Plasma Rocket Could Travel to Mars in 39 Days
October 6, 2009 by Lisa Zyga
In the VASIMR rocket, magnetic fields force the charged plasma out the back of the engine, producing thrust in the opposite direction. Image copyright: Ad Astra Rocket Company.
(PhysOrg.com) -- Last Wednesday, the Ad Astra Rocket Company tested what is currently the most powerful plasma rocket in the world. As the Webster, Texas, company announced, the VASIMR VX-200 engine ran at 201 kilowatts in a vacuum chamber, passing the 200-kilowatt mark for the first time. The test also marks the first time that a small-scale prototype of the company's VASIMR (Variable Specific Impulse Magnetoplasma Rocket) rocket engine has been demonstrated at full power.
"It's the most powerful plasma rocket in the world right now," says Franklin Chang-Diaz, former NASA astronaut and CEO of Ad Astra. The company has signed an agreement with NASA to test a 200-kilowatt VASIMR engine on the International Space Station (ISS) in 2013. The engine could provide periodic boosts to the ISS, which gradually drops in altitude due to atmospheric drag. ISS boosts are currently provided by spacecraft with conventional thrusters, which consume about 7.5 tonnes of propellant per year. By cutting this amount down to 0.3 tonnes, Chang-Diaz estimates that VASIMR could save NASA millions of dollars per year.
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But Ad Astra has bigger plans for VASIMR, such as high-speed missions to Mars. A 10- to 20-megawatt VASIMR engine could propel human missions to Mars in just 39 days, whereas conventional rockets would take six months or more. The shorter the trip, the less time astronauts would be exposed to space radiation, which is a significant hurdle for Mars missions. VASIMR could also be adapted to handle the high payloads of robotic missions, though at slower speeds than lighter human missions.
Chang-Diaz has been working on the development of the VASIMR concept since 1979, before founding Ad Astra in 2005 to further develop the project. The technology uses radio waves to heat gases such as hydrogen, argon, and neon, creating hot plasma. Magnetic fields force the charged plasma out the back of the engine, producing thrust in the opposite direction. Due to the high velocity that this method achieves, less fuel is required than in conventional engines. In addition, VASIMR has no physical electrodes in contact with the plasma, prolonging the engine's lifetime and enabling a higher power density than in other designs.
More information: www.AdAstraRocket.com
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14 hours ago
How long woudl a moon journey take with this?
On a return trip from Mars, you could become a fire trail zipping through the Earth's atmosphere just 2.5 minutes after speeding past the moon. Wicked!
(pedantry: assuming the math was correct, you could actually do it quicker.. since you wouldn't have to bother with the deceleration that would be necessary for a useful mission to Mars)
(127,600,00 miles) / (39 days) = 3,271,795 miles per day
(3,271,795 miles) / (24 hours) = 136,325 miles per hour
(236,424 miles) / (136,325 MPH) = 1.73
Or in other words, it would take 1 hour and 44 minutes to get to the moon. Maybe I'm a little slow, but I'm not understanding the get to the moon in 2.5 minutes scenario?
1) The figure they gave for a trip to Mars would have to involve accelerating for the first half and decelerating for the second half, unless the purpose of the mission was to make a nice new Martian crater. So you can't do direct math to get a moon transit time as was done above. (good question about the minutes figure though, your math was sound!)
2) A two minute flight to the moon would necessarily involve some radical acceleration well in excess of what the human body can tolerate, squashing your organs down to pancakes.
It's an amazing idea and I hope it works out, just don't get your hopes up for day trips to the moon.
Traditional spacecraft run out of fuel quickly. Everything is a ballistics trajectory, where the acceleration is quite severe, many times the force of gravity. Once a moon-bound spacecraft is heading toward its destination, the velocity, quite high, is constant for 99% of the trip.
Spacecraft using the plasma engine would still need the severe G traditional propellant engine to take off from a high-G mass like earth, but once bound for Alpha Proxima, a 1 G plasma engine could take over, getting to a star in under a decade easily. Just have to power that engine for 10 years to get there.
I'd also consider the possibility of some kind of battery (anything that could store energy slowly over time and release it quickly). To keep propellant payload to a minimum, thrust could be initiated only when the stored energy is sufficient to accelerate the propellant at the maximum reasonable rate.
Why would you assume that Mars is so far away? Reduce that figure by two-thirds and rerun your calc's.
But on a more serious note, this is an awesome achievement. The best thing about this drive is that the further the destination the more effective it becomes at reducing the transit time. Jupiter in 60 dys, Saturn in 70? Incredible.
http://www.wolfra...and+mars
Mars is currently 1.372 AU (astronomical units) away from Earth.
You may be falsely assuming that this is fact.
Enough bickering over values, let's all agree that this is a brilliant development.
Dibs on the first moon mansion!
Big but not extremely big. There's talk of powering vasimir rockets in the inner solar system with sunlight from PV panels but its impractical past the orbit of Mars.
Secondly HOORAY for the citing of a 39 day trip time to Mars. Anything quicker is just not reasonable in the real solar system. If you see someone talk about "14 days to Mars" they are simply full of crap (unless they have good old USS1701 at their disposal). Allow me to continue . . .
Third, none of the trip time estimates here are based on the way it actually works. You have to understand that everything travels in elliptical orbits. No estimate based on a straight line, or constant acceleration is even going to come close. Orbital mechanics and back-of-envelope calcs are not compatable. I studied the subject because of threads like this one.
Generally, you apply impulse to shift your orbit to a different shape which will intercept the orbit of the thing you want to rendezvous with. Then you coast on an elliptical path. Then you apply impulse again wh
Constant acceleration and then turning around and doing constant deceleration has NOTHING to do with the way it really works, period. It is possible to use constant acceleration and take a "spiraling" path, which is still based on an elliptical path, but one of constantly changing parameters. This is how low-thrust ion engines would be employed for interplanetary trips.
The most energy-efficient, and slowest, conventional trip time is called a Hohmann Transfer. This method has a path which is tangent to both the starting and ending orbits. It is faster than a spiraling path.
The next most energy-efficient, but quicker, method is to take a path which is tangent to one or the other of the start and finish orbits. This non-tangency gives rise to much higher impulse requirements (use the law of cosines to do the vector arithmetic).
Lambert's Solution allows you to stretch your elliptical path out so that the segment of the entire transfer orbit which you actually travel can get much shorter. To get really short trip times you need really short transfer paths, which require HUGE amounts of specific energy compared to Hohmann or single-tangent paths. These short paths in turn require really large orbits: essentially you are applying the amount of impulse needed to get to the outer solar system, and then when you get to Mars you apply huge energy again to hit the brakes. BTW you better time the whole thing so that Mars is there when you arrive or you're screwed.
In my computer implementations of Lambert's solution, the calculations break down at 35 days.
VASIMR is an acronym for Variable Specific Impulse Magnetoplasma Rocket. The breakthrough here is that it can achieve the high thrust of conventional rocket engines and also operate at astoundingly high specific impulse. This allows you to carry enough reaction mass to make fast Lambert missions possible.
As far as moon trips go, I'd have to do the calcs, but just a few minutes is out of the question. I would *guess* that 6 hours would be possible.
Are these gases readily available around gas and other planets? Could they be scooped up from very high orbit? This would mean a refueling technique before leaving the solar system or extending a mission.
Incidentally, 1G of acceleration is HUGE - 0.5 AU per day per day. If you could do that accelerating 25% of the distance, coasting half, and decelerating 25% (ignoring that orbital velocity match at the end), the average 5.2 AU trip to Jupiter only takes a week at 1G, 10 days at .5G, 3 weeks at .25G, 2.5 months at 0.1G, or 7 months at 0.05G. And 0.1G might be achievable with clusters of VASIMR thrusters. Note that 0.07G will get you to Mars in 39 days with this approach (at optimum alignment).
The thing that amazes me, actually, is the sight of those guys sitting casually nearby while that beast is in operation. They obviously have a lot of confidence in the technology. The fact that it is baselined for use on NASA's precious ISS speaks volumes.
http://www.esa.in...k103.pdf
In order to speed up the particles of plasma fast enough to equal the thrust of more, slower-moving traditional-fuel particles, you need some energy to do the speeding up.
What fuel is available to heat and propel the plasma, that doesn't weigh as much as the fuel just being burned in a traditional liquid or solid fuel rocket?
There must be some increase in efficiency via the plasma process -- that is the crux that needs to be explained.
You have to remember that timing is everything. Getting to the other orbit is only half the battle - the planet better be there at the same time or you're screwed. You cannot just "catch up" or slow down.
A round trip to Mars is typically somewhere around 900 days.
Yeah, and if you orient the passengers properly you can couteract the lack of gravity....1G would be perfect, ehh?
Yeah, then how the heck do you slow down...lol
I don't see an issue with that. We can make nuke reactors small enough to power a cellphone.
USE THIS TO MAKE A CHEAP STAB AT THE LUNAR-X PRIZE!
the designs are all already there. just see if you can minimize the need to repeat previous work, and use a better engine, and maybe contract tata nano to help you go minimalist, and wala......youve probably made the most practical stab at winning that prize.
why bother? it used to be better, but the more liberals they get on board the more its about control and forcing manipulating what end is desired.
it really only leaves enough space for those who have no idea of physics to spout, and those who do know physics dont have enough room to explain things in simple terms.
if i notice more comments disappearing down the memory hole, there will be no reason to post.
i guess that when they do that, they dont realize that they stole the time of a persons life in which they took the time to write and compose and threw it away!!!!!!!!!!!!!!!!!!!! why? because the policy they are implementing would chase people away faster if it was announced openly.
count me moving on to better pastures.
http://www.minima...res.org/
http://www.uberre...safe.htm
http://www.ess.wa...ce/M2P2/
its not a bad idea other than it wont work. the principals are right... though it wont create a force field. however i see waht you are trying to do.
your problem will not come from the idea of circulation and sheddnig particles... (which i think your idea can work that way).
it will fail in the fact that we will gain mass from material all aruond floating around, just like the planet does.
also, the bigger problem comes from small objects as they pass... without the field you would pass harmlessly by each other, with the field it swings into the ship cutting holes in it.
ultimately i think that we would end up using somethig like it, but first use it to gather mass around the ship. that is attract material from space and let that mass of powdered metal cover the ship... getting more dense as it gets closet to the fields.. such a powdered thing would capture things the way sand captures bullets.
i know its not as romantic as force fields... however its a lot more doable than almost anything else i have heard.
in this way, the partiles and things that the mag field would deposit would become part of the shield.
note that witout air in space, such soft to hard mass is easy to have and not shed.
in all the literature i have ever read, i have never heard any one say to use thi.
the benifit comes later as the stuff scales. that is you get a soft cloud... that makes a buffer, then you can pick up larger material for an outer coat. larger rocks. these then up your sheilding.
plenty of iron and nickle with other stuff available too.
right now i am working on a way to clean up the debris in space. its actually an easier problem
obviously, that's where this is all headed. it could take years, but mark my words.
How long will the trip take for the travellers? Time dilation should be easily measurable when you travel over such distances with such speed right?
For a "ballpark" figure, we can look at Mars' mean orbital radius (semi-major axis) of 1.54 AU and for Earth, 1.0 AU by definition so the minimum separation distance is
1.54 - 1.0 = 0.54 AU = 80.8E6 km
The actual path will be longer. Going by memory, I'd say about 25% longer, this is a really rough estimate.
1.25 * 80.8E6 = 101 million km in 39 days
Remember that you cannot use that number in Newton's equations of motion to look at other cases. It's burn-coast-burn on elliptical paths with Sol at one focus of the ellipse. The only reason this ballpark estimate is at all valid is because the 39 day trip is such a stretched-out ellipse that it looks kinda like a straight line.
BTW the stretched out orbit of this transfer path has a periapse at the Sun that would turn anything we can build into plasma.
No measurable time dilation, these velocities aren't even close to c. c~=3E5 km/s and the velocity we're talking here would be ~1E2 km/s
seems like they hyped it up to be more than it is...they spoke of breaking the 200kilowatt mark, then went on to talk about mars trips....
even if we need just 10mw to do the trip in 39 days...we're looking at boosting this by many times over to get close to acheiving this....
and what was that i read about some ridiculously long trip just to get to the moon of 6 months....
In the jpeg they have four connected. At current that would be 800 KW of thrust.
Now connect an array of 40 and you almost have 10MW.
If they boost from 200KW to 500KW you only need 20 in a row. That is doable and maybe even preferable.
I'd rather be in a spaceship with 20 trusters than with one.
Actually I'd rather be on earth.
They are in Costa Rica.
When I stand on the earth looking at the Moon and Mars hanging in the sky, it's natural to forget that all the bodies mentioned are perpetually moving at tremendous velocities over enormous distances in at least 3 dimensions...
For your next trick, are you able to explain how one would aim to rendezvous with Alpha Centauri?
:-)
I have to disappoint you on the Alpha Centauri mission. The brutal fact is that with current or foreseeable technology, VASIMR included, it simply is not feasible.
There is only one way I know of that is feasible, and that is "generation ships" with people spending their entire lives, or least most of them, on the journey. This in turn means that we need to know how to make babies in space and we haven't even begun to figure that out.
I cannot say that I have any insight on the math involved to plot the trajectory.
If only Science Fiction could be made real . . .
20% of lightspeed should be possible with theoretically valid fusion engine design.
http://nextbigfut...-of.html
So that might bring you to Alpha Centauri in 30 years, still a long time though.
Those numbers look reasonable, too.
Oh deary me.
SPOCK!!
But seriously... I don't understand how you could even conceive sending a manned ship to the Centauri system.
Wormhole transportation would be much easier.