# What type of propulsion system will get us to mars? **URL:** \ **Category:** Factual Questions\ **Created:** [July 28, 2011, 6:11am UTC](https://boards.straightdope.com/t/what-type-of-propulsion-system-will-get-us-to-mars/590595 "2011-07-28T06:11:56Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![GameHat](https://avatars.discourse-cdn.com/v4/letter/g/ed655f/32.png) [@GameHat](https://boards.straightdope.com/u/GameHat)\ **Post date:** [July 29, 2011, 1:28am UTC](https://boards.straightdope.com/t/what-type-of-propulsion-system-will-get-us-to-mars/590595/41 "2011-07-29T01:28:56Z")
I think the problem isn’t getting a propulsion system that will get us to Mars. Hell, we can do that already. The problem is a propulsion system to get a person back. As in, carrying enough fuel and equipment for a return trip would be so damn expensive it won’t happen for decades. Damn it all, I forgot the show, but about 3 weeks ago on NPR they had a slightly zealous but interesting guy arguing hard for a one-way manned mission to Mars. The justification for one-way being it would simply be too hard to get them back with current technology. So launch a few astronauts and scientists to Mars, have them set up a basic little shelter, then do experiments and tests and whatever, broadcasting back to Earth, until they die. A frighteningly lonely scenario, but he argued there were enough purely science/progress driven folks to find a qualified volunteer or two. ---
**Author:** ![Trinopus](https://avatars.discourse-cdn.com/v4/letter/t/2bfe46/32.png) [@Trinopus](https://boards.straightdope.com/u/Trinopus)\ **Post date:** [July 29, 2011, 2:28am UTC](https://boards.straightdope.com/t/what-type-of-propulsion-system-will-get-us-to-mars/590595/42 "2011-07-29T02:28:55Z")
> [@Mangetout](#): > > Are you talking about throwing the mass away, or just moving it backward within the ship? (the former will work, until you run out of mass to throw away, but the latter won’t get you anywhere at all) Grin! No worries! I’ve read the threads here on such “reactionless drives” – and know that they don’t work, and why. (They violate the law of conservation of momentum.) It would be really nifty if the “Dean Drive” or some other R.D. worked. It would be super convenient for space exploration, and would also throw classical physics into a total tizzy, which would be educational, revolutionary, and a lot of fun to watch! But, no, I was more envisioning the ship having a big magazine of “bowling balls” or other chunks of big, hard matter, which are hurled backward by mechanical energy, as stored up in springs or flywheels, powered by arenauts pedaling like crazy on stationary bicycles…um, unicycles…um…nilcycles… (If they don’t have wheels, they aren’t “cycles,” right?) And, aye, when you run out of reaction mass, you run out of “delta-V.” Trinopus P.S. my b.i.l. asks why there isn’t a sport of “Mountain Unicycling.” ---
**Author:** ![Grey](https://avatars.discourse-cdn.com/v4/letter/g/b782af/32.png) [@Grey](https://boards.straightdope.com/u/Grey)\ **Post date:** [July 29, 2011, 2:29am UTC](https://boards.straightdope.com/t/what-type-of-propulsion-system-will-get-us-to-mars/590595/43 "2011-07-29T02:29:47Z")
Getting back means making fuel on Mars instead of dragging it with you. Again, while it is a little dated, go read the link up thread. ---
**Author:** ![Darth\_Ayebaw](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darth_ayebaw/32/9870_2.png) [@Darth\_Ayebaw](https://boards.straightdope.com/u/Darth_Ayebaw)\ **Post date:** [July 29, 2011, 3:00am UTC](https://boards.straightdope.com/t/what-type-of-propulsion-system-will-get-us-to-mars/590595/44 "2011-07-29T03:00:38Z")
> [@robert\_columbia](#): > > Bad checks. There is truly nothing faster. _One of the problems has to do with the speed of light and the difficulties involved in trying to exceed it. You can’t. Nothing travels faster than the speed of light with the possible exception of bad news, which obeys its own special laws. The ingefreel people of Arkintoofle Minor did try to build spaceships that were powered by bad news but they didn’t work particularly well and were so extremely unwelcome whenever they arrived anywhere that there wasn’t really any point in being here._ ---
**Author:** ![outlierrn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/outlierrn/32/3005_2.png) [@outlierrn](https://boards.straightdope.com/u/outlierrn)\ **Post date:** [July 29, 2011, 5:53am UTC](https://boards.straightdope.com/t/what-type-of-propulsion-system-will-get-us-to-mars/590595/45 "2011-07-29T05:53:15Z")
> [@Trinopus](#): > > P.S. my b.i.l. asks why there isn’t a sport of “Mountain Unicycling.” Ahh, but there is [![](https://img.youtube.com/vi/1uPznTbus3g/hqdefault.jpg "Kris Holm Freeride video") ](https://www.youtube.com/watch?v=1uPznTbus3g) ---
**Author:** ![cmyk](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cmyk/32/3353_2.png) [@cmyk](https://boards.straightdope.com/u/cmyk)\ **Post date:** [July 29, 2011, 4:27pm UTC](https://boards.straightdope.com/t/what-type-of-propulsion-system-will-get-us-to-mars/590595/46 "2011-07-29T16:27:05Z")
> [@Chronos](#): > > How? Thank God we’re not engineers, huh?! > [@DrFidelius](#): > > Propellor? I was thinking of something more like space oa– > [@sparky\_1](#): > > Props don’t do too well in a vacuum. Neither do oars, unless they’re space oars. –CRAP! You stole my idea! > [@Chronos](#): > > I think the good **Dr** was probably referring to an ætheric propeller. Don’t be silly, Relativity did away with the æther. We’d have to surround the ship in a giant bubble of water… _then_ row. ---
**Author:** ![cmyk](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cmyk/32/3353_2.png) [@cmyk](https://boards.straightdope.com/u/cmyk)\ **Post date:** [July 29, 2011, 4:51pm UTC](https://boards.straightdope.com/t/what-type-of-propulsion-system-will-get-us-to-mars/590595/47 "2011-07-29T16:51:39Z")
Can one send some kickass, laser-guided rail guns to Phobos and/or Deimos, using rovers to load it with moon rocks, meanwhile… Do the same on our moon, while constructing a vessel with deflection plates, fore and aft, then just keep nailing it with lunar projectiles for acceleration (after initial chemical thrust to reach escape velocity), then, assuming the Martian remote tech is up to the task, nail the opposite side with Phobos rocks to decelerate. May I suggest naming the vessel _Goliath?_ I was thinking Olympus, but them Greeks have had their day… time for some biblical names. ---
**Author:** ![Kevbo](https://avatars.discourse-cdn.com/v4/letter/k/e47774/32.png) [@Kevbo](https://boards.straightdope.com/u/Kevbo)\ **Post date:** [July 29, 2011, 4:58pm UTC](https://boards.straightdope.com/t/what-type-of-propulsion-system-will-get-us-to-mars/590595/48 "2011-07-29T16:58:25Z")
> [@cmyk](#): > > Also, what about man-power? No, seriously. You could power a small ion thruster that way. But for the power a human can produce, you replace it with a few square feet of photo-voltaics. That could be used to build speed once out of earth’s gravity well, but you still need chemical rockets to do that. Apparently Dawn’s ion drive provides about .001g of acceleration allowing 0-60mph times of a few days. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 29, 2011, 5:01pm UTC](https://boards.straightdope.com/t/what-type-of-propulsion-system-will-get-us-to-mars/590595/49 "2011-07-29T17:01:20Z")
You _could_ use pedal-powered (or solar-powered or whatever) mechanisms to physically throw reaction mass out the back. But if you’re carrying all those bowling balls or whatever, why not just carry rocket fuel instead? It serves the same purpose, and it carries its own energy with it. ---
**Author:** ![cmyk](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cmyk/32/3353_2.png) [@cmyk](https://boards.straightdope.com/u/cmyk)\ **Post date:** [July 29, 2011, 6:01pm UTC](https://boards.straightdope.com/t/what-type-of-propulsion-system-will-get-us-to-mars/590595/50 "2011-07-29T18:01:57Z")
Space being practically frictionless is a huge benefit and a huge deficit. Why carry all that reaction mass, when you can just pelt it like a interplanetary game of Pong? ---
**Author:** ![sparky\_1](https://avatars.discourse-cdn.com/v4/letter/s/77aa72/32.png) [@sparky\_1](https://boards.straightdope.com/u/sparky_1)\ **Post date:** [July 29, 2011, 6:44pm UTC](https://boards.straightdope.com/t/what-type-of-propulsion-system-will-get-us-to-mars/590595/51 "2011-07-29T18:44:06Z")
> [@cmyk](#): > > Space being practically frictionless is a huge benefit and a huge deficit. Why carry all that reaction mass, when you can just pelt it like a interplanetary game of Pong? Pelting a ship like that would be freak’n insanely difficult to do. The sending gun would need to stay aligned with the ship, otherwise a hit that wasn’t dead center would slowly throw the ship off course. And since a planet orbits, we can forget about that. Likewise, just hitting the ship from such large distances would be an incredible feat. Neat concept, though. ---
**Author:** ![Rigamarole](https://avatars.discourse-cdn.com/v4/letter/r/77aa72/32.png) [@Rigamarole](https://boards.straightdope.com/u/Rigamarole)\ **Post date:** [July 29, 2011, 6:44pm UTC](https://boards.straightdope.com/t/what-type-of-propulsion-system-will-get-us-to-mars/590595/52 "2011-07-29T18:44:06Z")
> [@Chessic\_Sense](#): > > Are you new here? When has a point being moot EVER effected a thread? I know, it’s just the way he phrased it “_will_ get us to Mars” - as if it’s an inevitability - that rubbed me the wrong way. Discussing hypotheticals is great but I don’t think the OP actually understood that it is a hypothetical which will never come to pass. ---
**Author:** ![sparky\_1](https://avatars.discourse-cdn.com/v4/letter/s/77aa72/32.png) [@sparky\_1](https://boards.straightdope.com/u/sparky_1)\ **Post date:** [July 29, 2011, 6:45pm UTC](https://boards.straightdope.com/t/what-type-of-propulsion-system-will-get-us-to-mars/590595/53 "2011-07-29T18:45:38Z")
> [@Rigamarole](#): > > I know, it’s just the way he phrased it “_will_ get us to Mars” - as if it’s an inevitability - that rubbed me the wrong way. Discussing hypotheticals is great but I don’t think the OP actually understood that it is a hypothetical which will never come to pass. I predict man will one day inhabit Mars. Just not in my life time. But someday. ---
**Author:** ![cmyk](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cmyk/32/3353_2.png) [@cmyk](https://boards.straightdope.com/u/cmyk)\ **Post date:** [July 29, 2011, 6:49pm UTC](https://boards.straightdope.com/t/what-type-of-propulsion-system-will-get-us-to-mars/590595/54 "2011-07-29T18:49:33Z")
> [@sparky\_1](#): > > Pelting a ship like that would be freak’n insanely difficult to do. The sending gun would need to stay aligned with the ship, otherwise a hit that wasn’t dead center would slowly throw the ship off course. And since a planet orbits, we can forget about that. Likewise, just hitting the ship from such large distances would be an incredible feat. > > Neat concept, though. Oh, I’m sure it’s insanely difficult; everything is moving relative to each other… but, that’s where all the _fun_ is! Every shot would have to be timed perfectly, at the right velocity relative to the ship and the gun, as to where the ship will _be_ when the projectile gets there. Isn’t there an app for that yet? Also, I was thinking about any projectiles that didn’t hit dead center, and I’m sure some on-board thrusters could compensate for mid-course corrections. ---
**Author:** ![Washoe](https://avatars.discourse-cdn.com/v4/letter/w/ecae2f/32.png) [@Washoe](https://boards.straightdope.com/u/Washoe)\ **Post date:** [July 29, 2011, 7:10pm UTC](https://boards.straightdope.com/t/what-type-of-propulsion-system-will-get-us-to-mars/590595/55 "2011-07-29T19:10:48Z")
> [@Joe\_Cephalus](#): > > VASIMIR, people, the Variable Specific Impulse Magnetoplasma Rocket is going to take us to Mars. It’s just your classic sci-fi space ship engine. You take some radio waves, excite some gas till it’s plasma, then use powerful magnetic fields to force it out of the back of your Mars bound space craft. Looks like you’re right, despite the fact that everybody (myself included) ignored your post. I’ve just spent the last couple of hours on Wiki reading what I could find on the subject of making things move really fast. Looks like [VASIMR](http://en.wikipedia.org/wiki/Variable_specific_impulse_magnetoplasma_rocket) is the ticket. The technology exists right now—it’s real. It’s just a matter of scaling it up. It’s just an engineering problem. And it’s capable of generating the 100 m.p.s. speed that I mentioned earlier, which I brought up because I once read that that’s the minimum speed necessary to make interplanetary travel easy-peasy. ---
**Author:** ![Suburban\_Plankton](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/suburban_plankton/32/219_2.png) [@Suburban\_Plankton](https://boards.straightdope.com/u/Suburban_Plankton)\ **Post date:** [July 29, 2011, 7:36pm UTC](https://boards.straightdope.com/t/what-type-of-propulsion-system-will-get-us-to-mars/590595/56 "2011-07-29T19:36:05Z")
> [@GameHat](#): > > I think the problem isn’t getting a propulsion system that will get us to Mars. Hell, we can do that already. The problem is a propulsion system to get a person back. As in, carrying enough fuel and equipment for a return trip would be so damn expensive it won’t happen for decades. > > Damn it all, I forgot the show, but about 3 weeks ago on NPR they had a slightly zealous but interesting guy arguing hard for a one-way manned mission to Mars. The justification for one-way being it would simply be too hard to get them back with current technology. So launch a few astronauts and scientists to Mars, have them set up a basic little shelter, then do experiments and tests and whatever, broadcasting back to Earth, until they die. A frighteningly lonely scenario, but he argued there were enough purely science/progress driven folks to find a qualified volunteer or two. I’m only a layman, but my gut tells me that if NASA actually had a fully funded plan for a manned Mars mission, with the only caveat being that it was a one-way trip, that they would still have more qualified applicants than they could possibly use. It’s not every day that you get the chance to be a true pioneer, and the people we’re talking about are cut from a different cloth than most of us to begin with. ---
**Author:** ![cmyk](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cmyk/32/3353_2.png) [@cmyk](https://boards.straightdope.com/u/cmyk)\ **Post date:** [July 29, 2011, 7:39pm UTC](https://boards.straightdope.com/t/what-type-of-propulsion-system-will-get-us-to-mars/590595/57 "2011-07-29T19:39:39Z")
Oh sure… as if that’s cooler than slingin’ rocks! ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 29, 2011, 7:42pm UTC](https://boards.straightdope.com/t/what-type-of-propulsion-system-will-get-us-to-mars/590595/58 "2011-07-29T19:42:28Z")
They might get volunteers on board with the plan, but they wouldn’t get taxpayers. It’d be a PR disaster, and frankly, NASA is doing poorly enough in that area already. And I’m honestly not sure about the shooting the ship with cannonballs plan. It could certainly work in principle, but I’ve never seen it discussed before, and I’m not sure how practical it could be. You’d certainly need rockets on board the ship, the cannonballs, or both, for course correction, but the needs would be much less than if you were using rockets alone. ---
**Author:** ![sparky\_1](https://avatars.discourse-cdn.com/v4/letter/s/77aa72/32.png) [@sparky\_1](https://boards.straightdope.com/u/sparky_1)\ **Post date:** [July 29, 2011, 7:59pm UTC](https://boards.straightdope.com/t/what-type-of-propulsion-system-will-get-us-to-mars/590595/59 "2011-07-29T19:59:37Z")
> [@Suburban\_Plankton](#): > > I’m only a layman, but my gut tells me that if NASA actually had a fully funded plan for a manned Mars mission, with the only caveat being that it was a one-way trip, that they would still have more qualified applicants than they could possibly use. It’s not every day that you get the chance to be a true pioneer, and the people we’re talking about are cut from a different cloth than most of us to begin with. I’ll volunteer to be space-cook and space-janitor! Now where’s my jumpsuit with silver v-stripe? I make some great space-eggs! Jerry Sienfeld does a great bit about clothes in the future being jumpsuits with silver v-stripe, or some such. ---
**Author:** ![davidm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/davidm/32/225_2.png) [@davidm](https://boards.straightdope.com/u/davidm)\ **Post date:** [July 29, 2011, 8:43pm UTC](https://boards.straightdope.com/t/what-type-of-propulsion-system-will-get-us-to-mars/590595/60 "2011-07-29T20:43:14Z")
What about pre-positioning reaction mass or fuel depots (really just concentrated reaction mass) along the way? What about light sails? Could we eventually accelerate to a high enough speed with sunlight? If not sunlight, could we push the ship with a laser beam? Keeping the laser in position and aimed properly would be a challenge but I think it might be doable. For a completely unworkable ridiculous tongue in cheek suggestion just to get us thinking in unorthodox ways: how about sending an automated ship which lays a cable between here and Mars, anchors it on Mars, then reels it in after we attach the manned ship to the Earth end. 😛 [Previous page](https://boards.straightdope.com/t/what-type-of-propulsion-system-will-get-us-to-mars/590595.md?page=2) [Next page](https://boards.straightdope.com/t/what-type-of-propulsion-system-will-get-us-to-mars/590595.md?page=4)