Author Topic: A capability for crew to change ships in space.  (Read 2044 times)

Online aero

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A capability for crew to change ships in space.
« on: 10/10/2017 04:49 PM »
I had this thought while reading the various escape system threads and proposals to use Dragon.

I expect most of us here read or have read science fiction. In those novels the large ships always have a hanger bay of various sizes, with secondary craft ranging in size from single person sleds made of rails and thrusters, about the size of a motor scooter, to attack shuttles carrying a platoon or more of marines.

The BFS doesn't need an attack shuttle but sleds capable of transporting a single suited astronaut from the BFS to the ISS might be useful. The BFS station keeps near the ISS then NASA astronaut rides the sled over, secures it temporarily outside the ISS and enters the ISS via the same air lock used for space walks. Small items may be attached to the sled for return to the BFS and Earth before the sled is released to automatically home on the BFS and re-enter the hanger bay.

 The same sleds might be useful during transit to Mars, especially in a medical emergency where the proper specialist is on the wrong ship. Of course the range of the sled would be limited so its usefulness in transit depends on how closely the transiting fleet can fly in formation.

Other common uses for such sleds include search and recovery of crew forced to abandon a ship of the fleet, redistribute the recovered crew throughout the fleet, and to visit artifacts drifting in a reachable trajectory. Of course the capabilities of the science fiction sleds increases with the author's imagination but we're pretty imaginative here on NSF, and some even with the appropriate experience to flesh out this idea, if it is found worthy.
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Offline CraigLieb

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Re: A capability for crew to change ships in space.
« Reply #1 on: 10/10/2017 08:43 PM »
I had this thought while reading the various escape system threads and proposals to use Dragon.

I expect most of us here read or have read science fiction. In those novels the large ships always have a hanger bay of various sizes...
Just don't cede control of the pod bay doors to the shipboard computer. 
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Online Coastal Ron

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Re: A capability for crew to change ships in space.
« Reply #2 on: 10/10/2017 09:13 PM »
The BFS doesn't need an attack shuttle but sleds capable of transporting a single suited astronaut from the BFS to the ISS might be useful. The BFS station keeps near the ISS then NASA astronaut rides the sled over, secures it temporarily outside the ISS and enters the ISS via the same air lock used for space walks. Small items may be attached to the sled for return to the BFS and Earth before the sled is released to automatically home on the BFS and re-enter the hanger bay.

A space-only transfer vehicle could stationed at the ISS for such use. I've always thought it made sense to have such a vehicle as the "buffer" between stations and visiting spacecraft. That way you don't have to compromise on the design of either just to make them capable of docking - like the image of the ITSy docking with the ISS, which I think is unlikely.

Quote
The same sleds might be useful during transit to Mars, especially in a medical emergency where the proper specialist is on the wrong ship. Of course the range of the sled would be limited so its usefulness in transit depends on how closely the transiting fleet can fly in formation.

Other common uses for such sleds include search and recovery of crew forced to abandon a ship of the fleet, redistribute the recovered crew throughout the fleet, and to visit artifacts drifting in a reachable trajectory. Of course the capabilities of the science fiction sleds increases with the author's imagination but we're pretty imaginative here on NSF, and some even with the appropriate experience to flesh out this idea, if it is found worthy.

Many visionaries, from Von Braun to Musk, have talked about fleets of ships traveling between planets, and there is nothing that says every ship has to be the same. You could have support ships that travel with the fleet that carry space-only transfer vehicles for both people and cargo. Maybe those supports ships carry the cargo that will be left in orbit, while the transport ships carry people and cargo destined for the planet surface?

Lots of analogies from our navies around the world that we can use as inspiration for solutions...
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Online KelvinZero

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Re: A capability for crew to change ships in space.
« Reply #3 on: 10/10/2017 10:43 PM »
A space-only transfer vehicle could stationed at the ISS for such use. I've always thought it made sense to have such a vehicle as the "buffer" between stations and visiting spacecraft. That way you don't have to compromise on the design of either just to make them capable of docking - like the image of the ITSy docking with the ISS, which I think is unlikely.
Many people noticed the impossibility of certain scenes in "Gravity" where the heroine managed to get from the ISS to the Chinese space station. My thought was: wouldn't it be cool if these manned stations, and maybe more than two, were all in the same orbit, just a few hundred km in front or behind. Then you could shuttle back and forward between them in a Soyuz or similar. We could have exactly that situation with ISS and multiple BFS in orbit. Maybe they never come closer than several kilometers.

I suspect that to move to a station ahead you would thrust down, dipping closer to the earth, rather than directly towards your destination.

Offline eric z

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Re: A capability for crew to change ships in space.
« Reply #4 on: 10/10/2017 11:49 PM »
 Who says you may not need an attack capability?- Though hopefully not for so many years into the future that BFRS is itself obsolete! Based on the way things are going down here I wouldn't bet against it; not to mention your garden-variety revolt or two. >:(

Online Coastal Ron

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Re: A capability for crew to change ships in space.
« Reply #5 on: 10/11/2017 01:37 AM »
Many people noticed the impossibility of certain scenes in "Gravity" where the heroine managed to get from the ISS to the Chinese space station. My thought was: wouldn't it be cool if these manned stations, and maybe more than two, were all in the same orbit, just a few hundred km in front or behind. Then you could shuttle back and forward between them in a Soyuz or similar. We could have exactly that situation with ISS and multiple BFS in orbit. Maybe they never come closer than several kilometers.

I suspect that to move to a station ahead you would thrust down, dipping closer to the earth, rather than directly towards your destination.

My suggestion was mainly for fleets that were all traveling together between planets, or vehicles and stations clustered near each other in the same orbit.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Online aero

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Re: A capability for crew to change ships in space.
« Reply #6 on: 10/11/2017 02:15 AM »
A space-only transfer vehicle could stationed at the ISS for such use. I've always thought it made sense to have such a vehicle as the "buffer" between stations and visiting spacecraft. That way you don't have to compromise on the design of either just to make them capable of docking - like the image of the ITSy docking with the ISS, which I think is unlikely.
Many people noticed the impossibility of certain scenes in "Gravity" where the heroine managed to get from the ISS to the Chinese space station. My thought was: wouldn't it be cool if these manned stations, and maybe more than two, were all in the same orbit, just a few hundred km in front or behind. Then you could shuttle back and forward between them in a Soyuz or similar. We could have exactly that situation with ISS and multiple BFS in orbit. Maybe they never come closer than several kilometers.

I suspect that to move to a station ahead you would thrust down, dipping closer to the earth, rather than directly towards your destination.

The orbital mechanics for rendezvous and docking are pretty well understood. Just let your computer solve the orbital mechanics problem which gets you where you want to be, ie. match position and velocity. Then do your burn, or more likely, let your computer orient the sled and do the burn. Having radar or a location signal, range and range rate, would be almost essential.

Regarding sleds on the BFS, would the sled use cold gas thrusters, or gaseous methane and oxygen, or could the thrusters be designed as mini-raptors -- the tanks especially. How much total impulse could be achieved with a sled sized fuel load, say 20 kg total? Twenty kg of prop in the liquid state wouldn't take much volume, but its liable to be a large tank in the gaseous state.
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Offline Jim

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Re: A capability for crew to change ships in space.
« Reply #7 on: 10/11/2017 01:52 PM »

A space-only transfer vehicle could stationed at the ISS for such use. I've always thought it made sense to have such a vehicle as the "buffer" between stations and visiting spacecraft. That way you don't have to compromise on the design of either just to make them capable of docking - like the image of the ITSy docking with the ISS, which I think is unlikely.


So where is the sense in that?  Now you require all transfers to be done by EVA?  Personnel have to be in suits and items to be transferred have to be able to handle vacuum. Also, have to have airlocks compatible with different EVA suits.  And more suits than are normally would be carried. And everybody trained for EVA.  Oh, and every vehicle would need an airlock.

« Last Edit: 10/11/2017 01:53 PM by Jim »

Online docmordrid

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Re: A capability for crew to change ships in space.
« Reply #8 on: 10/11/2017 05:28 PM »
A minimalist version of SEV?

DM

Offline envy887

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Re: A capability for crew to change ships in space.
« Reply #9 on: 10/11/2017 06:21 PM »
How about a cylindrical pod that fits entirely inside the airlock space shown on the BFS?

With an IDA at each end of the cylinder, some open cycle life support, GNC, and minimal propulsion, it could eject from the BFS and dock with another BFS, Dragon 2, or ISS.

It wouldn't be very large, perhaps ~1.2m in diameter and ~3m long, big enough for 2 or 3 people for a few hours.

It could also function as both an airlock and a docking port while normally mated inside BFS. I think BFS will need both an airlock and a docking port anyway, so this fills three needs with one item.

Offline Lars-J

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Re: A capability for crew to change ships in space.
« Reply #10 on: 10/11/2017 07:57 PM »
How about a cylindrical pod that fits entirely inside the airlock space shown on the BFS?

With an IDA at each end of the cylinder, some open cycle life support, GNC, and minimal propulsion, it could eject from the BFS and dock with another BFS, Dragon 2, or ISS.

It wouldn't be very large, perhaps ~1.2m in diameter and ~3m long, big enough for 2 or 3 people for a few hours.

It could also function as both an airlock and a docking port while normally mated inside BFS. I think BFS will need both an airlock and a docking port anyway, so this fills three needs with one item.
My assumption is that the docking port collar would be extendable somewhat, to allow two BFS' to dock together. Either aligned, or rotated 90 degrees.

Offline envy887

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Re: A capability for crew to change ships in space.
« Reply #11 on: 10/11/2017 08:45 PM »
How about a cylindrical pod that fits entirely inside the airlock space shown on the BFS?

With an IDA at each end of the cylinder, some open cycle life support, GNC, and minimal propulsion, it could eject from the BFS and dock with another BFS, Dragon 2, or ISS.

It wouldn't be very large, perhaps ~1.2m in diameter and ~3m long, big enough for 2 or 3 people for a few hours.

It could also function as both an airlock and a docking port while normally mated inside BFS. I think BFS will need both an airlock and a docking port anyway, so this fills three needs with one item.
My assumption is that the docking port collar would be extendable somewhat, to allow two BFS' to dock together. Either aligned, or rotated 90 degrees.

Or protrudes slightly from the outer mold line of the BFS, but is covered in the atmosphere by a retractable aeroshell - much like the Dragon 2 docking adapter and nose cone, but on the side of the vehicle instead of the nose.

This is entirely compatible with the idea of the airlock as an ejectable mini-spacecraft. Simply make the craft slightly longer, or the same length but embedded less into the BFS.

Offline ThereIWas3

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Re: A capability for crew to change ships in space.
« Reply #12 on: 10/11/2017 09:43 PM »
If all transferring crew need EVA-capable suits anyway, and all items be vacuum-proof, then you do not need transfer vehicles at all - just a hand line.  Or for a step up, see the movie "2010".
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Online Coastal Ron

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Re: A capability for crew to change ships in space.
« Reply #13 on: 10/12/2017 12:08 AM »

A space-only transfer vehicle could stationed at the ISS for such use. I've always thought it made sense to have such a vehicle as the "buffer" between stations and visiting spacecraft. That way you don't have to compromise on the design of either just to make them capable of docking - like the image of the ITSy docking with the ISS, which I think is unlikely.

So where is the sense in that?  Now you require all transfers to be done by EVA?  Personnel have to be in suits and items to be transferred have to be able to handle vacuum. Also, have to have airlocks compatible with different EVA suits.  And more suits than are normally would be carried. And everybody trained for EVA.  Oh, and every vehicle would need an airlock.

I never mentioned EVA's, I said "a space-only transfer vehicle".

Think of something like a human-rated Cygnus that is designed to just shuttle between the ISS and a visiting BFR or other large spacecraft - actually any two vehicles or stations that are in close vicinity. An Earth analogy would be a tender, which is used to transport people and/or supplies to and from shore or another ship.

It simplifies the situation of having to design vehicles that can mate by eliminating the need to mate, all they need are common docking ports - NO EVA's REQUIRED. Plus it reduces the chances of docking collisions between large vehicles and stations.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline Jim

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Re: A capability for crew to change ships in space.
« Reply #14 on: 10/12/2017 12:47 AM »

A space-only transfer vehicle could stationed at the ISS for such use. I've always thought it made sense to have such a vehicle as the "buffer" between stations and visiting spacecraft. That way you don't have to compromise on the design of either just to make them capable of docking - like the image of the ITSy docking with the ISS, which I think is unlikely.

So where is the sense in that?  Now you require all transfers to be done by EVA?  Personnel have to be in suits and items to be transferred have to be able to handle vacuum. Also, have to have airlocks compatible with different EVA suits.  And more suits than are normally would be carried. And everybody trained for EVA.  Oh, and every vehicle would need an airlock.

I never mentioned EVA's, I said "a space-only transfer vehicle".

Think of something like a human-rated Cygnus that is designed to just shuttle between the ISS and a visiting BFR or other large spacecraft - actually any two vehicles or stations that are in close vicinity. An Earth analogy would be a tender, which is used to transport people and/or supplies to and from shore or another ship.

It simplifies the situation of having to design vehicles that can mate by eliminating the need to mate, all they need are common docking ports - NO EVA's REQUIRED. Plus it reduces the chances of docking collisions between large vehicles and stations.


not really
a.  if they have common docking ports for the  space-only transfer vehicle, then they can dock
b. Designing for docking doesn't really comprise the design.  docking isn't really much more than rendezvous
c.  Cruise ships prefer docking at a pier vs using tenders

Online aero

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Re: A capability for crew to change ships in space.
« Reply #15 on: 10/12/2017 02:13 AM »
The cruise ships I've watched dock used tug boats. Agree that a tug boat is not a tender, but it's a distinction without a difference.
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Offline RocketmanUS

Re: A capability for crew to change ships in space.
« Reply #16 on: 10/12/2017 02:30 AM »
Single Person Spacecraf
https://forum.nasaspaceflight.com/index.php?topic=40494.msg1547733#msg1547733

Could make it bigger for two crew our just larger cargo.
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Online Coastal Ron

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Re: A capability for crew to change ships in space.
« Reply #17 on: 10/12/2017 04:52 AM »
not really

Yes, really.

Jim, you have a lot of knowledge about a lot of things that have happened in the past, and I continue to click the "Like" button whenever I feel like you have educated me. But I'm pretty sure you have no special knowledge of the future, because otherwise we'd be talking about what Jim is doing in the field aerospace instead of some guy called Elon Musk...   ;)

Quote
a.  if they have common docking ports for the  space-only transfer vehicle, then they can dock

I'm thinking beyond vehicles that we have today, and beyond space stations we have today. For instance, when we have rotating space stations (which may not be that far in the future) we're not going to be docking BFR's to them so we'll need a way to transfer cargo and people between them safely.

Quote
b. Designing for docking doesn't really comprise the design.  docking isn't really much more than rendezvous

I never said it did, and in fact I said that transfer vehicles/tenders would be docking with every vehicle and station. However WHERE the dock is put can be a challenge if you're wanting to dock two large vehicles - and how do you transfer cargo and people between two nearby stations?

But apparently you don't think the size and design of spacecraft are going to change from what we have today, and I do think they will change. So we'll just have to see what the future brings.

Quote
c.  Cruise ships prefer docking at a pier vs using tenders

I never mentioned cruise ships, and tenders are used for more than just supporting cruise ships.
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Online Coastal Ron

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Re: A capability for crew to change ships in space.
« Reply #18 on: 10/12/2017 04:55 AM »
The cruise ships I've watched dock used tug boats. Agree that a tug boat is not a tender, but it's a distinction without a difference.

A tug is a tug, and a tender is a tender. They are functionally different.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Online aero

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Re: A capability for crew to change ships in space.
« Reply #19 on: 10/12/2017 05:13 AM »
The cruise ships I've watched dock used tug boats. Agree that a tug boat is not a tender, but it's a distinction without a difference.

A tug is a tug, and a tender is a tender. They are functionally different.

I stand corrected.
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