
SpaceX CEO claims he can send you on a round-trip to Mars for $500K  - evo_9
http://www.extremetech.com/extreme/122923-spacex-ceo-claims-he-can-send-you-on-a-round-trip-to-mars-for-500k
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damoncali
What is it about this guy that allows him to make such claims and not be
laughed out of the room? It's an amazing an useful talent that, oddly, I first
witnessed as a young engineer on NASA's Hubble Space Telescope project.

The head of the servicing missions was a boisterous, outrageous, personality
(some told me it was what held him from higher positions within NASA). He was
the kind of guy who brought in a sales guy for a rapid prototyping machine (a
3D printer starting at $1 million), walked in half way through the
presentation, and then promptly kicked the salesman out for not having a $200k
offering.

He was also the kind of guy who demanded composite structures yielding 10X the
mechanical properties of the current state of the art materials. But with no
research projects, development, or anything even close to it. Just "get it
done".

Of course, we didn't get it done (because it was impossible), but what we did
get done was a major leap forward. We used materials without, _gasp_ , flight
heritage. We used the absolute state of the art in some cases. We got _it_
done, it's just that _it_ wasn't what was asked for, at least not directly.

This smells of the same thing. But don't underestimate the shear force of
personality it takes to make such outrageous claims, _and still have people
follow you_ to something remarkable, yet more realistic.

~~~
mkn
There a couple of things that allow him to make these claims without being
"laughed out of the room," as you say, but they don't have to do with his
personality in the sense in which I take your meaning.

First, there is the rocket equation. That little gem tells us the amount of
fuel it takes to achieve a given change in velocity for a given energy density
of fuel. Then there are some results from orbital mechanics and aerodynamics
that tell us what that change in velocity is. For the curious, escape velocity
is just sqrt(2) times the circular speed at any given altitude.

I've laid this out before, but here it goes again. To put a pound of anything
into orbit has a fuel cost of a little over $20. "Incredible!," you say, "It
costs $10k/lb on the Space Shuttle! How can that be?!" Like so. Typical mass
fractions are on the order of 2%. That is, 2% of the stuff on the pad, fuel,
structure, payload, everything, actually ends up in orbit. About 12% of that
mass is structure, things like tanks and engines and the like. That leaves 86%
of the thing as fuel. 86:2 is 43:1. 43 lbs of fuel for every pound of payload.
Assuming that propellant is roughly as dense as water and roughly the price of
milk, both easily verified, that's under 6 gallons of propellant for every
pound of payload, which will run you $21 at $3.50/gallon.

Multiply sqrt(2) by $21/lb and you have something like $30/lb. If you and your
capsule weigh 2,000 lbs, That's $60,000 for a one way ticket. A little over 8
times that price may be a reasonable number. So, what makes up the difference
in cost for current launch systems, or even for antiquated and clunky systems
like the Shuttle? Low safety margins and their concomitant need for enormous
administrative costs for each part, disposable launch systems where that
administration cost burns up in the atmosphere or splashes down in the
Pacific, and enormous system complexity driven by a lowest-flight-weight-
results-in-the-cheapest-vehicle mentality.

We can begin to address, based on SpaceX's design philosophy and planned
vehicle, how they may be able to make these claims without deserving to be
"laughed out of the room."

First, SpaceX has reduced engineering and integration costs by reusing common
components and simplifying designs at every step. they were (and I think,
still are) using a pintle injector which is much less susceptible to
catastrophic combustion oscillations than the more typical injector-face
solution, at a cost of some performance. The tanks for all of their stages are
the same diameter, allowing them to engineer and build one capital-intensive
jig rather than two or three, and they get more experience with that hardware
since all their work is done on it. They're using a pneumatic stage sep
mechanism rather than a pyrotechnic one to eliminate material-handling,
static, and other safery concerns related to pyrotechnics. Rather than relying
on one or a few very large engines to power the first stage, they've chosen to
use 9 smaller engines on the first stage and isolate each one in its own cato-
proof container, again allowing them to gain more experience with a single
system, prove its reliability, and leverage that experience and track record
to perform a larger job.

Second, they have plans for full reusability of the launch system based on
incremental changes to their existing systems. Yes, there is a fuel and
performance penalty for going this route, but the savvy armchair aerospace
critic will note that those penalties are expressed in tens of dollars per
pound, whereas 100% disposal is measured in thousands to tens of thousands of
dollars per pound. That is to say, even if reusability results in a 10-fold
increase in fuel cost but allows vehicle cost to be amortized to
negligibility, we're still approaching Musk's $500k/flight number. As to his
actual plan, the fuel cost to land a booster segment is tiny compared to the
cost of launching a vehicle. The first stage will simply reenter without
having to retro-burn, and the second stage will need to retro-burn just enough
to enter the atmosphere to achieve the rest of the braking. After that, the
delta-v required is on the order of 100m/s, hardkly the 10km/s needed for
orbit. You seem to know what you're doing, so I leave the derivation of that
penalty, using the rocket equation, to you.

tl;dr: You're absolutely wrong in the most irrelevant way, and had you
addressed SpaceX's achievements and plans in anything like a rigorous way, you
could easily have answered your own question.

EDIT: The fuel cost for escape will not be sqrt(2) times the cost for circular
speed. The real factor will be something more like 2 or 3, not 1.414... Still,
we're in the range of $60/lb, not $6,000/lb.

~~~
jackpirate
_which will run you $21 at $3.50/gallon_

So I was going to call bullshit on your price for rocket fuel given that
regular gasoline is more expensive than this, but I looked up the price
[<http://www.desc.dla.mil/DCM/DCMPage.asp?PageID=722>] and it turns out that's
pretty close to the current price for JP-5. The most expensive fuel the DOD
uses, JTS, is only $6/gallon.

------
ef4
Robert Zubrin published a detailed plan for generating rocket fuel on Mars
several years ago. His book "The Case for Mars" is a good read.

Such a technology really is a game changer for the economics of the mission.
And you can send your robotic fuel factory and make sure it's working before
you commit to launching people.

~~~
inchcombec
I've actually got that book in my collection and you're right, it is a good
read.

The idea of producing rocket fuel on Mars is not only a good one, but quite
likely the only way such a mission would even be viable. The idea of hauling
all that extra rocket fuel for the return trip to Mars and back simply doesn't
work.

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warpspeed
While I'm sure it's a technical hurdle in itself, I didn't think that fuel or
weight were the big problems with a manned mission to Mars. I'm curious as to
what Mr. Musk's plan is for shielding passengers from intersteller radiation
that one would experience outside of our magnetosphere.

The Apollo astronauts were exposed to approximately 1140 millirem over a 9 day
mission, while the average here on earth is 350 millirem per year. Nuclear
workers are limited to about 2000 millirem per year... so the approximately
52,000 millirem per year the astronauts would receive on a Mars mission is a
problem.

~~~
mrsebastian
Obligatory XKCD link: <http://xkcd.com/radiation/>

(100 rem = 1 sievert)

~~~
Groxx
Following that math, the 9 day Apollo trip got 0.0114 sieverts. We'll round
that to 11 mSv.

So in 9 days, they got 11x more than the EPA's yearly limit to the public, or
1/5th of the EPA's yearly limit to radiation workers.

The 520mSv warpspeed listed as a trip's radiation exposure comes out to 5x the
lowest yearly radiation exposure 'clearly linked' to increased cancer risk.

So yeah. A problem, barring adequate shielding, if that number is correct.

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benl
The full-length interview this story is based on is on this page:

<http://www.bbc.co.uk/news/health-17439490>

Just skip the stories and listen to the audio, it's much more informative.

------
Androsynth
This is great and I fully applaud him for this. But when I go, I won't be
coming back <http://en.wikipedia.org/wiki/Mars_to_Stay>

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sgt101
How is he going to do the landing? Human manned craft are going to be too big
for bags, and the atmosphere is too thin for parachutes to work. Landing on
thrusters is somewhat fuel heavy (so to speak).

~~~
warpspeed
Like this: <http://www.youtube.com/watch?v=BudlaGh1A0o>

edit- Parachutes are probably more practical. They work if you make them big
enough.

~~~
ballooney
Your mass scales with the cube of linear dimension. Parachute drag scales as a
square of linear dimension.

What this means is that the chute gets bigger much more quickly than the
payload as you increase lander mass, to the point that you quickly get
outlandishly large and impractical chutes for manned landers. Hence the
research into alternatives.

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vannevar
He's relying on generating fuel on Mars, which considering that we've barely
scraped the Martian surface with robots is highly speculative. Mars travel is
still beyond business planning and into the realm of futures studies. I love
SpaceX, but they haven't yet demonstrated they can reliably deliver payloads
to Earth orbit on a regular basis. They're a long, long way from Mars.

~~~
mkramlich
I've heard some experts in the field say that the hardest parts about space
travel are the launching and the landing. The middle parts, like the long
boring flight and keeping the crew alive and not crazy, are massively easier
and less risky in comparison, engineering-wise. They've shown they can put
something into orbit. Landing on Mars with humans will be tricky, but the
technology seems to exist to allow it, and that general kind of thing has been
done before. Parachutes and thrusters, etc.

~~~
vannevar
I don't doubt that SpaceX can get to Mars eventually, maybe even within 10
years. I really hope they do, I'm rooting for them. But I seriously doubt they
will be ferrying space tourists out there for $500K apiece in any timeframe
that would fit in a business plan, even a very long-term one. We're decades
away from that kind of capability.

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pygorex
> Of course, there are many skeptical experts out there that have pointed out
> the fact that SpaceX has only attempted a rocket launch seven times. Of
> those seven, three were total failures.

Ouch. I hope that $500,000 is refundable in case of death or accident.

> Any human that makes the trip will be stuck inside the vehicle for the 214
> days it would take to actually travel to the Red Planet.

I once made a road trip from Seattle to Tennessee in 3 days. In the middle of
a frigid winter. During blizzard conditions. Of course we took breaks to get
out of the car, stretch our legs, have a piss and get some fresh air. At the
end of the trip I was ready to hang myself. The boredom and rigor of endless
driving became unbearable. The prospect of taking a similar trip, over a much
longer timespan, in much more hostile conditions and paying for the privilege
is not appealing, at all.

~~~
pjscott
To be more specific about their flight record: the _first_ three test flights
were failures, back when they were still working out the kinks on the Falcon
1. The flights since then -- including both Falcon 9 launches -- have been
successful.

------
adaml_623
I'd rather go to the moon. The view is better.

~~~
pjscott
If you're interested in spectacular views, it's hard to compete with a
mountain three times the height of Mount Everest:

<http://en.wikipedia.org/wiki/Olympus_Mons>

Mars also has an atmosphere suitable for flying around in with helium or
hydrogen balloons. You could mount a camera on a bunch of balloons and get
some _amazing_ pictures.

If you don't mind my saying so, "The view is better" doesn't sound like your
real reason for preferring the moon.

~~~
pyrotechnick
He means the view of Earth from the moon vs from Mars.

~~~
za
<https://en.wikipedia.org/wiki/Earthrise>

------
rwhitman
So you can drop a half million dollars and spend 2 years of your life in a
tiny compartment millions of miles from home to visit a dead, cold, rusty rock
without a breathable atmosphere?

Does that sound unappealing to anyone else?

~~~
Zaak
I expect there are many people who would find that very unappealing. I also
expect that there are people who would put down the money right now if you
would let them.

~~~
repsilat
There are people who would put down the money for a one-way trip.

------
linuxhansl
Maybe fly to the moon first before you tackle mars?

~~~
pjscott
If anybody feels like going to the moon, I'm sure SpaceX would love to handle
the launches.

~~~
kamaal
To me going to moon looks like a more interesting prospect than going to mars.

------
duxup
Can't get that much time off of work. What can you do for me over a couple
weeks?

------
bstpierre
In other news, a one-way trip to Mars only costs $50k. If you don't make it,
you can sue for a refund, but you have to sue in Martian courts, which won't
be set up for a few more decades.

~~~
xspence
Is mars established as a credible planet/nation zone, or does it count as
space (international)? Its an interesting perspective that the "zone" of mars
could be a place of legal jurisdiction. But it seems that space is a free for
all "zone", so maybe your lawsuit would be void?

~~~
warpspeed
According to the 1967 U.N. Outer Space Treaty, "outer space, including the
Moon and other celestial bodies, is not subject to national appropriation by
claim of sovereignty, by means of use or occupation, or by any other means.
However, the State that launches a space object retains jurisdiction and
control over that object. The State is also liable for damages caused by their
space object and must avoid contaminating space and celestial bodies." (from
Wikipedia)

So any crimes on Mars would probably fall under the jurisdiction of the
country who launched the mission. Enforcement on the other hand might be
tricky.

~~~
mkramlich
Laws and treaties are just words on paper. They can be changed. They can be
ignored. They have in the past and it's reasonable to assume they will
continue to be in the future. So, I wouldn't rule out having some existing
nation declare sovereignty over some part of Mars or an asteroid. They will
give whatever excuse they need to justify it. Businesses would have powerful
private profit incentive to be able to claim rights to things, and to have the
protection of a patron national government's military to back it up, like the
US, China, etc. We can also expect silly unnecessary wars to be ginned up by
propagandists working for those same private profit interests. History is
littered with examples, and no reason to expect it won't happen again in the
future.

~~~
elithrar
> So, I wouldn't rule out having some existing nation declare sovereignty over
> some part of Mars or an asteroid.

Perhaps it will end up in a situation akin to Antarctica.

