[Rod_Cloutier]

It seems someone has hijacked my 'Import methane from Jupiter thread' that I am still quite fond of. The thread dealt will all these issues and more, and was later merged into 'the Titan thread merged'.

I first posted on the utility of harvesting space based resources when I joined peakoil.com in 2004. I must admit, however, that six years of reading here daily about entropy, energy returned vs energy invested, diminishing returns on complexity, collapse and other issues; that I am now very much more skeptical about space possibilities.

Its also clear that this year when Obama cancelled the 2020 return to the moon missions that we are not heading down this path. The lunar regolith has Helium 3 deposits of 0.02% in the regolith samples brought back to Earth. That may not sound like much, but a few spaceshuttles full of refined Helium 3 per year and the development of the related fusion techologies could solve all the world's energy problems for the long term. We're not on that path.

Had JFK not been assinated by who knows who in his own government, humans could be doing things like this by now. We never went that way, instead the last 20 years of human spaceflight has focused on taking pigs to orbit to prove the theory that 'Pigs can fly' and other white elephant projects.

Its is really sad, what could have been but wasn't!

[Jenab]

Space-based resources are a boon, a God-send... for people living in space. In general, however, they will not avail anyone in need of resources on Earth. They almost always cost to deliver to Earth more than they are worth.

But what is important is not where people live. What's important is that people live. It doesn't matter where technological civilization continues, so long as it continues. If it can't afford to have much to do with Earth in trade, then so be it. The universe is better for having permanently off-planet human residents enjoying and preserving the sum of human knowledge and technical know-how, than it would be for the lack of them while the same post-Industrial-Age conditions prevail on Earth in any case.

[Aging gypsy]

Why doesn`t NASA just build the space escalator they`ve spoke of?
They could then send robotic drilling machines with bl**dy long hoses up it to tap into Titan and it`s reserves.
I think I`m more likely to grow breasts before mankind ever gets to Titan to extract anything, they can`t mine the moon for it`s Helium-3 yet so I`m damn sure Titan is simply a dream.

http://www.technologyreview.com/energy/ ... fteradbody

[efarmer]

I see your point, but I also assume you actually have breasts suitable to your present requirements.
If I am in error and you are not male, I hope they are perky and you are down with them at the present time.

[ian807]

New Discovery! There's natural gas on Uranus. Act now!

[Aging gypsy]

I see your point, but I also assume you actually have breasts suitable to your present requirements.
If I am in error and you are not male, I hope they are perky and you are down with them at the present time.

Last time I checked I was of the masculine caste, can`t wait for the breasts to come though I love to dabble at DIY.
If that escalator becomes too expensive maybe a ladder would suffice?

[Sys1]

Have you heard about Titan Oil and Gas company?
http://titanoilinc.com/

[Timo]

I think you're referring to Titanic Industries, although i hear they were demised by frozen hydro something or other.

[Ferretlover]

I understand; however, what happens on Titan, stays on Titan. That's why this is not a 'Titan's Methane' website.

[Rod_Cloutier]

(Bump) I'm bored with doom tonight. Everything seems possible again when you take Ayahausca.

[jato]

It's been 10 years since you started this thread. Has anyone done the energy calculation for a round trip tanker ship to/from Jupiter? I don't want to slog through 17 pages for the answer!

[Keith_McClary]

It's been 10 years since you started this thread. Has anyone done the energy calculation for a round trip tanker ship to/from Jupiter? I don't want to slog through 17 pages for the answer!

If you're in a hurry you could make the trip in 10 years, but a more leisurely orbit would be more fuel efficient.

[Sixstrings]

Sunlight glinting off Titan's sea (I think those are methane seas, if I recall):



A methane ocean on Titan:



Titan is definitely a top most fascinating place in the solar system. It has all the weather effects of earth, but it's topsy-turvy with methane oceans and methane rain, rocks and boulders that are really frozen water ice but don't look like "ice."

It has sahara deserts, with huge wind-whipped dunes that stretch for hundreds of miles. It's has varying climates.

A sub probe would be cool, maybe this is a first step to doing a sub probe to the salt water ocean on Europa.

Ultimately, the coolest would be to get some sub to Europa (a more complicated mission, having to melt through the ice cap). Go check out some thermal vents. See if there's critters!

[lpetrich]

Jenab6 stated earlier in this thread much of what I wanted to state. Getting Titan's hydrocarbons would be very expensive and time-consuming.

I'm half-thinking of starting a thread on rocketry and space travel because a lot of people have rather naive notions about it, or at least have not thought it through very much.

[lpetrich]

Naive notions like that it is much easier than it actually is. Some of us may have discussed earlier in this thread how naive that notion is, but I think it helpful to work it out in detail.

Let's look at launch costs. Capabilities & Services | SpaceX is about SpaceX's Falcon 9 rocket and its advertised prices (Standard Payment Plan for a 2016 launch):

• LEO: $4650/kg, $2110/lb
• GTO: $12620/kg, $5720/lb

LEO = Low Earth Orbit -- minimum for getting out of the Earth's atmosphere
GTO = Geosynchronous Transfer Orbit -- near the Earth's escape velocity

To see how expensive that is, consider flying between New York City and Perth, Australia, two nearly antipodal cities. Looking in Orbitz and checking on dates a few months ahead, I find that it's about $1000 each way. That could launch 200 grams into LEO or 80 grams into GTO on a Falcon 9 rocket at the prices that SpaceX is asking.


Now look at how much one can expect out of a rocket engine. A century or so ago, Konstantin Tsiolkovsky figured it out from Newtonian mechanics:

v = ve * log(mi/mf)

v = change of velocity (delta V)
ve = exhaust velocity (specific impulse in velocity units)
mi = initial mass
mf = final mass

ve = (exhaust momentum) / (exhaust mass + radiated waste-heat mass (E = mc^2))

So to increase v, one can increase ve or increase mi relative to mf, or both.

For chemical rockets, ve is limited by chemical-reaction energy.

The best value for any chemical engine that has ever been in service is around 4.4 km/s, and that's for hydrogen-oxygen. Hydrogen-fluorine would be better, but fluorine is expensive and very toxic and corrosive, and I don't think that anyone has ever used fluorine in a full-scale rocket. But hydrogen and oxygen also have problems. They must be aboard the rocket in liquid form, but oxygen boils at 90 K and hydrogen at 20 K. So they'd be hard to store for an interplanetary journey.

If one wants room-temperature liquids, one has to use fuels like hydrazine and nitrogen tetroxide, or chemical relatives of them like UDMH and nitric acid. One can get a ve of about 3.5 kms, about what one can get with kerosene-oxygen.

A good solid-rocket booster can have a ve approaching 3 km/s.


Electric rocket engines can do much better. For instance, the Dawn spacecraft has 3 NSTAR ion engines (GRC - NSTAR Ion Thruster):
Mass: 8.2 kg
Size: 30 cm
Power: 2.3 kilowatts
Thrust: 92 millinewtons
Specific impulse: 30 km/s (3100 s)
Propellant: xenon

It can only run in a vacuum. Its thrust is 9 grams-force for Earth's gravity, and it thus cannot lift itself from the Earth's surface. But it can be operated almost continuously for years, and the Dawn spacecraft's engines have successfully done exactly that.

[lpetrich]

Getting off the Earth:

Earth's surface-satellite velocity is about 7.9 km/s. To get from the Earth's surface to low Earth orbit, about 300 km altitude, takes about 7.9 km/s of delta-V. Furthermore, it must be done with a high-thrust rocket, and that means a multistage chemical one. The Falcon 9 and similar rockets won't be put out of business anytime soon.

From Falcon 9 - Wikipedia, version 1.1 has a fully-loaded mass is 505.846 metric tons and its LEO and GTO payload limits are 13.15 mt and 4.85 mt. Both its stages use kerosene-oxygen propellant.


Earth - Saturn:

The orbit with lowest delta-V is a Hohmann transfer orbit. One needs about 10.3 km/s delta-V near the Earth and 5.4 km/s delta-V near Saturn.

If one has a rocket with high enough thrust, one can leave the Earth fast enough to be at the right speed at interplanetary distances, with the help of the Oberth effect as it's called. One needs a delta-V of only 7.3 km/s, but one has to apply it in a half hour or less. For a hydrogen-oxygen rocket, that means a mass ratio of 5.25, and that's propellant only. That means that the empty escape stage + payload can weigh at most 2.5 mt if launched by a Falcon 9.

For a low-thrust engine, it's worse. One's delta-V is 18.0 km/s

Formulas:
High-thrust: sqrt( (escape velocity)^2 + (final velocity)^2 ) - (orbital velocity)
(escape velocity) = sqrt(2) * (orbital velocity)
Low-thrust: (orbital velocity) + (final velocity)


It will take about 6 years to make the trip.


At Saturn, we need to get to Titan's orbit distance, about 1,221,000 km from Saturn on average. Titan orbits Saturn at about 5.57 km/s with a period of 15.945 Earth days. So if an engine can deliver the necessary delta-V in a day or two, it should be enough. Delta-V's:
High thrust: 4.0 km/s
Low thrust: 11.0 km/s

Next to get into Titan's orbital plane. It's close to Saturn's equatorial plane, which is inclined about 26.73 degrees to its orbital plane. One will need about 2.6 km/s of delta-V to do so.

Formulas:
High thrust: vorb * 2 * sin(inc/2)
Low thrust: vorb * inc (in radians)

Finally, Titan itself. Its radius is about 2575 km, but the safest altitude for a low orbit is likely 1000 km. At that orbit, its orbital velocity is 1.6 km, its escape velocity is 2.2 km/s, and its period is 2.8 hours.
High thrust: 0.6 km/s
Low thrust: 1.6 km/s

To de-orbit takes only 0.1 km/s, though one will crash into Titan's atmosphere at something like 1.5 - 2 km/s. That's a standard mode of re-entry for Earth spacecraft, however, so it's a pretty much solved engineering problem. One could do that while arriving at Saturn, though one will crash faster, at 10 km/s or so.


To get back into that orbit from Titan's surface will require 2.1 km/s, calculated by doing a Hohmann transfer orbit from Titan's surface. Once one leaves Saturn, one can arrive at the Earth by crashing into its atmosphere at about 18 km/s.

[lpetrich]

So if one tries to get hydrocarbons from Titan, one will have an atrociously low EROEI, the Energy Returned On Energy Invested ratio.

Let's see about the Falcon 9's propellant. One will get the most energy out of it with a stoichometric ratio or close to it of kerosene and oxygen. That's easy to calculate.

[CH2O] + (3/2) O2 -> CO2 + H2O

That's about 23% kerosene, 77% oxygen by weight. Applied to 505 tons, that's 114 tons of kerosene and 391 tons of oxygen.

Oxygen one gets by refrigerating air until its oxygen condenses, so it may not be very energy costly. Does anyone have any good numbers on that? Like how many watt-hours of electricity per kg of oxygen?

An upper limit is set by its LEO payload limit. If one can somehow return its weight in kerosene, then its returned kerosene will be about 0.115 of the rocket's kerosene.

So we get an EROEI upper limit of 0.1.


One could get around that by doing lots of asteroid mining and interplanetary manufacturing, but one has to send up some mining and manufacturing machines to bootstrap the process. So one still loses.