Slashdot Mirror
Electric Rockets Set To Transform Space Flight
An anonymous reader sends this quote from an article at Txchnologist:
"The spectacle of a booster rocket lifting off a launch pad atop a mass of brilliant flames and billowing smoke is an iconic image of the Space Age. Such powerful chemical rockets are needed to break the bonds of Earth's gravity and send spacecraft into orbit. But once a vehicle has progressed beyond low-earth orbit chemical rockets are not necessarily the best way to get around outer space. That's because chemical propulsion systems require such large quantities of fuel to generate high speeds, there is little room for payload. As a result rocket scientists are increasingly turning to electric rockets, which accelerate propellants out the back end using solar-powered electromagnetic fields rather than chemical reactions. The electric rockets use so much less propellant that the entire spacecraft can be much more compact, which enables them to scale down the original launch boosters."
Tesla would love this shit!
Is there even enough material on Earth to produce a power cord long enough to propel a rocket to the moon!?
Aren't you going to need one humongous extension cord?
"I'd rather be a lightning rod than a seismometer." -Ken Kesey
Maybe this will mean a trip to the moo
This is old technology and the benefits of this have already been realized in many satellites. There is literature going back well over a decade documenting the trade space.
The best part about living where I live is that they are building VASMIR engines down the street. It would be a long walk, but I could still walk to a freaking starship drive factory.
http://en.wikipedia.org/wiki/Ion_thruster
Like the idea was thought up in 1911, first functioning one built in 1959...?
Proper tested in space in 1964 in the SERT-1 (http://en.wikipedia.org/wiki/SERT-1_%28spaceship%29)...
( Very, VERY old . )
Transcontinental flight?
Zzzzzzzzzz.
Yours In Minsk,
We are going to get shiny metallic space suits next.
Robots that flails its arms screaming "Danger Will Robinson Danger !"
This is great stuff we are back to ION propulsion which is kind of cool. Remember the spaceships that sail like Solar wind and stuff?
That would be cool too. Perhaps next we can actually get someone to care and fund this stuff and some of it will end up actually mattering in the long run.
ACK
Well, it's still a lot of fluff. Yes, you can create an electric propulsion system that over a long period of time can absorb enough energy to move an object. But should the object need to change direction these drives may take weeks to change a ships direction by 10-20 degrees. If you are thinking of sending people up in a ship that can't has such limited mobility you might as well give the passengers their last rites before lift off.
For each and every action there is an opposite reaction. While jettisoning 100lbs out the back of a rocket the mass is constant and the reaction is limited. Chemical reactions are used because 1. They give more energy output per pound of weight. 2. They give out energy in the quickest period of time. So you can have an ion drive but without additional engines it will take years to accelerate and decelerate.
This piece piques one of my pet peeves, the confusion between scientists and engineers. Scientists do not build rockets--engineers build rockets. Even if a person trained in, say, physics, is designing a rocket, that person is effectively acting as an engineer.
I object to attempts to glorify certain kinds of engineers by calling them scientists. There is no such need to glorify engineers--they are glorious in their own right. Calling them scientists is a slap in the face and an insult.
Engineering and science could hardly be different. Engineers put things together; scientists take things apart.
I've actually been following ion powered (and all space flight) for a long time now and have wondered that ever since Deep Space 1 (no, not a TV series) "proved" the technology worked (that was one of its main jobs, it was a technology demonstrator) they didn't use ion engines on the space craft that used RTGs.
In particular New Horizons has travelled billions of miles coasting to Pluto, 99% of the time in hibernation despite the fact that its plutonium powered RTG is generating electricity whether used or not (it's not a reactor, it is always "on"). Considering the distance it has to travel, an ion drive could've really sped things up (or conversely allowed it to brake, and orbit Pluto!). Cassini might not have been such a good choice because maybe having the drive on doesn't allow good scientific observations (Cassini doesn't have its instruments on a scan tilt platform) and anyway the many delta - V changes might have required more thrust than the very weak ion drives can provide.
Actually, maybe ANY probe headed further than the moon or mars would find this useful. Juno, the Jupiter orbiter had huge solar panels which, during the cruise phase could have powered a decent ion engine. Messenger, the Mercury orbiter, although not going "far", had a huge delta-V requirement and had access to plenty of solar power.
Oh well, at least more and more probes like DAWN use this. I would presume when we return to the outer planets with any really ambitious probes (Europa lander/sub, Titan balloon/boat) they'll use this.
Someday, when we talk about sample return missions and the delta-V requirements at least double (and the fuel requirements go up geoemetrically!), ion drives (or their derivatives like the Vasimir drive) will be essential.
The HS601 and its XIPS system is technically electric since it is an Ion propulsive device. The above FTA is more about plasma thrust, but again all these concepts have been around for 50yrs: it's well known higher specific impulse == more acceleration for space flight == a better engine (and ions have more impulse than anything chemical)...
Turns out I was wrong. I made myself sad. Here's the technology that might actually transform space flight.
http://www.adastrarocket.com/aarc/
http://en.wikipedia.org/wiki/Variable_Specific_Impulse_Magnetoplasma_Rocket
The guy who invented it is an ex-Astronaut and VASIMR (or its tech underpinnings) was his PhD thesis at MIT for Applied Plasma Physics. I guess what I'm saying is he isn't a crank.
Cool!
Space Age 2: Electric Boogaloo.
SEP has been in regular use for over a decade now...first EP-powered deep space mission was in 1998 (Deep Space 1), and just about every Earth-orbiting satellite relies on EP.
I built an ion rocket in 6th grade that was suspended from a string, and would increase the height to which it swung every time the high-voltage transformer was pulsed. Deep Space One had an electric rocket. These have been around awhile.
www.backwoodsengineer.com
1/4 Impulse power Mr. Sulu...
Stardate 45280.4
My crew and I have just left Earth's orbit, it took a mere 15 minutes to accelerate enough to reach escape velocity. Unfortunately, we ran out of batteries the moment we passed the moon and are now waiting for the Vulcans to come rescue us. Unfortunately, there are no electric charding stations out past the great-divide so we will have to be taken back earth where our crew will double the number of lithium ion batteries.
"That's the way to do it" - Punch
I've long since given up on there being any semblance of proper research done in such articles, particularly when a nod might have to be given to anyone outside the US.
I'm no expert in the history of solar electric ion propulsion systems, but believe that NASA's Deep Space-1 mission in 1998 was (I think) the first to use SEP as its primary post-launch propulsion, as several subsequent NASA missions, including Dawn, as discussed in the article.
However, several European Space Agency missions have also used similar systems, including the ARTEMIS satellite in 2001 to get itself to geostationary orbit, the SMART-1 mission to the Moon (launched 2003, ended in a deliberate crash onto the Moon in 2006), the GOCE gravity-mapping mission, and the BepiColombo mission to Mercury (due for launch in 3 years) will be using one. The Japanese Hayabusa-1 asteroid sample return mission also used one.
Just trying to set the record at least a little straighter ...
A better approach is the Electrodynamic tether. Basically, create a linear motor against the earth's mangnetic field. This can only be used in orbit, BUT, there would be no fuel.
I prefer the "u" in honour as it seems to be missing these days.
All the electric propulsion methods have thrust in the order of Newtons. That's usually enough for interplanetary cruises but doesn't solve the most important problem - putting things into the orbit.
it was never incorporated into a tug. It has always been part of sats. With this approach, you will have a sat that can plug into a tug. The tug can be chemical, electric, or nuke (or combinations thereof). By separating the engine/fuel from the payload, it will mean that all we have to do is put something into LEO and then use a tug to move items around. A cargo load or a sat, can be done via electric. A human load, might get chemical to move up and around quickly.
I prefer the "u" in honour as it seems to be missing these days.
To get decent acceleration on these things, like VASIMR, the power requirements are far higher than what can be reasonably accomplished with solar. If we wanted to use one of these to explore the outer solar system (manned or unmanned), where it makes the most sense, its so far away from the sun that solar energy density drops to just a few watts per square meter.
If we wanted to go to Mars, Nuclear Thermal Rockets are a better choice. Either way nuclear energy will be the foundation of true interplanetary spacecraft.
This is not about creating an electric engine. It is about creating a TUG or Tractor that is electric powered. With such a device, it would be cheap to put a load into GEO or to EML1 cheaply.
I prefer the "u" in honour as it seems to be missing these days.
I mean cause everyone knows weight is a factor when lifting objects into orbit, so no doubt batteries to power the engines wouldn't be a factor.
I am Bennett Haselton! I am Bennett Haselton!
Yeah. Dawn's ion engines (linked to in TFS) have a very high ISP (3100s), but an equally low thrust (90 mN).
As a comparison, the F-1 engines on the Saturn V Stage I-C had pretty low ISP (about 250s), but a massive 34 MN of thrust.
Basically you can have high ISP (electrical) or high thrust (chemical), but not both.
Unless you go VASIMR, of course, and we're not quite there yet.
"Total destruction the only solution" - Bob Marley
Watch that the electrostatics don't go near the cryo O2 H2 launch propellant tanks, they go off with quite a bang!
The purpose of existence is to make money.
How about this; NASA should equip the upcoming 8 BILLION DOLLAR JWST with an ion drive. And put a little extra xenon fuel in the tank!
That way, if something should go wrong with the 8 BILLION DOLLAR spacecraft, there's at least a small chance we'd be able to bring it back to LEO where it could be fixed (like Hubble). We won't have man-rated capability to fix it where it is for probably for another decade. :(
Actually since it's probably way too late to add an ion drive and fuel tank to this thing, why not at least put on some "hard points" so that something could grapple with it without damaging it? We should also develop a space tug, like the one the Swiss (of all people) are doing to de-orbit space junk; but bigger, more powerful and able to go out into deep space (radiation hardened, big fuel tanks). That, combined with tele-operated robots could be very useful. Like when we want to upgrade this thing's optics or instruments (like was done on Hubble several times). I think it's safe to say that sensor technology will likely improve substantially during this thing's lifetime (if it hasn't already!)
These single, super expensive probes (Curiosity, I'm looking at you too!) might be the only way to push back the frontiers of science and technology but they are very scary from a risk management perspective. We're not as rich as we used to be. :(
This is about Ion drives right? Sounds like it.. There are probes/satellites out there that have ion drives - they were conceived of in something like the 1960s. Not exactly news, but indeed it is awesome. Though Ion drives don't produce the necessary thrust to be used for atomopheric travel. But one can hope.
Which have been found to work in a vacuum.
Furthermore, those "tests" done by some that "prove" a lifter doesn't work in a vacuum are as flawed and absurd as a test of a car being driven into deep water and upon being found not to work, being declared by engineers that this "proves" internal combustion engines (ICE) don't work underwater.
Well one of the central features of an ICE is combustion and water getting into such an engine prevents that.
As for how this relates to lifters, it's as such: A lifter is composed of 3 main parts, a dielectric, and two asymmetrical conductors. Now virtually all lifters to date have been constructed using air as the dielectric, therefore when a lifter is placed in a vacuum it won't function as one part of it is missing, which in this case is the dielectric.
This is of course not because the lifter doesn't work in a vacuum anymore than an ICE can't work underwater. When an ICE is protected as it is in a submarine it works perfectly well and when a lifter has a solid dielectric like plastic instead of air it works in a vacuum.
Hopefully experimentalists take note of this fact and work to bring this highly useful technology to society.
You do realize the dielectric constant of vacuum vs air is pretty much exactly the same? A handy chart.
More importantly, that web site you linked to notes that thrust in a vacuum is greatly reduced. Gee, I wonder why that could be - could it be because it's not actually a perfect vacuum, and thus there's still some medium for lifter to accelerate against?
" which enables them to scale down the original launch boosters."
Why scale them down ?
Why not use the biggest boosters and use the extra capability to bring more propellant into space
Even if you just dropped it in a parking orbit till it was needed for a different mission
http://Lenny.com
4 great justice!
It's been around since the year Tet. NASA have been playing with the idea for years; they have even deployed it. In 1968 a certain TV show used it as a plot device. Said show reused the plot device in several subsequent episodes and at least one movie.
The problem with EIP is that it produces such a small amount of thrust (although large compared with the amount of propellant it uses, it's still less thrust than you get from a can of hairspray), a human in a capsule wouldn't even feel the pressure in the small of his back. Current deployments are designed to produce a small amount of thrust continuously for extended periods of time - such that over /months/ or /years/ rather than a dozen minutes, the capsule (probe, whatever) is accelerated to a significant portion of the speed of light. Hence, for unmanned deep space probes, it is perfect. For manned spaceflight, crews would go mad waiting for a perceptible change of speed or orbit in the (normally 3-day) trip to the Moon or the (normally eight month) trip to Mars. If they were patient enough to wait the several months, they'd eventually reap the benefit of a compact, low-thrust system - but you'd be faced with the problem of consumables such as oxygen, food and water bulking out the vehicle to keep them alive - you'd be back to square one and wondering why you didn't pack for a shorter journey and use chemical boosters which in the long run would have saved weight. Score point for unmanned EIP.
Operation Guillotine is in effect.