"Larry [Page] asked me a couple weeks ago how much it would cost to send people one way to Mars and I told him $10 billion, and his response was, ‘Can you get it down to 1 or 2 billion?’ So now we’re starting to get a little argument over the price.”
Larry is currently listed on Forbes as being worth $14b, so $1b really isn’t a huge amount of his total cashpile.
IMHO designing a system that would enable a pretty good odds of coming back would be at least an order of magnitude more expensive than a similarly reliable one way system.
Think of all the additional R&D and engineering difficulties involved in keeping a human alive long enough to get there, do something there come back and survive.
More to the point, what's the cost of a Moon base - where a return and even a rescue is feasible - AND a one-way extensive robotic exploration of Mars. It just seems an overly dramatic waste (there will be no shortage of people willing to go) to send people to die on Mars when we can get the same off-Earth habitation expertise and Mars scientific data for the same price or cheaper.
The thing with Mars is, once you're on the surface, you can manufacture fuel for the return trip in-situ. Dr Robert Zubrin covers this in his Mars Direct mission blueprint.
And you get oxygen to breathe for free! The Mars Direct plan calls for the initial deployment of an unmanned mission to set up a fuel station on the surface - then unmanned missions to cache supplies there - and only when you have enough stuff pre-deployed for the return trip and/or a permanent presence, send humans.
The moon may be closer, but until you have a working fusion reactor, there's not much you can usefully do there in terms of resource extraction.
A bajillionaire whose name is hardly household might be able to buy eternal, historical name recognition by taking such a one-way trip as a way of "going out in style".
Robert Zubrin estimated that his Mars Direct plan would cost about $20B to develop the vehicles and other equipment, then $1B per launch with two launches per year.
Each launch enables a one-way trip to or from Mars.
In the past when someone had a challenge, they would pull out their sliderule. Now when someone claims something is impossible they pull out their wallet.
I find it somewhat astounding how much we are still reliant on blowing stuff up whenever we want to go fast. At least this is being somewhat mitigated on land with electric cars. I'll venture that we won't see any deep improvements in space propulsion until we get a better (i.e. quantum) understanding of gravity. However this beaming power idea is interesting.
I didn't think this through all the way, but something seems fishy about that article:
... if the exhaust velocity can be made to vary so that at each instant it is equal and opposite to the vehicle velocity then the absolute minimum energy usage is achieved. When this is achieved, the exhaust stops in space [1] and has no kinetic energy; and the propulsive efficiency is 100%
This argument is not Galilean invariant, which makes it seem highly dubious to me. There is no "stopping in space"; what absolute inertial frame defines what "stopped" means?
You always want to have an exhaust velocity as high as possible. The energy you have to impart to the exhaust is 1/2 mv^2, but you get m*v momentum. So small exhaust mass at very high speed will give you the same momentum, and cost you much less energy than bigger mass and less speed.
Sorry, this I'm completely wron... I mean: I was testing if you read the comments before upvoting.
The 1/2mv^2 vs mv points to an exhaust speed as low as possible, to get as much momentum as possible from as little energy expenditure as possible.
Now, if your exhaust comes from the outside world then that makes perfect sense. And this is why you have turboprop and turbofan engines: you slow down the exhaust of the turbine, speed up outside air, and do a favorable energy/momentum trade.
But in space you have to carry the mass you will exhaust. You don't have much choice: all the energy you get from burning fuel will be transfer to kinetic energy of your exhaust (in the reference frame of the rocket).
Yeah, you're right. A bit of algebra reveals that your delta-V per MASS of fuel (which is a frame-independent quantity) goes as the (propellant specific chemical energy)^.5.
However, it is also true that if you calculate the delta-V per unit propellant ENERGY used, it decreases with the propellant specific energy.
Since you don't really care about how much energy you carry but only about how much fuel you need to use per delta-V, it's always better to have higher exhaust energy. (As long as you are using a chemical propellant, i.e. the mass carrying the energy and the reaction mass are the same.)
The statement in the article about "propulsive efficiency" is total bogus. First: the relative kinetic energy of the rocket and the exhaust IS a frame-dependent quantity, so it's meaningless. Second, any reasonable measure of efficiency, like the delta-V per fuel energy, reveals that the "optimal" value is an exhaust velocity of zero. (Optimal in the sense that it's more energy efficient, but only because the delta-V goes to zero slower than the energy. It's still a useless optimum, because it results in no delta-V at all...)
Pretty sure the implied inertial frame is the one relative to the spaceship, and not any other encapsulating frames.
But I linked that mainly for the table just down the page a little comparing various efficiency measures of different propulsion systems. I'm pretty sure that chemical rockets are the least efficient we've ever implemented or imagined, barely sufficient for travel within the solar system, and certainly not efficient enough for any trips, round or one-way, beyond our solar system.
I think you're right. You get acceleration in one direction by accelerating and ejecting mass in the opposite direction. The degree to which it's efficient depends on how much of your energy source was converted into kinetic energy of the ejected mass, and how directional that ejection mass was. The relative velocity ("stopped" versus moving relative to some external frame of reference) only determines how much propulsion you're getting with respect to that frame of reference, nothing to do with efficiency at all.
On the other hand, this doesn't make blowing stuff up efficient. An explosion, unless it's lensed properly, will push mass equally in all directions.
somehow reading that, i'm more and more sure that i'll be Branson not Worden who gets us to Mars. I'm not a "free market" zealot, and it isn't about how Branson is good, it is more about how Worden is bad.
There is also Musk, whose drive to change things makes me awe in respect (while his technical decisions may be debatable, the most important thing here is that he actually DOES things). Google guys got the money, and
if they still have the same drive...
Pretty interesting. I'm sure a lot of people would be interested in a one way ticket to Mars if we could somehow make it livable over there.. I know I am!
It's not like a one way trip is unprecedented in human history. Many of the Europeans coming to North America did it one way to conditions that were very much more primitive than the old world.
For those Europeans, there was still the option of turning it into a round trip. Granted, it was probably an expensive and arduous option, and required a ship in port ready and willing to take you, but it was there.
Right now, a one-way trip to Mars really is a one-way trip. That is, until we can put enough provisions up there to get a ship back out of that gravity well.
And keep the occupants alive long enough to get back here.
Interesting ideas. I just can't get past the fact the a Director as NASA actually said, "Anybody that watches the [Star Trek] Enterprise, you know you don’t see huge plumes of fire". As if, instead of drawing from science fiction as inspiration, he uses it as a blueprint.
You know what else we don't see, Director Worden? Human Teleportation. And Klingons.
"Larry [Page] asked me a couple weeks ago how much it would cost to send people one way to Mars and I told him $10 billion, and his response was, ‘Can you get it down to 1 or 2 billion?’ So now we’re starting to get a little argument over the price.”
Larry is currently listed on Forbes as being worth $14b, so $1b really isn’t a huge amount of his total cashpile.