On January 25, 2015, the animated comedy, The Simpsons, first aired the Season 26, 12th episode titled The Musk Who Fell to Earth. In the concluding part of the episode, Elon entered his Dragon spacecraft ( a SpaceX reusable spacecraft) and jetted out. As he was departing, one of the fictional character Lisa sassily said, "for a man who likes electric cars he sure burns a lot of rocket fuel."
Her sassy reply may not have gone down well with Elon Musk as he tweeted later.
If u saw @TheSimpsons and wonder why @SpaceX doesn't use an electric rocket to reach orbit, it is cuz that is impossible Twitter: @elonmusk
Testing a BE-4 Rocket Engine at Night
Wikipedia CC0 He went ahead on the thread to show the reason that is not possible is due to the Newton's Third Law of motion.
The Newton's Third Law of motion states that for there to be an action, that you must have another action that is equal but in opposite direction.
Space Fueled Rocket vs Electric Rockets
For an object to travel out of earth's atmosphere to space, it beat the gravitational force of the massive object (earth). In order to do that, the escape velocity.
Ve= √(2GM/r)
where G= graviational constant measured in meters cubed per kilogram per second squared (m3.kg-1.s-2) and has an approximated value of 6.67 x 10-11m3.kg-1.s-2
M= mass of the body where the object is escaping from in kg
r= the radius or centre of the body's distance to where the object is located in km
The earth radius R= 6371 km, acceleration due to gravity = 9.8 m/s2 = 0.0098 km/s2
The Earth's escape velocity or speed
se =√(2gR)= √[2(0.0098 km/s2)(6371 km)]
= √(124.872 km2/s2)
= 11.186 km/s
The value of the velocity needed to travel out from earth to space is given by the value of 11.186 km/s (40,279 km/h or 25,020 mph or 6.95 miles/second).
You will need to propel the spacecraft to an acceleration which is higher than 11.2km/s to enter orbit.
Spacecraft weighs many tonnes, eg. SpaceX Falcon Heavy weighs, according to the SpaceX's webiste, 1,420,788 (3,125,735 lb) and has the capacity to lift more than 64 metric tonnes (64,000kg or 141,000 lb). The weight of that specified payload weighs more than a fully loaded (both passenger, crew and fuel) Boeing 737 jetliner.
Every space engineer or scientists knows the process of achieving space velocity is one that is critical. It involves a tremendous amount of fuel which scientists/researchers are fervently looking for an alternative to using a more efficient propulsion technology or lighter fuel to achieve.
So, why won't Elon Musk, known for his top of the class luxurious electric car consider building an electric rocket that uses electricity instead of the fuel to blast off the Earth?
The Newton Third Law Problem
Rocket launch, notice the huge fuel burn exhaust:
Pixbay The Newton Third Law looks at the force exerted on another body and the corresponding opposite reaction which takes place. The rocket's engine accelerates fuel downwards and creates a vast thrust in the upward direction which is huge enough to generate the escape velocity needed to get into orbit.
In the case of an electric rocket, we would need something to push out in the downward direction to create upward movement.
We can borrow from the similar technology of helicopters by building a rotor that creates vertical thrust through spinning and pushing air downwards.
Why are we not using this method? The answer is simple; they are not easy to implement. It requires a massive ton of materials (batteries, etc.) to create such a machine.
The current SpaxeX Falcon heavy has 28 engines which are capable of producing a thrust of 934 kilos Netwon (kN) 22,819 kN sea level and 24,681 kN. The first stage booster propellant mass was 395,700kg with a burn time of 162 seconds, and the second stage was 92,670kg with the burn time of 397 seconds, which makes a total of 488,370kg mass for the fuel used in less than 10 minutes.
Currently, the world does not have the technology to store such an amount of energy required for an electric all-powered rocket.
We all know the "pushing" out of gases (at extreme speeds/rates) by burning fuel creates a "push back" on the rocket to propel it forward.
Testing an ion engine in a vacuum chamber at NASA's Jet Propulsion Laboratory. You can observe the faint blue glow which is the ions emitted by the engine:
Wikipedia CC0 Simulating this electrically, involves the pushing out of charged particles such as ions. These ion thrusters may be powered by a radioistope thermoelectric generator (RTG). It is an electric generator that which converts heat produced by some specific radioactive materials to produce electricity with no need of a moving part in it.
These electric ion thrusters are only used in space for low thrust application such positioning and orientation of satellites in space.
It can only be used in space as the little thrust cannot overcome air resistance. So the idea of using it to blast a rocket into space is something we may not achieve in decades to come.
References
- Elon Musk debunks electric space rockets after Simpsons lampooning
- Elon's Dragon V2 Space Machine
- Escape Velocity
- SpaceX Falcon Heavy
- Falcon Heavy Overview
- Ion Thruster
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If there is anything I have learnt over the past years, its to never bet against technology advancements. Maybe not possible today or tomorrow but I'm certain you will just hear one day that a Dr. in MIT has created a model of such. ☺ ☺
In the meantime, you did a great job explaining why we can't have such rockets yet and for that I applaud you.
The scientists love surprising themselves by creating the impossible.
I didn't know the Simpsons were busy with Musk... I however haven't watched any episode for more than 2 decades... ;)
Propulsion it is, propulsion it will be ^^
Everyone's on Musk. That's what changing the world looks like :)
His companies are changing the world... not him alone ;)
That is so very correct..there is no "i" in Musk :)
Nice way to phrase it ;)
Just out of curiosity: would something like a giant catapult work? those could be electronically charged.
Hahaha. That is something I've not thought of.
Quite humorous yet worth the thought. It could actually propel the rocket to a decent velocity...
Be careful about the word power. Batteries do power rockets, but they don’t propel rockets. I think your question is about propulsion. You might be thinking about how we have electric cars and we have petroleum fueled cars on Earth and wondering why the same thing can’t happen in space.
Whenever discussing the motion of an object, we should throw some light on Newton's laws of motion.
The first law tells us that a spacecraft will continue along its path until forces act upon it instituting a change in the motion. This is the part that a lot of people are confused about when it comes to understanding that spacecraft are not constantly firing their engines. They only fire their engines when they need to make a change or have to counteract an external force.
The third law explains how a car moves down the road, on Earth. The rotating tires experience friction against the ground and push backwards against the ground. For that action, there is an equal and opposite reaction - the car moves forward. Electrical motors can make wheels rotate just as well as a chemical combustion engine can.
In space, there is no ground to grip. There is nothing to push against - wheels are useless, so how do we change the motion of our spacecraft.
That's very true, the electric power some satellites in space; the title says it all, all-powered..
i was just wondering... has anyone toyed with the idea of building a scale model variable speed rocket for this type of application?
To the best of my knowledge, I have no idea of anyone that did.
Reading through this I was unconsciously transcended back to my secondary school days.
In Science anything is possible, perseverance is the key, and I believe these great scientist won't relent on their efforts to actually make it possible to use electricity to power rocket 🚀 .
One-day it will happen, just been optimistic ☺
Good morning
There is something I've learnt in human history, never say it can't be done if there are people willing to try to make it work. Yes, it may happen just that it may not be any time soon. Keep steeming.
I would say we live in a world where technology keeps "bursting our brain", considering your well-laid explanation of the reason why we can't get that yet, maybe we would agree but then, we might get wowed soon...
I love how you wrote out the formulas and make it relatable. Thanks for this educative post..
Thank you.
Always a pleasure
Very impressive technology information
I love to follow such articles
The world is evolving every day, and access to space is easier and safer
Thanks.
I love technological article...
Yes, i think it possible to we ever have an electric powered rocket in future...@greenrun
That will be awesome to see.
i think with daily innovation and discoveries an all electric rocket will soon be a reality
Thank you.
Why would you want to use electric power anyway? Its the type of energy thats the hardest to aquire (we use chemical energy in lots of powerplants to create electrical energy with bad efficency). For a enviromental friendly rocket you could still rely on chemical propelants, e.g. hydrogen created by electrolysis of renewable energy. Thats way easier due to the high energy density of chemical propulsion...
Elon Musk (SpaceX) said every form of transportation will eventually go electric…with the exception of rockets.
You just mentioned one of it. What if going electric makes for a lighter booster? Wouldn't that save some cost in terms of being more efficient and cheaper? There are loads of reason to go electric, if (that's a big if) it's practical. You know it can also be easily reused if based on batteries, etc.
Still finding my way to put this together
With the pace at which you technology is going there should be a time where there will be more than 934 kilos Netwon (kN) 22,819 kN sea level and 24,681 kN of energy in the world..... So speaking from the futuristic part of it... Soon there will be
That would be good to see. Thanks.
Although the power is greater than that generated by existing rocket propellers, this result has been the starting point for rocket-making without fuel.
Cannae Drive machines do not use fossils or nuclear fuel to find energy drives. Conversely, many scientists think things are against the fascist laws and the preservation of momentum. Then what's the secret? NASA uses the technology used from a variety of sealed containers. To create microwaves that generate a boost, it takes a solar panel to be used as a motion trigger.
As a result, this rocket can continue to 'adventure' in the sky just by using stars and microwaves. If you manage to do something big, many are optimistic when people in decades can travel out of the solar system faster. Even within a period of 30 years, the journey from Earth to Mars can only be used in weekly time, not production anymore. On the other hand, the latest satellites can be used, almost half of the present size, in the absence of additional space to carry fuel.
30 micro newtons is quite small, but a step in the right direction nonetheless.
That was truly fascinating to read interesting topic you shared the more we learn is always awesome and thanks to you for sharing today's post :D
Thanks
early to bed , and early to rise makes a man healthy wealthy and wise!!
that is damn true..
technology have the power to change our life
Lots of things play a role in this interesting to read about it @greenrun thanks for sharing
i love science contributions
way to go :D
With the way science and technology is evolving in this jet age. We never can tell. We might not know if there has been researches on it as we speak.. As @addempsea has said. I can't stake my money on the intelligence of science because they will never stop amazing you with unimaginable technology.
I gained alot reading this your post.. The mathematical approach in breaking points down were dope. Keep up the good works
Hmmmnn...
I am just imagining....
Whatever can be imagined can be seen
Electric Rocket....
Nicely laid out formulae @greenrun
To a measure i also believe if or when this plays out, we would have a more healthy atmosphere as burning fossil fuels would reduce (To a measure).
@steem881 you're on the @abusereports naughty list! Bad Steemian!