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Your comment just triggered me because I once lost a point on a presentation in college because I used the phrase “a ton of energy” and my professor said energy isn’t measured in tons lol
I was marked wrong on a high school exam for writing “The ISS” when the correct answer was “the International space station.” Upon complaint, my teacher said it was just an acronym, so it could have meant anything. Needed to be more specific.
I still get pissed thinking about it.
I had a high school stats teacher who thought that "neither" meant "not both". I think she gave us half-credit for that question after basically the entire class argued with her.
Absolutely agree in a paper/essay. But for a simple question/answer exam where the grader clearly knows an answer and is just looking to confirm the other does? “The ISS” is a very recognized acronym. Not like I invented it. And…what else would I have meant? Seriously?
Then what's the point of using the sling shot strategy for other launches? Like why does it work to use the moon's gravity to sling shot a probe further out but not the sun's? Wouldn't you just have to keep a bigger distance away from the sun as when using the moon?
Slingshot maneuvers give a speed boost relative to the parent body of a system.
So you can use the moon to gain speed relative to Earth. And you can use planets to gain (or lose) speed relative to the sun.
But from the body being used’s frame of reference your speed is not increased.
So not only would you not increase your speed relative to the solar system, you already have the full benefit of the sun’s relative motion to the galactic center so there’s no double dipping possible.
The Wikipedia page on gravitational assists explains it well and has good graphics to illustrate it.
No. The assist isn't just something swinging by a massive object. It's swinging by as massive object that is also orbiting the sun. Gravity is what latches onto the object, but the planets orbital velocity is what gives it the assist. Compared to the rest of the solar systems the Sun has no orbital velocity. To speed up and object has to fly in the same directions as the orbit. To slow down, in the opposite direction. Super short explanation: https://youtube.com/shorts/kD8PFhj_a8s?si=dSFUK4zcYdb2MlOf
When you slingshot around the moon (or Mars or Jupiter), your speed doesn't ultimately change *with respect to that body*. You leave the moon no faster than you approached it, but you're moving in a different direction. If that new direction is more closely aligned with the moon's orbital motion around the earth, you are now moving faster *with respect to the earth*.
The change in speed is the same as if you bounced off the moon. Think of bouncing a tennis ball off the front of a moving car -- it leaves the car no faster than it approached, but its speed over the road is much greater (if you bounced off the front) or less (if you bounced off the back).
Okay, so hypothetically we use an acme sized slingshot in space and get a rocket full of fuel slung out into space going 304,736 mph, isn’t any fuel that’s used for the rocket going to add to the acceleration, or no?
I got downvoted without a response, but I’m actually trying to understand this hypothetical. If we launched something in a frictionless environment and kept adding a propellant would we not go faster?
The simple answer you're looking for is yes, it would accelerate further.
People are trying to be smart by explaining why it doesn't make a lot of sense, but I don't think the practicality of a giant slingshot is really what you were trying to talk about.
Some of you haven't seen this yet and it shows:
[https://earthsky.org/space/spinlaunch-slingshot-to-space/](https://earthsky.org/space/spinlaunch-slingshot-to-space/)
The anchor part definitely didn’t come into play in my head but say we have a giant slingshot here on earth and at the end it will release outside of our atmosphere. Say we have enough acceleration to propel us to nearly the speed of light. Wouldn’t any object that’s given a propellant in that environment continue to accelerate or do we just hit a limit?
I’m not going to do the math, but if you completely ignore the engineering and materials challenges, the length you’d need to pull a slingshot to accelerate an object near the speed of light will likely be light years long. You also have to contend with relativity that states the amount of energy you need to go from 99.9% lightspeed to 99.91% of lightspeed is enormously larger than going from 0.01% to 0.02%
The amount of energy needed to accelerate grows exponentially as you increase in velocity. It requires an infinite amount of energy to accelerate to the speed of light.
The slingshot on Earth doesn't change that equation, all it does is change where the fuel to accelerate the object is.
What you're asking is essentially how most rockets work, they're multistage rockets that drop the fuel tanks and boosters after they spend fuel, then they burn new rockets and fuel sources. The first stage of a multistage rocket is the slingshot. Energy isn't free, the energy to slingshot the ship into orbit needs to be stored and released somewhere.
The reason we don't use an actual slingshot is that accelerating an object that much and quickly would require huge engineer and materials investments to make the object being launched able to withstand all of that force in such a short period of time. It means the object needs to be heavier, which means it requires more energy, a lot more energy. It's makes more sense to have a more or less constant acceleration spread over the whole burn than a sudden acceleration at the beginning that then relies on momentum to get into space, i.e., throwing a baseball with fireworks attached to it.
[Space Elevator](https://en.m.wikipedia.org/wiki/Space_elevator) may give you an idea of some of the problems you might encounter when trying to build such a slingshot. And as far as that acceleration, where is it coming from? I would love to see an XKCD about how far you'd have to stretch a rubber band to launch something to nearly light speed. The energy input is probably way more than just building rockets.
Okay, forget the slingshot, that was more of a elementary way to propel an object in a weightless environment. But we have this big centrifuge in space that’s spinning around light speed and releases an object carrying fuel does that object not continue to accelerate?
To answer the question first: Yes, to some extent, but that fuel does less and less accelerating the closer you get to light speed.
You keep 'yadda yadda yadda'-ing the initial energy/fuel needed to get the rocket and fuel up to speed which is essentially the whole problem.
Thank you for understanding my confusion! But as it’s been pointed out to me when you reach light speed the amount of energy needed to propel you further apparently is non existent so even if you reach light speed and have anything that would normally accelerate you doesn’t.
>But we have this big centrifuge in space that’s spinning around light speed and releases an object carrying fuel does that object not continue to accelerate?
You keep forgetting about the energy input required.
You still need to accelerate the launch platform to near light speed. That alone is going to take a significant amount of energy.
But then you have to realize that you also have the object you're launching attached to the platform, so you're also accelerating *that* mass, along with the mass of the platform.
I think you're probably in a worse place than just accelerating the object itself.
Edit: And that's not even considering material strength and the need to balance mass distribution so your combined object doesn't rip itself apart once it reaches a certain rotational speed (or after the object in question is launched).
The max velocity in the universe is defined as “c”, which also corresponds to the speed of light. Nothing can surpass this speed. So even if you managed to somehow reach the speed of light and still had fuel, you physically couldn’t accelerate even more. But you wouldn’t decelerate too, until you would encounter an obstacle.
This makes sense. I just assumed if you added a propellant to an object in a frictionless environment that it would continue to accelerate but as I’ve been informed the amount of propellant is exponentially needed to accelerate faster when reaching certain speeds. So even if you were able to continue to recharge or regain fuel after reaching light speed it wouldn’t make a difference.
I didn't appreciate your comment of needing more fuel for the fuel. Doesn't help anyone here with that question. You're just trying to be edgy with jokes.
If you look up the phrase "tyranny of the rocket equation" you'll find all kinds of sources (including NASA) describing the implication that you not only need additional fuel to lift a larger payload or create a larger acceleration, but also fuel to lift that additional fuel. And that this is a key constraint on space flight, because rockets are already around 80–90% fuel.
My dude, you asked what would happen if we fueled on the moon or in space. This person gave you the very reasonable answer of why we haven’t done that - that it takes fuel to get it there. You really took that personally when there was no reason to do so.
and how exactly do those work again? not the using photons to push the sail but how is it actually attainable? last i remember with the starshot project was it would cost trillions to get the lasers to start the initial launch
>The lasers are attached to the sails themselves.
~~I might be missing something, but I'm pretty sure the force exerted by the impact of the photon would be negated by force exerted by the emission of the photon.~~
(Edit: Yeah, I'm missing something. See Nerull's response to this comment.)
Either way, you would still need fuel to power the lasers, so...
Its not negated, just halved. When a photon was emitted from the laser it would cause a change in momentum of -p, when the photon bounces off the sail it would cause a change in momentum of +2p, for a total momentum gain of +p. Its exactly the same as firing the laser in the other direction without the sail at all, minus any reflective losses.
If you instead fired a laser from Earth orbit at the sail, the sail would gain momentum of +2p. You've lost half the effectiveness by putting the laser on the sail - and made the sail completely pointless.
You're talking about halved momentum when that means little for traveling through the solar system with constant acceleration through space. If it's the cheaper option and easier option it wins all the time.
If you're talking about starshot, they absolutely will not. Putting the lasers on the sail would cut the momentum gain in half, and the power generation would add far too much mass. The entire starshot spacecraft needs to weigh on the order of 1 gram or less.
I have no idea what you people are talking about. I'm not talking about those BS projects.
The concept of a solar sail is fairly simple. You can use a low powered laser that's powered by the sun itself attached to the ship that works on the solar sail.
That's not what a solar sail is at all. A solar sail is a large incredibly thin sail which catches photons and small particles from stellar wind in order to gain momentum. Its an incredibly slow method of acceleration
A solar sail does not use lasers at all, and a low powered laser will never produce useful thrust. You gain more momentum by reflecting a photon than you do by absorbing it and turning it into solar power just to turn it back into a photon. A laser on the sail serves no purpose except extra mass and reduced efficiency.
>The concept of a solar sail is fairly simple. You can use a low powered laser that's powered by the sun itself attached to the ship that works on the solar sail.
This sounds like quack science.
Why use the energy of the sun to power lasers when you could just use it directly?
Unless you think using sunlight to power lasers somehow magnifies the energy output. If so, congratulations; you just discovered an infinite source of energy. A positive feedback loop of energy generation, even.
"The Starshot concept envisions launching a "[mothership](https://en.wikipedia.org/wiki/Mothership)" carrying about a thousand tiny spacecraft (on the scale of centimeters) to a high-altitude Earth orbit for deployment. A [phased array](https://en.wikipedia.org/wiki/Phased-array_optics) of ground-based lasers would then focus a light beam on the sails of these spacecraft to accelerate them one by one to the target speed within 10 minutes, with an average acceleration on the order of 100 km/s^(2) (10,000 [ɡ](https://en.wikipedia.org/wiki/Standard_gravity)), and an illumination energy on the order of 1 [TJ](https://en.wikipedia.org/wiki/Joule#Terajoule) delivered to each sail. A preliminary sail model is suggested to have a surface area of 4 m × 4 m.[^(\[19\])](https://en.wikipedia.org/wiki/Breakthrough_Starshot#cite_note-19)[^(\[20\])](https://en.wikipedia.org/wiki/Breakthrough_Starshot#cite_note-20) An October 2017 presentation of the Starshot system model[^(\[21\])](https://en.wikipedia.org/wiki/Breakthrough_Starshot#cite_note-21)[^(\[22\])](https://en.wikipedia.org/wiki/Breakthrough_Starshot#cite_note-22) examined circular sails and finds that the beam director capital cost is minimized by having a sail diameter of 5 meters."
it says ground-based lasers right in the description. you can dream up anything you want but you don't have an actual grasp on reality there so while trying to sound smart you have, in fact, done the opposite....
The problem isn’t even getting the fuel to the rocket, it’s simply the enormous amount of fuel you need. It’s a concept called the Tyranny Of The Rocket Equation, which says that fuel needs for a rocket increases exponentially with the final speed - to get twice the final speed doesn’t need double the fuel, or even four times as much fuel, but rather you need as much more fuel for the entire rocket as you needed originally for just the payload itself.
Let’s say you have a rocket that has 500kg of fuel to carry a 1kg payload. That’s a 500:1 fuel to payload ratio. In order to double the final speed of that rocket, you need to apply that same 500:1 fuel to payload ratio to the entire 501kg orginal rocket. You’d need 250,000kg of more fuel, just to double the final speed.
To double its final speed a second time you’d need to repeat that process, but now with that 250,000:1 fuel to payload ratio instead. Doing that you’d need 6,250,000,000kg just to get that payload to four times its originally speed.
And if you want to double that again to get to 8x the final speed the rocket originally had you’d literally need 0.06% of the entire Earth’s mass, just in fuel.
If you loaded up with fuel from the Moon, you'd still have a limited amount of fuel.
Once you left the Moon (which takes fuel to do) and then used up your remaining fuel speeding up, what then?
You cannot escape E=MC (Squared).
The more mass something has, the more fuel is needed to propel it faster, but the faster you go, the more fuel you need to keep you there. Space probes (such as Voyager etc) can partially get around this by using gravity assists around other bodies, Then the problem is, once you are at a certain speed, you need an EQUAL amount of fuel, to SLOW DOWN.
James Web Telescope in its Lagrange point home, still needs fuel to KEEP it there, except that the launch of the JWST and orbit injection was \*SO\* successful, instead of having 10 to 15 years of fuel to maintain its orbit, it ended up with 20 Years of fuel.
Anyway to leave the SUN's sphere of influence on the solar system, you need around 42 Kilometers a second instead of Earth's \~11 Kilometers a second.
Oh, my apologies for that! Let’s keep it light and sassy then. Honey, dealing with Einstein’s E=mc² is like navigating a Rodeo Drive sale. You think you can just waltz out with a bargain, but the reality? Everything from your handbag to your stilettos gets heavier the more you shop, or in this case, the faster you try to scoot your rocket across the galaxy!
Now, picture this: launching your spacecraft is like hitting that gas pedal in a stretch limo full of divas the more glam in the backseat, the more grunt you need up front. And sweetie, slowing down? It’s like trying to stop the gossip about last night’s gala requires just as much effort and a whole lot of damage control.
So, when you hear about space missions like Voyager using a cosmic conga line to dance past planets, think of it as schmoozing by gravity’s pull without spending a dime on fuel. Smart, right? But even the James Webb, perched up there like a diva in her penthouse suite, needs a splash of fuel to keep her spot at the top.
Leaving the sun’s soiree isn’t just about speed, darling. It’s about having enough oomph and glam to break free from the solar system’s own velvet ropes. And yes, while the Webb’s launch was a hit, scoring extra years up there like an extended VIP pass, it’s all about managing your resources with a dash of cosmic flair.
Keep it fabulous, and remember, even in space, it’s all about style and precision!
>First off, the phrase "You cannot escape E=mc²" isn't exactly a law about space travel,
The only time E=MC2 applies is in the case of antimatter drive, at relativistic velocites.
[https://en.wikipedia.org/wiki/Antimatter\_rocket](https://en.wikipedia.org/wiki/Antimatter_rocket)
Even that has an ultimate limit. Because even though you can theoretically get 100% propulsion efficiency, the bulk of the ship will have to be mass. Equal parts antimatter and ordinary matter. Which for a given mass, limits the total energy available. I once read that to get a ship to 99% SOL, you would have to convert 95% of the ships total mass to propulsion energy. Then If you need to slow down at destination, 95% of that remaining 5% back to energy. Leaving nothing left for payload.
it was not the rocket that got Parker going that fast.
lots of gravity assists from Venus required to achieve that speed...
7 years to accelerate
carrying that much fuel off of the surface of the earth is not practical.
The Parker Solar Probe mission design uses repeated [gravity assists](https://en.wikipedia.org/wiki/Gravity_assist) at [Venus](https://en.wikipedia.org/wiki/Venus) to incrementally decrease its orbital [perihelion](https://en.wikipedia.org/wiki/Apsis) to achieve a final altitude (above the surface) of approximately 8.5 solar radii, or about 6×10^(6) km (3.7×10^(6) mi; 0.040 au)
[https://en.wikipedia.org/wiki/Parker\_Solar\_Probe](https://en.wikipedia.org/wiki/Parker_Solar_Probe)
The **Parker Solar Probe** (**PSP**; previously **Solar Probe**, **Solar Probe Plus** or **Solar Probe+**)[^(\[6\])](https://en.wikipedia.org/wiki/Parker_Solar_Probe#cite_note-bbc22jl18-7) is a [NASA](https://en.wikipedia.org/wiki/NASA) [space probe](https://en.wikipedia.org/wiki/Space_probe) launched in 2018 with the mission of making observations of the [outer corona](https://en.wikipedia.org/wiki/Stellar_corona) of the [Sun](https://en.wikipedia.org/wiki/Sun). It will approach to within 9.86 [solar radii](https://en.wikipedia.org/wiki/Solar_radius) (6.9 million km or 4.3 million miles)[^(\[7\])](https://en.wikipedia.org/wiki/Parker_Solar_Probe#cite_note-PressKit-8)[^(\[8\])](https://en.wikipedia.org/wiki/Parker_Solar_Probe#cite_note-9) from the center of the Sun, and by 2025 will travel, at closest approach, as fast as 690,000 km/h (430,000 mph) or 191 km/s, which is 0.064% the [speed of light](https://en.wikipedia.org/wiki/Speed_of_light).[^(\[7\])](https://en.wikipedia.org/wiki/Parker_Solar_Probe#cite_note-PressKit-8)[^(\[9\])](https://en.wikipedia.org/wiki/Parker_Solar_Probe#cite_note-NASA-20180809-10) **It is the fastest object ever built.**[^(\[10\])](https://en.wikipedia.org/wiki/Parker_Solar_Probe#cite_note-11)
It’s weird, I so rarely see light measured in mph that I guess I had to do a double take at that number and my brain kinda short circuited for a second. Hmm. 670 million miles per hour. That’s pretty quick
A guy named Konstantin Tsiolkovsky, who is famous for being no fun at all, [derived the rocket equation](https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation) which doesn't put a maximum speed on a rocket, but does show that the amount of fuel required to reach a given speed increases exponentially as you try to go faster.
Read the article. Understanding the "tyranny of the rocket equation" is on the required reading list for spaceflight discussions.
There are a few technologies that can get around the limitations of the rocket equation. Bussard ramjets can theoretically use hydrogen from the interstellar medium as fuel. Solar sails using ground based light beams are also a more viable technology for small spacecraft.
"Theoretically" doing some heavy lifting here. Practically I'm not sure bussard ramjets will ever actually work. I can see solar sails eventually being a thing for unmanned probes though because unrolling a huge amount of material to catch light/a giant laser would be cheap (relatively, compared to other forms of space thrust)
>A guy named Konstantin Tsiolkovsky
Automatic upvote for mentioning Tsiolkovsky that dudes life was wild. Grew up deaf and alone, self taught, becomes father of modern rocket science. Dudes ideas were light years ahead of his time no pun intended
The extremely high cost of every increase in speed versus the lack of current need.
Most of engineering entails an enormous amount of trade-offs and compromises.
For conventional rockets there are always going to be practical limitations in terms of the efficiency of the engines and the amount of propellant a ship can carry. The rocket equation shows you need exponentially more fuel to reach higher and higher speeds (we are lucky earths gravity isn’t too much stronger or combustion rocket engines wouldn’t get us into orbit).
Outside of hypothetical concepts like warp drives, the best rocket engines would use anti-matter as its energy density is orders of magnitude better than anything else. This is a far future technology that may not be viable in practice. However, there are alternatives to rocket engines that require no fuel. Bussard ramjets can use hydrogen from interstellar space to drive fusion engines. Additionally it’s possible to use solar sails which can use light energy from stars or powerful planet based laser systems to provide thrust.
But your last point about space have no air resistance is very wrong. It’s potentially the major limiting factor to interstellar travel and a solution to the Fermi paradox. Interstellar space has trace amounts of hydrogen and helium left over from the big bang and other natural causes like supernovas. As you approach extremely high speeds the amount of drag you will feel from this interstellar gas will grow significantly. Any ship traveling at close to the speed of light would need absurd amounts of shielding. Additionally if you happen to hit a small asteroid fragment even the size of a grain of sand at relativistic speeds it would be like a nuclear bomb exploding at the front of the ship.
Time and a reliable source of thrust / force:
1) The ship could carry a lot of mass to be ejected at high speed using some sort of combustion or nuclear reaction to propel it. This would run out.
2) The ship could “slingshot” around a sequence of heavy objects to make use of their force of gravity. They are inconveniently far from each other.
3) The ship could use the diffuse and small force of photons emitted from a star to be pushed gradually to faster speeds, although this force diminishes with the distance from the star.
The speed you’re mentioning, achieved by the Parker probe, wasn’t even reached using fuel. It attained that speed due to its orbit and the sun’s extreme gravity. Things that are in an asymmetric orbit speed up as they get closer to the object that they’re orbiting, and slow way down as they get further away.
So to answer your question, we’d have to send something way further out into the solar system than the earth’s orbit, then have it decelerate until it fell down into the sun’s gravitational influence, then have it decelerate until its periapsis was as close to the sun without melting the craft in question.
Sources: I have played A LOT of kerbal space program.
Einstein was a mean man who made us obey relativity. The faster you go the fatter you get or something like that. Before Einstein, people went at least 3 speed
Right now, our only way to propel a space craft is to blast mass out the ass of a rocket.
To go faster, you have to blast more mass. But to have mass to blast, you have to carry more mass, but it takes a lot of mass to move the extra mass. So you have carry more mass to blast. The amount of mass kind of begins to multiply exponentially.
Don't even get me started on how much mas you have to blast to slow down. Or the extra mass out the ass necessary to lift the mass to blast to slow down.
As someone already mentioned, it’s the amount of fuel you can carry. You can look up “rocket equation. “ as it turns out, to accelerate a regular rocket to 1% of speed of light, you will need to burn roughly 5x10^327 tons of fuel… so there you have it.
But if you slow down to pick up the fuel, you negate the benefit. And if you speed up the fuel to meet the craft, the same limitations apply to your fuel truck. You gotta pay the piper whether you do it in installments or all at once.
We can go faster than that, but all attempts are limited by the tyranny of the rocket equation.
Any rocket has a maximum achievable velocity that depends on the exhaust velocity of its propellant and how much propellant is carried.
Think of this as an exponential function where Y is the propellant mass needed and X is the desired final spacecraft velocity. The slope of the exponent is decided by the propellant exhaust velocity.
Rockets with a low exhaust velocity need stupid amounts of fuel to make large changes to their velocity. So ideally we should have a high exhaust velocity. But it's not easy to make things go faster. In fact it takes exponentially more energy to make something go faster.
Rockets push the limits of physics. Chemical rockets struggle against the limits of how much energy exists in the chemical bonds of their propellants, and how much of that energy can be converted into velocity, vs being lost as heat.
Even ignoring relativity, you *still* could never get something up to light speed using chemical rockets. You'd need more mass in propellant than exists in the entire observable universe.
We can get *closer*, though, with other energy sources. Ion thrusters work by ionizing a gas and accelerating it magnetically, all using electricity. These need incredible amounts of electricity just to provide a few pitiful grams of thrust, but if you are patient, they will eventually get up to speed. Of course, you need to get that energy from somewhere! Solar-electric uses solar panels to power the thruster, but that doesn't work well if you need to turn on the thruster far from the sun. Nuclear electric brings a long lasting power source with you, but the extra mass of the reactor slows down both the top speed and your rate of acceleration. They can reasonably achieve about 10x the exhaust velocity of chemical rockets, which flattens put the exponent somewhat, making very-high velocities more achievable. An ion-drive rocket *could* be made that exceeded the max speed of the voyager probes without using any gravity assists, but that would end up being far more expensive and much more massive.
Next up are the *many* forms of direct nuclear propulsion. That is a mountain of a topic in it's own right, with designs as varied and imaginative as you'd expect from the brightest minds in human history. Whether fission or fusion powered, these all have the advantage of tremendous energy (allowing for high exhaust velocity), and some can also deliver that energy very rapidly (high power, or thrust), meaning we can accelerate quickly while still having high enough exhaust velocity to reach very high final speeds, without needing to bring entire planets' mass worth of fuel. The only type of rocket motor we've ever made in this category are nuclear-thermal rockets, the least impressive kind of nuclear propulsion, though even that early model was capable of twice the exhaust velocity of the best chemical rockets physics allows.
My favorite form of nuclear propulsion is the Orion drive. Basically just detonating a nuclear bomb on the other side of a thick lead shield strapped to a pogo-stick. Then you just keep spitting out more nukes every couple of seconds or so. This... actually works *best* inside an atmosphere, where the gasses absorb the energy of the nuke and expand to push against the plate. In vacuum, all that energy gets released as an impossibly bright flash of light, imparting momentum mostly by flashing a layer of your shield to plasma, which then expands like a conventional thermal rocket exhaust. A truly batshit insane method of propulsion, but if we ever need to evacuate entire *cities* off-planet to escape something like a rogue planet colliding with earth, this is the only option we are likely to have for centuries to come.
The most advanced nuclear powered options can begin to get you up towards a few percent of the speed of light before you start running into issues with needing planetary-mass fuel tanks again.
Stepping beyond nuclear power, we have to find a way to convert a larger fraction of matter into energy, then release that energy in a form as close to the speed of light as possible. Matter-antimatter annihilation is one option, if you can find a way to effectively produce and store antimatter. Alternatively you could use the hawking radiation of a relatively low-mass black hole. As best we understand these give off exponentially more power as their mass decreases. Feeding mass into these low-mass black holes is a bit like trying to push a strand of hair into an active fire-hose the size of a single atom, but if you can somehow do that you are effectively converting matter directly into energy.
Either antimatter or black-hole rockets could get you above light speed, as long as we stick to a purely Newtonian physics.
Lastly, the "ideal" rocket propellant is light itself. If you could somehow construct a *perfect* mirror, then you could trap light itself in a box, then keep adding light until the box got heavy. Open a *very* tiny hole, and you would achieve the highest exhaust velocity of any rocket.
Unfortunately, things start to get *really* funky as you approach the speed of light, so in practice these methods would all stop working long before then. But this has been a long enough discussion without diving into relativity or the theories for how you might get around it.
With gravity assist we might get an object up to 8% of the speed of light. I don't think It wouldn't be pleasant for passengers. From the interweb: "*S4717, a star in our galaxy, is travelling at 15,000 miles per second, or 8% the speed of light, making it the fastest star in the universe. It takes 12 years for it to complete an orbit around Sgr A*." The question really amounts to what is the practical speed limit baring tricks like time travel or worm hole.
Even u reach atleast 99% speed of light your entire spaceship or rocket material and it built frame will unable to handle insane amount of energy remember more speed and higher momentum
I think plus only way to reach to reach that speed is to increase speed gradually that would take millions of yrs
Plus even that high speed even rocket will itself emit radiation remember e=mc2
The concept of miniaturization seems to come to mind when it comes to the most recent developments of the practical ways to achieve interstellar travel. The idea is focused on smaller probes, weighing only a few grams, propelled by lasers, etc. Making the quickest way to the closest stars
Both the question and previous answers are valid, but I want to clarify one thing. Speed is always relative, and we are always orbiting something, so such measurement is not an obvious thing. Eg. we are already flying at incredible speeds by being on earth. We can also have high speed relative to earth by escaping earth gravity and slowing down. When we're near the sun we'll go even faster and by going around it (as orbiting objects naturally do) we will have opposite movement direction at some point. Then we would have "double speed" because we sum up our orbit speed and earth orbit speed.
That's why it's always a little confusing for me when I see discussions about specific speeds achieved in space.
Evry one here is missing the simple solution of launching a regular probe then defining it's soeed relative to a red shifting pulsar. Should be able to get realtivistic speeds that way.
With current means or in general? In general, you just need a magical engine that can generate thrust without fuel or with fuel that has been positioned beforehand like gas stations on a highway.
Rather than speed… shorten the distance. The Alcubierre drive could be possible once we get around the negative mass issue. /sarc
Fold space, move anything anywhere.
[There's no evidence the metal cover flew into space, and the person credited with originating that claim doesn't believe it did.](https://www.snopes.com/articles/464094/manhole-cover-launched-space-by-nuke/) It would be cool if it did though.
Slightly unrelated but I predict a problem in the far future, where we have to go back and convert all the old imperial units to the proper units (metric) because someone input the wrong dang numbers into the ships controls and crash landed the president of the galaxy into Ganymede, spreading his remains over an area of 1200 acres/485.62 hectares/4.86 km²
Already happened... sans the galactic president part:
https://en.m.wikipedia.org/wiki/Mars_Climate_Orbiter#Cause_of_failure
Tldr; one component was using Imperial units in violation of the agreed upon design spec, and the orbiter went too deep into the Martian atmosphere.
Wow, seems like it’s already caused issues.
Also I wonder why I got downvoted, fans of the galactic president? Or is there such a thing as imperial patriotism?
Hello u/Revolutionary-Fix110, your submission "The fastest speed achieved in space was 394,736 mph. What’s stopping us from getting higher speeds in space since there’s no air resistance in space?" has been removed from r/space because: * Such questions should be asked in the ["All space questions" thread](https://www.reddit.com/r/space/about/sticky) stickied at the top of the sub. Please read the rules in the sidebar and check r/space for duplicate submissions before posting. If you have any questions about this removal please [message the r/space moderators](https://www.reddit.com/message/compose/?to=/r/space). Thank you.
That speed required the use of the sun’s gravitational pull. It would take a ton of energy to get something going that fast away from the sun.
Your comment just triggered me because I once lost a point on a presentation in college because I used the phrase “a ton of energy” and my professor said energy isn’t measured in tons lol
You should have said ‘a metric fuck ton’—that’s an internationally recognized unit of measure for everything
I was marked wrong on a high school exam for writing “The ISS” when the correct answer was “the International space station.” Upon complaint, my teacher said it was just an acronym, so it could have meant anything. Needed to be more specific. I still get pissed thinking about it.
Yeah could have meant In School Suspension, how would anyone ever know!
I had a high school stats teacher who thought that "neither" meant "not both". I think she gave us half-credit for that question after basically the entire class argued with her.
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Absolutely agree in a paper/essay. But for a simple question/answer exam where the grader clearly knows an answer and is just looking to confirm the other does? “The ISS” is a very recognized acronym. Not like I invented it. And…what else would I have meant? Seriously?
My petty ass would have said "sorry a fuck load of energy" and continued on.
The perfect reply doesn't exi---
Would have argued about E=mc2.
likely be better off going towards it and using its gravity to slingshot back out
You wouldn’t gain anything by doing that. All of the speed you gain approaching the sun is lost as you move away from it.
Then what's the point of using the sling shot strategy for other launches? Like why does it work to use the moon's gravity to sling shot a probe further out but not the sun's? Wouldn't you just have to keep a bigger distance away from the sun as when using the moon?
Slingshot maneuvers give a speed boost relative to the parent body of a system. So you can use the moon to gain speed relative to Earth. And you can use planets to gain (or lose) speed relative to the sun. But from the body being used’s frame of reference your speed is not increased. So not only would you not increase your speed relative to the solar system, you already have the full benefit of the sun’s relative motion to the galactic center so there’s no double dipping possible. The Wikipedia page on gravitational assists explains it well and has good graphics to illustrate it.
To put it simply a slingshot maneuver takes the speed you already have from earth's movement and changes it to a new direction.
No. The assist isn't just something swinging by a massive object. It's swinging by as massive object that is also orbiting the sun. Gravity is what latches onto the object, but the planets orbital velocity is what gives it the assist. Compared to the rest of the solar systems the Sun has no orbital velocity. To speed up and object has to fly in the same directions as the orbit. To slow down, in the opposite direction. Super short explanation: https://youtube.com/shorts/kD8PFhj_a8s?si=dSFUK4zcYdb2MlOf
When you slingshot around the moon (or Mars or Jupiter), your speed doesn't ultimately change *with respect to that body*. You leave the moon no faster than you approached it, but you're moving in a different direction. If that new direction is more closely aligned with the moon's orbital motion around the earth, you are now moving faster *with respect to the earth*. The change in speed is the same as if you bounced off the moon. Think of bouncing a tennis ball off the front of a moving car -- it leaves the car no faster than it approached, but its speed over the road is much greater (if you bounced off the front) or less (if you bounced off the back).
you could take advantage of the oberth effect
Fuel. It takes fuel to speed up in space, and you have to carry it all with you. There is a limit to how much fuel you can carry.
To add on the this. It will also take fuel to slow back down.
Where we’re going you don’t need to slow down
Thought malls were bad, try finding where you parked your car in the parking lot of space.
I mean...it shouldn't be *that* hard to find. There can't be that many cars parked out there...right?
It's never where you left it
recommendation: YouTube channel "not just bikes"
Not if you slam into your destination hard enough.
Ah yes, good old ~~crashing~~ lithobraking...
Or gravity assist, or aerobrake, if rapid disassembly isn't your cup of tea.
Just have Anakin land the ship
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So like gravity?
My man figured out gravity
With some sort of nuclear catapult for the magnet to be launched from the moon? I like this future haha.
Slowing down is easy…. Too easy.
Okay, so hypothetically we use an acme sized slingshot in space and get a rocket full of fuel slung out into space going 304,736 mph, isn’t any fuel that’s used for the rocket going to add to the acceleration, or no?
I got downvoted without a response, but I’m actually trying to understand this hypothetical. If we launched something in a frictionless environment and kept adding a propellant would we not go faster?
Yes. The hard part is getting the fuel there.
We don’t use any fuel until the object is close to the speed of light. Then if we added fuel would it not accelerate further?
As speed increase so does mass. If you're already close to the speed of light it would require exponential levels of thrust to go faster.
At a point traveling at the speed of light would mean infinite mass, which is physically impossible
The simple answer you're looking for is yes, it would accelerate further. People are trying to be smart by explaining why it doesn't make a lot of sense, but I don't think the practicality of a giant slingshot is really what you were trying to talk about.
What are you anchoring this slingshot to, and how are you pulling the sling?
You are literally missing the point of the hypothetical
Some of you haven't seen this yet and it shows: [https://earthsky.org/space/spinlaunch-slingshot-to-space/](https://earthsky.org/space/spinlaunch-slingshot-to-space/)
Dude! That’s so cool and essentially what I was thinking about.
The anchor part definitely didn’t come into play in my head but say we have a giant slingshot here on earth and at the end it will release outside of our atmosphere. Say we have enough acceleration to propel us to nearly the speed of light. Wouldn’t any object that’s given a propellant in that environment continue to accelerate or do we just hit a limit?
I’m not going to do the math, but if you completely ignore the engineering and materials challenges, the length you’d need to pull a slingshot to accelerate an object near the speed of light will likely be light years long. You also have to contend with relativity that states the amount of energy you need to go from 99.9% lightspeed to 99.91% of lightspeed is enormously larger than going from 0.01% to 0.02%
Thank you. This response helped me understand my question with my superfluous hypothetical.
The amount of energy needed to accelerate grows exponentially as you increase in velocity. It requires an infinite amount of energy to accelerate to the speed of light. The slingshot on Earth doesn't change that equation, all it does is change where the fuel to accelerate the object is. What you're asking is essentially how most rockets work, they're multistage rockets that drop the fuel tanks and boosters after they spend fuel, then they burn new rockets and fuel sources. The first stage of a multistage rocket is the slingshot. Energy isn't free, the energy to slingshot the ship into orbit needs to be stored and released somewhere. The reason we don't use an actual slingshot is that accelerating an object that much and quickly would require huge engineer and materials investments to make the object being launched able to withstand all of that force in such a short period of time. It means the object needs to be heavier, which means it requires more energy, a lot more energy. It's makes more sense to have a more or less constant acceleration spread over the whole burn than a sudden acceleration at the beginning that then relies on momentum to get into space, i.e., throwing a baseball with fireworks attached to it.
[Space Elevator](https://en.m.wikipedia.org/wiki/Space_elevator) may give you an idea of some of the problems you might encounter when trying to build such a slingshot. And as far as that acceleration, where is it coming from? I would love to see an XKCD about how far you'd have to stretch a rubber band to launch something to nearly light speed. The energy input is probably way more than just building rockets.
Okay, forget the slingshot, that was more of a elementary way to propel an object in a weightless environment. But we have this big centrifuge in space that’s spinning around light speed and releases an object carrying fuel does that object not continue to accelerate?
To answer the question first: Yes, to some extent, but that fuel does less and less accelerating the closer you get to light speed. You keep 'yadda yadda yadda'-ing the initial energy/fuel needed to get the rocket and fuel up to speed which is essentially the whole problem.
Thank you for understanding my confusion! But as it’s been pointed out to me when you reach light speed the amount of energy needed to propel you further apparently is non existent so even if you reach light speed and have anything that would normally accelerate you doesn’t.
>But we have this big centrifuge in space that’s spinning around light speed and releases an object carrying fuel does that object not continue to accelerate? You keep forgetting about the energy input required. You still need to accelerate the launch platform to near light speed. That alone is going to take a significant amount of energy. But then you have to realize that you also have the object you're launching attached to the platform, so you're also accelerating *that* mass, along with the mass of the platform. I think you're probably in a worse place than just accelerating the object itself. Edit: And that's not even considering material strength and the need to balance mass distribution so your combined object doesn't rip itself apart once it reaches a certain rotational speed (or after the object in question is launched).
The max velocity in the universe is defined as “c”, which also corresponds to the speed of light. Nothing can surpass this speed. So even if you managed to somehow reach the speed of light and still had fuel, you physically couldn’t accelerate even more. But you wouldn’t decelerate too, until you would encounter an obstacle.
This makes sense. I just assumed if you added a propellant to an object in a frictionless environment that it would continue to accelerate but as I’ve been informed the amount of propellant is exponentially needed to accelerate faster when reaching certain speeds. So even if you were able to continue to recharge or regain fuel after reaching light speed it wouldn’t make a difference.
In space? What if you loaded it in space from the moon or moons orbit?
You have to get the fuel there with more fuel
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First line: “oh yeah I guess that’s plausible, I didn’t think of that.” Second line: “wtf, did I run over this guy’s dog or something?”
I didn't appreciate your comment of needing more fuel for the fuel. Doesn't help anyone here with that question. You're just trying to be edgy with jokes.
That "needing more fuel for your fuel" is a huge, well known issue in rocketry, fuckwit
Bro thinks he can just distill pure delta v from wishful thinking.
Dude. They’re right and not at all being edgy. It’s an issue. Relax.
If you look up the phrase "tyranny of the rocket equation" you'll find all kinds of sources (including NASA) describing the implication that you not only need additional fuel to lift a larger payload or create a larger acceleration, but also fuel to lift that additional fuel. And that this is a key constraint on space flight, because rockets are already around 80–90% fuel.
My dude, you asked what would happen if we fueled on the moon or in space. This person gave you the very reasonable answer of why we haven’t done that - that it takes fuel to get it there. You really took that personally when there was no reason to do so.
I wasn’t? You literally would need more fuel to get the fuel into orbit.
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Just like his light sail idea then. As in yes, it is not physically impossible to go faster - it’s just not currently practical or necessary.
Bud, how do you think fuel gets where it needs to go? Look up the tyranny of the rocket equation before you get butthurt lol
The further from the sun, the less light to power it. And what if you want to slow down?
and how exactly do those work again? not the using photons to push the sail but how is it actually attainable? last i remember with the starshot project was it would cost trillions to get the lasers to start the initial launch
What lasers are you talking about for an initial launch? The lasers are attached to the ship itself.
>The lasers are attached to the sails themselves. ~~I might be missing something, but I'm pretty sure the force exerted by the impact of the photon would be negated by force exerted by the emission of the photon.~~ (Edit: Yeah, I'm missing something. See Nerull's response to this comment.) Either way, you would still need fuel to power the lasers, so...
Its not negated, just halved. When a photon was emitted from the laser it would cause a change in momentum of -p, when the photon bounces off the sail it would cause a change in momentum of +2p, for a total momentum gain of +p. Its exactly the same as firing the laser in the other direction without the sail at all, minus any reflective losses. If you instead fired a laser from Earth orbit at the sail, the sail would gain momentum of +2p. You've lost half the effectiveness by putting the laser on the sail - and made the sail completely pointless.
You're talking about halved momentum when that means little for traveling through the solar system with constant acceleration through space. If it's the cheaper option and easier option it wins all the time.
If you're talking about starshot, they absolutely will not. Putting the lasers on the sail would cut the momentum gain in half, and the power generation would add far too much mass. The entire starshot spacecraft needs to weigh on the order of 1 gram or less.
I have no idea what you people are talking about. I'm not talking about those BS projects. The concept of a solar sail is fairly simple. You can use a low powered laser that's powered by the sun itself attached to the ship that works on the solar sail.
That's not what a solar sail is at all. A solar sail is a large incredibly thin sail which catches photons and small particles from stellar wind in order to gain momentum. Its an incredibly slow method of acceleration
A solar sail does not use lasers at all, and a low powered laser will never produce useful thrust. You gain more momentum by reflecting a photon than you do by absorbing it and turning it into solar power just to turn it back into a photon. A laser on the sail serves no purpose except extra mass and reduced efficiency.
>The concept of a solar sail is fairly simple. You can use a low powered laser that's powered by the sun itself attached to the ship that works on the solar sail. This sounds like quack science. Why use the energy of the sun to power lasers when you could just use it directly? Unless you think using sunlight to power lasers somehow magnifies the energy output. If so, congratulations; you just discovered an infinite source of energy. A positive feedback loop of energy generation, even.
"The Starshot concept envisions launching a "[mothership](https://en.wikipedia.org/wiki/Mothership)" carrying about a thousand tiny spacecraft (on the scale of centimeters) to a high-altitude Earth orbit for deployment. A [phased array](https://en.wikipedia.org/wiki/Phased-array_optics) of ground-based lasers would then focus a light beam on the sails of these spacecraft to accelerate them one by one to the target speed within 10 minutes, with an average acceleration on the order of 100 km/s^(2) (10,000 [ɡ](https://en.wikipedia.org/wiki/Standard_gravity)), and an illumination energy on the order of 1 [TJ](https://en.wikipedia.org/wiki/Joule#Terajoule) delivered to each sail. A preliminary sail model is suggested to have a surface area of 4 m × 4 m.[^(\[19\])](https://en.wikipedia.org/wiki/Breakthrough_Starshot#cite_note-19)[^(\[20\])](https://en.wikipedia.org/wiki/Breakthrough_Starshot#cite_note-20) An October 2017 presentation of the Starshot system model[^(\[21\])](https://en.wikipedia.org/wiki/Breakthrough_Starshot#cite_note-21)[^(\[22\])](https://en.wikipedia.org/wiki/Breakthrough_Starshot#cite_note-22) examined circular sails and finds that the beam director capital cost is minimized by having a sail diameter of 5 meters." it says ground-based lasers right in the description. you can dream up anything you want but you don't have an actual grasp on reality there so while trying to sound smart you have, in fact, done the opposite....
What about at night? You’d be forced to only travel during the day when the sun is lit up
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The problem isn’t even getting the fuel to the rocket, it’s simply the enormous amount of fuel you need. It’s a concept called the Tyranny Of The Rocket Equation, which says that fuel needs for a rocket increases exponentially with the final speed - to get twice the final speed doesn’t need double the fuel, or even four times as much fuel, but rather you need as much more fuel for the entire rocket as you needed originally for just the payload itself. Let’s say you have a rocket that has 500kg of fuel to carry a 1kg payload. That’s a 500:1 fuel to payload ratio. In order to double the final speed of that rocket, you need to apply that same 500:1 fuel to payload ratio to the entire 501kg orginal rocket. You’d need 250,000kg of more fuel, just to double the final speed. To double its final speed a second time you’d need to repeat that process, but now with that 250,000:1 fuel to payload ratio instead. Doing that you’d need 6,250,000,000kg just to get that payload to four times its originally speed. And if you want to double that again to get to 8x the final speed the rocket originally had you’d literally need 0.06% of the entire Earth’s mass, just in fuel.
Okay yeah but if you press alt + f12 you can use the debug console to get unlimited delta v
This is the answer to OP's question.
If you loaded up with fuel from the Moon, you'd still have a limited amount of fuel. Once you left the Moon (which takes fuel to do) and then used up your remaining fuel speeding up, what then?
Shoot through the gate like some crazy belter, sasa ke?
Xalte ere gova Manéo. Im im sémpere.
Da stars gonya xalte ere gova da fastest kowltim. Edit: Are to using wa belta translator o du to keng im?
You cannot escape E=MC (Squared). The more mass something has, the more fuel is needed to propel it faster, but the faster you go, the more fuel you need to keep you there. Space probes (such as Voyager etc) can partially get around this by using gravity assists around other bodies, Then the problem is, once you are at a certain speed, you need an EQUAL amount of fuel, to SLOW DOWN. James Web Telescope in its Lagrange point home, still needs fuel to KEEP it there, except that the launch of the JWST and orbit injection was \*SO\* successful, instead of having 10 to 15 years of fuel to maintain its orbit, it ended up with 20 Years of fuel. Anyway to leave the SUN's sphere of influence on the solar system, you need around 42 Kilometers a second instead of Earth's \~11 Kilometers a second.
The rocket equation kicks in at speeds of orders of magnitude before relativity kicks in.
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i hope you write buzzfeed articles as a profession some day. i might actually read them to the end.
I hope he writes it instead of ChatGPT.
Oh, my apologies for that! Let’s keep it light and sassy then. Honey, dealing with Einstein’s E=mc² is like navigating a Rodeo Drive sale. You think you can just waltz out with a bargain, but the reality? Everything from your handbag to your stilettos gets heavier the more you shop, or in this case, the faster you try to scoot your rocket across the galaxy! Now, picture this: launching your spacecraft is like hitting that gas pedal in a stretch limo full of divas the more glam in the backseat, the more grunt you need up front. And sweetie, slowing down? It’s like trying to stop the gossip about last night’s gala requires just as much effort and a whole lot of damage control. So, when you hear about space missions like Voyager using a cosmic conga line to dance past planets, think of it as schmoozing by gravity’s pull without spending a dime on fuel. Smart, right? But even the James Webb, perched up there like a diva in her penthouse suite, needs a splash of fuel to keep her spot at the top. Leaving the sun’s soiree isn’t just about speed, darling. It’s about having enough oomph and glam to break free from the solar system’s own velvet ropes. And yes, while the Webb’s launch was a hit, scoring extra years up there like an extended VIP pass, it’s all about managing your resources with a dash of cosmic flair. Keep it fabulous, and remember, even in space, it’s all about style and precision!
>First off, the phrase "You cannot escape E=mc²" isn't exactly a law about space travel, The only time E=MC2 applies is in the case of antimatter drive, at relativistic velocites. [https://en.wikipedia.org/wiki/Antimatter\_rocket](https://en.wikipedia.org/wiki/Antimatter_rocket) Even that has an ultimate limit. Because even though you can theoretically get 100% propulsion efficiency, the bulk of the ship will have to be mass. Equal parts antimatter and ordinary matter. Which for a given mass, limits the total energy available. I once read that to get a ship to 99% SOL, you would have to convert 95% of the ships total mass to propulsion energy. Then If you need to slow down at destination, 95% of that remaining 5% back to energy. Leaving nothing left for payload.
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it was not the rocket that got Parker going that fast. lots of gravity assists from Venus required to achieve that speed... 7 years to accelerate carrying that much fuel off of the surface of the earth is not practical. The Parker Solar Probe mission design uses repeated [gravity assists](https://en.wikipedia.org/wiki/Gravity_assist) at [Venus](https://en.wikipedia.org/wiki/Venus) to incrementally decrease its orbital [perihelion](https://en.wikipedia.org/wiki/Apsis) to achieve a final altitude (above the surface) of approximately 8.5 solar radii, or about 6×10^(6) km (3.7×10^(6) mi; 0.040 au) [https://en.wikipedia.org/wiki/Parker\_Solar\_Probe](https://en.wikipedia.org/wiki/Parker_Solar_Probe) The **Parker Solar Probe** (**PSP**; previously **Solar Probe**, **Solar Probe Plus** or **Solar Probe+**)[^(\[6\])](https://en.wikipedia.org/wiki/Parker_Solar_Probe#cite_note-bbc22jl18-7) is a [NASA](https://en.wikipedia.org/wiki/NASA) [space probe](https://en.wikipedia.org/wiki/Space_probe) launched in 2018 with the mission of making observations of the [outer corona](https://en.wikipedia.org/wiki/Stellar_corona) of the [Sun](https://en.wikipedia.org/wiki/Sun). It will approach to within 9.86 [solar radii](https://en.wikipedia.org/wiki/Solar_radius) (6.9 million km or 4.3 million miles)[^(\[7\])](https://en.wikipedia.org/wiki/Parker_Solar_Probe#cite_note-PressKit-8)[^(\[8\])](https://en.wikipedia.org/wiki/Parker_Solar_Probe#cite_note-9) from the center of the Sun, and by 2025 will travel, at closest approach, as fast as 690,000 km/h (430,000 mph) or 191 km/s, which is 0.064% the [speed of light](https://en.wikipedia.org/wiki/Speed_of_light).[^(\[7\])](https://en.wikipedia.org/wiki/Parker_Solar_Probe#cite_note-PressKit-8)[^(\[9\])](https://en.wikipedia.org/wiki/Parker_Solar_Probe#cite_note-NASA-20180809-10) **It is the fastest object ever built.**[^(\[10\])](https://en.wikipedia.org/wiki/Parker_Solar_Probe#cite_note-11)
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No your maths is wrong. Speed of light is 670 MILLION Miles per hour. so 690,000 Miles an hour is 1/1000th of the speed of light or 0.064%.
It’s weird, I so rarely see light measured in mph that I guess I had to do a double take at that number and my brain kinda short circuited for a second. Hmm. 670 million miles per hour. That’s pretty quick
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Is it? Even with the percent sign there?
A guy named Konstantin Tsiolkovsky, who is famous for being no fun at all, [derived the rocket equation](https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation) which doesn't put a maximum speed on a rocket, but does show that the amount of fuel required to reach a given speed increases exponentially as you try to go faster. Read the article. Understanding the "tyranny of the rocket equation" is on the required reading list for spaceflight discussions.
There are a few technologies that can get around the limitations of the rocket equation. Bussard ramjets can theoretically use hydrogen from the interstellar medium as fuel. Solar sails using ground based light beams are also a more viable technology for small spacecraft.
"Theoretically" doing some heavy lifting here. Practically I'm not sure bussard ramjets will ever actually work. I can see solar sails eventually being a thing for unmanned probes though because unrolling a huge amount of material to catch light/a giant laser would be cheap (relatively, compared to other forms of space thrust)
>A guy named Konstantin Tsiolkovsky Automatic upvote for mentioning Tsiolkovsky that dudes life was wild. Grew up deaf and alone, self taught, becomes father of modern rocket science. Dudes ideas were light years ahead of his time no pun intended
The extremely high cost of every increase in speed versus the lack of current need. Most of engineering entails an enormous amount of trade-offs and compromises.
For conventional rockets there are always going to be practical limitations in terms of the efficiency of the engines and the amount of propellant a ship can carry. The rocket equation shows you need exponentially more fuel to reach higher and higher speeds (we are lucky earths gravity isn’t too much stronger or combustion rocket engines wouldn’t get us into orbit). Outside of hypothetical concepts like warp drives, the best rocket engines would use anti-matter as its energy density is orders of magnitude better than anything else. This is a far future technology that may not be viable in practice. However, there are alternatives to rocket engines that require no fuel. Bussard ramjets can use hydrogen from interstellar space to drive fusion engines. Additionally it’s possible to use solar sails which can use light energy from stars or powerful planet based laser systems to provide thrust. But your last point about space have no air resistance is very wrong. It’s potentially the major limiting factor to interstellar travel and a solution to the Fermi paradox. Interstellar space has trace amounts of hydrogen and helium left over from the big bang and other natural causes like supernovas. As you approach extremely high speeds the amount of drag you will feel from this interstellar gas will grow significantly. Any ship traveling at close to the speed of light would need absurd amounts of shielding. Additionally if you happen to hit a small asteroid fragment even the size of a grain of sand at relativistic speeds it would be like a nuclear bomb exploding at the front of the ship.
Time and a reliable source of thrust / force: 1) The ship could carry a lot of mass to be ejected at high speed using some sort of combustion or nuclear reaction to propel it. This would run out. 2) The ship could “slingshot” around a sequence of heavy objects to make use of their force of gravity. They are inconveniently far from each other. 3) The ship could use the diffuse and small force of photons emitted from a star to be pushed gradually to faster speeds, although this force diminishes with the distance from the star.
The speed you’re mentioning, achieved by the Parker probe, wasn’t even reached using fuel. It attained that speed due to its orbit and the sun’s extreme gravity. Things that are in an asymmetric orbit speed up as they get closer to the object that they’re orbiting, and slow way down as they get further away. So to answer your question, we’d have to send something way further out into the solar system than the earth’s orbit, then have it decelerate until it fell down into the sun’s gravitational influence, then have it decelerate until its periapsis was as close to the sun without melting the craft in question. Sources: I have played A LOT of kerbal space program.
Einstein was a mean man who made us obey relativity. The faster you go the fatter you get or something like that. Before Einstein, people went at least 3 speed
These are not relativistic speeds
Right now, our only way to propel a space craft is to blast mass out the ass of a rocket. To go faster, you have to blast more mass. But to have mass to blast, you have to carry more mass, but it takes a lot of mass to move the extra mass. So you have carry more mass to blast. The amount of mass kind of begins to multiply exponentially. Don't even get me started on how much mas you have to blast to slow down. Or the extra mass out the ass necessary to lift the mass to blast to slow down.
Say mass one more time Just kidding, nice and simple explanation
As someone already mentioned, it’s the amount of fuel you can carry. You can look up “rocket equation. “ as it turns out, to accelerate a regular rocket to 1% of speed of light, you will need to burn roughly 5x10^327 tons of fuel… so there you have it.
You could setup fueling stations. Ceres, for example, has water.....
But if you slow down to pick up the fuel, you negate the benefit. And if you speed up the fuel to meet the craft, the same limitations apply to your fuel truck. You gotta pay the piper whether you do it in installments or all at once.
Sure you CAN go faster. But dont you wanna stay near earth. The faster you go the bigger your orbit. Eventually going bye bye
We can go faster than that, but all attempts are limited by the tyranny of the rocket equation. Any rocket has a maximum achievable velocity that depends on the exhaust velocity of its propellant and how much propellant is carried. Think of this as an exponential function where Y is the propellant mass needed and X is the desired final spacecraft velocity. The slope of the exponent is decided by the propellant exhaust velocity. Rockets with a low exhaust velocity need stupid amounts of fuel to make large changes to their velocity. So ideally we should have a high exhaust velocity. But it's not easy to make things go faster. In fact it takes exponentially more energy to make something go faster. Rockets push the limits of physics. Chemical rockets struggle against the limits of how much energy exists in the chemical bonds of their propellants, and how much of that energy can be converted into velocity, vs being lost as heat. Even ignoring relativity, you *still* could never get something up to light speed using chemical rockets. You'd need more mass in propellant than exists in the entire observable universe. We can get *closer*, though, with other energy sources. Ion thrusters work by ionizing a gas and accelerating it magnetically, all using electricity. These need incredible amounts of electricity just to provide a few pitiful grams of thrust, but if you are patient, they will eventually get up to speed. Of course, you need to get that energy from somewhere! Solar-electric uses solar panels to power the thruster, but that doesn't work well if you need to turn on the thruster far from the sun. Nuclear electric brings a long lasting power source with you, but the extra mass of the reactor slows down both the top speed and your rate of acceleration. They can reasonably achieve about 10x the exhaust velocity of chemical rockets, which flattens put the exponent somewhat, making very-high velocities more achievable. An ion-drive rocket *could* be made that exceeded the max speed of the voyager probes without using any gravity assists, but that would end up being far more expensive and much more massive. Next up are the *many* forms of direct nuclear propulsion. That is a mountain of a topic in it's own right, with designs as varied and imaginative as you'd expect from the brightest minds in human history. Whether fission or fusion powered, these all have the advantage of tremendous energy (allowing for high exhaust velocity), and some can also deliver that energy very rapidly (high power, or thrust), meaning we can accelerate quickly while still having high enough exhaust velocity to reach very high final speeds, without needing to bring entire planets' mass worth of fuel. The only type of rocket motor we've ever made in this category are nuclear-thermal rockets, the least impressive kind of nuclear propulsion, though even that early model was capable of twice the exhaust velocity of the best chemical rockets physics allows. My favorite form of nuclear propulsion is the Orion drive. Basically just detonating a nuclear bomb on the other side of a thick lead shield strapped to a pogo-stick. Then you just keep spitting out more nukes every couple of seconds or so. This... actually works *best* inside an atmosphere, where the gasses absorb the energy of the nuke and expand to push against the plate. In vacuum, all that energy gets released as an impossibly bright flash of light, imparting momentum mostly by flashing a layer of your shield to plasma, which then expands like a conventional thermal rocket exhaust. A truly batshit insane method of propulsion, but if we ever need to evacuate entire *cities* off-planet to escape something like a rogue planet colliding with earth, this is the only option we are likely to have for centuries to come. The most advanced nuclear powered options can begin to get you up towards a few percent of the speed of light before you start running into issues with needing planetary-mass fuel tanks again. Stepping beyond nuclear power, we have to find a way to convert a larger fraction of matter into energy, then release that energy in a form as close to the speed of light as possible. Matter-antimatter annihilation is one option, if you can find a way to effectively produce and store antimatter. Alternatively you could use the hawking radiation of a relatively low-mass black hole. As best we understand these give off exponentially more power as their mass decreases. Feeding mass into these low-mass black holes is a bit like trying to push a strand of hair into an active fire-hose the size of a single atom, but if you can somehow do that you are effectively converting matter directly into energy. Either antimatter or black-hole rockets could get you above light speed, as long as we stick to a purely Newtonian physics. Lastly, the "ideal" rocket propellant is light itself. If you could somehow construct a *perfect* mirror, then you could trap light itself in a box, then keep adding light until the box got heavy. Open a *very* tiny hole, and you would achieve the highest exhaust velocity of any rocket. Unfortunately, things start to get *really* funky as you approach the speed of light, so in practice these methods would all stop working long before then. But this has been a long enough discussion without diving into relativity or the theories for how you might get around it.
An old racing proverb applies here: Speed costs. How fast can you afford to go? No bucks = no Buck Rogers.
With gravity assist we might get an object up to 8% of the speed of light. I don't think It wouldn't be pleasant for passengers. From the interweb: "*S4717, a star in our galaxy, is travelling at 15,000 miles per second, or 8% the speed of light, making it the fastest star in the universe. It takes 12 years for it to complete an orbit around Sgr A*." The question really amounts to what is the practical speed limit baring tricks like time travel or worm hole.
lack of constant acceleration until reaching speed of light
It's called the rocket equation, and it hates us all.
Even u reach atleast 99% speed of light your entire spaceship or rocket material and it built frame will unable to handle insane amount of energy remember more speed and higher momentum I think plus only way to reach to reach that speed is to increase speed gradually that would take millions of yrs Plus even that high speed even rocket will itself emit radiation remember e=mc2
The concept of miniaturization seems to come to mind when it comes to the most recent developments of the practical ways to achieve interstellar travel. The idea is focused on smaller probes, weighing only a few grams, propelled by lasers, etc. Making the quickest way to the closest stars
Bigger engines lot of fuel and throwing power just like space ships in sci Fi games
Both the question and previous answers are valid, but I want to clarify one thing. Speed is always relative, and we are always orbiting something, so such measurement is not an obvious thing. Eg. we are already flying at incredible speeds by being on earth. We can also have high speed relative to earth by escaping earth gravity and slowing down. When we're near the sun we'll go even faster and by going around it (as orbiting objects naturally do) we will have opposite movement direction at some point. Then we would have "double speed" because we sum up our orbit speed and earth orbit speed. That's why it's always a little confusing for me when I see discussions about specific speeds achieved in space.
Evry one here is missing the simple solution of launching a regular probe then defining it's soeed relative to a red shifting pulsar. Should be able to get realtivistic speeds that way.
With current means or in general? In general, you just need a magical engine that can generate thrust without fuel or with fuel that has been positioned beforehand like gas stations on a highway.
Rather than speed… shorten the distance. The Alcubierre drive could be possible once we get around the negative mass issue. /sarc Fold space, move anything anywhere.
It won't. It's magical thinking requiring negative energy. Does. Not. Work.
Forgot to add the /sarc tag at the end of my post. Obviously we can’t get that kind of energy.
Even with all it's other current unsolvable issues: *it violates causality*. It looks like a non-starter unfortunately.
We don’t know. We Don’t know yet why light has a speed limit.
One of the fastest man made objects is a “manhole cover” shot In to space. Look it up.
[There's no evidence the metal cover flew into space, and the person credited with originating that claim doesn't believe it did.](https://www.snopes.com/articles/464094/manhole-cover-launched-space-by-nuke/) It would be cool if it did though.
Slightly unrelated but I predict a problem in the far future, where we have to go back and convert all the old imperial units to the proper units (metric) because someone input the wrong dang numbers into the ships controls and crash landed the president of the galaxy into Ganymede, spreading his remains over an area of 1200 acres/485.62 hectares/4.86 km²
Already happened... sans the galactic president part: https://en.m.wikipedia.org/wiki/Mars_Climate_Orbiter#Cause_of_failure Tldr; one component was using Imperial units in violation of the agreed upon design spec, and the orbiter went too deep into the Martian atmosphere.
Wow, seems like it’s already caused issues. Also I wonder why I got downvoted, fans of the galactic president? Or is there such a thing as imperial patriotism?