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back to article Super 'sun-hot' plasma rocket in fullbore bench test triumph

A radical, highly fuel-efficient plasma rocket whose interior operates at temperatures close to those found inside the sun has passed a key test milestone. Trials of the space drive aboard the International Space Station are expected within the next few years. The superpowered rocket design is known as the Variable Specific …

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Flame

Nuclear protests

"Anti-nuclear protests have occurred when such tech has been used in civil craft."

In accordance with the common policy of allowing use of nuclear power _only_ if its to build epic slaughterfest machines like ICBMs and battleships, but not for civilian purposes like providing power to make drinking water or send probes to Mars.

That'd be wrong, you know.

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Anonymous Coward

Anti-nuclear idiots

We get it guys, you don't like bombs, but nuke power is really, really useful in space. NASA or whoever needs to just tell these people to f-off, because without technology like that we're never going to leave this planet, and one day something will happen and it'll be bye-bye humanity.

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stopping?

One thought occurs to me. I can see that a good lick of speed can be built up over a long period of time with a low powered engine, the problem, however, would be stopping. The low power would take an eqivalently long time to de-accelerate the craft. Net result: no real saving in time (though maybe in fuel?).

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@stopping

Aerobraking. The probe has to decelerate by creating drag through the atmosphere at the other end. It'll create an excellent meteor streak looking up from the ground.

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"Pushing for longer..."?

Perhaps the explanation of why plasma rockets work could focus more around factual science? The reason they go so much faster is that the stuff they're pushing with goes much faster, i.e. a chemical rocket cannot go faster than the speed of it's propellant (or something like that...I'm no rocket scientist!).

=].

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@this..

Speed builds faster. Which means you reach midpoint far faster. You flip at midpoint, and decelerate using the same thrust. As you accelerate and decelerate faster, you reach your destination faster.

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Bronze badge

DANGER, Will Robinson!

Strange that folks find a better replacement for the rocket engine, but can't find a (useable) replacement for the "suck-squeeze-bang-blow" infernal combustion engine. Good concept.

However, one worrying thought...

<<Trials of the space drive aboard the International Space Station are expected within the next few years>> and <<hotter than the sun?>>

Is this what they'll use to de-orbit the troublesome piss filter and the large aluminium can it's housed in - known affectionately as the "ISS"? I wouldn't be on the mission to take it to the station and fire it up, that's for sure. Unless there's a serious quantity of beer and some lad's mags involved in the deal, natch.

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Coat

It's not brain surgery...

Just put a fission pile at the back of the craft and you only need heavy shielding forward of the reactor. Light shielding to the rear just for maintenance safety while the reactor is shut down.

Assemble it in space, no need to worry about polution to planet Earth... well other than the massive burning of fuels to achieve orbit in the first place.

Mines the lead-lined surgical scrubs.

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Coat

@yogi

Pretty much true, but it's about the specific impulse of the motor. The reason these go much faster is because they can accelerate for much longer. It's just that the thrust (and thus the acceleration) is much smaller than a conventional rocket. You could never lift off with one of the these because it could never overcome the force of gravity close to a body of any particular size, but once you're in "free space" (so to speak) these are definitely king of the hill. It's just not exactly going to be a thrill ride.

"Ah, buckle this. LUDICROUS SPEED, GO!"

Mine's the one with a ridiculously over-sided Darth Vader helmet.

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Boffin

RE: Pushing for Longer

Basically, Yogi, Momentum. Objects in motion stay in motion as long as nothing is stopping them. So in space, once they're moving, they move at the same rate until something slows them down (Like atmosphere, rockets going the other way, very large rocks, etc).

(Oversimplification Alert!)

Let's say you have a chem rocket that pushes at force 10 for 2 seconds, and a plasma rocket that pushes at force 5 for 20 seconds. The total motive force from the Chem rocket would be 20 in space, and we'd get 100 from the plasma rocket. Because nothing is slowing it down in space, they keep on going at the same rate, so the Plasma one would be moving 5 times faster than the chem one (In this extremely basic example).

Clear as mud?

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Alien

is partly British made

Well, I look forward to watching it spin out of control and eventually colliding with Saturn then.

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Rik
Silver badge
Boffin

@yogi

"i.e. a chemical rocket cannot go faster than the speed of it's propellant (or something like that...I'm no rocket scientist!)."

Indeed, it's clear you're not. Powering rockets is about impulse, and the law of conservation thereof applies. If you're sitting in a space craft, you wind down the window and flick a piece of chewing gum out, backwards, your craft will go faster (an infintesimally tiny bit, but still) even though you can't seriously expect to be able to flick it faster (backwards) than the craft is going (forwards).

APART FROM THAT, THE POSSESSIVE ITS HAS NO APOSTROPHE.

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Gold badge
Coat

And Ar is *cheap*

It's the only noble gas routinely used in arc welding. It's very much cheaper than xenon, the usual ion drive reactant, because it's the most abudant one in the atmosphere.

Of course as Wired has reported you *could* get a 30 day trip to mars with the Oberth 2 burn trajectory if you started at the moon.

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Anonymous Coward

@ stopping? #

Your an idiot.

Half way there you skewflip and slow down.

Look at the math here.

http://www.mathcentre.ac.uk/students.php/all_subjects/mechanics/intro/resources/602

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Boffin

@This

Space ships dont have brakes!

They use thrust one way then flip and use it the other...

Accelerate for longer and deccelerate for longer...

Equal and Opposite..

Changing the thrust parameters does not change physics.

@Yogi - Unless of course it throws out more mass of propellant than the mass of the rocket craft?

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What you fail to understand is

how difficult it is to 'flip 180' in space. Side retro-rockets get fired, you flip 179 degrees and end up in Jupiter instead of Mars.

The way I see it is two rockets on side pods.After 1/2 way to Mars, you have to switch off the engines (good luck in restarting them in the middle of no where), spin them (in sync) 180 on the pods and fire them up (fully in sync to the nano second) and hope you don't wiggle abit, else hello Jupiter.

Not going to happen with current human technology. Best pull out the crashed UFOs from Area 51 and reverse engineer their technology.

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Stop

@Juillen 1

The point is that you are accelerating slower, so your way would still take a whole lot longer.

Aerobraking, as someone above has already pointed out, will be the intended solution. It's pretty well understood, simple and requires very little extra mass to make it work.

You accelerate much slower but it goes on longer- so your top speed is vastly higher. Just like a Mondeo that's accelerated for 9 seconds is going much faster (~40mph faster based on some quick googling) than a Ferrari 360 that's been accelerating for 4.

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180 flip

It is routine for both probes and spaceships to re-orient themselves before applying thrust - including the afformentioned '180 flip'. With a decent guidance system and a slow rate of turn, you can re-angle the ship/probe with a very high degree of accuracy.

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Boffin

@ Your alien overlord

Flipping 180 degrees in space is easier than you make out. the rocket will have to be started in space to begin with. It will be designed to restart in space. Gyroscopic controls can VERY accurately determine the rotational angles of the ship and correct midcourse if any error occurs. If rotation is required, rather than movement then you dont even need rockets, you can use a spinning reaction wheel along the axis of rotation. Granted rockets are easier but a reaction wheel requires no fuel, just electricity which can be got from solar and stored in batteries.

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Headmaster

@ AC 15.38

Is that a diesel or petrol Mondeo? And what colour is it? I believe the red car is faster.

Well that seems about the right level for the fysix acumen displayed so far.....

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Alien

@ Alien Overlord

Half true, I suppose. But when you slow your car down do you simply not bother to steer? Most vehicles on land, sea and air change direction slightly when braking. If you only flip 179.9 degrees then, yes, you'll wind up miles of course after a while. But, if you notice you're going slightly off course (preferably before hitting something the size of Jupiter) then you simply* fire your retro thrusters a bit in a different direction until the computer says you're back on course. this is pretty much similar to what geo-stationery satellites do now. And space stations. And Death stars, too for that matter.

*Yeah, I know it's not *that* simple, but hey-ho...

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@AC who called me an idiot

a)I know perfectly well how it would be done - by firing thrust in the opposite direction - that was precisely my point.

b)You can't spell - idiot.

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re: What you fail to understand is #

Turning around precisely 180 degrees, in space, is trivially easy with modern technology.

Precision maneuvering goes on every day up there in space, with satelites maneuvering to avoid eachother and known debris all the time.

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Joke

@Your alien overlord

Ever heard of Thrust Reversers?

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Bronze badge
Boffin

Time and distance

It gets complicated, because you're working in a gravity field, and that modifies the basic speed/time/distance/acceleration equations taught at school. Let's make it easy and assume a trip distance of 100 million kilometres and a time of 4 million seconds.

A constant-acceleration trip, ignoring the sun's gravity, would have a turn-round at the half-way mark, accelerating and decelerating under power, all the way. So 50 million kilometres in 2 million seconds.

distance = acceleration * time-squared / 2

Re-arrange: acceleration = 2 * distance / time-squared

1E11 / (4E12) = 1/40 = 2.5 cm/sec/sec

Average speed is 25 km / sec for the whole trip, and must be the same for each half, which gives a maximum speed of 50 km / sec. Aerobraking is so fast that the time taken can be ignored for our purposes, and the same for a chemical booster. We'd need a heat shield that could stand to an aerobraking speed some five times faster than Apollo.

Yes, I know the reality is more complicated. Not only there is the gravity of the sun, there is the difference in the orbital speed of Earth and Mars. If you want more rigorous math, and pretty pictures, I recommend http://www.projectrho.com/rocket/

I'll wait for the torchship.

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What you fail to understand is???

I thonk you are overestimating the difficulty of navigating in space. You can align your spacecraft with great precision using the stars as a reference. The current and future positions of the destination are known with great precision. You can observe your trajectory and correct as needed. All this was done on the lunar missions with sixties technology. There was even some fairly "seat of the pants" navigation done on Apollo 13 when things were turning to custard. They had a problem with the craft drifting, due to non thrusting vents creating some thrust, and had to correct for that from the lunar module, which was not normally intended to do mid course corrections.

Apart from using thrusters to adjust atitude, you can use an inertia wheel, which gives a more precise control.

For the other problem of how do you stop, there are two choices, depending on the mission. Aerobraking is fine if you intend to land, the landing venue has some sort of atmosphere, and if the velocity reached is not too high. It means you can potentially accelerate for the whole trip, which would be faster. Otherwise you do the mid flight turn, which can be done without turning the engine off, especially with low thrust engines like these. So you accelerate for half the trip and decelerate for the other half.

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@alien overlord

"""how difficult it is to 'flip 180' in space. Side retro-rockets get fired, you flip 179 degrees and end up in Jupiter instead of Mars."""

Keep in mind 2 things: 1) The flip is not the final possible maneuver, and by directing the braking propulsion a bit, the course can be corrected at any point along the way. 2) All inter-planetary navigation is more or less equally difficult and sensitive to error, but it's been done before as well. Or did you think that all of those slingshot trajectories around moving planets just worked by themselves?

"""The way I see it is two rockets on side pods.After 1/2 way to Mars, you have to switch off the engines (good luck in restarting them in the middle of no where), spin them (in sync) 180 on the pods and fire them up (fully in sync to the nano second) and hope you don't wiggle abit, else hello Jupiter."""

Clearly you don't know basic dynamics - conservation of angular momentum indicates that, were you to try such a thing, your pods would rotate 180 degrees compared to the rest of the craft, but the craft itself would rotate at the same time, somewhat less than 180 degrees, depending on the comparative rotational moments of inertia about the axis of the pods and main craft. Your method would cause a massive error in propulsion angle. Plus with such low-impulse drives, nanosecond precision wouldn't be at all necessary, since a staged startup would only cause a tiny thrust offset.

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Alien

What I do understand is....

That although flipping 180 may be tricky, it's onviously far from impossible, as every space mission to date has used it, except perhaps the non-stopping ones.

Aliens, of course, can remove inertia, so don't have all these problems.

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Alert

aerobraking

Aerobraking is useful, for sure, but you'd still have to slow the ship down to some degree before you got there. You can't expect the tenuous atmosphere of Mars to stop you when you're going many miles per second---it's likely you'd skip off, breakup or burn up, regardless of what shielding is used. Then there's the matter of lifting off from Mars when you're ready to come back---the escape velocity of Mars is much lower than Earth, but you will still need a conventional rocket (and the fuel for it) to get free of Mars' gravity well.

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FAIL

@Your alien overlord - fear me

What YOU clearly fail to see, is that with continuously operating engines they can do these wacky things called "course-corrections." They had four main ones during Apollo; a plasma drive and a computer could make it continuous and automatic. In other words, navigation accuracy and efficiency would also improve, not get worse.

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race!

I say slap on some large solar panels, load er up and set on running figure 8's around the inner solar system and see if we can set a speed record (and a fianl trajectory leaving our system.)

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Happy

Hmmm

So i suppose the fact/theory that the interior of the sun would start at about 100,000 degrees was missed on everyone?

I seriously doubt this engine would be that hot.

Still very good none the less!!!

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FAIL

Morons!

"nearly as hot as "the interior of the sun"

For a earth based plasma that is fvcking cold. Most plasmas are many times hotter. (Try 50000+ °K)

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Silver badge

Commonplace even

"The use of nuclear power in space is actually fairly routine..."

Well, the Sun has certainly got away with doing it for a few billion years. Unless some Nu Labour plonker has recently charged it with generating radioactive waste...

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Heat and Temperature are not the same thing!

@Hmmm.

Heat and temperature are not the same thing. You have have extreme temperatures without actually having a great deal of heat. Temperature is effectively the vibration of atoms. If you don't have a lot of atoms you don't have much heat, regardless of the temperature of those atoms.

The Sun at its surface is around 6000 celcius, in the core several million. Pick a number in between and you will find that 'somewhere in the interior of the sun' there's your number.

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Anonymous Coward

@this

You obviously don't know how its done, judging from your comments. Whether that makes you an idiot or just uninformed I'll leave up to others.

Try reading up on the standard equations of motion.

http://en.wikipedia.org/wiki/Equations_of_motion

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IT Angle

Face it

If you want to send a manned ship to mars you have two choices.

a> Assemble a conventional fuelled craft in orbit about the same size and mass of a Saturn V

(somebody care to work out how many shuttle launches that would take?)

b> Go nuclear, plenty of work done in the 1950-1960 period for the NERVA project..

Here's a thought for you, when they build the craft whose O/S would you want running the onboard computers?

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IT Angle

@Face it by jon72

HP-UX of course. Linux would be second choice. Both Apple and Microsoft are right out except for some networked laptops for games.

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