Author Topic: Gas Giant ISRU?  (Read 6268 times)

Offline furniture

  • Member
  • Posts: 7
  • Liked: 3
  • Likes Given: 0
Gas Giant ISRU?
« on: 03/16/2022 04:20 am »
I don't know if this has ever been considered, or if there's some fundamental flaw that would derail the whole plan, but I was trying to think of a way a manned spacecraft might reach the Galilean moons (Ganymede, Callisto, Io, and Europa), when I remembered that Jupiter is over 90% hydrogen, which happens to be a very popular rocket fuel. Thinking about this concept, I came up with the following plan:
Vehicle Design:
I propose a mid-sized lifting-body spaceplane (like a big Dream Chaser) with a small crew section (maybe similar volume to NASA's Orion?) and large fuel tanks. The vehicle would either be powered by hydrolox (Hydrogen/Liquid Oxygen, with much larger (proportionally) Lox tanks than usual) or some sort of advanced Hydrogen fusion reactor (Tanks contain only hydrogen). In the vehicle's underside would be a series of large intake vents, designed to handle the intense heat of interplanetary reentry.
Flight Profile:
The vehicle is launched from Earth, using a reusable first stage similar to SpaceX's Superheavy. It acts as a second stage, and is refueled in orbit. It then fires up its engines for an interplanetary transfer to Jupiter (or, conceivably, Saturn). After a few mid-course corrections, it arrives and enters the atmosphere. As this aerobraking maneuver causes the spacecraft to decelerate, the vents open, taking in hydrogen gas and feeding it into a device that chills and pressurizes it into fuel. Because the vehicle is a lifting-body shape, it can go deeper into the atmosphere than a capsule while still returning safely into space. The newly refueled spacecraft exits the atmosphere into an unstable orbit, which is soon stabilized by a quick engine burn. The vessel then charts a course for whatever moon the mission is targeting, and lands propulsively in an upright position.
Again, I'm not sure of the logistics here, but I would love to hear your feedback. Would this work? Or do you think there's something I missed? If so, would there potentially be solutions?

Offline darkenfast

  • Member
  • Full Member
  • ****
  • Posts: 1551
  • Liked: 1842
  • Likes Given: 8897
Re: Gas Giant ISRU?
« Reply #1 on: 03/16/2022 06:02 am »
Just to start with, here's a couple of things to consider:

Jupiter is surrounded by a high level of radiation, far higher than that in the Van Allen Belts around Earth. I believe Callisto (edit to add: of the major moons you mentioned) is the only moon far out enough to considered accessible by humans. Even probes suffer damage while transiting the higher level regions.

Even with higher speeds than we can now obtain, we are still looking at travel times far longer than a vehicle with a cabin the size of Orion can support with humans on board.

Aerobraking generates heat. A lot of heat. The gas that the spacecraft is passing through will be a very hot plasma. I see no way that any technology that we can think of would be able to chill that plasma while undergoing that sort of atmospheric entry.

Others more knowledgeable than I can probably give you more information. 
« Last Edit: 03/16/2022 09:43 am by darkenfast »
Writer of Book and Lyrics for musicals "SCAR", "Cinderella!", and "Aladdin!". Retired Naval Security Group. "I think SCAR is a winner. Great score, [and] the writing is up there with the very best!"
-- Phil Henderson, Composer of the West End musical "The Far Pavilions".

Offline ppnl

  • Full Member
  • ***
  • Posts: 312
  • Liked: 209
  • Likes Given: 19
Re: Gas Giant ISRU?
« Reply #2 on: 03/16/2022 07:38 am »
Just get water from the moons. With fusion power you can have all the hydrogen you could ever want plus some stuff some people like to breath. Or don't as there may be cheaper hydrogen elsewhere. After all 73% of the universe is hydrogen.


Getting it from Jupiter for example would really really be doing it the hard way.

Offline libra

  • Full Member
  • ****
  • Posts: 1818
  • Liked: 1230
  • Likes Given: 2357
Re: Gas Giant ISRU?
« Reply #3 on: 03/16/2022 01:11 pm »
Daedalus was to harvest He3 from Jupiter so the idea has been considered in theory.

There were also atempts at creating an "agnostic NTR" engine able to heat any atmosphere for propulsion, whatever the gas in it: Venus, Mars... Zubrin NIMF is one example, although for Mars first and foremost.

Offline redliox

  • Senior Member
  • *****
  • Posts: 2547
  • Illinois USA
  • Liked: 686
  • Likes Given: 97
Re: Gas Giant ISRU?
« Reply #4 on: 03/16/2022 02:12 pm »
If the needs were on the scale of a Kardashev 2 civilization, certainly.  However, when our civilization does reach the Outer Planets utilizing the ices of Callisto, Titan, and the other moons should suffice and would be less dangerous.  Isaac Arthur has a youtube series that does mention harvesting both gas giants and stars which would be worth looking into.
"Let the trails lead where they may, I will follow."
-Tigatron

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 39283
  • Minnesota
  • Liked: 25276
  • Likes Given: 12124
Re: Gas Giant ISRU?
« Reply #5 on: 03/16/2022 03:10 pm »
Makes more sense to mine Uranus than the Moon for Helium 3 and maybe even regular bulk helium (helium 4) and deuterium.

The price for regular old helium is up over $500/(thousand cubic feet), or about $3000/kg. It’s not as crazy as you might think. But the market is relatively small, about $3 billion per year. But not nothing!

So it could be after we use up the fossil helium on Earth that we could harvest it from Uranus, which has a higher escape velocity than Earth but whose gravity at the cloudy layers at Earth-like pressure is actually slightly lower than Earth.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Stan-1967

  • Full Member
  • ****
  • Posts: 1130
  • Denver, Colorado
  • Liked: 1185
  • Likes Given: 615
Re: Gas Giant ISRU?
« Reply #6 on: 03/16/2022 03:39 pm »
I don't think the concept works at all.  Jupiter's gravity field is 24.79 m/s^2.  Consider the type of vehicle needed to dip into the atmosphere and the type heatshield needed to not be vaporized before you even start to to capture gasses for propellant.  ( see Galileo probe)

Best case is you invent some miraculous method to capture gasses through the plasma sheath.  A more realistic assumption is that you will rapidly decelerate to a suborbital velocity and than have to capture gasses.  You won't have time to compress & cool them to a liquid, so how much can you store in a high pressure COPV.   What is the propellant mass ratio of you tanker ship at this point

Show the calculations for the DV needed to get the tanker ship and any relevant payload into a low Jovian orbit.  A primary guiding rule of ISRU for propellants is to not go down any gravity wells.  Asteroids and comets make much better sense for that type of ISRU.

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 39283
  • Minnesota
  • Liked: 25276
  • Likes Given: 12124
Re: Gas Giant ISRU?
« Reply #7 on: 03/16/2022 04:23 pm »
Why pick Jupiter? It’s the closest, sure, but the other 3 have basically Earth-like gravity at cloud level.

Uranus is the best option IMHO.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline lamontagne

  • Senior Member
  • *****
  • Posts: 4418
  • Otterburn Park, Quebec,Canada
  • Liked: 3862
  • Likes Given: 730
Re: Gas Giant ISRU?
« Reply #8 on: 03/16/2022 04:50 pm »
Is is practically impossible to leave Jupiter's atmosphere with just chemical propulsion.  The deltaV requirements are too high.
Just to get to Low Jupiter orbit requires over 33-12 = 21 km/s of deltaV compared to less than 10 for Earth.
You need SF level nuclear propulsion.

And as many mention it's easier to get propellant from Uranus.

Offline lamontagne

  • Senior Member
  • *****
  • Posts: 4418
  • Otterburn Park, Quebec,Canada
  • Liked: 3862
  • Likes Given: 730
Re: Gas Giant ISRU?
« Reply #9 on: 03/16/2022 04:53 pm »
There are a number of papers on the subject.  Just use google scholar and look for papers by Palaszewski, B  on atmospheric mining.  It's all there.

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 39283
  • Minnesota
  • Liked: 25276
  • Likes Given: 12124
Re: Gas Giant ISRU?
« Reply #10 on: 03/16/2022 05:13 pm »
Is is practically impossible to leave Jupiter's atmosphere with just chemical propulsion.  The deltaV requirements are too high.
Just to get to Low Jupiter orbit requires over 33-12 = 21 km/s of deltaV compared to less than 10 for Earth.
You need SF level nuclear propulsion.

And as many mention it's easier to get propellant from Uranus.
No, it’s not “practically impossible to leave Jupiter’s atmosphere with just chcemicql propulsion” and no, you don’t need “SF level nuclear propulsion.” An expendable Starship (shortened to increase thrust to weight) with a Falcon 1e as payload (and maybe a Falcon 9 first stage to get it going) could get about 1 ton to low Jupiter orbit.

People who make such claims should learn about the rocket equation. Jupiter ISRU is impractical for the fuel ISRU purposes given, but if there was something extremely valuable that you could afford a couple hundred million dollars’ worth of expendable rocket per mission, and all the engineering required to get it there (which would be the expensive part), then it is most certainly possible.

I agree about Uranus, of course, but you CAN just spam the logarithm with a huge mass ratio. And it’s not particularly hard to do IF you had a good reason for it.
« Last Edit: 03/16/2022 05:16 pm by Robotbeat »
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Online edzieba

  • Virtual Realist
  • Senior Member
  • *****
  • Posts: 6286
  • United Kingdom
  • Liked: 9612
  • Likes Given: 41
Re: Gas Giant ISRU?
« Reply #11 on: 03/16/2022 06:02 pm »
If all you want to do is harvest volatiles, collecting them from the various condensed lumps floating around the solar system is better than screaming down into deep gravity wells. You'd need an extreme demand for gasses in the immediate near-Jupiter (or near-Saturn or near-Neptune, etc) space for it to make sense to try scooping rather than shipping them in from low-delta-V sources elsewhere.

Offline lamontagne

  • Senior Member
  • *****
  • Posts: 4418
  • Otterburn Park, Quebec,Canada
  • Liked: 3862
  • Likes Given: 730
Re: Gas Giant ISRU?
« Reply #12 on: 03/16/2022 06:08 pm »
Is is practically impossible to leave Jupiter's atmosphere with just chemical propulsion.  The deltaV requirements are too high.
Just to get to Low Jupiter orbit requires over 33-12 = 21 km/s of deltaV compared to less than 10 for Earth.
You need SF level nuclear propulsion.

And as many mention it's easier to get propellant from Uranus.
No, it’s not “practically impossible to leave Jupiter’s atmosphere with just chcemicql propulsion” and no, you don’t need “SF level nuclear propulsion.” An expendable Starship (shortened to increase thrust to weight) with a Falcon 1e as payload (and maybe a Falcon 9 first stage to get it going) could get about 1 ton to low Jupiter orbit.

People who make such claims should learn about the rocket equation. Jupiter ISRU is impractical for the fuel ISRU purposes given, but if there was something extremely valuable that you could afford a couple hundred million dollars’ worth of expendable rocket per mission, and all the engineering required to get it there (which would be the expensive part), then it is most certainly possible.

I agree about Uranus, of course, but you CAN just spam the logarithm with a huge mass ratio. And it’s not particularly hard to do IF you had a good reason for it.
Are you certain?  Because I'm just getting 11 km/s at best out of pretty optimistic 60 tonnes Starship and that won't lift you out of Jupiter's atmosphere.  Single stage Starship, no payload.  I don't see two stage Starships in Jupiter's atmosphere!!
column 'v' in the joined spreadsheet.  I'm pretty certain the post author is talking about an Jupiter SSTO.
« Last Edit: 03/16/2022 06:09 pm by lamontagne »

Offline lamontagne

  • Senior Member
  • *****
  • Posts: 4418
  • Otterburn Park, Quebec,Canada
  • Liked: 3862
  • Likes Given: 730
Re: Gas Giant ISRU?
« Reply #13 on: 03/16/2022 06:22 pm »
In other words, the rocket equation V=ve*ln(mo/mf)  can also be expressed as e^(v/ve)=mo/mf

33 00021 000 m/s / 3700 m/s = 8.9 5.67

e^8.95.67 = 7331290

for Earth 10000 m/s / 3700 = 2.7

e^2.7= 14.5 or for 250 tonnes in orbit a 3625 tonnes rocket.  Many mistakes in the details but that's about it.

I don't believe in a 7300290 mass ratio.  Whatever the value of the resource.
(So many mistakes! sorry.  Still the conclusion was correct, I believe.  Orbital velocity is 33 km/s and you can save 12 km/s because Jupiter is rotating really fast, so the actual number to use is 21 km/s)
« Last Edit: 03/16/2022 06:33 pm by lamontagne »

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 39283
  • Minnesota
  • Liked: 25276
  • Likes Given: 12124
Re: Gas Giant ISRU?
« Reply #14 on: 03/16/2022 06:39 pm »
Add more stages like I said. SuperHeavy +expendable starship + F9 first stage+ Falcon 1e first stage + Falcon 1e upper stage.

I get about 21.5km/s (24km/s with a small payload). In reality, you’d be better off replacing the F9 and F1e first stages with some Raptor-based stages. And replace the F1e upper stage with a centaur. That pushes the delta-v above 25km/s (about 29km/s if you have a very small payload). You need more than just the bare minimum 21km/s because of gravity losses and aero losses. But the overall idea holds. Chemical expendable rockets can do this job, if you had a really good reason to do it and needed just a small payload.

The hard part is getting that rocket stack there, along with the propellants.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline lamontagne

  • Senior Member
  • *****
  • Posts: 4418
  • Otterburn Park, Quebec,Canada
  • Liked: 3862
  • Likes Given: 730
Re: Gas Giant ISRU?
« Reply #15 on: 03/16/2022 06:51 pm »
Add more stages like I said. SuperHeavy +expendable starship + F9 first stage+ Falcon 1e first stage + Falcon 1e upper stage.

I get about 21.5km/s (24km/s with a small payload). In reality, you’d be better off replacing the F9 and F1e first stages with some Raptor-based stages. And replace the F1e upper stage with a centaur. That pushes the delta-v above 25km/s (about 29km/s if you have a very small payload). You need more than just the bare minimum 21km/s because of gravity losses and aero losses. But the overall idea holds. Chemical expendable rockets can do this job, if you had a really good reason to do it and needed just a small payload.

The hard part is getting that rocket stack there, along with the propellants.
Are you seriously contemplating superheavy at Jupiter? 
The flight plan was for hydrogen scooping, not he3 refining on the fly.  I agree you might get a tiny payload up but that was not the author's question at all.
You cannot fly down and fly up again with any conceivable chemical rocket.
Plus ISRU.  It's in the title.
« Last Edit: 03/16/2022 06:52 pm by lamontagne »

Offline furniture

  • Member
  • Posts: 7
  • Liked: 3
  • Likes Given: 0
Re: Gas Giant ISRU?
« Reply #16 on: 03/16/2022 07:09 pm »
There's a lot of discussion on the impracticality of this due to the extreme Delta V costs in a large gravity well. While this is true, that's not exactly what I meant. The idea here was to only make one pass through the atmosphere, when the vehicle is approaching at interplanetary velocity. It wouldn't use its engines at all in the atmosphere - it would simply aim for a periapsis that would result in sufficient deceleration to get into orbit, without getting stuck in the atmosphere. A small burn could be performed if necessary, but I'm not talking about getting into orbit and then entering the atmosphere; I'm talking about simply opening a vent when you use the atmosphere to enter orbit. Ideally, the Delta V requirements for this would then be minimal.
Also, I agree that other gas giants might work much better. Jupiter was just the first that came to mind, but Saturn's low gravity, decent proximity to Earth (compared to Uranus and Neptune, which are also decent targets), and interesting moon system may also be a good site for this maneuver.

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 39283
  • Minnesota
  • Liked: 25276
  • Likes Given: 12124
Re: Gas Giant ISRU?
« Reply #17 on: 03/16/2022 07:53 pm »
Think about it this way. If you’re in an elliptical orbit dipping down only at perigee, you’re moving at almost 59-12= 47km/s. Exhaust velocity of chemical rockets tops out at a tenth of that. You have to make that propellant then match the velocity of your vehicle (and the energy is dissipated as heat). So you’re dissipating more inertia by capturing the propellant than that propellant will give you if burned. By an order of magnitude.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline rakaydos

  • Senior Member
  • *****
  • Posts: 2835
  • Liked: 1872
  • Likes Given: 69
Re: Gas Giant ISRU?
« Reply #18 on: 03/17/2022 10:13 am »
Think about it this way. If you’re in an elliptical orbit dipping down only at perigee, you’re moving at almost 59-12= 47km/s. Exhaust velocity of chemical rockets tops out at a tenth of that. You have to make that propellant then match the velocity of your vehicle (and the energy is dissipated as heat). So you’re dissipating more inertia by capturing the propellant than that propellant will give you if burned. By an order of magnitude.

Perhaps this would apply more to denser atmospheres like Uranus, but how much could you reduce those requirements with an airship mounted SpinLaunch? Refine the HE on site, load the refined product on spinlaunch orbiters dropped to the station, and throw them outside the worst of the atmosphere before they need to circularize?

Offline lamontagne

  • Senior Member
  • *****
  • Posts: 4418
  • Otterburn Park, Quebec,Canada
  • Liked: 3862
  • Likes Given: 730
Re: Gas Giant ISRU?
« Reply #19 on: 03/17/2022 12:39 pm »
There's a lot of discussion on the impracticality of this due to the extreme Delta V costs in a large gravity well. While this is true, that's not exactly what I meant. The idea here was to only make one pass through the atmosphere, when the vehicle is approaching at interplanetary velocity. It wouldn't use its engines at all in the atmosphere - it would simply aim for a periapsis that would result in sufficient deceleration to get into orbit, without getting stuck in the atmosphere. A small burn could be performed if necessary, but I'm not talking about getting into orbit and then entering the atmosphere; I'm talking about simply opening a vent when you use the atmosphere to enter orbit. Ideally, the Delta V requirements for this would then be minimal.
Also, I agree that other gas giants might work much better. Jupiter was just the first that came to mind, but Saturn's low gravity, decent proximity to Earth (compared to Uranus and Neptune, which are also decent targets), and interesting moon system may also be a good site for this maneuver.
The problem with a single pass is that you will be collection reaction mass, but practically no fuel.  If you are only looking for reaction mass, the bottom of a gravity well is pretty much the worst place for it.  If you are looking for fuel, he3 or deuterium, presumably, you need to refine very large amounts of atmosphere to extract it.  That is why most extractions schemes include a long residence in the planet's atmosphere.  You probably want three crafts:  a carrier, a refinery and a transportation shuttle.

Here is an example of what might be done at Uranus:
https://sites.google.com/view/worldships/home-base/fuel-acquisition

Extracting reaction mass (oxygen) from one of Uranus' moon as ISRU might be a simple way to increase output of the system from a single load to a production system.

 

Advertisement NovaTech
Advertisement Northrop Grumman
Advertisement
Advertisement Margaritaville Beach Resort South Padre Island
Advertisement Brady Kenniston
Advertisement NextSpaceflight
Advertisement Nathan Barker Photography
1