# Mining a gas giant

#### T.Neo

##### SA 2010 Soccermaniac
Lately I've been wondering about 'mining' hydrogen, as well as other gases, from the atmosphere of a gas giant.

My vague idea would be some sort of nuclear-powered scramjet, that could skim the upper atmosphere and slowly collect gases. It would maintain a high enough altitude that reaching orbit from that altitude would not be too problematic.

I don't know how plausible that would be...

Is there a better concept than this? Balloons maybe? How would you launch from the upper atmosphere of a gas giant?

What would the ideal altitude for gas-harvesting be? What is the abundance of isotopes such as Deutarium and Helium 3 in the atmospheres of gas giants? Is there any data on this, or at least estimates/vague figures of some kind?

What other chemicals could be extrated from the atmospheres of gas giants?

Can collisions between spacecraft and ring particles be avoided when operating in close proximity to planets with such formations around them?

#### T.Neo

##### SA 2010 Soccermaniac
I would imagine that thread was more about the "if", I am asking more about the "how", and have presented several concepts for others here to critique and/or add to if they wish.

Still, if the mod team decides to merge this thread, I certainly won't complain...

#### Wishbone

##### Clueless developer
Several considerations: if it is cheaper to mine a moon, mining a giant is a non-issue. How much energy does it take to deliver gases from the grazing (collection) orbit to the base on a giant's moon (I assume you're not hauling it back to Mother Earth)?
The GRAZER would have to be sized in accordance with the principle of maximizing the return per unit of time per one "standard" fission core (yes I know ISRU and propulsion reactors have different designs).
The inputs:
1. cross-section of the inlet, with the inflow being divided into two parts. One part goes for the propulsion, the other for liquefaction.
2. cross-section and length of the LH2 tank.
3. liquefaction efficiency
4. operating altitude
5. thermal protection properties (mass, efficiency)

The equations:
1. atmo density from altitude
2. orbital velocity from altitude
2. ballistic coefficient from a combination (max) of inlet and tank cross-sections and current GRAZER's mass (will change from orbit to orbit BTW)
3. dV lost per orbit from density and ballistic coefficient
4. thrust needed to compensate for lost dV
5. reactor power remaining for liquefaction
6. amount of gas liquefied per orbit
7. atmospheric heating per orbit
8. boiloff losses per orbit
9. number of orbits needed to fill the tank
10.time in transit to and from giant's moon base.
11.boiloff in transit
12.dV needed for transit
13.LH2 used off as fuel for transit.

Think that's all for now

#### tori

##### New member
The PROFAC concept came close - mining Earth's atmosphere.

Profac, PRopulsive Fluid ACcumulator, was described by its inventor, Sterge Demetriades, in the pages of the British Interplanetary Society's Journal as long ago as 1959. In this concept, a nuclear electric vehicle would orbit in the Earth's atmosphere - only 75 miles (120km) up - scooping up the rarefied air, separating out the oxygen and using the residual nitrogen in an electric propulsion thruster to make up the drag losses caused by the reaction of the tenuous atmosphere on the vehicle. A 10Mw reactor could provide enough oxygen every 20-30 days to launch 15 tons of payload into lunar orbit for the cost of a single Space Shuttle launch. On paper, Profac wins over all other proposed nuclear transport systems simply because it does not have to move the huge mass of the nuclear reactor to and from the Moon with each payload launch. With a system like this the cost of putting cargo on the Moon might approach the $54/lb ($1,000/kg) mark by the year 2000.

http://www.bisbos.com/rocketscience/spacecraft/profac/profac.html

#### Wishbone

##### Clueless developer
There was also the dissociation-based engine of 1958 (aka ionospheric ramjet - see NTRS under no.1993085302 IIRC).

#### Eagle1Division

##### New member
I was looking at writing a short story that had to do with mining the upper atmosphere of a Gas giant...

The Scenario where it would be necessary is this: Interstellar mission to another solar system to survey possibility of colonization, and gather other endless torrents of scientific data not possible through interstellar telescopic observation.

The ISV only carries enough Fusion Delta-V for braking when arriving to the destination, and a small supply of shuttles and probes among other things.
The shuttles would de-orbit over the gas giant, mine, come back to the mothership and deposit their collection in the mothership's fuel tanks.
Once the tanks are full, there's enough Delta-V to head back, and it uses some ground-based method of braking. (Be it the Hydrogen Repeller, Photon Sail, or Plasma sail.)

Not much work on the design so far, only specifications are using a nuclear ramjet (not scramjet, for long operation times shock layer heating, instantly melting the exposed forward surfaces of the vehicle at scramjet thrust velocities, would give scramjets a short service life, either because of ablation or active cooling, which would mean short mission duration.) for atmospheric flight, and powerful fusion engines for de-orbit and orbital insertion.

I think any process of entering a gas giant's atmosphere would either call for an ablative heat shield, active cooling, or a powered descent to avoid the peak velocity.

Just try entering Jupiter's (or even Saturn's) atmosphere with a DGIV. Not easy... Less than 0.01 m/s deceleration, at 40 km/s, with heat shield at max heat load. The Galileo probe had to withstand over 230 G's! [source]

I found that This Music was absolutely perfect for re-entering over those massive, beastly, hellish 5-G worlds.[ame=http://www.youtube.com/watch?v=cEneeYiuzEg]Orbiter Soundtrack: The Might(Mass?) of Jupiter, King of the Gods[/ame]

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