EzinX
-
Posts
153 -
Joined
-
Last visited
Content Type
Profiles
Forums
Developer Articles
KSP2 Release Notes
Bug Reports
Posts posted by EzinX
-
-
Why is their final orbit so high? Surely they'd get better pictures if they were just a couple kilometers from the surface, right?
-
I'm not sure what kind of input you are expecting from this thread. You seem to have it all figured out already, although none of that makes any sense with modern technology.
First of all, a lifting body or spaceplane makes no sense for a multi-purpose exploration lander. By definition, you are exploring, so you don't really know what kind of atmosphere (or lack of) you will encounter. A space plane or lifting body would be pointless if the planet has an atmospheric density or composition that is different than Earth.
You would be better off with propulsive landing and takeoff. You could add some sort of aerobraking device (parachute, ballute, inflatable heatshield) to save some fuel when you can, but you will still need enough dV to do a fully propulsive braking and takeoff if you have zero atmosphere.
You talk about NERVA, but that isn't much of a high-thrust engine for leaving the ground. It was a low-thrust high ISP space-only engine. However, high ISP doesn't make it a miracle engine. That means that it needs less propellant. Something like half less. So using a magical high thrust NERVA engine with a magical nozzle that works efficiently at all altitudes, your 18000m/s dV SSTO rocket still needs to be twice the size of a Saturn V.
So the whole idea is ludicrous. If you have magical warp engines that can send you to another star, then why bother with boring chemical propulsion for your shuttle.
Maybe you built the descent vehicle after you already arrived, or sent a probe earlier. So you know the parameters of the landing environment.
NERVA is a high thrust engine. Saturn V upper stage. And reaching Mach 4 at sea level. And, presumably, you can optimize the design a bit since the 1960s designs.
And I specifically said to just take it as granted you have warp drive but nothing else. Please stop pooping on my thread. If it helps make the problem easier to see, let me rephrase it. Space aliens have opened a magic portal located in geosynchronous orbit over an earth like planet. How to get down and then back up again? You have only tech we have right now, or can develop from known prototypes.
If it's impossible, just say so.
-
So, an SSTO trumps a starship, huh?
I'm assuming the starship is powered by pixie dust that ceases being magical when you get near a planet.
I see your point, though. At the tech level you needed to even get here in the first place, you have control of antimatter and also molecular manufacturing. Heck, you probably don't even need crew to reach the surface and return - you could just send landers, and have the crew personalities digitally take control of robots on the ground, uploading the changes in their memories after they are done exploring.
-
So, alright. We've all seen the image of a hypothetical warp drive equipped spacecraft. Probably total science fantasy, but it sure looks pretty. Seeing that image, I immediately began to wonder : let's suppose you could build a spacecraft that vaguely resembles the rendering, with a working FTL warp drive, but other than the warp engine, you did not have any technology we cannot reasonably extrapolate from known principles and physics.
Again, this discussion is not about the warp engine. Let's just pretend it works, and suppose that you could travel 10s of light years in a matter of months. So you are out exploring, and you encounter a planet similar to the Earth in that it has a similar atmosphere composition, at least half the surface is water, and it has a surface gravity of 10 m/s^2. How convenient.
You are quite excited to land on that planet with a landing party and meet the alien <strike>women</strike> organisms up close and personal.
Fortunately, the wizards back at NASA have loaded up your starship with a vehicle capable of, at a minimum :
1. Taking off and landing from an earth like planet (in atmosphere, gravity, and element mix) without help from the ground with humans onboard
2. For an even harder challenge, it's an SSTO that must make orbit with no missing parts except fuel
What would the form of the vehicle even look like to pass a napkin test? This is, to me, a fascinating challenge.
Here's where I'm at so far.
Vehicle starts with a similar lifting body design to the space shuttle and various space-planes, but it has to be even larger than the space shuttle orbiter. It has a massive reactor in the back, similar to the one used by Project Pluto, but it's dual mode, capable of working to superheat both atmospheric gas and stored onboard hydrogen for thrust. There's a crew capsule in the very nose, protected by a shadow shield. (this is the main reason it has to be large : the larger it gets, the relative mass penalty for shielding against radiation from the reactor becomes smaller)
There's 7 main phases of flight.
1. Reentry - Vehicle uses similar mechanism to previous spaceplanes. Though it's quite rear-heavy from the reactor and it has mostly empty fuel tanks.
2. Soft Landing - Once it reaches cooler altitudes, damper doors over 2 turbine air intakes at the front of the vehicle are slid open. These are turbines powered by the reactor (via a hot-air power take-off turbine in the back and a long driveshaft) and they compress incident air and feed it to the reactor in the back. With sufficient power, you land this vehicle onto a calm patch of the ocean's surface on hydrofoil skis that deploy from the bottom.
3. Take off. After a stay on the ground, you have to start from 0 m/s to even get enough speed to get off the water. Good thing you have compressor turbines that can compress outside air to feed to the engine. You don't need a TWR of >1 to take off like a seaplane, maybe 0.3-0.4 or so will do it. (not certain how much skis reduce drag compared to tires on a runway). The moment you depart the water surface, you jettison the modules containing the skis and any floats.
4. Fueling. Once already in the air on nuclear thrust, you fly around for hours to days to fill your onboard fuel tanks. On an earth like planet, you do this by collecting water from the atmosphere with condenser coils, electrolyzing it for the hydrogen, then filling your onboard tanks with liquid hydrogen. Once you have full tanks, you jettison the modules containing the electrolysis equipment. You might have done this stage before takeoff if the atmospheric concentration of water is low.
5. Transition to ramjet flight. Faster and faster you go. Once you are going fast enough, you jettison the modules containing your main wings and the compressor turbines and all the equipment needed to drive them. The craft is now only flying due to nuclear ramjet thrust and the main fuselage, sans wings, is enough of a lifting body to stay in the air.
6. Transition to scramjet flight. You shed part of your ramjet air intake...at high speeds...leaving only a smaller intake for scramjet air.
7. To space. From extremely high altitude, and up to half orbital velocity, it's time to go to space today. Let's say you're going at 1/3 orbital velocity already, and your nuclear engine gives 1000 ISP when configured for hydrogen. So your scramjet is already going 2.6 km/second, and you need 6 km/second, even, plus a little margin. Half the mass of your remaining craft has to be fuel, stored as liquid hydrogen which is not very dense, and you've still got your crew compartment, radiation shield, and monster nuclear engine. If you had several modules to the nuclear engine, you could make this more efficient by dumping the extra modules later in the burn once you have shed enough weight in propellant. For bonus points, these modules would be optimized for handling atmospheric air, while the core would be designed with channels for liquid hydrogen.
8. Waiting in orbit. You need enough stuff working to wait in orbit. Your monster nuclear engine is still incredibly hot and dangerous, producing 1/3 of the many gigawatts of power it had to produce right up to engine cut off. Realistically you're gonna have to dump it, you don't have the mass budget for radiators to keep it cool once you're out of propellant. So you jettison the entire propulsion section, leaving just the crew capsule and enough batteries and life support on board to stay alive until the mothership picks you up.
Frankly, this design barely seems plausible on a napkin. Even if you posit incredible engineering talent, better than anyone who has ever lived, to develop this vehicle, I don't know if it could ever actually work.
If we're gonna land and take off with an intact vehicle we can use for another shuttle run, this isn't gonna work. What design could work? Once we send down the red-shirts to make sure it's safe, the captain is going to want to join them in the interspecies exchange with the alien women. So the shuttle needs to be able to ascend to orbit and pick him up.
-
We may all be mostly amateur rocket scientists, but I think the consensus is unanimous in this thread that the Moon is a better choice. You know, even for long term goals, it might be a lot easier to build fully artificial stations in various orbits around the Earth Moon system than to try to settle Mars.
-
I figure you'd use a hybrid system. A mass accelerator would fling the payload into a ballistic arc. Then, as it hurtles above the lunar surface (in a nice clear vacuum with no atmosphere to get in the way), you precisely focus a large laser focusing mirror on the back of the payload capsule and vaporize some of the material. The laser impingement would lase off vapor at very high velocity, giving you just enough of a push to make it to an elliptical orbit.
After that, you'd probably use some kind of electric space tug to move these capsules around to their ultimate fates.
-
The engines are on the Shuttle (so they can be recovered and re-used). The center of mass is below the shuttle's belly. If you aim the thrust vectors of the three engines along the long axis of the rocket, you CAN'T use the engines to cancel out the torques (they will all produce pitch-down torques).
Ah. Ok, that makes much more sense. So you can only "balance" the thrusts if the center of mass is located at the midpoint between the three engines. Since it isn't, you can't. All our rockets in ksp, we stick the center of mass directly above generally, between all the engines.
-
You can obviously have prebuilt rockets that only need their payloads loaded ready to launch rescue missions for a Moon colony.
You're going to have to build a lot more rockets either way, which would mean that you'd have a big line of rockets in various stages of assembly at several factories around the world. It would be a lot easier to find a rocket to launch an unscheduled payload if the world production of rockets were 10 times higher.
Also, Moon has actual economic value. We can envision some day building massive self replicating robot plants on the Moon that spread out to cover the entire surface. Any products produced by these plants could be easily put into lunar orbit or even earth orbits. It is _much_ easier to reach orbit from the Moon : a pure vacuum, so electromagnetic accelerators should work perfectly. Or you can build a lunar elevator using kevlar as the elevator cable.
With full or partial self replicating machinery, the Moon represents a source of limitless raw materials with no human beings to get in the way or whine about environmental damage. You could power your electric grid with barely shielded fission reactors and dump toxic waste wherever you like. Since the Moon is a big blob of materials that is thought to have come originally from the Earth, all the elements should be there with similar prevalence.
-
In another thread, it was mentioned that the space shuttle main engines are aligned with the center of mass of the orbiter. This center of course shifts quite a bit during flight, as the SRBs rapidly shed mass and are jettisoned and the orange fuel tank also rapidly drops in mass.
Ok, so I know why : if the engines are each aligned with the center of mass, then each will create no net torque on the vehicle.
But, do you have to do it this way? While there isn't any net torque, you've got 3 competing velocity vectors and some of the thrust will be canceled out by the other vectors. If, instead, you align the engines such that their thrust is in line with the direction of travel, and just balance the thrust generated with the other 2 engines (so the torques cancel), won't you get more dV for your fuel?
This thread probably needs some drawings. Will add them later if anyone is having trouble visualizing what I'm talking about.
-
My guess is they are there to carry boiloff away, rather than to replace it. After all, you really don't want clouds of high-concentration oxygen and fuel hanging around if you can avoid it.
What's the big white cloud of mist, then? With the Falcon 9 launches, that rocket uses kerosene(RP-1) and LOX. RP-1 is just a more refined variant on jet fuel (according to Ignition, specs are very loose and it's just been tweaked to have less clogging of the nozzles). So the fuel must stay in it's tank. I don't think letting LOX boiloff into the air causes any harm.
-
Found the gif of it. Sorry if it's linked on another page. I came in here to say : this looks exactly like my bad landings on the Mun or when testing out a lander on Kerbin and messing up. That is, playing KSP, this happens more often than I succeed in a soft landing
-
At liftoff (16 minutes), you can see flexible hoses still attached to the rocket. Is the rocket still being provided with fuel/oxidizer (to replace that burned up at engine start and the fuel/oxidizer to get it the first meter up) and power (so you can use smaller batteries) until the very instant the hoses break loose?
This would make logical sense, to eek out that last little bit of dV by making sure the tanks are at capacity as it clears the tower, but the fuel flow rate is so immense I'm not sure how practical it would be. -
Space is 3 dimensional, and the third dimension is not nearly as constrained as it is for aircraft. This means that, except for choke points like specific orbits and approaches to space stations, elevators, etc, the probability of collision is infinitesimal - even if there were billions of spacecraft.
You might not need a space traffic control system for most places in space, just some infrared sensors on all spacecraft that track other contacts for potential collisions.
We wouldn't need air traffic control except right at the airports if all jet aircraft had 360 degree radars and perfect computerized analysis of the resulting signals, either - jets could simply avoid obstacles on their own, and the skies are so vast that there would always be somewhere to go.
-
Ok, so the next problem with Venus. So you've got your balloon habitat. You've got carbon, oxygen, nitrogen...but is 20 ppm of water vapour high enough of a concentration to gain protons? You need hydrogen in order to make decent rocket fuel, or to make plastics, drinkable water, etc etc etc. I suppose you could bring hydrogen from Earth but I really like the idea of ISRU that is able to get you limitless rocket fuel.
Apparently, the pressure is "only" comparable to 920 meters deep on the Earth's surface. The Seawolf class submarine has a crush depth at 720 meters - so it isn't unreasonable to think you could build a large, "seawolf sized" interior space for your mining apparatus.
One thing that is really cool is that the "cloud city" of Rapture totally works in the upper atmosphere of Venus. You just need a thin layer of plastic to separate the living areas from the outside, right? And, since breathable air is a lift gas, you could have reasonably small balloons suspending the thing. You could easily have gigantic ballrooms and other interior places with vast windows looking out on the murky haze. That's kind of a problem, though - the view isn't anything to write home about.
-
If Venus has 84% of the gravity of Earth, why is it practical for a SSTO to reach orbit from 52 kilometers on Venus? What's the delta-V requirement for that maneuver?
Regardless of whether going to Venus is a good idea or not, I'm just wondering how you get from your cloud city back to orbit without needing a spacecraft about the size of the one that got you from the ground on Earth to orbit. Balloon launchers have been proposed for Earth but they don't pass the pencil test.
This does make me wonder : suppose you wanted a long term cloud city. Could you send down robots by basically compressing the lift gas in the balloons they use so they fall to the surface slowly and gracefully? They would descend to the surface, mine it for resources, then ascend back up. Most of the robots would be made of systems that can take the pressure evenly across all the parts.
-
One of the reasons what you have tried to do has failed is because KSP does not have a good way to "package up" a payload into a real fairing that structural supports all the parts inside correctly. If you could package a wide variety of mission payloads into a universal payload fairing, where KSP would model the forces on the outside of the payload fairing only, and assume that all payload inside was "strapped down" and unable to move at all in any dimension (realistic), it would be much easier. With these "universal" payload fairings, all launches of a rocket would be consistent every time. In fact, you could even make the fairings automatically have ballast added to them so that they always weigh the same even if the payload is lighter than the max capacity of the fairing.
Has any mod already done this?
-
Here's the answer to the original post :
Sabatier Reaction :
CO2 + 4 H2 → CH4 + 2 H2O + energy
Pyrolysis :
CH4 + heat → C + 2 H2
Electrolysis :
2 H20 -> 2 H2 + 02
You need a catalyst that is not consumed for all 3 reactions, made of platinum or something. Hydrogen in this case is also acting as a catalyst. The pyrolysis of CH4 to carbon residue and hydrogen gas leaves this dirty soot over your catalyst which has to be removed somehow (maybe you can blast it loose with ultrasonic sound waves or something)
-
You do this :
CO2 + 2H2 -> HCO2H + H2O
HCO2H -> CO + H2O
H2O -> 1/2H2 + O2
To summarize : react the C02 gas you isolated from the air (you can remove the C02 by refrigeration or using a regenerative absorber material) with hydrogen gas in the presence of a catalyst. Heat the water/methanoic acid mixture to high temperature. CO will bubble off. Electrolyze the water to hydrogen and oxygen.
That's phase 1. Now, phase 2 :
You need some method to crack CO to straight oxygen. Well, ..... 5000 degree kelvin is required. Ideas?
This process would work fine on Mars, though. So there is that. You can get limitless CO2 from the atmosphere of mars, strip off the oxygen, breathe it, scrub the CO2 from your habitat, recycle half the oxygen back to O2 and vent the rest as CO.
-
Anyhow... all current "solutions" on this thread imply we either have to flee or act on Pallas directly. In stead of trying to push Pallas, which is going to be difficult, why not redirect something far smaller, but with enough impact to do some decent damage.
So you want to shove something far enough from it's current trajectory to intersect Pallas within a couple years. Also, you don't want to launch a 100 megaton warhead, which is fairly small, but a spacecraft carrying hundreds of warheads so you can fine tune the new trajectory of the object you are shoving.
It's probably possible but only if the "pool table" of stellar objects is set up just right for it to work. I suspect out of all possible configurations of the solar system, the proportion where such a "pool shot" maneuver is possible is a small fraction of the possibilities.
-
Gravitons are massless force carriers that travel at c, exactly like photons, so they appear to travel at c from all reference frames. So exactly as you cannot travel faster than light, you cannot travel faster than gravity.
I'm using the wrong terms here. What I was getting at is that suppose you built a photon sail. As you sail away from earth and gain speed, the light from the laser at earth would appear red shifted, and you would get less thrust. If you could interact with gravitons, and they are actually super awesome and current physicists are dead wrong, and those gravitons are coming from the stars of the universe, then as you gain speed you'd have something similar to red/blue shift occur and your thrust would reduce.
It is really important that this happenes, because otherwise you could violate conservation of energy.
-
Why bother absorbing radiation? Conservation of momentum means that even if you could make the exchangers one way, any radiation absorbed at the front slows you down by the same amount that re-emitting that radiation out the back speeds you up.
What you are describing actually does work just fine as an engine, but a nuclear reactor won't cut it. You need to tame a small black hole and convert matter directly to gamma rays via Hawking radiation. If this can even be done (there are...issues....with such a thing) you could get actually acceptable rates of acceleration running on pure photon thrust (1/10-1/100 of a g or so)
Or you need to carry a lot of antimatter onboard and do the same thing. Good luck not blowing up if a micrometeorite punctures a fuel tank, though.
-
You know, if there was a lot of interstellar hydrogen floating around in the universe, such that there was a significant amount in every direction, you could make a much more efficient rocket that scooped it up in flight and flung it out the back extremely fast. You're not at the tyranny of the rocket equation because you are gaining mass during flight. This is what a Bussard ramjet is, now, the problem with one is that :
1. There isn't as much interstellar hydrogen as expected when the idea was proposed 2. Fusion doesn't give you enough energy to fling the hydrogen fast enough. You would need to convert the protons directly to energy somehow
If the mass of the universe was emitting an ocean of "gravitons", and there was a way to interact with these gravitons and fling them away like a rocket thruster, and whatever particle comprises a graviton has inertia, you'd also get a benefit here. It would be more energy efficient than a photon drive, again, assuming the gravitons have significantly more momentum than a photon.
No FTL interactions here, and if gravitons travel at C, there would be some kind effect similar to red-shift blue-shift as your spacecraft travels faster, which would make your "graviton engine" behave differently as your spacecraft reaches velocities faster than the average velocity of all those gravitons
Also, tampering with this "graviton sea" might result in changes to the way the mass of the universe moves, long term, possibly speeding up expansion.
This is tenuous, perhaps...but is it violating any physical laws?
-
Unfortunately, it doesn't work this way. Energy has no rest mass, but it still has an inertial mass equivalent to the inertial mass the matter you would get if you converted the energy to matter.
Basically, conservation of momentum.
As I understand it, the woodward effect "device" is plugged right into the wall. It can't be that simple, can it? Electrons rush in from the wall, making it heavier during part of the cycle and they are sent back to the wall during the other half.
Well, technically, AC power doesn't involve a transfer of electrons, but DC power supplies have capacitors in them that would act like the other half of the problem. An external capacitor on the lab power supply stores the electrons during half the cycle. Since a spacecraft can't do this (you can't store mass in another tank and have it not count against the spacecraft's inertial mass), there you have it.
Someone must have noted this. I'm not arrogant enough to think I'm the first to propose this. Huh.
-
A fundamental question here is whether self-replication is even possible to that extent, at least in an environment as simple as an asteroid. The only examples on nontrivial self-replication we've seen so far work, because they're part of a huge and ridiculously complex ecosystem. Surely life began somehow somewhere in the distant past, but we still don't have any idea how it happened.
Actually, it's in no way an open question. We have self replicating equipment right now*, it just needs a biological component to operate that we don't have full replacements for yet. An asteroid has all of the elements needed to make the self replicating equipment we already have.
The catch is that it's far too heavy to launch into space.
*Add up enough of the factories in China, such that you have a minimum set for self replication. Don't forget to include the support structures for the human workers.
Why do people think the Moon is a safer choice than Mars?
in Science & Spaceflight
Posted
Which need partially or fully self replicating robotic systems. Even if the self replication is only partial, it's a game changer. A partial system would look like a factory with a number of robots, some ore handling and chemical processes, and various milling and additive manufacturing machines. All the machines in the factory would share simple parts made of common alloys that can be milled or additively made from blocks of metal (probably aluminum) that the factory itself can make.
All the machines would use electronics that are composed of modular circuit boards, of which there would be a limited number of types, so you could stock and ship just 10 or so kinds of circuit boards. More advanced versions of this factory would be able to etch their own circuit boards onto some kind of blank that the factory could make, so you would only have to stock/ship the chips.
This kind of thing would make money right now on Earth. Putting it on the moon, though, means the machines could build a vast complex of larger factories from a relatively small amount of mass landed on the lunar surface.
And then, from these generic aluminum parts and ISRU circuit boards and key parts from Earth, they'd be able to make life support equipment and the pieces for underground habitats and earth moving equipment to build the habitats and so on. Be a heck of a lot easier to go to Mars after we have debugged and working equipment at this tech level.
This same equipment would also make space travel loads easier. A fully automated, robotic factory line that does both the milling and additive manufacturing steps could build you expendable rockets for cargo launches. You'd collect the wreckage from the expended rocket stages and use them as inputs for the factory.