 09:49:15

In another topic in this Index level, RobertDyck and friends are developing a concept for a large Solar System passenger transport vessel.

In recent days, a colloquy between RobertDyck and GW Johnson had a surprising result ...

It became clear that a model that is proven to work, for safe delivery of space travelers to the surface of a planet (that has an atmosphere) is that of the Apollo spacecraft, that visited the Moon and then returned multiple sets of crew safely to Earth.

In an age on Earth when ** all ** seafaring nations regulate passenger ships, it is notable that all licensed carriers MUST provide sufficient emergency devices (ie, lifeboats) so that everyone on board can survive if the vessel itself goes down.

In the age of Space, it would seem reasonable for mission planners to anticipate regulation and head it off at the pass by planning for safe delivery of passengers to the surface of the destination (or suitable alternative in the case of Venus).

The well proven Apollo capsule is well worth considering for the lifeboats which will be required (eventually if not immediately) on all spacecraft licensed by a space faring nation on Earth.

This new topic is offered for those who would care to refine and perhaps to develop the concept.

Future space faring citizens will thank you for your service!

(th)

RobertDyck · 2021-12-01 11:02:33

Thank you Tom. In one post of that thread, I did address lifeboats. The issue is the environment. On an ocean on Earth, if a ship's hull is breached it can fill with water. That will cause the ship to sink. There's no air at the bottom of the ocean, so passengers must abandon ship. There must be something to support passengers on the surface so they don't drown. Space is different. During an interplanetary journey, the ship is drifting at a speed to take it to it's destination, eg Mars. If you abandon ship, your lifeboats will be drifting beside the ship and still headed to your destination. There's no way a rescue vessel can come out to get you. You will have to wait until you arrive at your destination. During that time, the damaged ship will not sink because there's no water and no gravity. The ship will just continue to drift with you toward that destination. All your resources are on that large ship, so why did you abandon it? The ship won't sink, and won't explode. A common trope in Sci-Fi movies and TV shows is the nuclear reactor explodes, but anyone who knows anything about reactors knows it can't. A bomb is built completely differently than a reactor, and reactors specifically designed so they can't explode. So again, why abandon all your resources? Even if a swarm of large meteoroids punch holes in the hull of your ship, you're still better off staying with the damaged ship. Use what's left of the ship as a source of resources: food, air, spacesuits, etc.

What I did for the large ship is design it with many pressure compartments that can be sealed off. Modern ocean going ships on Earth are separated into water tight compartments, so if one compartment is breached the remaining compartments will provide sufficient buoyancy to keep the ship afloat. For space, the large ship is separated into multiple pressure tight compartments. If one compartment is breached, it can be sealed off. Also life support is distributed. My ship design has primary life support for each cabin, recycling air and water with a regenerable CO2 sorbent and oxygen generator. Each cabin also has urine and water processors for the toilet and sink, and desiccates feces to rock-hard dry waste that is then ground with a garburator to powder. Distributed life support means in case of an accident, remaining pressure compartments *ARE* your lifeboats. I also designed each pressure compartment with further life support that is shared among all cabins in that compartment: air conditioning for temperature control, final water filtration for potable water, and batteries to store electrical power. Each compartment has a means of using sunlight to provide power to oxygen generators. If you don't like my oxygen generator, then use one that has independent power generation for that compartment. Again, decentralization so each compartment basically *IS* a lifeboat. Central life support for the ship has more advanced features: processing concentrated urine to extract salt, processing urine to provide fertilizer for hydroponics, and hydroponics to grow some food. Don't expect a ship in space to grow all food, but a very large ship could produce fresh vegetables for a salad bar. I could list some other advanced life support features, but notice the tiers: cabin life support, common features for a compartment, and final central life support for the ship. All designed so compartments of the ship *ARE* lifeboats.

For Apollo, the Lunar Module (LM) acted as the lifeboat. If something went wrong with the Command and Service Module (CSM), then the LM would act as the lifeboat. This was designed on purpose. When the Apollo 13 accident happened, all the designed safety features had to be used. Apollo used a free return trajectory so that in case of a catastrophic accident the vehicle would use the gravity of the Moon to make a U-turn, return to Earth. And the LM was a lifeboat to provide life support. These were deliberately designed features, and had to be used. But notice the LM could not enter the Earth's atmosphere. The Command Module (CM) was the capsule with heat shield, parachutes, etc for atmospheric entry. The life boat didn't duplicate that function.

NASA originally planned Apollo 8 to be an unmanned test of the CSM. It was to fly around the far side of the Moon, return to Earth and reenter the atmosphere at full speed. This would prove the CSM was safe. But the Soviets sent a Soyuz capsule on that same trajectory just 3 months before Apollo 8 was to fly. The Soyuz capsule had a pair of Russian tortoises and capsules of bacteria to prove it was safe. Soyuz was supposed to skip off Earth's atmosphere, reenter over Siberia and land on the steppes of Kazakhstan. The skip didn't work, it went straight in and splashed down in the Indian ocean. NASA analyzed the trajectory and found if human crew were on board they would have survived. It would have been a rough ride, but crew would have had nothing more than bruises. This meant the Soviets once again beat NASA, they did the Apollo 8 mission just 3 months prior. So NASA asked for volunteers. This would be a very risky mission because they didn't have a LM available as a lifeboat. If anything went wrong, they would be dead. To their surprise, absolutely every astronaut volunteered. Luckily Apollo 8 was a success; they didn't need a lifeboat. Since humans were onboard, they changed the mission to orbit the Moon instead of just a fly-by. This was the first major success that America did before the Soviets. Gemini did some minor things before the Soviets, but Apollo 8 was the first major achievement that America did first. That's when America was seen as pulling ahead of the Soviets.

But this thread is about lifeboats. I mention Apollo because the lifeboat did not return crew to the surface of Earth; instead the lifeboat provided life support. My design for the large ship provides compartments that act as lifeboats onboard the ship.

tahanson43206 · 2021-12-01 11:44:09

For RobertDyck re #2

Thank you for giving this new topic a resounding and memorable start!

This topic has safely moved off the "Zero Replies" dead spot that SpaceNut recently highlighted in a post to Louis.

After thinking about the history you provided for a few minutes, I've come to a better understanding of the need for definition of terms.

It is worth noting that on Earth, lifeboats have served as landing craft. The most famous example that I am aware of is from the Mutiny on the Bounty (not the movie, the real thing). In that historical episode, Captain Bligh and a small group were abandoned at sea with (if I recall correctly) a compass and a chart, and they made their way under sail for a very considerable distance in the open Pacific, to land everyone safely.

For purposes of planning for Space misadventures, as RobertDyck has pointed out, there is a difference between an emergency life support structure (such as the LEM) and an actual vessel capable of landing in an atmosphere.

For the purposes of ** this ** topic (since I created it) I will consider carefully over several days before arriving at a firm definition.

As an interim step, I will define "lifeboat" for space as the vehicle that carries passengers safely to the surface of a planet. However, I will think long and hard about the definition of "lifeboat" as something that remains in space, as RobertDyck has argued.

SearchTerm:lifeboat definition of, for space applications

(th)

GW Johnson · 2021-12-01 17:13:43

I think RobertDyck may be right. There would appear to be little reason to abandon a damaged spaceship while in transit. Unless it is totally destroyed, the supplies and equipment for survival are still aboard it. It seems unlikely that the exact analog to lifeboats aboard an ocean ship applies to spaceships.

What seems far more likely is a loss of propulsion capability, so that the spaceship is unable to do the required delta-vee to arrive at its destination. It also seems extremely unlikely that a rescue mission could be launched from the destination to rescue the people aboard the crippled spaceship. The orbits would be all wrong to do that.

That is where the "lifeboat" notion could come into play, as a set of escape craft that could land directly upon the destination, thus evacuating the crippled craft. That might apply only to worlds with atmospheres significant enough to do aerobraking. For airless worlds, the delta-vee required to land may well be insuperably high. In that event, the abort orbit idea, with enough supplies aboard to support it, may be the only option.

The shortfall with the lifeboat idea is going to be life support supplies after you land. If you are not landing on Earth, how do you survive long enough to be rescued? Tough question. I have no answers, either.

GW

kbd512 · 2021-12-01 19:04:19

If a space ship is destroyed so quickly that rapid escape becomes necessary, then it's highly probable that nobody will survive. Lifeboats are required back on Earth because rescue is only a radio call away in most cases, with six hours of elapsed time prior to other vessels arriving at most. It would be insufferably stupid to lose the lives of people wealthy enough to pay for transport when a minor quantity of inflatable rubber and plastic can sustain them long enough for help to arrive. That happy state of affairs would not be the situation for the crew of a stricken interplanetary transport tens of millions of miles away from home. The natural remedy for the situation presented to crews far from home is convoy operations. Sending a small fleet of ships in a convoy is a better than average way to assure the survival of the colonists during the transit. If a ship truly has no sisters, then she's an exploration class vessel, not an interplanetary colonization transport.

RobertDyck · 2021-12-01 20:49:01

In the case of the Large Scale Colonization Ship, I had proposed a free return trajectory. That's 6 months to Mars, not faster. It means if something serious goes wrong so entry into Mars orbit is not possible, then it will use the gravity of Mars to turn for a return to Earth. It will be 18 months from Mars back to Earth, but at least they will be headed there.

Also, I'm counting on at least one SpaceX Starship to be permanently based on Mars. So Starship would be the rescue vessel. Starship configured for a mission from Earth to Mars can only carry 100 passengers, but that's with room to move around inside and life support for the entire transit. A shuttle to carry passengers from Mars orbit to the surface would have airline seating configuration. A Starship with that configuration could carry 200 passengers at a time. And most likely there would be at least one other Starship that could dock nose-to-nose but configured for pressurized cargo. And a Starship able to carry propellant from Mars surface to refuel for return to Earth. The propellant tanker couldn't carry passengers, but the cargo vessel could. So Starships to rescue passengers as the ship passes by Mars?

RobertDyck · 2021-12-01 21:33:43

Tom said he wants this thread to be about lifeboats. Ok, I'll try. As something to abandon ship, not just life support for a damaged vessel. Aeroshells have already been shown to work on Mars. Mars Curiosity Rover used an aeroshell (heat shield & back shell) for thermal phase of atmospheric entry, then parachutes, then a skycrane for touch-down. The skycrane is not necessary, that was just to land the rover on its wheels, so landing legs were not needed. Spirit and Opportunity used airbags instead of a skycrane, bounced and rolled until it stopped. Then the airbags deflated and the tetrahedron opened to reveal a platform for the rover to drive off. Acceleration during bounce impact is more than a human could survive, so we can't do that. Viking, Phoenix and InSight landers used landing rockets and legs with shock absorbers. Apollo LM also used and rocket and legs to land, but no parachute due to no atmosphere, and Earth's Moon has a lot lower gravity. You could design a lifeboat to use the Viking/Phoenix/InSight system.

Ships at sea used to use hard hulls. First wooden hulls, then modern materials, then finally size and mass were reduced by using inflatable rubber rafts. Aircraft carriers have inflatable lifeboats stored in containers that surround the edge of the flight deck. Small and lightweight to keep them out of the way, but enough for the entire crew complement of the ship.
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Can we design compact entry vehicles compatible with Mars? In the 1960s, part of the Apollo program designed a one-man lifeboat called "Man Out Of Space Easiest" MOOSE. This was a plastic bag that an astronaut in a spacesuit would climb into. It had two large pockets: one for the astronaut, the other would be filled with spray foam to form an aeroshell shape and mould around the astronaut. Panels of heat shield would be unfolded and placed on the back of the aeroshell. A parachute would be strapped to the astronaut's chest, and he would hold a retrorocket pack in his hands for deorbit. Some features would not apply: chaff to confuse Soviet radar, and survival gun to fight off wildlife.

Aircraft carrier lifeboats are fairly large, reducing number required by carrying several crewmen in each. The image show is labelled for 10 men. Ford class carriers have a crew of 2,600, a significant reduction from the 6,000 for Nimitz class. That still means a lot of lifeboats. We could do that. An inflatable that inflates from a hatch of the ship, opening the internal space for passengers. The Mars lifeboat would be fully assembled when inflated, so no spacesuit is necessary. The heat shield would have to be robust. Rather than landing legs, just an inflatable air cushion between heat shield and pressure shell. To ensure rocket exhaust doesn't damage the soft pressure shell, a skycrane would make sense. Rather than a separate skycrane, why not just attach to parachute cords? Apply lift in the last seconds before ground contact. Life support would be required, and a beacon. But if this will only be used after a Mars settlement is built, then life support would only require hours. Should Mars surface spacesuits be included? If so, they would have to be very lightweight.

More analogies: Soyuz capsules use small rockets on the parachute cords to pull up just second before ground contact. They don't have an airbag or landing legs, but seats inside are mounted on shock absorbers. Astronauts that returned in one said it feels like a car crash. Boeing Starliner uses parachute and airbag to land, no rockets. But the atmosphere of Mars is not thick enough to land humans without some sort of landing rocket.

But again, I question the need. They only work if rapid rescue if available on Mars, and if rescue by SpaceX Starships is not reliable.

SpaceNut · 2021-12-01 21:35:32

Safe haven is a situation where one must retreat to a location that is closed off from the ship. It must provide all necessary items that a man might need for a period of time such that you can access what is to be done to get your self back into the ship that still remains. You will cannibalize anything to get the ship back into working order in order to be able to succeed with the mission or to be able to get a safe return home.

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#1 2021-12-01 09:49:15

Lifeboats for Space Travel based on Apollo Example

#2 2021-12-01 11:02:33

Re: Lifeboats for Space Travel based on Apollo Example

#3 2021-12-01 11:44:09

Re: Lifeboats for Space Travel based on Apollo Example

#4 2021-12-01 17:13:43

Re: Lifeboats for Space Travel based on Apollo Example

#5 2021-12-01 19:04:19

Re: Lifeboats for Space Travel based on Apollo Example

#6 2021-12-01 20:49:01

Re: Lifeboats for Space Travel based on Apollo Example

#7 2021-12-01 21:33:43

Re: Lifeboats for Space Travel based on Apollo Example

#8 2021-12-01 21:35:32

Re: Lifeboats for Space Travel based on Apollo Example

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