

NASA's NEXT engine  (Source:







Source: NASA

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By drycrust3 on 12/31/2012 6:29:04 PM , Rating: 1

I was wondering if, besides boosting the speed of a space craft, the motor could also be used as a means to communicate with earth, e.g. via the heat signature from the rocket motor.

By james007 on 12/31/2012 7:51:43 PM , Rating: 2
I don't see how that would be of any help.

A heat-signature is really just light, whose spectral distribution reflects the temperature of whatever heated surface is emitting it. Trying to communicate by modulating the temperature of the engine exhaust would, I would expect, offer no advantages over using normal electromagnetic-based technology that is specifically designed for communication (ie, radio).
James H

By StevoLincolnite on 12/31/2012 10:57:29 PM , Rating: 3
It won't really "boost" the speed over your regular chemical rockets as the amount of thrust they produce is relatively small.

The advantage however is that where Chemical rockets will boost for minuets/hours an ION engine would be able to boost for days/months. - Perfect for a long voyage as it will gather up speed the entire trip.
Combine it with Nuclear and it may even last a century provided you have enough Xenon.








It is just over a much longer period of time.

By FaaR on 1/1/2013 7:22:41 AM , Rating: 2

Well, uh actually they do, as the ion drive is - as Tiffany's article states - a lot more efficient than a chemical rocket engine or cold gas thruster. Since a probe can't carry much fuel with it, this difference in efficiency would let the ion drive build up more velocity over time - perhaps a lot more, depending on the length of the trip.

By drycrust3 on 1/1/2013 1:47:42 PM , Rating: 2
I think part of the way it works is based on the "Relativity" idea that as you accelerate something up towards the speed of light you add to the mass of the object, so with ions, which have a mass of next to nothing (but, importantly, not nothing), as you accelerate them their mass goes up. Say you happened to increase the mass of the ions by 10%, that's 10% less fuel than you'd otherwise need to carry.



By Gurthang on 1/2/2013 12:14:04 PM , Rating: 2

The simplest way to think about the efficency of ion thrusters versus chemical rockets is that a chemical rocket gets its thrust from a chemical reaction of the propellants thus the propellant is both energy source and the mass used to accelerate the ship. With ion drive the energy source can be any source of electricity which can come from far more compact sources like nuclear fission or from outside via solar/beamed power. Also ion drive acellerates the "probellant" far more than any chemical rocket so the space ship gets more acceleration from a given mass of propellent. So the spaceship can be lighter or at least devote less mass to thrust/manuvering or be able to accelerate more or longer.

The downside is that the various ion drive ideas don't push very hard without mindbogglingly huge amounts of electricity. Which makes them impractical at this time to launch anything.

By theapparition on 1/3/2013 12:36:54 PM , Rating: 2
Just for reference, this article indicates that over 5 years, this Ion engine:

The Saturn V first stage, in 168 seconds of burn produced 1193 million-newton seconds of impulse. In less than 3 minutes, produced 40X what the ion engine was capable in 5 years.

Granted it weighs much more, and wastes a lot of fuel, etc. But it's just a quick look at the relative performance difference between the technologies.

By ameriman on 1/15/2013 3:10:32 PM , Rating: 2
Your example is a difference of scale and size, not technology.
An ion drive the size of a Saturn V would generate a lot of thrust

The ion drives have an ISP of 3100, over ten times the propulsive efficiency
of the Saturn's F-1 engine.

By DarkUltra on 1/1/2013 8:36:58 PM , Rating: 2
Another important property is the speed of the ions. A rocket engine can only efficiently speed up to a certain velocity, while the ion drive keeps accelerating the spaceship. Or have I misunderstood?




By half_duplex on 1/2/2013 2:01:21 PM , Rating: 2
Actually... I read a while back that there were efforts to collect the particles ionized for propulsion well behind the engine, in the vapor trail if you will.

This would make the NEXT more green!!


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