Why Spaceships Travelling In Pairs Is Safest..

[Spacescifi]

Even in scifi settings like the Expanse where they can have gravity via constant acceleration I dare say traveling by twos at the very least is better than going solo against the airless expanse of the universe.

Why? Fuel is finite, and when you do orbit anywhere your engines won't provide any gravity.

Now you may say use rotation to get gravity, but you simply cannot design your ship for thrust based gravity AND self rotational gravity without making it needlessly complex.

A simpler solution is to send spaceships in pairs at the bare minimum.

Never alone. I know there are narrative reasons why scifi has stories about lone spaceships (or they have fictional artifcial gravity floors that don't require rotation), but it really is a dangerous choice to make for the safety of the crew for all the times the spaceship will be cruising on inertia.

The main reason to send spaceships in pairs is because they can tether to each other and use each other as a counterweight as they rotate for gravity.

Last I checked you need 100 meters wide at 1 RPM (revolution per minute) to feel 1g (earth gravity)... if you want a SOLO spaceship to do it by itself.

You can avoid having to build super fat spaceships by simply tethering a pair of spaceships with a 100 meter long tether (or longer if desiired or needed) and using their manuevering thrusters to rotate. After which inertia does the rest.

I think even Musk plans on sending his spaceships in pairs to mars for the same tethered rotational gravity reason.

Even in ultra scifi settings where you have constant thrust acceleration or even artificial gravity flooring having a plan B option when plan A fails is a wise move.

Fuel is finite, and as often as spaceship get blown to hell in scifi you would think their artificial gravity field floors would go offline once in a while (but they never do because of plot).

So my reasoning is having a plan B option available is ALWAYS better than nothing.

What happens when you have to orbit? What about when your fancy artificial gravity floor goes offline? What? Get weak bones? Get vision problems from all the blood pooling up in your skull?

You don't have to even have the potential to suffer... send two ships, then tether and rotate them together as counterweights.

Potential danger or ill health averted.

I know the Expanse and much of scifi tells stories as they do for narrative reasons as opposed to what the most safe option available to use is.

Your thoughts?

I dunno... it just bothered me... more for settings like The Expanse that could have used it but chose not to.

Star Trek puts absolute trust in their artificial gravity fields... and perhaps rightly so.

The one and only time I saw a trek ship lose artificial gravity in battle was in Star Trek VI and it was a klingon ship getting sucker punched without even raising it's shields.

 

 

Edited Saturday at 07:41 AM by Spacescifi

[SunlitZelkova]

2 hours ago, Spacescifi said:

Your thoughts?

You’re basically right. In the 1969 Mars mission proposal created by Von Braun, he proposed building two identical Mars Transfer Vehicles and having them fly side-by-side to the Red Planet (in 1981). He wanted lifeboat-style redundancy as Apollo had with the separation of the CSM and LM, but a Mars lander would not be capable of sustaining the entire crew in the same the LM did on Apollo 13, so he proposed two entire spacecraft.

Caveat: The 1969 proposal was part of the Integrated Program Plan, which itself was a pretty unserious proposal for post-Apollo human spaceflight. The NASA administrator was proposing to fly 45 Saturn Vs throughout the 1970s with a straight face… and Saturn V production had already been mothballed in ‘68 and was effectively dead by 1970. Von Braun was a realist, so maybe he saw the writing on the wall on just decided to indulge a little.

The spacecraft itself was pretty weird. It involved docking some S-II stage derived Nuclear Shuttles side-by-side (like strap on boosters around a core stage) but no docking system was ever detailed. I’ve never understood how that might work and thus was never able to build a replica in KSP.

[Spacescifi]

46 minutes ago, SunlitZelkova said:

You’re basically right. In the 1969 Mars mission proposal created by Von Braun, he proposed building two identical Mars Transfer Vehicles and having them fly side-by-side to the Red Planet (in 1981). He wanted lifeboat-style redundancy as Apollo had with the separation of the CSM and LM, but a Mars lander would not be capable of sustaining the entire crew in the same the LM did on Apollo 13, so he proposed two entire spacecraft.

Caveat: The 1969 proposal was part of the Integrated Program Plan, which itself was a pretty unserious proposal for post-Apollo human spaceflight. The NASA administrator was proposing to fly 45 Saturn Vs throughout the 1970s with a straight face… and Saturn V production had already been mothballed in ‘68 and was effectively dead by 1970. Von Braun was a realist, so maybe he saw the writing on the wall on just decided to indulge a little.

The spacecraft itself was pretty weird. It involved docking some S-II stage derived Nuclear Shuttles side-by-side (like strap on boosters around a core stage) but no docking system was ever detailed. I’ve never understood how that might work and thus was never able to build a replica in KSP.

Don't get me wrong, I think space travel is awesome, but our aim should be to send people to space and back with the same bodies they came with.

Unfortunately that is not what has been happening.

Granted I can accept that some are willing to suffer for science research on the effects of weightlessness on the human body, but by now we already know so there is no need for people to be coming back less than what they were when they lifted off.

Former astronauts have reported reduced visual ability and beyond that I don't know why, but multiple astronauts who have been to space look as if theur adam's apple on their throat is larger than normal.

My dream is for one day in the future for astronauts to come back from space with strong bones, good vision, and with bodies overall good as they were when they left.

We are not kerbals who don't worry about those issues. We are human.

Edited Saturday at 07:40 AM by Spacescifi

[Nuke]

in pairs, nah, whole floatillas is the way to go. especially if they can link up in transit to share resources and possibly use a modular truss system to form centrifuges. redundancy beyond tumbling pigeon config. if anything goes wrong you can scrap the offending ship, reconfigure your latticework, distribute the crew/passengers/equipment/consumables to other craft. and continue on no worse for wear.

[Spacescifi]

5 hours ago, Nuke said:

in pairs, nah, whole floatillas is the way to go. especially if they can link up in transit to share resources and possibly use a modular truss system to form centrifuges. redundancy beyond tumbling pigeon config. if anything goes wrong you can scrap the offending ship, reconfigure your latticework, distribute the crew/passengers/equipment/consumables to other craft. and continue on no worse for wear.

 

Seems like you are talking about sending at bare minimum two squadrons (equal to one floatilla). Since a floatilla is anywhere between 3 and 10, we are talking about a fleet that can be anywhere between 6 or 20 ships in total.

 

[SunlitZelkova]

7 hours ago, Nuke said:

in pairs, nah, whole floatillas is the way to go. especially if they can link up in transit to share resources and possibly use a modular truss system to form centrifuges. redundancy beyond tumbling pigeon config. if anything goes wrong you can scrap the offending ship, reconfigure your latticework, distribute the crew/passengers/equipment/consumables to other craft. and continue on no worse for wear.

Ironically this also brings to mind another of Von Braun's proposals, the 1952 one that was eventually published as a novel. Ten spacecraft flying in formation, each with 70 crew, all weighing in excess of 3,000 tons (a mass approaching the weight of a WWII Gearing-class destroyer).

9 hours ago, Spacescifi said:

Don't get me wrong, I think space travel is awesome, but our aim should be to send people to space and back with the same bodies they came with.

Unfortunately that is not what has been happening.

Granted I can accept that some are willing to suffer for science research on the effects of weightlessness on the human body, but by now we already know so there is no need for people to be coming back less than what they were when they lifted off.

Former astronauts have reported reduced visual ability and beyond that I don't know why, but multiple astronauts who have been to space look as if theur adam's apple on their throat is larger than normal.

My dream is for one day in the future for astronauts to come back from space with strong bones, good vision, and with bodies overall good as they were when they left.

We are not kerbals who don't worry about those issues. We are human.

Assuming all goes well, I think there will be a day in the future when spaceflight does start having such considerations. We just don't see people thinking about it because despite many civilians having become astronauts, the whole is basically still in "test pilot" phase. We're still proposing the sorts of missions people were already thinking about when the first test pilot-turned-astronauts were selected; moon bases, Mars expeditions, more research space stations. So it makes sense we'll continue to see test pilot levels of risk acceptance.

Even the small amount of tourist stuff is more comparable to daredevils giving rides to locals in their (very dangerous) barnstorming planes, or supersonic joyrides in retired MiG-21s. Current commercial spaceflights are more like that than they are a trip to a Disney resort.

So it's a little bit silly to worry too excessively about, say, Starship's safety... even Isaacman is blown to smithereens on Polaris 3, that is not reflective of the kind of safety hazard interplanetary ferries of centuries later will have.

Eventually the level of safety only achievable by formation flying will be required, but we're not there yet.

[magnemoe]

10 hours ago, SunlitZelkova said:

You’re basically right. In the 1969 Mars mission proposal created by Von Braun, he proposed building two identical Mars Transfer Vehicles and having them fly side-by-side to the Red Planet (in 1981). He wanted lifeboat-style redundancy as Apollo had with the separation of the CSM and LM, but a Mars lander would not be capable of sustaining the entire crew in the same the LM did on Apollo 13, so he proposed two entire spacecraft.

Caveat: The 1969 proposal was part of the Integrated Program Plan, which itself was a pretty unserious proposal for post-Apollo human spaceflight. The NASA administrator was proposing to fly 45 Saturn Vs throughout the 1970s with a straight face… and Saturn V production had already been mothballed in ‘68 and was effectively dead by 1970. Von Braun was a realist, so maybe he saw the writing on the wall on just decided to indulge a little.

The spacecraft itself was pretty weird. It involved docking some S-II stage derived Nuclear Shuttles side-by-side (like strap on boosters around a core stage) but no docking system was ever detailed. I’ve never understood how that might work and thus was never able to build a replica in KSP.

Yes and the lifeboat part is the second reason why you want two or more ships. Its also why many of the age of exploration tended to use multiple ships but more useful in space as spaceships don't get separated by storms. 

[Nuke]

ideally any one ship should still be able to reach its destination on its own, multiplied it has a safety factor.

[magnemoe]

On 4/5/2025 at 10:15 PM, Nuke said:

ideally any one ship should still be able to reach its destination on its own, multiplied it has a safety factor.

Who is true, however one ship failing towards the target you abort unless waiting for next mission is an better option for you. 

[monophonic]

On 4/5/2025 at 7:17 AM, Spacescifi said:

Now you may say use rotation to get gravity, but you simply cannot design your ship for thrust based gravity AND self rotational gravity without making it needlessly complex.

Why not? The technical bits already have to keep working with accelerations towards any direction or around any axis, when the ship is maneuvering. The problem of configuring living and working spaces to accommodate two different gravity vectors was solved in 1962. (See https://en.wikipedia.org/wiki/RP_FLIP) Now, you may have to adjust some things for stronger or longer accelerations than they would have been expected to handle before, but that's just engineering. I don't see any reason why that couldn't be physically achieved.

On 4/5/2025 at 12:45 PM, Nuke said:

in pairs, nah, whole floatillas is the way to go. especially if they can link up in transit to share resources and possibly use a modular truss system to form centrifuges. redundancy beyond tumbling pigeon config. if anything goes wrong you can scrap the offending ship, reconfigure your latticework, distribute the crew/passengers/equipment/consumables to other craft. and continue on no worse for wear.

Sounds like in-orbit assembly of a big single ship, with added complexity from having said ship be able to rebuild itself while underway. If you drop the scrapping and reconfiguring parts, you are essentially left with a highly redundant, compartmentalized vessel with ability to close off failed compartments and continue to function with the remaining compartments.

[Spacescifi]

5 hours ago, monophonic said:

Why not? The technical bits already have to keep working with accelerations towards any direction or around any axis, when the ship is maneuvering. The problem of configuring living and working spaces to accommodate two different gravity vectors was solved in 1962. (See https://en.wikipedia.org/wiki/RP_FLIP) Now, you may have to adjust some things for stronger or longer accelerations than they would have been expected to handle before, but that's just engineering. I don't see any reason why that couldn't be physically achieved.

Sounds like in-orbit assembly of a big single ship, with added complexity from having said ship be able to rebuild itself while underway. If you drop the scrapping and reconfiguring parts, you are essentially left with a highly redundant, compartmentalized vessel with ability to close off failed compartments and continue to function with the remaining compartments.

 

While it it is not impossible, my argument was that design is simpler if you just have two vessels working in tandem to simulate gravity.

I will admit part of the reason I am a fan of this approach is that I love the idea of spaceships being able to do SSTO to planets and back to outer space on their own thrust.

Doing this IRL is nigh impossible since you pay a severe propellant cost and the only way to lower it we know how is by radiating your launch site or dropping expended rockets as you ascend (and you will run out sooner or later). Of course scifi offers other options like antigravity and etc but I digress.

Your idea is definitely possible, but it works better for orbital interplanetary cruisers that are not designed to ever land.

[monophonic]

18 hours ago, Spacescifi said:

I will admit part of the reason I am a fan of this approach is that I love the idea of spaceships being able to do SSTO to planets and back to outer space on their own thrust.

Well if you insist on having your ships being all-in-one SSTO lander and interplanetary+ cruisers, your best option is to have Ships That Just Do It™. The requirements of landing/launching and interplanetary transfers are just so contradictory, that any attempt at making physics of the combination vessels even semi-plausible is going to dig you into a way deeper hole than handwaving the problem away does.

[Spacescifi]

2 hours ago, monophonic said:

Well if you insist on having your ships being all-in-one SSTO lander and interplanetary+ cruisers, your best option is to have Ships That Just Do It™. The requirements of landing/launching and interplanetary transfers are just so contradictory, that any attempt at making physics of the combination vessels even semi-plausible is going to dig you into a way deeper hole than handwaving the problem away does.

 

Hmmm... not necessarily. Babylon 5 is a setting with both centrifugal gravity and cliche artificial gravity floors.

Could even utilize both

That said, I am considering the idea of spaceships rotating together being tied together by their version of forcefield beams. Which can extend to the needed length for 1g at 1 RPM.

Scifi gravity floors would exist, but would drain as much power generating 1g as thrusting with the engines at 1g. Thus to conserve power for engines it would be advisable to use rotational gravity with the help of another vessel unless for some reason you have to use artificial gravity (such as your partner ship is out of range or was destroyed).

Other alternatives are just finding a planet with sufficient gravity to land while you send out a hyperspace distress signal for another ship to link up with you so you don't have to drain your engine power on generating floor gravity.

And if you are thinking why not just use constant acceleration for thrust the reason they don't is because they don't have drives that can accelerate for tens of hours or more like in the Expanse (2, 4, and 6 hours max would be more common instead)). If they did they would run out of power and become adrift hulks without any ability to change course... until a rescue ship comes to recharge them anyway

Artificial gravity floors while not accelerating would be a newer technology used mostly for emergencies or as a luxury.

You are probably also thinking how do ships get around fast if they lack constant acceleration that lasts for tens of hours?

There are scifi ways around that too. The main reason you need to accelerate at all is to make course corrections for orbital insertion, landing, takeoff, and intercept. But if all you want is to get NEAR somewhere in interplanetary or interstellar space fast then all you need are scifi jump drives or their equivalent.

I honestly don't think centrigugal gracity is going anywhere... it would remain useful even in stupidly advanced settings if only because it is cheaper and simpler to make than the  cliche scifi gravity floors. The power bank alone for those likely would have the energy of a bomb.

Spaceships are already full of stuff that can go boom so it does not hurt to add one more thing.

Spacestations on the other hand...

Edited yesterday at 08:01 AM by Spacescifi

[GluttonyReaper]

Having spacecrafts in pairs is a fun idea, but narratively speaking, it's not that interesting to have three (four?) different ways of generating gravity, especially when the backup is just "spend power to generate gravity by magic". If anything it should be the other way around: artificial gravity is the standard method, and the lower tech solutions are a fun thing you bring up when that inevitably fails. The obvious problem here is if you're already at the level of abstraction where you've got magic interstellar drives, claiming that your ships are cheaping out on the artificial gravity in particular is difficult to suspend disbelief for... unless you build your entire universe to allow that particular scenario, which feels contrived.

[Spacescifi]

1 hour ago, GluttonyReaper said:

Having spacecrafts in pairs is a fun idea, but narratively speaking, it's not that interesting to have three (four?) different ways of generating gravity, especially when the backup is just "spend power to generate gravity by magic". If anything it should be the other way around: artificial gravity is the standard method, and the lower tech solutions are a fun thing you bring up when that inevitably fails. The obvious problem here is if you're already at the level of abstraction where you've got magic interstellar drives, claiming that your ships are cheaping out on the artificial gravity in particular is difficult to suspend disbelief for... unless you build your entire universe to allow that particular scenario, which feels contrived.

 

Makes the setting unique. They won't have scifi bubble shields either (inasmuch I think both it and artificial gravity floors are both easy and silly cheats).

Besides, it's a new technology, and even if they ever did make it more efficient, doing it would be like coating every deck floor with dynamite.

Which you may wanna avoid when you don't have scifi shields and some kinetic kill shots will gut the ship clean through like in the Expanse. Hitting gravity tiled floors with enemy fire (or even shooting them with a handgun) would be enough to detonate them.

Which is why they are at least covered with thick carpet as a cushion for any accidents that could happen onboard. Still won't help much against relativistic kinetic weapons impacting upon it though.

I figure if we are gonna include some silly scifi conceits that are not absolutely necessary to tell a space story then I can at least make using it incur a cost that you never see in scifi. otherwise.

Edited yesterday at 11:33 AM by Spacescifi