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Interstellar Spaceflight: Is It Possible?

That's why the best spaceship would be in a hollowed out asteroid.
Also, you'd need some kind of huge magnetic shield out in front of the spaceship, to divert rocks away.
I was re-reading this thread and thought;
"That's sensible, if another race had done that and travelled here, where would be the best place to hide one of those...if only there was a belt of asteroid like objects that could be used as cover or a larger planet with a lot of moons."
 
Here's a picture I made a few years ago of an asteroid starship. Trouble is, real asteroids are probably too fragile and fragmented to be much use if you tried to hollow them out, so you would be better off dismantling the asteroid completely and using the rock as shielding on the outside of your ship.
med_GenerationShip.jpg
 
I was re-reading this thread and thought;
"That's sensible, if another race had done that and travelled here, where would be the best place to hide one of those...if only there was a belt of asteroid like objects that could be used as cover or a larger planet with a lot of moons."
Yes, if only...
 
Here's a picture I made a few years ago of an asteroid starship. Trouble is, real asteroids are probably too fragile and fragmented to be much use if you tried to hollow them out, so you would be better off dismantling the asteroid completely and using the rock as shielding on the outside of your ship.
med_GenerationShip.jpg
I remember reading an SF story many years ago (might have been by Larry Niven) that had the idea of drilling a hole in an asteroid, filling the hole with water and then sending it on an orbit close to the sun. The asteroid melts, the water expands and blows it up like a balloon and you get a hollow asteroid.
 
Yeah; that was Niven's Confinement Asteroid, where Belter women went to give birth. Might work, if you were very careful- something like blowing glass in microgravity.
 
Has anyone hypothesized an electric pulse as an accelerator? If the electromagnetic force could be built up, retained and released at ignition in opposition to a massive launch platform with less gravity than a planet, and if a way could be found for human bodies to withstand the stupendous acceleration, it could push off to immense speed instantaneously. Boom. Gone.
 
Has anyone hypothesized an electric pulse as an accelerator? If the electromagnetic force could be built up, retained and released at ignition in opposition to a massive launch platform with less gravity than a planet, and if a way could be found for human bodies to withstand the stupendous acceleration, it could push off to immense speed instantaneously. Boom. Gone.
The use of a huge linear accelerator based on the Moon has been mooted before, a long time ago.
In fact, I thought of it myself when I was a teenager back in the 70s. Then, just a couple of years later, some famous professor of astronautics proposed it (and got all the glory).
I think after that, it was depicted in one or two SF films/TV shows.
 
Bloody typical. Scientist gets all the credit. Anyone know his name?

Was it Gerard O'Neil? I remember his book about space colonies which had the idea of getting raw materials from the Moon and using a linear accelerator to launch the stuff into space.
 
Bloody typical. Scientist gets all the credit. Anyone know his name?
Can't remember.
But lots of people came up with similar ideas once linear motors had become more popularly available. They'd been around for a while before they started getting used for real applications.
 
Was it Gerard O'Neil? I remember his book about space colonies which had the idea of getting raw materials from the Moon and using a linear accelerator to launch the stuff into space.
That may be it.
 
The use of a huge linear accelerator based on the Moon has been mooted before, a long time ago.
In fact, I thought of it myself when I was a teenager back in the 70s. Then, just a couple of years later, some famous professor of astronautics proposed it (and got all the glory).
I think after that, it was depicted in one or two SF films/TV shows.

Robert Heinlein had a Lunar linear accelerator in The Moon Is A Harsh Mistress published in 1966.
 
Thanks for replying to my post, guys. The conception I had in mind works like a massive reflection of light off a surface. A pulse of EM energy to create the equal and opposite reaction Stan talked about earlier. I hadn't thought as far as guidance, which is what I assume the linear accelerator offers. Just a massive wall reflecting the energy back on the agent to send it flying off at high speed. Nothing new in the concept but still keen to get some more names from within astroscience. I haven't had time to explore, but when I do I'll post what else I can find.
 
NASA measured ‘impossible’ EM thrust – but is it really a big deal?
The copper bucket that supposedly breaks physics has finally passed peer-review. But, Cathal O'Connell writes, don't start packing your bags for Proxima b just yet.
281116_emdrive_1.jpg

The 'copper bucket' – or EM drive prototype – in a vacuum chamber.
NASA
Two years ago, NASA scientists announced they measured something that should not be possible – thrust from an engine that does not use propellant.

Now, after a year-long review process, a paper describing the work has been published in the Journal of Propulsion and Power. It describes how the NASA team measured a thrust of about 1.2 millinewtons per kilowatt from the controversial electromagnetic or EM drive, though they are at a loss to explain how.

The new work will add fresh impetus to the technology which has been touted by some as the future of space travel and by others as pseudoscientific hokum. But it is far from conclusive proof that the EM drive really works.

What is an EM drive?
Down on Earth, we get around with the help of friction. A car’s wheels pushing on the road make it move forwards (or backwards if you’re in reverse).

The problem in space is there’s nothing to push off – that’s why you need a propellant. According to Newton’s third law, where every action has an equal and opposite reaction, ejecting material in one direction will push the spacecraft in the other. In a rocket, the propellant is the exhaust gas fired out through thrusters at tremendous speed.

The EM drive is a proposed new way of propelling without propellant – making spacecraft much lighter, cheaper and faster, because they don’t need to lug propellant around.

While only a handful of physics groups take the EM drive idea seriously, popular media has buoyed global interest in EM drive with reports so breathless they must have been written in a vacuum.

If it works, the EM drive could take us to Mars in just 10 weeks (as opposed to about six months). Meanwhile, a trip to Alpha Centauri, the closest star system to our solar system and home to the possibly Earthlike planet Proxima-b, would take 92 years (as opposed to millennia using conventional thrusters).

Oh, and its inventor, the British electrical engineer Roger Shawyer, also claims it will give us flying cars, unlimited energy and solve the global warming crisis. His company, Satellite Propulsion Research Ltd, is currently seeking investment to commercialise the technology.

How is it supposed to work?
The basis of EM drive is a metal drum, empty but for the microwave photons bouncing around inside it millions of times a second.

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Launching a solar sail


As the photons bounce back and forth, they generate a small pushing force on each end of the drum like ping pong balls hitting a wall.

So far, this is nothing controversial. We know photons carry momentum – that’s how sunlight can propel spacecraft equipped with a solar sail.

If the drum is a cylinder, the forces on each end cancel out and nothing happens. But Shawyer’s idea, proposed around 2001, is to use a tapered drum, with one end wider than the other.

Because of relativistic effects, he said, this shape would create an imbalance in the bouncing force and push the whole drum from the inside. This “pushing from within” is what breaks Newton’s law.

As John Baez, a mathematical physicist at the University of California, Riverside, puts it, “it's like sitting inside a car and making it roll forwards by pushing on the steering wheel”.

Has the EM drive been tested before?
Yes, but not conclusively.

In 2012, a team of Chinese scientists from Northwestern Polytechnical University in Xi’an reported measuring a large net thrust (720 millinewtons at 2,500 watts of input power).

Later they realised that this measurement was an error stemming from a dodgy a power cable. They repeated their experiment in early 2016 and the measured thrust disappeared.

Meanwhile, in July 2015, a German group led by Martin Tajmar at the University of Dresden also tested an EM drive device in a vacuum.

They did measure a thrust, but in several directions besides the intended one. Tajmar concluded this to be a “null result”.

So where does NASA come in?
Back in 2013, a small team at NASA’s Advanced Propulsion Physics Laboratory started to tinker around with the EM drive and another related technology called Cannae drive.

The team is headed by Harold “Sonny” White, the scientist trying to warp spacetime using electromagnetic fields.

In early EM drive work, White’s team did detect a net thrust, though they were criticised at first for performing the work only in air.

That meant they couldn’t rule out the role of air molecules, kicked away from the heated device during operation, as the source of the anomalous thrust.
continued in next post
 
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Part II
Recommended






NASA engages warp drive

The Future
lock-grey-7abc721c6a124b34d895716a9ce07fb0048959f7e9a870e774b352588d0ee7b6.png

Now, the same team has published a paper describing their latest vacuum tests of their EM drive. The results seem to dispel the role of air because the team measures the same thrust in normal atmosphere and in a vacuum.

They also found that this force increased in rough proportion to the increased microwave power, which would be expected if microwaves were the source.

In the experiment, White’s team sat their EM drive on the end of a torsion balance – an instrument that measures tiny forces.

They measured a thrust of 1.2 millinewtons per kilowatt. That's the force you feel if you place seven grains of rice on your palm. A kilowatt is what a power-hungry household appliance, such as a vacuum cleaner, might use.

The measured force is tiny but still more than 100 times stronger than that generated by a solar sail. If generated continuously, even one millinewton could be enough to propel a spacecraft to tremendous speeds, given enough time.

The team noted nine possible sources of anomalous thrust in their set-up and accounted for as many as possible.

For instance, to account for any systematic bias in their measuring instrument, they mounted the device on the swinging arm in both directions. In both cases, the thrust was towards the narrow end of the device.

Puzzlingly, the original theory proposed by Shawyer seems to predict the thrust should go in the opposite direction than the NASA results show. Instead, White’s team suggests the device may work instead by pushing off the “quantum vacuum”, meaning the sea of virtual particles that fill even empty space.

Does this mean NASA has ‘validated’ the EM drive?
No. Getting a paper through peer-review is not conclusive proof that the EM drive really works. It just means that a bunch of independent scientists have pored over the methods and found nothing obviously wrong.

Nothing in standard physics can explain how the EM drive might work. That is not necessarily a reason to reject the result out of hand – we know physics is not complete – but it is a reason to maintain scepticism. As Carl Sagan said, “extraordinary claims require extraordinary evidence”.

We can only learn from “anomalies” of the past. The faster-than-light neutrinos detected by CERN in 2011 turned out to be the fault of an improperly connected fibre optic cable. The source of the EM drive anomaly is most likely something just as mundane.

Caltech physicist Sean Carroll tweeted back in 2014: “The eagerness with which folks embrace sketchy claims about impossible space drives would make astrology fans blush.”



Explore #NASA #electromagnetic #space travel





Cathal_2016.png


Cathal O'Connell is a science writer based in Melbourne.
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Source: https://cosmosmagazine.com/technology/nasa-measures-impossible-em-thrust-how-big-a-deal-is-this
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A very good examination of the EM Drive experiments, both NASA's efforts and in China.
http://www.centauri-dreams.org/?p=36830
The third and most egregious shortcoming in the report is that they apply a vaguely described “conceptual simulation” (which is never mathematically detailed) as their primary tool to deduce which part of the data is attributable to their device and which is due to thermal effects. They assume a priori the shapes of both the “impulsive thrust” (their device) and thermal effects and how those signals will superimpose. There is no consideration of chamber wall effects, power lead forces, tilting, etc. As a reflection of how poorly defined this assumed superposition, the ‘magnitude’ and ‘time’ axes on the chart showing this relation (Fig. 5) are labeled as “arbitrary units.” Another problem is that their assumed impulsive thrust curve does not match the shape of most of the data that they attribute to impulsive thrust. Instead of the predicted smooth curve, the data shows deviations about halfway through the thrusting time. They then apply this subjective and arbitrary tool to reach their conclusions. Because they are biased that the effect is genuine and because their methods overlook critical measurements, I cannot trust the authors’ interpretations of their results.
This device seems to produce nearly as much thrust when it is switched off as when it is switched on, a situation which is less than convincing.
 
This device seems to produce nearly as much thrust when it is switched off as when it is switched on, a situation which is less than convincing.
Leave it turned off. Save power.
 
NASA planning interstellar mission for 2069
By Mike Wehner, BGR

December 20, 2017 | 10:54am

Mankind hasn’t yet explored some of the most interesting objects in our own solar system — heck, we still don’t even know all that much about Earth itself — but that isn’t stopping NASA from setting its sights at a destination so distant that it would take decades for a spacecraft to even get there. A tentative mission is currently being outlined that would see NASA send a spacecraft on an interstellar mission to explore the Alpha Centauri system.

The proposed journey, which was revealed by scientists with NASA’s Jet Propulsion Laboratory at the 2017 Geophysical Union Conference and reported by New Scientist, was born out of a budget mandate to make progress on interstellar travel. Now, NASA is working on technology that, if all goes as planned, could allow a spacecraft to reach ten percent of light speed and the goal is to have it ready by 2069 with Alpha Centauri in its sights.

More at https://nypost.com/2017/12/20/nasa-planning-interstellar-mission-for-2069/
 
A laser-sail mission is feasible, although it does presuppose a dramatic increase in laser technology. Lasers capable of sending a probe up to 0.1c would have a lot of potential for military use.

The problem is, what will such a probe see when it gets there? A small probe, maybe the size of a shoebox, zipping past at 107,900,000 kilometres per hour? If gets a clear photo of even one planet we'd be very lucky.
 
Consider the distances and time involved for a trip to Earth from the nearest possible life supporting planet outside our solar systems. I.E.: "Proxima Centauri b" is one of the closest planets that's may have earth like properties. It's > 4.2 light year from earth = ~ 2.5 x E10^13 miles. Since nothing (with the possible exception of a few subatomic particles like Tachyon's) can even approach the speed of light =186,000 mile/ second, a trip to Earth is unlikely. Sci-Fi and some sensationalistic documentaries has dreamed up propulsion systems that can surpass the speed of light. However the engineering - scientific (nuts and bolts) for this are virtually nil.
https://en.wikipedia.org/wiki/Proxima_Centauri_b
 
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Consider the distances and time involved for a trip to Earth from the nearest possible life supporting planet outside our solar systems. I.E.: "Proxima Centauri b" is one of the closest planets that's may have earth like properties. It's > 4.2 light year from earth = ~ 2.5 x E10^13 miles. Since nothing (with the possible exception of a few subatomic particles like Tachyon's) can even approach the speed of light =186,000 mile/ second, a trip to Earth is unlikely. Sci-Fi and some sensationalistic documentaries has dreamed up propulsion systems that can surpass the speed of light. However the engineering - scientific (nuts and bolts) for this are virtually nil.
^this^
 
Consider the distances and time involved for a trip to Earth from the nearest possible life supporting planet outside our solar systems. I.E.: "Proxima Centauri b" is one of the closest planets that's may have earth like properties. It's > 4.2 light year from earth = ~ 2.5 x E10^13 miles. Since nothing (with the possible exception of a few subatomic particles like Tachyon's) can even approach the speed of light =186,000 mile/ second, a trip to Earth is unlikely. Sci-Fi and some sensationalistic documentaries has dreamed up propulsion systems that can surpass the speed of light. However the engineering - scientific (nuts and bolts) for this are virtually nil.
https://en.wikipedia.org/wiki/Proxima_Centauri_b
As a proponent of interstellar travel, I have to disagree. If we discount the possibility of faster-than-light travel (which I do, emphatically) we are left with the prospects for slower-than-light travel. These require very large amounts of power, and very large-scale infrastructure- if we want to transport entities as complex as humans, with all their environmental requirements. Given a certain amount of luck our own civilisation should be capable building this sort of infrastructure, and of transporting humans and their supporting environment to Proxima within a thousand years. We should be capable of transporting robotic devices to the stars in a few hundred years.

Note that this sort of interstellar travel does not resemble the magical technology supposedly used by the UFOnauts; that sort of technology almost certainly does not, and cannot exist. If aliens came to our solar system they would be propelled by very powerful propulsion systems that would be detectable by a wide range of methods, not by wishes and superstition.
 
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..at which point someone has to mention the "dimensional" element, rapidly on the up as the next Fortean theory of everything. Look hard enough and it's cropping up all over the place. Am working on a thing about it (I know it appears that I'm working on lots of things atm, but actually it's only a couple of them, and the dimension thing is a lot of that.)
 
Given a certain amount of luck our own civilisation should be capable building this sort of infrastructure, and of transporting humans and their supporting environment to Proxima within a thousand years. We should be capable of transporting robotic devices to the stars in a few hundred years.

While the distances traversed look feasible on paper, you also have to factor in the odds of machine failures and being hit by or hitting something else (the same thing). I'd be surprised if the chances of getting a ship big enough to sustain a small group of people to something even as close as the nearest star, without colliding with something that causes fatal damage, are almost nil. They're pretty iffy for a trip to Mars, and if they don't make a compartmentalised ship with protocols limiting crew distribution, they're going to lose a few crews and ships.

Even for robots you need look at failure rates - for modern electronics they are not nearly as good as you might think. To get (for example) a 4000 component piece of electronics to an MTBF of 9,000 hours (as near as dammit a year) is nigh on impossible, and that before you factor in extreme cold and ionising radiation. Most modern electronics are covered with tiny discrete components to ensure (among other things) proper operation of the silicon, and the failure rates of those add up pretty fast.

You might even do better with simpler and older technology, Voyager has done surprisingly well...

..at which point someone has to mention the "dimensional" element, rapidly on the up as the next Fortean theory of everything. Look hard enough and it's cropping up all over the place. Am working on a thing about it (I know it appears that I'm working on lots of things atm, but actually it's only a couple of them, and the dimension thing is a lot of that.)
This might just be 'reaching' for the next 'You can't prove it's not...' gooj.

We're ticking off empirical reasons for the mysterious to be 'normal', cognitive biases, actual interstellar travel, no Loch Ness monster, (as the Loch simply can't sustain such a creature) and so on.

Humans are odd in that we view the world through a social lens, despite having sophisticated language skills and an understanding of empirical reasoning. We evolved by means of social interaction in small groups (30-40 say), which interaction provided the means for communication, cohesion, social dominance structures, showing the other proto-humans where the best fruit is and other things.

Language came after this, but we're still using that social lens with people and also use to to interpret the rest of the world, so ascribe social values to trees (dryads), water (naiads, Neptune etc), cars (which conveniently have two eyes and are often named by the owner) and ships (given names and are always 'she') to name a few. They have genders or spirits and sometimes both. That's who we are and how we see the universe.

This need to ascribe social values to objects and even life and the universe itself, was a function once filled by religion, then (arguably) by political regimes (communism, once 'God was dead'), and then in the 1970's 'Fortean' stuff, a thing which rumbles on, and latterly we're even seeing a kind of deification of science, which is quite bizarre if you think about it.

[Never mind the teenage vampire trope, 'forever young, beautiful and thin' wish-fulfilment.]

People will look for something else on which to pin beliefs, if you take away the thing they believe in currently.

So if you prove UFO's can't traverse space, then people will invent another dimension. If you show empirically Loch Ness cannot support one monster, never mind a population, then Nessie will morph into a dimension travelling creature. Or something.

(I've rather cut this down from a more detailed and supported argument of about 3000 words...)
 
So if you prove UFO's can't traverse space, then people will invent another dimension. If you show empirically Loch Ness cannot support one monster, never mind a population, then Nessie will morph into a dimension travelling creature. Or something.
Pretty much :) . There are other.. erm.. dimensions to it as well, which is that upon which I am working.
 
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