Timescale Abstraction in Gameplay Video (Aug 21, 2017)

[Tavior]

I have been thinking on this topic for a while ever since I watched the gameplay video.

It bother me so much that I can't believe that you have not tried hard to do it differently. When I saw the bit about shuttlecraft landing on Mars barely a day later. It made me cringe.

You could instead of using day time periods. Use month time period instead and it solve many issues at once. The same way Child of the Nile dealt with season/month.

To explain how Child of the Nile dealt with time abstraction I have to explain a bit about the gameplay. First off instead of forcing the player to wait through 12 months for a single harvest. They abstracted the year/month time period into "3 days night/light cycle" representing the flooding season, planting season, and finally harvesting season without making the player wait through 12 months of the year.

You can do something similar here. Instead of using a single day to represent an in-game day; Use a month to represent an in-game day night/light cycle.

I don't see enough of the in-game calendar to know if you used "Earth year" or "Mars year". I know that Mars has a year length that is nearly twice as long as Earth (365 days vs 687 days).

I don't think you would want to torture players with a longer years right? So abstracting that into a 12 or 24 "Mars month" whatever works best.

My next subject is somewhat slightly more complicated but bear with me. Because Mars and Earth don't stay at the same distance through out time due to different year period. Time to travel between two isn't a constant value. It can various as much as 150 days to 300 days (better engine can narrow that down a bit such as antimatter or whatever). So if it takes 2-3 months to start up the colony and the next ship is it's on way at the same time. Then there isn't a "large netflix time" waiting for your colonist to get there.

So please change shuttlecraft getting to Mars under day to something else less cringe!

 

[King Korihor]

My next subject is somewhat slightly more complicated but bear with me. Because Mars and Earth don't stay at the same distance through out time due to different year period. Time to travel between two isn't a constant value. It can various as much as 150 days to 300 days (better engine can narrow that down a bit such as antimatter or whatever). So if it takes 2-3 months to start up the colony and the next ship is it's on way at the same time. Then there isn't a "large netflix time" waiting for your colonist to get there.

So please change shuttlecraft getting to Mars under day to something else less cringe!

I think that aspect of colonizing Mars really needs to be added to the game in a significant fashion. The logistics of going to Mars involve being on the end of a very long logistical train that literally no matter how much money you can throw at the problem you aren't going to get the supplies there any sooner from the Earth beyond maybe getting it there a bit earlier... like by a couple weeks earlier over the period of nearly a year.

Going to Mars ought to feel a whole lot like travel on the Oregon Trail in the 1850's, where you needed to be extremely careful about what supplies you brought and once you left "civilization" that you were on your own from that point forward. If you've ever played the Oregon Trail game by MECC, you can appreciate how engaging in a game you can make trying to stretch resources out to the last possible item. Another game that dealt with logistics in even a space environment was Project: Space Station that had you arranging how you brought up building supplies, components, and other resources needed for survival (in that case it was essentially building the ISS).

Hohmann Transfer Orbits and the hopefully famous Aldrin Cycler Orbits ought to be something that is a key feature of this game that governs the logistical deliveries of both colonists and external supplies. Those would be carefully planned launches that would have preparations happening years in advance. Knowing that you have a hundred colonists that will be arriving in two years and under some sort of time pressure to set up the living space and basic infrastructure to keep them alive can and ought to be at least one of the game play options that really sharpens what you are doing. Colonists can't and won't simply turn around because you've been goofing off and wasting resources.

At the moment Surviving Mars (in terms of what I've seen in preview let's play videos) landing supplies in under a day sort of feels like there is a huge established colony on Phobos of a million+ people and infinite supplies that can land at will on the surface of Mars. That lonely distance from the Earth and how far from help that folks like Mark Watney would face trying to simply stay alive until a resupply could happen don't seem to exist right now.

indeed I would love to see a Mark Watney-like scenerio where you need to struggle to dig up old landers and random parts and odd resources simply to keep one lone colonist alive with a couple of survival shelters until some sort of emergency resupply mission finally shows up to relieve that lonely colonist. That shouldn't even take that much of a rework of the current game to make it happen either.... based on what I've seen.

 

[DukeLeto42]

This may also come down to a "numbers are not final" issue. This may be sped up simply to show rapid gameplay, or an aspect of the game as yet incomplete.

 

[Tavior]

I think that aspect of colonizing Mars really needs to be added to the game in a significant fashion. The logistics of going to Mars involve being on the end of a very long logistical train that literally no matter how much money you can throw at the problem you aren't going to get the supplies there any sooner from the Earth beyond maybe getting it there a bit earlier... like by a couple weeks earlier over the period of nearly a year.

Except you can get everything up to running capacity in 300 day or less. By then the shortest window will be around for colonist to get there with less traveling time. You can plan around launch windows.

If they don't want to force player to wait so long they can make the travel time shorter by using engine to speed it up.

For example, this VASIMR (variable specific impulse magnetoplasma rocket) is posit to be able to make the Earth-Mars travel time down to 39 days at the most!!! It can do that because it burn far less fuel and doesn't ever stop accelerating which allow it to build up lot of velocity to make the travel time dramatic less.

http://www.spaceflightinsider.com/c...mars/vasimr-plasma-engine-earth-mars-39-days/

In the gameplay video those shuttle apparently still use what looks like chemical engines which would take far longer than that. If it was a mothership with a better engine carrying a smaller shuttle for landing that would be far less cringe compared to what I saw.

Going to Mars ought to feel a whole lot like travel on the Oregon Trail in the 1850's, where you needed to be extremely careful about what supplies you brought and once you left "civilization" that you were on your own from that point forward. If you've ever played the Oregon Trail game by MECC, you can appreciate how engaging in a game you can make trying to stretch resources out to the last possible item. Another game that dealt with logistics in even a space environment was Project: Space Station that had you arranging how you brought up building supplies, components, and other resources needed for survival (in that case it was essentially building the ISS).

Hohmann Transfer Orbits and the hopefully famous Aldrin Cycler Orbits ought to be something that is a key feature of this game that governs the logistical deliveries of both colonists and external supplies. Those would be carefully planned launches that would have preparations happening years in advance. Knowing that you have a hundred colonists that will be arriving in two years and under some sort of time pressure to set up the living space and basic infrastructure to keep them alive can and ought to be at least one of the game play options that really sharpens what you are doing. Colonists can't and won't simply turn around because you've been goofing off and wasting resources.

Yeah I grew up playing Oregon Trails as well. I have nothing against shuttles ferrying back and forward between Earth and Mars. It is the travel time that makes me cringe.

I already covered travel time topic earlier.

At the moment Surviving Mars (in terms of what I've seen in preview let's play videos) landing supplies in under a day sort of feels like there is a huge established colony on Phobos of a million+ people and infinite supplies that can land at will on the surface of Mars. That lonely distance from the Earth and how far from help that folks like Mark Watney would face trying to simply stay alive until a resupply could happen don't seem to exist right now.

indeed I would love to see a Mark Watney-like scenerio where you need to struggle to dig up old landers and random parts and odd resources simply to keep one lone colonist alive with a couple of survival shelters until some sort of emergency resupply mission finally shows up to relieve that lonely colonist. That shouldn't even take that much of a rework of the current game to make it happen either.... based on what I've seen.

Yeah that does sound fun and a very different game than a colony simulation.

This may also come down to a "numbers are not final" issue. This may be sped up simply to show rapid gameplay, or an aspect of the game as yet incomplete.

Except in the video they said they were "ok" with abstracting the gameplay when they was looking at low earth orbit (similar to how ISS orbit is like) shipyards and ordering colonist + supplies. Which got to Mars shortly afterward.

This was the most cringe part of the whole video.

Comparing to having robot with VERY "short range" tether when in reality you can control a drone very far away due to Satellites in orbit in a position to cover larger area than what I saw in-game. I can live with a silly short tether gameplay abstraction because it isn't as a big break away from reality as shuttle earth-mars travel time. Anyone recall Spirit and Opportunity? No?

https://en.wikipedia.org/wiki/Mars_Exploration_Rover

For the tether/logistic of controlling remote robots. I would gone with how many robots can you effectively control at once with limited resource?

IE for example, primitive early phase colony robot controller can only control up to 1-2 but much more advance versions can control up to 15 each.

Then the choice shift from where do you want to put control tower/rover? To do you want to commit a robot to commit to a long task or do a bit of everything?

 

[Orlunu]

So, 39 days if we assume this absurd tech. 39 days around opposition, which happens every 28 Earth months or so.

For cost reasons, if nothing else, launch windows are what they are and are more important than the actual travel time. Do hope a decent system will be in game for it, it's one of the things really killing my hype atm.

 

[Tavior]

So, 39 days if we assume this absurd tech. 39 days around opposition, which happens every 28 Earth months or so.

For cost reasons, if nothing else, launch windows are what they are and are more important than the actual travel time. Do hope a decent system will be in game for it, it's one of the things really killing my hype atm.

I don't think you are quite grasping how powerful that engine is.

The reason there are launch windows is because most chemical rocket in use today (Russia, China, India, EU, Japan, USA, etc...) all can only push a certain amount of mass which limits most spacecraft size and fuel capacity. Hence the launch window so they can min-max fuel usage.

The advantage that vasimr has is it use even less fuel than say a chemical eninge that can only burn at most four times (first burn to leave earth orbit, decelerate burn for Mars, leave Mars, decelerate burn for Earth).

If half of what vasimr is true. Then it can just burn far less fuel (read launch from Earth mass) and use either large solar array or a nuclear reactor to be able to build up large velocity. Instead of lugging chemical fuel tanks up into space on top of a rocket. That is essentially a recipe for disaster!

This week, Ad Astra reported that it remains on target toward that goal. The company completed a successful performance review with NASA after its second year of the contract, and it has now fired the engine for a total of 10 hours while making significant modifications to its large vacuum chamber to handle the thermal load produced by the rocket engine.

Source: https://arstechnica.com/science/201...ket-making-progress-toward-a-100-hour-firing/

Can you find a chemical rocket that can burn for 10 hours using less fuel? Thought so.

 

[King Korihor]

I don't think you are quite grasping how powerful that engine is.
The reason there are launch windows is because most chemical rocket in use today (Russia, China, India, EU, Japan, USA, etc...) all can only push a certain amount of mass which limits most spacecraft size and fuel capacity. Hence the launch window so they can min-max fuel usage.

Launch windows also exist because of energy budgets. You are talking about going from one moving object (the Earth) to another moving object (Mars). The Hohmann Transfer Orbit happens to be the ideal kind of orbital transfer between two bodies for chemical rockets, because it is also the lowest amount of energy needed to travel between the two bodies. Every single spacecraft and vehicle that has gone to Mars so far has used this kind of trajectory precisely because it allows organizations like JPL to maximize the payload given a size of a rocket.

Even other propulsion systems still have launch windows though including ion drives and VASIMR engines. Even an Alcubierre drive would have launch windows to travel between the Earth and Mars if only to make sure you are pointed in the correct direction and not trying to travel through the Earth itself. It is a significant aspect of space travel in general and sad that it isn't included in the game so far.

The advantage that vasimr has is it use even less fuel than say a chemical eninge that can only burn at most four times (first burn to leave earth orbit, decelerate burn for Mars, leave Mars, decelerate burn for Earth).

I think you are confusing the term fuel (which is a source of energy) with propellant mass. VASIMR engines don't actually consume fuel but instead have some sort of gas that is heated up to a very high temperature that is in turn expelled for thrust. The energy needed to make that happen is enormous though and requires something external to the drive.... just as you sort of pointed out but didn't elaborate upon. The neat thing about chemical engines is that they can simultaneously heat the propellant through combustion and act as that reaction mass needed in Newton's Laws of Motion to move a rocket through a vacuum.

You also run into Tsiolkovsky's rocket equation if you are going to add on any additional power sources like solar panels or a nuclear reactor in order to power any non-chemical reactor. In addition to the propellant, you also need to deal with the mass of the power plant. For a chemical rocket, that is called the engine combustion chamber, something that is generally relatively small and has also almost negligible mass compared to the rest of the engine and dry (empty) rocket mass.

The Dawn mission is one of the more famous missions to use an ion drive (which the VASIMR engine is a variant of) and used solar panels as its power source. It also has the distinction of being the only spacecraft to have successfully orbited two different astronomical objects besides the Sun. Still, keep in mind that the solar panels which powered the engine were of such low power that it has a 0-60 mph time of 4 days.... hardly the thing of massive acceleration. Its advantage is that it can keep accelerating for a very long period of time, thus is able to maneuver in ways that a chemical rocket can't.

The ISS happens to have a 100kW power source, which is one reason why it was targeted as a test platform for the VASIMR engine. The unfortunately cancelled project was supposed to be used to help with station keeping, where the engine would be used to help boost the ISS to a higher orbit periodically. At the moment, chemical engines are the only thing used to perform that station keeping to prevent the ISS from crashing down on some unfortunate city it may pass over from time to time including my own house. That was a really good application of it. Still, keep in mind that this engine wasn't proposed to be installed in order to move the ISS to the Moon or do anything other than simply keep it in orbit around the Earth. And that was a full sized engine about the size of the on the link of that above NASA video. It didn't really produce all that much thrust.

What made the VASIMR engine different from other designs is that it had variable thrust, which could be either a very high thrust with low efficiency or low thrust with high efficiency. That variability is what gives the first "V" in its name.

At the moment, every single realistic proposal for getting to Mars including the SpaceX ITS reference design all use chemical rockets for the trip. This isn't accidental but is there due to the fact that designing rockets with the more exotic engines is extremely hard and getting that proper balance of mass and energy working is far easier done with chemical engine. The ITS is going to use a non-Hohmann trajectory, but it is still going to have launch windows to work with and certainly won't be instantaneous. Baseline Mars reference missions by NASA using the SLS rocket are only going to get there even slower than the ITS.

Perhaps some rocket in the next century will be using something like a VASIMR engine and a molten salt Thorium reactor as a power plant, or better yet a Polywell fusion reactor (where core temperatures are definitely going to be high enough for direct power of an ion stream). Those are exotic technologies powering an exotic engine though and not something that would really be in any sort of realistic if you are talking about a game portraying what it will be like for the first pioneering steps onto colonizing Mars.

Launch windows and significant lags from when you request supplies to when they arrive really ought to be a part of this game. If it isn't there, it will definitely be one of the first things I will mod into the game.

 

[nomen]

I have a bet were I give a bottle of champagne to a friend if VASIMR is ever used to get to Mars in 39 days. It has no time limit.
I'll leave it at that.

The only system I know of that can do it on the developers timescale is an 'orion project' derivative which would be awesomely retro future if they did.

Alt history: Kennedy decided to turn swords into plowshares?

 

[Tavior]

Launch windows also exist because of energy budgets. You are talking about going from one moving object (the Earth) to another moving object (Mars). The Hohmann Transfer Orbit happens to be the ideal kind of orbital transfer between two bodies for chemical rockets, because it is also the lowest amount of energy needed to travel between the two bodies. Every single spacecraft and vehicle that has gone to Mars so far has used this kind of trajectory precisely because it allows organizations like JPL to maximize the payload given a size of a rocket.

Even other propulsion systems still have launch windows though including ion drives and VASIMR engines. Even an Alcubierre drive would have launch windows to travel between the Earth and Mars if only to make sure you are pointed in the correct direction and not trying to travel through the Earth itself. It is a significant aspect of space travel in general and sad that it isn't included in the game so far.

Definitely missing out on the significant travel time aspect between Mars and Earth.

I think you are confusing the term fuel (which is a source of energy) with propellant mass. VASIMR engines don't actually consume fuel but instead have some sort of gas that is heated up to a very high temperature that is in turn expelled for thrust. The energy needed to make that happen is enormous though and requires something external to the drive.... just as you sort of pointed out but didn't elaborate upon. The neat thing about chemical engines is that they can simultaneously heat the propellant through combustion and act as that reaction mass needed in Newton's Laws of Motion to move a rocket through a vacuum.

You also run into Tsiolkovsky's rocket equation if you are going to add on any additional power sources like solar panels or a nuclear reactor in order to power any non-chemical reactor. In addition to the propellant, you also need to deal with the mass of the power plant. For a chemical rocket, that is called the engine combustion chamber, something that is generally relatively small and has also almost negligible mass compared to the rest of the engine and dry (empty) rocket mass.

The Dawn mission is one of the more famous missions to use an ion drive (which the VASIMR engine is a variant of) and used solar panels as its power source. It also has the distinction of being the only spacecraft to have successfully orbited two different astronomical objects besides the Sun. Still, keep in mind that the solar panels which powered the engine were of such low power that it has a 0-60 mph time of 4 days.... hardly the thing of massive acceleration. Its advantage is that it can keep accelerating for a very long period of time, thus is able to maneuver in ways that a chemical rocket can't.

The ISS happens to have a 100kW power source, which is one reason why it was targeted as a test platform for the VASIMR engine. The unfortunately cancelled project was supposed to be used to help with station keeping, where the engine would be used to help boost the ISS to a higher orbit periodically. At the moment, chemical engines are the only thing used to perform that station keeping to prevent the ISS from crashing down on some unfortunate city it may pass over from time to time including my own house. That was a really good application of it. Still, keep in mind that this engine wasn't proposed to be installed in order to move the ISS to the Moon or do anything other than simply keep it in orbit around the Earth. And that was a full sized engine about the size of the on the link of that above NASA video. It didn't really produce all that much thrust.

What made the VASIMR engine different from other designs is that it had variable thrust, which could be either a very high thrust with low efficiency or low thrust with high efficiency. That variability is what gives the first "V" in its name.

At the moment, every single realistic proposal for getting to Mars including the SpaceX ITS reference design all use chemical rockets for the trip. This isn't accidental but is there due to the fact that designing rockets with the more exotic engines is extremely hard and getting that proper balance of mass and energy working is far easier done with chemical engine. The ITS is going to use a non-Hohmann trajectory, but it is still going to have launch windows to work with and certainly won't be instantaneous. Baseline Mars reference missions by NASA using the SLS rocket are only going to get there even slower than the ITS.

Perhaps some rocket in the next century will be using something like a VASIMR engine and a molten salt Thorium reactor as a power plant, or better yet a Polywell fusion reactor (where core temperatures are definitely going to be high enough for direct power of an ion stream). Those are exotic technologies powering an exotic engine though and not something that would really be in any sort of realistic if you are talking about a game portraying what it will be like for the first pioneering steps onto colonizing Mars.

Launch windows and significant lags from when you request supplies to when they arrive really ought to be a part of this game. If it isn't there, it will definitely be one of the first things I will mod into the game.

I didn't mixed fuel and energy.

One of the proposed Vasimr vehicle for Earth-Mars journey required usage energy upward of 600 kW. Which is a nice way of saying you need same power as a nuclear powered Nimitz-class carrier in use today. From what I can find they, two A4W reactor, generate about 550 k W and throw in bit of solar array and you can power one of those Vasimr vehicle. While mass/tonnage of the fuel used in a vasimr is nearly tiny compared to the entire payload/craft itself. Which is very important considering how expensive it is to launch something into space.

Whereas chemical engine the opposite is true. In that you need way way way more tonnage of mass launched into space and each mass launch on a rocket up to space is super-expensive. Which restrict what we can do in term of delta velocity when using chemical rockets. It cost $27,000 to launch a pound (cost of launch divide by mass payload delivered) for the most cheap private rocket company, which is SpaceX. Although those figure may change in the future depending on factors.

Vasimr allow you to drop the tonnage of fuel to few tonnage mass, non-reactive gasses, at the most and you can collect gas up there (space isn't a true vacuum per se). Instead most of the energy for delta velocity comes from either solar array or few nuclear reactor.

I have a bet were I give a bottle of champagne to a friend if VASIMR is ever used to get to Mars in 39 days. It has no time limit.
I'll leave it at that.

The only system I know of that can do it on the developers timescale is an 'orion project' derivative which would be awesomely retro future if they did.

Alt history: Kennedy decided to turn swords into plowshares?

Oh god don't get me start on the Outer Space Treaty against nuclear weapons. That treaty basically bans nuclear weapon in outer space and Orion Project essentially use nuclear warhead and nevermind the EMP side effect if it was done close to low earth orbit (International Space Station and lot lot of communication satellites).

https://en.wikipedia.org/wiki/Outer_Space_Treaty

There is also the problematic aspect of having the nuclear material on a rocket blowing up over say a huge metropolis city. Anyone remember Chernobyl? Fukushima Daiichi? WW2? At least with Vasimr you can either rely entirely on solar power or transport a reactor on a rocket but isn't quite same as weaponized nuclear material on a rocket.


Edit: Ugh a missing ] ate part of my post. Had to fix.

 

[King Korihor]

Vasimr allow you to drop the tonnage of fuel to few tonnage mass, non-reactive gasses, at the most and you can collect gas up there (space isn't a true vacuum per se). Instead most of the energy for delta velocity comes from either solar array or few nuclear reactor.

Yes, something like the VASIMR is highly efficient in terms of its propellant mass, but the casual handwaving you have done to something like a nuclear reactor even the size of something on a nuclear submarine is what I'm talking about here. Perhaps something smaller could be engineered and targeted toward a propulsion system, but I'm going to presume that you are talking something like a 20 metric ton power system at a bare minimum, and let's presume this is also something like a 1 MW reactor too (for argument's sake). Keep in mind that when you do the calculations of the Rocket equations, you need to treat that reactor as payload mass and not propellant.... which makes a huge difference. When you are pushing stuff around with that VASIMR engine, you need to not only push around the expected payload, but that reactor mass as well. The delta-v that it produces is thus considerably less than you are claiming here.

Regardless, one of those VASIMR driven vehicles going between the Earth and Mars is going to be a enormous vehicle that would likely need to be constructed in orbit made up of dozens of flights simply to get the materials up there to build it. I'm talking something on the scale of the ISS construction here, although it might be a tiny bit smaller in cost than the $100 billion price tag for the ISS. Perhaps not either though. Even assuming refueling, it is going to cost an insane amount of money to operate.


More to my point though, there is not a single current Mars architecture by anybody credible in the spaceflight industry that is even considering this approach either now or any time in the distant future. It isn't even remotely a consideration to use anything but Chemical rockets to get the job done. I tried to explain calmly why that is the case, but it is important to note that it isn't being for very realistic and practical reasons that are all in the engineering of the vehicles.

To note also, if you really want to have some fun, the following video is a fantastic overview of what the current architectures for going to Mars actually will be like by actual rocket scientists who are building actual rockets that are actually likely to get to Mars anytime in my lifetime:

https://livestream.com/viewnow/HumansToMars2017/videos/155974408

While as a game it could be fun to throw in some alternatives like VASIMR, it would be helpful if there was a bit of grounding in reality and current plans too.

I really hope the base game is something believable and based upon the stuff in this video link I posted above. Robots helping build stuff and dome designs are certainly interesting and based upon ideas suggested for Martian colony designs, but the current 1 day flight from somewhere random to the surface of Mars is definitely unrealistic.

As a mod, throwing something in like VASIMR would be wonderful. I hope it gets in too that way. Perhaps even throwing this in as a part of a difficulty mode where "easy" would get something like VASIMR to bring supplies but harder modes would require chemical engines alone. I'm all for reasonable abstractions and this would be one of them.

That is also one of the things that the designers of this game need to keep track of too is that this isn't some far of sciencey fantasy like the Edgar Rice Burrows' Barsoom books. This is something that some very real rocket scientists are really working on, and perhaps this game might even be eventually played on the surface of Mars by actual Paradox customers. That is sort of why this topic is relevant to the game design.

 

[keynes2.0]

https://livestream.com/viewnow/HumansToMars2017/videos/155974408

Do you have a transcript? It's a five hour video...

While as a game it could be fun to throw in some alternatives like VASIMR, it would be helpful if there was a bit of grounding in reality and current plans too.

Even if the VASIMR is in the game, it wouldn't really show up in game. Any craft going to the surface of mars where it is visible on screen would still need chemical rockets. So VASIMR would be something done off map, maybe a technology that makes rockets have a slightly larger payload and shorter travel time.

 

[nomen]

Definitely missing out on the significant travel time aspect between Mars and Earth.

Oh god don't get me start on the Outer Space Treaty against nuclear weapons. That treaty basically bans nuclear weapon in outer space and Orion Project essentially use nuclear warhead and nevermind the EMP side effect if it was done close to low earth orbit (International Space Station and lot lot of communication satellites).

https://en.wikipedia.org/wiki/Outer_Space_Treaty

There is also the problematic aspect of having the nuclear material on a rocket blowing up over say a huge metropolis city. Anyone remember Chernobyl? Fukushima Daiichi? WW2? At least with Vasimr you can either rely entirely on solar power or transport a reactor on a rocket but isn't quite same as weaponized nuclear material on a rocket.

You wondering what could get there in a short enough time QED.

Not sure what you mean by 'weaponised'?...

hmm is a quick nuclear knowledge level check okay? (might help me understand what you mean)

"Whats the 3 letter abbreviation for the fuel used in nuclear subs/navel reactors?"

 

[Tavior]

You wondering what could get there in a short enough time QED.

Not sure what you mean by 'weaponised'?...

hmm is a quick nuclear knowledge level check okay? (might help me understand what you mean)

"Whats the 3 letter abbreviation for the fuel used in nuclear subs/navel reactors?"

Sure no problem.

U-235 and U-238 are both isotope of Uranium with different property. U-238 isn't really sustainable for fission reaction. Meanwhile U-235 is much more easier to start a nuclear reaction with.

Weaponized nuclear material has far more fissionable material (more higher density than need for nuclear reactor). For nuclear reactor you only need just enough U-235 to generate lot of heat. I don't know the exact ratio off my head.

You start off mining for Uranium. Initially that stuff can't be use to really blow up anything. So you process it through spinner to filter U-238. Because naturally occuring Uranium has like 99% of U-238. You want less of that and more U-235. So you create a lot of waste as a by-produce.

The longer you spin/filter Uranium the more "enriched" it is. The more useful it is to initiate a nuclear bomb with. It also help to have a longer/taller spinner to filter them much more quicker which make spotting a nuclear warhead manufacturer facility easier judging by how long they run a batch and the length of spinner.


A4W is a military designation/name. A = aircarrier, 4 = contractor 4th generation, and W = westinghouse, contractor designer.

I couldn't find much else info on those reactor. Like exactly how much space is it actually taking up? Mass? I suppose those may/may not be classified info. No need to stir any more trouble there.

Yes, something like the VASIMR is highly efficient in terms of its propellant mass, but the casual handwaving you have done to something like a nuclear reactor even the size of something on a nuclear submarine is what I'm talking about here. Perhaps something smaller could be engineered and targeted toward a propulsion system, but I'm going to presume that you are talking something like a 20 metric ton power system at a bare minimum, and let's presume this is also something like a 1 MW reactor too (for argument's sake). Keep in mind that when you do the calculations of the Rocket equations, you need to treat that reactor as payload mass and not propellant.... which makes a huge difference. When you are pushing stuff around with that VASIMR engine, you need to not only push around the expected payload, but that reactor mass as well. The delta-v that it produces is thus considerably less than you are claiming here.

Regardless, one of those VASIMR driven vehicles going between the Earth and Mars is going to be a enormous vehicle that would likely need to be constructed in orbit made up of dozens of flights simply to get the materials up there to build it. I'm talking something on the scale of the ISS construction here, although it might be a tiny bit smaller in cost than the $100 billion price tag for the ISS. Perhaps not either though. Even assuming refueling, it is going to cost an insane amount of money to operate.


More to my point though, there is not a single current Mars architecture by anybody credible in the spaceflight industry that is even considering this approach either now or any time in the distant future. It isn't even remotely a consideration to use anything but Chemical rockets to get the job done. I tried to explain calmly why that is the case, but it is important to note that it isn't being for very realistic and practical reasons that are all in the engineering of the vehicles.

To note also, if you really want to have some fun, the following video is a fantastic overview of what the current architectures for going to Mars actually will be like by actual rocket scientists who are building actual rockets that are actually likely to get to Mars anytime in my lifetime:

https://livestream.com/viewnow/HumansToMars2017/videos/155974408

While as a game it could be fun to throw in some alternatives like VASIMR, it would be helpful if there was a bit of grounding in reality and current plans too.

I really hope the base game is something believable and based upon the stuff in this video link I posted above. Robots helping build stuff and dome designs are certainly interesting and based upon ideas suggested for Martian colony designs, but the current 1 day flight from somewhere random to the surface of Mars is definitely unrealistic.

As a mod, throwing something in like VASIMR would be wonderful. I hope it gets in too that way. Perhaps even throwing this in as a part of a difficulty mode where "easy" would get something like VASIMR to bring supplies but harder modes would require chemical engines alone. I'm all for reasonable abstractions and this would be one of them.

That is also one of the things that the designers of this game need to keep track of too is that this isn't some far of sciencey fantasy like the Edgar Rice Burrows' Barsoom books. This is something that some very real rocket scientists are really working on, and perhaps this game might even be eventually played on the surface of Mars by actual Paradox customers. That is sort of why this topic is relevant to the game design.

Yes I never said building a vasimr would be easy far from it. If anything the saving on transport of fuel repeatedly vs one large craft with more upfront cost but less launch-to-orbit need over long term is already strongly in favor of Vasimr due to how long a nuclear reactor can run typically above 40 years lifetime. Depending on what type of reactor anyway moving on.

I found some stat that might help you realize how powerful this engine is relatively. For a chemical rocket, NASA estimate it would take 60 metric ton of LOX-LH2 (liquid oxygen/hydrogen) to move 34 metric tons. If I switch to 5 vasmir engines powered by only 1 MW solar array. To push 34 metric tons those 5 engines would use barely 8 metric ton of argon. To address the upfront cost, that same craft would be ONLY 49 metric tonnage. That 60 metric tonnage you burnt? I already saved 11 tonnage by ditching LOX-LH2 + whatever mass difference between your craft and mine.

To make matter worse. I can burn more argon to reduce the travel speed even further. You can't because then you would have to bring even more fuel to burn to carry more fuel at a higher rate than vasimr would have to.

God help you if you go somewhere there isn't any oxygen to harvest for engine fuel except for the O2 you use to breath. But at least with vasimr you can use hydrogen which is everywhere as well.

Sure there are a few problem like lack of a large power source that is usable in space (largest nuclear power was barely 6 kiloWatt). However this won't stop people from creating a larger solar array to generate more power.

The only reason why I mention those aircarrier nuclear reactor is that the technology to provide 200 mW exists. Just need to develop a space-based variation if you want 39 day travel time.

TL,DR version: No matter how you look at it. There are always "trade-offs".

I also recommend find a transcript for that 5 hours video.

 

[keynes2.0]

The only reason why I mention those aircarrier nuclear reactor is that the technology to provide 200 mW exists. Just need to develop a space-based variation if you want 39 day travel time.

And fish show that you dont need air to breathe. So just develop a space based version of the fish and you can get rid of those spacesuits.

If you made a spaceship with a nuclear carrier like they have on an aircraft carrier, the heat would kill everyone. Space based nuclear propulsion requires very different technology.

Yes I never said building a vasimr would be easy far from it. If anything the saving on transport of fuel repeatedly vs one large craft with more upfront cost but less launch-to-orbit need over long term is already strongly in favor of Vasimr due to how long a nuclear reactor can run typically above 40 years lifetime. Depending on what type of reactor anyway moving on.

Nuclear plants dont run 40 years without major repair. And an investment that takes 40 years to pay off is a bad investment, a lot of things can change in 40 years. This is a big part of why so many nuclear projects turn out exactly the way the naysayers go. Sure it looks great according to your predictions of sustained high demand... anything looks good if you just handwave in that assumption. And meanwhile there is this solar energy thing that is cheaper and provides a higher specific energy density anywhere within the orbit of mars and could reasonably be used out to the orbit of Jupiter.

Nuclear for space made sense back in the 50s to the 70s. With every passing decade it makes less sense. At a time that Telerobotics are allowing for ever smaller spacecraft (just look at cubesats), nuclear demands a grand scale. Plummeting launch costs mean the spacecraft cost far more then the launch but nuclear treats the fabrication costs as no object. With reusable spacecraft you want faster missions but nuclear is based on slow times. But most of all the rapid technological advancement means that solutions have more immediacy then ever and nuclear has quietly shifted from the simple brute force concepts of 70s flight to pie in the sky engineering of complex new machines that would probably take decades to actually make flight rated. Nuclear is compromising everything that is important to get everything that isn't needed.

 

[Tavior]

And fish show that you dont need air to breathe. So just develop a space based version of the fish and you can get rid of those spacesuits.

If you made a spaceship with a nuclear carrier like they have on an aircraft carrier, the heat would kill everyone. Space based nuclear propulsion requires very different technology.

Like I said earlier. It doesn't have to be exactly that same reactor design. Only that the target yield is do-able with two reactor with current technology. I never said that they would use the exact same design just yields.

The same way Solar Array work both in space and earth. With one critical difference, solar array in space will receive far more photon per-square meter than equivalent earth bounded ones. Even if 200 mW nuclear reactors turn out to be unfleasible. Building a larger solar array can still fulfill the power requirement up to a point where adding more solar array would not yield as much benefit due to diminish return.

QED: Trade off.

Nuclear plants dont run 40 years without major repair. And an investment that takes 40 years to pay off is a bad investment, a lot of things can change in 40 years. This is a big part of why so many nuclear projects turn out exactly the way the naysayers go. Sure it looks great according to your predictions of sustained high demand... anything looks good if you just handwave in that assumption. And meanwhile there is this solar energy thing that is cheaper and provides a higher specific energy density anywhere within the orbit of mars and could reasonably be used out to the orbit of Jupiter.

Nuclear for space made sense back in the 50s to the 70s. With every passing decade it makes less sense. At a time that Telerobotics are allowing for ever smaller spacecraft (just look at cubesats), nuclear demands a grand scale. Plummeting launch costs mean the spacecraft cost far more then the launch but nuclear treats the fabrication costs as no object. With reusable spacecraft you want faster missions but nuclear is based on slow times. But most of all the rapid technological advancement means that solutions have more immediacy then ever and nuclear has quietly shifted from the simple brute force concepts of 70s flight to pie in the sky engineering of complex new machines that would probably take decades to actually make flight rated. Nuclear is compromising everything that is important to get everything that isn't needed.

What are you talking about? Where have you been in the past few years?

Curiosity (rover on Mars) is powered by a RTG (radioisotope thermometric generator) which is pretty darn close as you can get to a nuclear reactor. This rover was launched not that too long ago in Nov 26, 2011.

It is currently killing endurance records of any rover on Mars since then.

Furthermore the next rover (2020 Mars assuming fund isn't pulled back etc...) will be using THE backup RTG left over from construction of Curiosity.

What are you talking about nuclear reactor compromising designs?


No it will not take 40 years to pay off the investment not even close. Look at my stat earlier again. 60 tonnage of liquid oxygen/hydrogen + 34 tonnage payload + unknown craft mass (lets assume at least 9) vs 34 tonnage payload + 8 tonnage of argon for vasimr + 9 tonnage of spacecraft.

Mass to launch into orbit for chemical rocket craft would be total 103 metric tonnage.

Mass to launch a vasimr craft would be 48 tonnage. I already paid off investment by halving the freaking launch cost. It will NOT take 40 years to pay off that. The fuel saving alone is already enough to sent up a SECOND vasimr fully loaded and fueled to go. That is ignoring use nuclear reactors to save travel time consideration btw.

 

[keynes2.0]

What are you talking about? Where have you been in the past few years?

Curiosity (rover on Mars) is powered by a RTG (radioisotope thermometric generator) which is pretty darn close as you can get to a nuclear reactor. This rover was launched not that too long ago in Nov 26, 2011.

RTGs generation hundreds of watts. I was under the impression we were talking about hundreds of kilowatts to hundreds of megawatts. Can you imagine the cost of a thousand RTGs, let alone a million?

Only that the target yield is do-able with two reactor with current technology. I never said that they would use the exact same design just yields.

It doesn't show this. You are removing multiple indispensible components. The type of nuclear reactor designs used on earth aren't remotely applicable to an environment where you can neither expect heat nor input water.

No it will not take 40 years to pay off the investment not even close. Look at my stat earlier again.

Everything about that design can be done with solar...

 

[Tavior]

RTGs generation hundreds of watts. I was under the impression we were talking about hundreds of kilowatts to hundreds of megawatts. Can you imagine the cost of a thousand RTGs, let alone a million?

I never said that a rover-sized RTG would be used to power a Vasimr engine. Only that the design constriction are not as bad as you seem to claim it is with respect to spacecraft.

It doesn't show this. You are removing multiple indispensible components. The type of nuclear reactor designs used on earth aren't remotely applicable to an environment where you can neither expect heat nor input water.

Again if it is even possible to design an outer space 200 mW nuclear reactor then that would solve a few problems with interplanetary distance traveled. Would it require as much space as those other nuclear reactors? I don't know but it is certainly worthwhile consideration given the dramatic reduction in travel time. Would you rather spend 150 days soaking cosmic ray or 31 days?

Even if it ending up being half as true as what they promise it is still a nice though to hop over to Mars in matter of 3 months. As opposite to upward of 5 months.

Everything about that design can be done with solar...

I think I see why you are bit confused. That 8 tonnage fuel use is for a 1 mW vasimr craft taking 150 day to get to Mars. I don't know the fuel weight used for 200 mW with 31 days but it is certainly safe to say it will be a bigger boat in terms of tonnage.

 

[keynes2.0]

Again if it is even possible to design an outer space 200 mW nuclear reactor

And, if as has been explained to you, that is not possible?

 

[Tavior]

And, if as has been explained to you, that is not possible?

Which part isn't possible? You would have to be more specific because vasimr isn't the only proposed spacecraft using nuclear power. You have to keep in mind although I am only familiar with USA ones. Russia has been experimenting with nuclear power far more extensively and I don't read Russia language. Nevermind that they, Ad Astra inventor of vasimr, also have a 1 kW design on paper for solar array if nuclear reactor option didn't pan out for any kind of reasons.

I already acknowledge that designing a 200 kW spacecraft might not be feasible anytime soon. Not once but several times. No need to beat that particular subject again.

 

[keynes2.0]

Which part isn't possible?

Come on, dude:

If you made a spaceship with a nuclear carrier like they have on an aircraft carrier, the heat would kill everyone. Space based nuclear propulsion requires very different technology.

It doesn't show this. You are removing multiple indispensable components. The type of nuclear reactor designs used on earth aren't remotely applicable to an environment where you can neither expect heat nor input water.