Author Topic: Refueling Ion Drive from Atmospheric Scooping  (Read 23428 times)

Offline sanman

  • Senior Member
  • *****
  • Posts: 5975
  • Liked: 1312
  • Likes Given: 8
Refueling Ion Drive from Atmospheric Scooping
« on: 12/27/2017 06:56 pm »
Is it possible to have an orbital satellite replenish the propellant for its ion engine by scooping it from the atmosphere?
What are the key considerations for this?
What orbital range are you restricted to?
Are there any proposed experiments on the horizon, to prove such an idea?

Could this technique be useful around any other bodies, besides the Earth? If so, what missions could it benefit?

I've read about ion-propelled satellites having been put up that fly so low that they need to have some aerodynamic features to reduce atmospheric resistance, but they didn't scoop anything up. I've also read about ideas for hypothetical nuclear-powered scramjets driven by MHD that would suck in thin ionized air and expel it out the back propulsively, but they didn't use feeble ion drives.
« Last Edit: 12/27/2017 07:12 pm by sanman »

Offline IanThePineapple

Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #1 on: 12/27/2017 07:05 pm »
There wouldn't be much air to "scoop" in LEO, to get a good amount you'd probably want to be in the lower atmo.

Xenon is pretty rare in the atmo, so since there's very little air in LEO, there's almost no Xenon up there.

Offline JasonAW3

  • Senior Member
  • *****
  • Posts: 2443
  • Claremore, Ok.
  • Liked: 410
  • Likes Given: 14
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #2 on: 12/27/2017 07:17 pm »
There wouldn't be much air to "scoop" in LEO, to get a good amount you'd probably want to be in the lower atmo.

Xenon is pretty rare in the atmo, so since there's very little air in LEO, there's almost no Xenon up there.

Does the gas have to be Xenon?

      As I understand it, most if not all ion drive craft can run on a wide variety of gases.  You just have to select the one best suited to your needs, and is the least reactive with your drive system.  (It would suck to corrode your ion drive using the wrong gas).
My God!  It's full of universes!

Offline nacnud

  • Extreme Veteran
  • Senior Member
  • *****
  • Posts: 2691
  • Liked: 981
  • Likes Given: 347
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #3 on: 12/27/2017 07:21 pm »
I think that you could refuel a satellite in this way.

You'd need to collect more energy via solar than the energy lost via drag. You could do this with solar panels, a battery and a highly elliptical orbit.

Then you would need to use the mass collected to increase the velocity of the satellite in some way, probably an ion drive.

So you'd also need to know the composition of the upper atmosphere to have an understanding of the collected mass.

So to answer your question you'd need to research these topics.
« Last Edit: 12/27/2017 07:24 pm by nacnud »

Offline mheney

  • The Next Man on the Moon
  • Global Moderator
  • Full Member
  • *****
  • Posts: 780
  • Silver Spring, MD
  • Liked: 398
  • Likes Given: 199
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #4 on: 12/27/2017 07:30 pm »
Here's one major problem.  If you dip your perigee into the atmosphere, the drag is going to decrease your apogee.  And your next perigee is going to be back in the atmosphere again.

The only way to raise your perigee out of the atmosphere is with a burn at apogee.  But if you're using an ion drive, whch uses low
thrust over an extended time, you're not going to be able to manage a significant perigee boost before you're heading back down again.  Your orbit is going to quickly degrade, until you end up re-entering and burning up.

So, basically, the answer is "No."

Offline nacnud

  • Extreme Veteran
  • Senior Member
  • *****
  • Posts: 2691
  • Liked: 981
  • Likes Given: 347
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #5 on: 12/27/2017 07:38 pm »
I'm sure it's more subtle than that. If you had a VASIMR type drive that went from high efficiency near perigee, boosting time at apogee, to high thrust at apogee, booting height of perigee an equilibrium could be found.

It could also be possible to scoop mass from the atmosphere in the process.

This conversation needs calculus.
« Last Edit: 12/27/2017 07:53 pm by nacnud »

Offline ncb1397

  • Senior Member
  • *****
  • Posts: 3497
  • Liked: 2310
  • Likes Given: 29
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #6 on: 12/27/2017 07:49 pm »
Anything with protons can be ionized(i.e. everything made out of atoms) and then controlled with magnetic fields. Different gases work better as fuel than others because of density and difficulty in stripping electrons.

We will see how the recently launched SLATS experimental satellite goes. That would be a significant step in showing you can maintain orbit in lower parts of the atmosphere for enough time to start mining the upper atmosphere. Next step would be to mount hardware on the front of a similar satellite that would liquefy and divert gas to different storage tanks. Perhaps the heat exchanger technology being developed for SABRE would be useful for that. The exhaust velocity of even low isp ion engines is far above earth orbital velocity, so you should be able to gain more gas than is required to be used to maintain velocity. Even for Jupiter with an orbital speed of ~42 km/s, that would correspond to a ion engine isp of ~4000 to maintain velocity. Anything above that and you should be able to gain gas faster than you consume it.

Offline LMT

  • Lake Matthew Team
  • Senior Member
  • *****
  • Posts: 2351
    • Lake Matthew
  • Liked: 424
  • Likes Given: 0
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #7 on: 12/27/2017 09:21 pm »
Here's one major problem.  If you dip your perigee into the atmosphere, the drag is going to decrease your apogee.  And your next perigee is going to be back in the atmosphere again.

The only way to raise your perigee out of the atmosphere is with a burn at apogee.  But if you're using an ion drive, whch uses low
thrust over an extended time, you're not going to be able to manage a significant perigee boost before you're heading back down again.  Your orbit is going to quickly degrade, until you end up re-entering and burning up.

So, basically, the answer is "No."

Right, the aerobrake delta-v loss must be countered with a delta-v gain before next planetary approach, to raise periapsis.  Since you're running an ion engine, continuous thrust would be applied.  You might try scripting that sort of mission plan in GMAT, to see whether the required ISP is feasible.

One other possibility:  If you controlled the aerobrake very precisely, you could conceivably plan your trajectory to perform a lunar close-approach, raising periapsis via gravity-assist.  Earth's Moon would give a deflection and gravity-assist for up to ~1.7 km/s delta-v.  That also would be something to see in GMAT.
« Last Edit: 12/27/2017 11:15 pm by LMT »

Offline sanman

  • Senior Member
  • *****
  • Posts: 5975
  • Liked: 1312
  • Likes Given: 8
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #8 on: 12/27/2017 09:34 pm »
So it sounds like a limiting case can be calculated based on planetary mass / escape velocity, solar flux, etc.

The lighter the planet (or moon) that you're orbiting, the heavier its ions are going to have to be. The closer you are to the Sun, the better the solar flux you'll get per unit spacecraft mass - unless somehow the solar array is separate and physically detached from the ion-driven spacecraft, sending power by microwave beam, for example.

Venus is slighter lighter and has much better solar flux - if this approach could work for Earth, then it would likely work for Venus. But Venus doesn't have the magnetic field and associated ionosphere - so does that affect the composition and availability of ionic species?

What about doing this around Titan, Jupiter, Saturn, Uranus, Neptune?
« Last Edit: 12/27/2017 10:10 pm by sanman »

Offline stefan r

  • Full Member
  • *
  • Posts: 122
  • pennsylvania
  • Liked: 23
  • Likes Given: 51
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #9 on: 12/28/2017 12:17 am »
Atomic oxygen tends to destroy things.  Ion drives move charged ions in a controlled way.  When a pair of single ionized atoms become one double ionized atom and one neutral atom the neutral atom can ignore both your magnetic fields and electric fields.  The ion drive has to be firing ions much faster than orbital velocity or you lose momentum scooping.  Hot (high velocity) atomic oxygen should etch away the wall fairly quickly. 


You might be able to scoop atmospheres if you combined with a tether. 

Offline Patchouli

  • Senior Member
  • *****
  • Posts: 4490
  • Liked: 253
  • Likes Given: 457
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #10 on: 12/28/2017 04:29 am »
A grid type ion engine needs a relatively non reactive propellant that is easily ionized which is why xenon is the propellant of choice.

Now a VASIMR engine might be able to be made to work with a crude mix of gases that contain undesirable stuff like oxygen,water, and CO2 since there are no grids and the plasma is magnetically contained.
The same goes for an arcjet rocket but in both cases engine would have to be designed to deal with this from the start.
Though the concept had been thought of before with PROFAC.
http://www.bisbos.com/space_n_profac.html
The oxygen was kept for use for refueling conventional rockets and the nitrogen was used in the electric engines to keep it in orbit.
« Last Edit: 12/28/2017 04:40 am by Patchouli »

Offline dkirtley

  • Member
  • Posts: 18
  • Redmond, WA
  • Liked: 51
  • Likes Given: 0
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #11 on: 12/28/2017 10:11 pm »
We've looked at these air-breathing electric propulsion systems extensively. The ASPW (advanced space propulsion workshop) has featured several of these concepts, ours was a number of years ago.

My view was this was tough, but maybe not impossible. As others have noted, the orbital mechanics is pretty easy as long as you 'burn' as you collect, so that you are at least counteracting your drag. Hall Effect, FRC, and Helicon thrusters have all shown to work on some combination of N2 and O2 (and maybe stored Xenon for the cathode). The basic idea as we understand it is you need an Isp that is atleast the orbital velocity divided by all of your propulsive/collection efficiencies to make up for drag and more if you want to store. At 100% efficiency and assuming your vehicle was a flow-through 'scoop' and stored nothing, you'd only need 800-ish seconds.

But, with a 50% collection and pressurization efficiency, a 75% thruster mass utilization efficiency, and storing 25% of the gas each orbit you need an ISP of 2700 seconds. This assumes the entire front end of this thing is all scoop.

I think the biggest concern is heat rejection and power. If your spacecraft is much bigger than the scoop/inlet (ie solar panels) the amount of thrust needed to counteract all of the drag gets a lot harder. And while the thruster puts most of its energy into the propellant, either heat or kinetic, the scoop doesn't have a natural way to loose energy.

Cool stuff, I bet NIAC would want to take a look at this.

-David

Offline brickmack

  • Full Member
  • ****
  • Posts: 975
  • USA
  • Liked: 3273
  • Likes Given: 101
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #12 on: 12/29/2017 12:33 am »
I vaguely remember some DARPA project meant to study exactly this, but can't remember the name and google turns up nothing. Anyone know of it?

Offline LMT

  • Lake Matthew Team
  • Senior Member
  • *****
  • Posts: 2351
    • Lake Matthew
  • Liked: 424
  • Likes Given: 0
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #13 on: 12/29/2017 02:04 am »
...you 'burn' as you collect, so that you are at least counteracting your drag. Hall Effect, FRC, and Helicon thrusters have all shown to work on some combination of N2 and O2...  you need an Isp that is at least the orbital velocity divided by all of your propulsive/collection efficiencies to make up for drag and more if you want to store...

Hmm.  Typically those thruster designs give a few Newtons of thrust, at most.  I don't understand how they could be used to counteract drag as you collect, unless the collection altitude were extremely high, and collection mass extremely small; setting an impractically low limit on collection.  Can you clarify with some more quantitatives?
« Last Edit: 12/29/2017 02:10 am by LMT »

Offline DarkenedOne

  • Full Member
  • ****
  • Posts: 955
  • Liked: 58
  • Likes Given: 9
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #14 on: 12/29/2017 05:52 pm »
We've looked at these air-breathing electric propulsion systems extensively. The ASPW (advanced space propulsion workshop) has featured several of these concepts, ours was a number of years ago.

My view was this was tough, but maybe not impossible. As others have noted, the orbital mechanics is pretty easy as long as you 'burn' as you collect, so that you are at least counteracting your drag. Hall Effect, FRC, and Helicon thrusters have all shown to work on some combination of N2 and O2 (and maybe stored Xenon for the cathode). The basic idea as we understand it is you need an Isp that is atleast the orbital velocity divided by all of your propulsive/collection efficiencies to make up for drag and more if you want to store. At 100% efficiency and assuming your vehicle was a flow-through 'scoop' and stored nothing, you'd only need 800-ish seconds.

But, with a 50% collection and pressurization efficiency, a 75% thruster mass utilization efficiency, and storing 25% of the gas each orbit you need an ISP of 2700 seconds. This assumes the entire front end of this thing is all scoop.

I think the biggest concern is heat rejection and power. If your spacecraft is much bigger than the scoop/inlet (ie solar panels) the amount of thrust needed to counteract all of the drag gets a lot harder. And while the thruster puts most of its energy into the propellant, either heat or kinetic, the scoop doesn't have a natural way to loose energy.

Cool stuff, I bet NIAC would want to take a look at this.

-David

You guys should look at the GOCE spacecraft.  It was able to maintain an altitude of 229 km.  It had ion thrusters that had an ISP of 4000s and a thrust of 20 mN.  The satellite was aerodynamically shaped to minimize drag. 
https://en.wikipedia.org/wiki/Gravity_Field_and_Steady-State_Ocean_Circulation_Explorer

So clearly you can do it, but there are still a number of challenges including building an ion thruster with the necessary performance, being able to collect the gas at such low pressure and refining the gas into something usable. 


Offline Dao Angkan

  • Full Member
  • **
  • Posts: 233
  • Liked: 77
  • Likes Given: 44

Offline Asteroza

  • Senior Member
  • *****
  • Posts: 2836
  • Liked: 1084
  • Likes Given: 33
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #16 on: 01/04/2018 11:07 pm »
helicon/VASIMR is the most prominent electric (in the conventional sense) drive, though the original PROFAC scooper concept used a nuclear reactor driven resistojet thruster. Choice of orbit matters in other interesting ways, such as a solar powered scooper in a terminator riding SSO orbit would be continuously lit by the sun (providing power all the time, but also heat all the time). An interesting alternative is beaming laser power from the earth from 4 or so laser stations.

Offline adrianwyard

  • Full Member
  • ****
  • Posts: 1140
  • Liked: 322
  • Likes Given: 367
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #17 on: 03/05/2018 05:12 pm »
World First Firing of Air Breathing Thruster

http://www.esa.int/Our_Activities/Space_Engineering_Technology/World-first_firing_of_air-breathing_electric_thruster

Quote
5 March 2018
In a world-first, an ESA-led team has built and fired an electric thruster to ingest scarce air molecules from the top of the atmosphere for propellant, opening the way to satellites flying in very low orbits for years on end.

ESA’s GOCE gravity-mapper flew as low as 250 km for more than five years thanks to an electric thruster that continuously compensated for air drag. However, its working life was limited by the 40 kg of xenon it carried as propellant – once that was exhausted, the mission was over. 

Replacing onboard propellant with atmospheric molecules would create a new class of satellites able to operate in very low orbits for long periods.

...

Offline adrianwyard

  • Full Member
  • ****
  • Posts: 1140
  • Liked: 322
  • Likes Given: 367
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #18 on: 03/05/2018 05:19 pm »
Depending on its efficiency it seems this could enable a number of things. What are the possibilities?

A couple of obvious ones are:
+ Lowest possible latency satellite links.
+ Cheaper or better earth observation.

But what else?

Propellent-less plane changes? (Maybe slowly.)
Military?

Offline Comga

  • Senior Member
  • *****
  • Posts: 6466
  • Liked: 4572
  • Likes Given: 5136
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #19 on: 03/05/2018 05:42 pm »
http://www.esa.int/Our_Activities/Space_Engineering_Technology/World-first_firing_of_air-breathing_electric_thruster

Given the Japanese article it’s not clear if this is “first” for the Europeans or claiming a “wirld’s First” but they are both working on this.

Not clear how it could be used for other than steady state orbit maintenance in the lower exosphere.
Escape trajectories seem particularly problematic.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline adrianwyard

  • Full Member
  • ****
  • Posts: 1140
  • Liked: 322
  • Likes Given: 367
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #20 on: 03/05/2018 06:40 pm »
I agree escape velocity is a bit much to hope for, but how about propellant-less plane changes? If possible that would be a big deal.

I'm not sure if it would be better to just thrust off-axis, or descend into very slightly thicker air to make the change with the help of aerodynamics and then (slowly) thrust your way up again once in the new plane.

Offline sanman

  • Senior Member
  • *****
  • Posts: 5975
  • Liked: 1312
  • Likes Given: 8
« Last Edit: 03/08/2018 02:56 pm by sanman »

Offline chipguy

  • Member
  • Posts: 92
  • Ottawa Canada
  • Liked: 97
  • Likes Given: 30
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #22 on: 03/06/2018 05:02 pm »
ESA's new electric thruster harvests atmospheric ions:

http://m.esa.int/Our_Activities/Space_Engineering_Technology/World-first_firing_of_air-breathing_electric_thruster



I wonder what fraction of satellite cross sectional area to the direction of motion has to be intake
for thrust to match or exceed drag.

I guess it depends on the ratio of the velocity at which air molecules/atoms impinge on the windward
face of the satellite to the velocity they exit the thruster. The former is basically orbital velocity.

If the thruster ISP is 2000 s then that is an exit velocity of ~19600 m/s vs ~8000 m/s orbital velocity
which suggests 8000/19600 or at least 41% of the front of the satellite has to be intake to cancel
drag.

Anyone see any flaws in this logic?

Offline speedevil

  • Senior Member
  • *****
  • Posts: 4406
  • Fife
  • Liked: 2762
  • Likes Given: 3369
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #23 on: 03/06/2018 05:05 pm »
If the thruster ISP is 2000 s then that is an exit velocity of ~19600 m/s vs ~8000 m/s orbital velocity
which suggests 8000/19600 or at least 41% of the front of the satellite has to be intake to cancel
drag.

Anyone see any flaws in this logic?

Something like that seems plausible. It's going to constrain your solar panel pointing a lot.
In principle, you may be able to effectively steer the ions, which helps if you don't solely want to use it for drag cancellation.

Offline Asteroza

  • Senior Member
  • *****
  • Posts: 2836
  • Liked: 1084
  • Likes Given: 33
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #24 on: 03/07/2018 10:15 pm »
ESA's new electric thruster harvests atmospheric ions:

http://m.esa.int/Our_Activities/Space_Engineering_Technology/World-first_firing_of_air-breathing_electric_thruster



Interesting that this takes on a beehive inlet, rather than some designs which use a hypersonic cone.

Offline jee_c2

  • Full Member
  • *
  • Posts: 127
  • Budapest, Hungary
  • Liked: 19
  • Likes Given: 45
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #25 on: 03/08/2018 05:55 am »

...It's going to constrain your solar panel pointing a lot.
In principle, you may be able to effectively steer the ions, which helps if you don't solely want to use it for drag cancellation.
I was wondering, that solar panels could be used in this case for steering (changing direction - plane change)  like sails in the wind of the very thin upper layer atmosphere.

Also, in some cases solar panels (and their drag) should be minimized, when the sat is "submerged" (densest environment). Could some battery (or supercapacitor) help in these time frames? Only the question of capacity, and the power consumption of the engine (and onboard systems).

BTW, minimum drag can be achieved by turning the solar panel with it's edged in the direction of the movement. This can also be optimal, if your plane of orbit is orthogonal to the direction of the Sun. (which are polar orbits, mostly)

Offline sanman

  • Senior Member
  • *****
  • Posts: 5975
  • Liked: 1312
  • Likes Given: 8
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #26 on: 03/08/2018 09:25 am »
Interesting that this takes on a beehive inlet, rather than some designs which use a hypersonic cone.

Maybe that's to maximize the charge coupling with the incoming atmospheric stream?

Anyway, it seems like these kinds of satellites would be suitable for the lowest orbits, and thus able to offer the sharpest imagery and the lowest communication latency with the ground.

Offline speedevil

  • Senior Member
  • *****
  • Posts: 4406
  • Fife
  • Liked: 2762
  • Likes Given: 3369
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #27 on: 03/08/2018 10:01 am »
Anyway, it seems like these kinds of satellites would be suitable for the lowest orbits, and thus able to offer the sharpest imagery and the lowest communication latency with the ground.
Macroscopic orbital debris is also going to be very small.

Offline sanman

  • Senior Member
  • *****
  • Posts: 5975
  • Liked: 1312
  • Likes Given: 8
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #28 on: 03/08/2018 02:52 pm »
So will these lowest-altitude orbital slots become the most coveted orbital space above Earth?

Will we see some kind of technological race to enable lower and lower orbits, with satellites becoming more and more streamlined to reduce atmospheric friction, and equipped with better and better performing electric thrusters to maintain those orbits against deterioration?

If so, then it sounds like an interesting niche to specialize in, regarding satellite construction.

Such a trend would also help to mitigate the space junk problem, since there's relatively less danger of such lower orbiting satellites producing junk that stays up for a long time.

From cubesats to "tubesats"?
« Last Edit: 03/08/2018 02:55 pm by sanman »

Offline speedevil

  • Senior Member
  • *****
  • Posts: 4406
  • Fife
  • Liked: 2762
  • Likes Given: 3369
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #29 on: 03/08/2018 03:30 pm »
So will these lowest-altitude orbital slots become the most coveted orbital space above Earth?

At some fairly rapid point, the gains you get from being closer are outweighed by the operational cost.
A satellite at (say) 150K may be quite plausible technically, but is going to be ten times the drag as at 200km.
Ten times again at 120.

You also need way more satellites per constellation as the footprint goes down.

Offline alexterrell

  • Full Member
  • ****
  • Posts: 1747
  • Germany
  • Liked: 184
  • Likes Given: 107
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #30 on: 03/08/2018 03:45 pm »
Hi, I started a similar discussion back in 2009:
https://forum.nasaspaceflight.com/index.php?topic=17984.msg443506#msg443506

My concept was to have a scoop at low altitude, connected by a tether to a mother ship at about 350km altitude, where solar panels can work without excessive drag.

I think what has changed since then is the promise of BFR reducing the costs of shipping fuel to orbit - so raising the question, why bother?

This concept could have more value in the far future where large orbiting space craft need millions of tons of nitrogen for their atmosphere. But for now, there is a feeling that more launches is easier than more complexity.

Offline sanman

  • Senior Member
  • *****
  • Posts: 5975
  • Liked: 1312
  • Likes Given: 8
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #31 on: 03/08/2018 03:50 pm »
Gee, I'm imagining a flattened lenticular shape would be best for solar collection, as well as RF reception from below. It would also present a reduced cross-section for oncoming atmosphere.

As long as your solar power is being used to boost the Isp, then don't you benefit from maximizing solar collection? On the other hand, you need to be able to coast through the nighttime phases without losing too much speed.

Offline speedevil

  • Senior Member
  • *****
  • Posts: 4406
  • Fife
  • Liked: 2762
  • Likes Given: 3369
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #32 on: 03/08/2018 04:32 pm »
Gee, I'm imagining a flattened lenticular shape would be best for solar collection, as well as RF reception from below. It would also present a reduced cross-section for oncoming atmosphere.

As long as your solar power is being used to boost the Isp, then don't you benefit from maximizing solar collection? On the other hand, you need to be able to coast through the nighttime phases without losing too much speed.
Drag in this case is essentially not as it is with normal aerodynamics, but is purely the frontal area of the satellite - due to the atmospheric molecules moving so fast compared to the speed of sound.

So, extending the solar panels back along the orbit (or indeed forward) is free, drag-wise.
You want them to be edge-on to the oncoming flow.
You can of course spin them (or the craft) around the velocity vector in order to point them at the sun, and end up with around half of the average solar input you might otherwise get with fully pointed at the sun panels.


Offline dror

  • Full Member
  • ****
  • Posts: 730
  • Israel
  • Liked: 245
  • Likes Given: 593
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #33 on: 03/08/2018 07:14 pm »
Depending on its efficiency it seems this could enable a number of things. What are the possibilities?

A couple of obvious ones are:
+ Lowest possible latency satellite links.
+ Cheaper or better earth observation.

But what else?

Propellent-less plane changes? (Maybe slowly.)
Military?
+ Self filling oxygen depot (to reduce the number of refueling flights or fill up station tanks)
+ with a little stretch, a full on surface-to-orbit airplane
Space is hard immensely complex and high risk !

Offline speedevil

  • Senior Member
  • *****
  • Posts: 4406
  • Fife
  • Liked: 2762
  • Likes Given: 3369
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #34 on: 03/08/2018 07:46 pm »
+ Self filling oxygen depot (to reduce the number of refueling flights or fill up station tanks)
+ with a little stretch, a full on surface-to-orbit airplane

The second really isn't plausible at all.
This technology is several orders of magnitude too low thrust, and doesn't really scale meaningfully.
Once you get to perhaps to 70km or so the plasma physics changes, and you can't simply accellerate the gas in the same way.

Flying 'slowly' to orbit, you require hypersonic lift, which only comes with really high amounts of drag.
This means your heatshielding problems get orders of magnitude worse, as well as your power requirements being utterly ridiculous.

Offline Asteroza

  • Senior Member
  • *****
  • Posts: 2836
  • Liked: 1084
  • Likes Given: 33
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #35 on: 03/08/2018 10:16 pm »
+ Self filling oxygen depot (to reduce the number of refueling flights or fill up station tanks)
+ with a little stretch, a full on surface-to-orbit airplane

The second really isn't plausible at all.
This technology is several orders of magnitude too low thrust, and doesn't really scale meaningfully.
Once you get to perhaps to 70km or so the plasma physics changes, and you can't simply accellerate the gas in the same way.

Flying 'slowly' to orbit, you require hypersonic lift, which only comes with really high amounts of drag.
This means your heatshielding problems get orders of magnitude worse, as well as your power requirements being utterly ridiculous.

JP Aerospace and their Ascender design begs to differ, but they are the epitome of slow boat methods. Then again, they haven't gone bankrupt either...

Offline rakaydos

  • Senior Member
  • *****
  • Posts: 2825
  • Liked: 1869
  • Likes Given: 69
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #36 on: 03/09/2018 07:48 pm »
+ Self filling oxygen depot (to reduce the number of refueling flights or fill up station tanks)
+ with a little stretch, a full on surface-to-orbit airplane

The second really isn't plausible at all.
This technology is several orders of magnitude too low thrust, and doesn't really scale meaningfully.
Once you get to perhaps to 70km or so the plasma physics changes, and you can't simply accellerate the gas in the same way.

Flying 'slowly' to orbit, you require hypersonic lift, which only comes with really high amounts of drag.
This means your heatshielding problems get orders of magnitude worse, as well as your power requirements being utterly ridiculous.

JP Aerospace and their Ascender design begs to differ, but they are the epitome of slow boat methods. Then again, they haven't gone bankrupt either...

IIRC, JP is relying on some expirimental, in the lab methods of actively reducing drag, to work at least 60% of the in the lab theoretical values. Also they reduce the need for hypersonic lift via atmospheric displacement...

Offline indaco1

  • Full Member
  • **
  • Posts: 283
  • Liked: 64
  • Likes Given: 37
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #37 on: 03/24/2018 10:12 am »
I think Oberth effect makes things even more difficult for elliptic orbit scooping.
Non-native English speaker and non-expert, be patient.

Offline eugenio.ferrato

  • Member
  • Posts: 1
  • Italy
  • Liked: 1
  • Likes Given: 0
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #38 on: 04/11/2018 07:50 am »
To whom it may concern,

 I link you to two interesting article recently published on the topic:

Development and Experimental Validation of a Hall Effect Thruster RAM-EP Concept (IEPC-2017-377)==>
https://iepc2017.org/sites/default/files/speaker-papers/iepc-2017-377_ram_final.pdf

and

Conceptual Design of an Air-Breathing Electric Thruster (IEPC-2015-271) ==>
http://erps.spacegrant.org/uploads/images/2015Presentations/IEPC-2015-271_ISTS-2015-b-271.pdf

Moreover, an other article on this topic (ID:0431) will soon be released for the Space Propulsion 2018 Conference (to be held on May 14th-18th 2018 in Seville, Spain).

All the best,

Eugenio

Offline LMT

  • Lake Matthew Team
  • Senior Member
  • *****
  • Posts: 2351
    • Lake Matthew
  • Liked: 424
  • Likes Given: 0
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #39 on: 05/05/2018 02:50 pm »
SpaceX Trawler

Hi, I started a similar discussion back in 2009:
https://forum.nasaspaceflight.com/index.php?topic=17984.msg443506#msg443506

My concept was to have a scoop at low altitude, connected by a tether to a mother ship at about 350km altitude, where solar panels can work without excessive drag.

I think what has changed since then is the promise of BFR reducing the costs of shipping fuel to orbit - so raising the question, why bother?

Or conceivably you could combine the two concepts, using ITS as the "scoop", and using a marshalling yard as the "mother ship".  That might make economic sense.

--

At 250 km a notional km3 marshalling yard with ISEP booms of Voronka et al. 2006 could generate thrust roughly an order of magnitude greater than the deceleration of atmospheric drag.  Thrust exceeds requirement.  How might excess thrust be used to good effect?

One possibility:  a SpaceX trawler

Trawling lowers a collector system from orbit, to scoop O2 from the thermosphere and deliver it to the orbiting platform as LOX. 

Benefit: 78% tanker reduction

Where trawlers deliver all LOX for LEO burns, tankers deliver only LCH4.  This results in a 78% cut in tanker payload mass, corresponding with a 78% cut in the number of required tanker launches.

It’s an old idea, but of course trawler drag is a vexing problem.   For this reason the great and propellant-free propulsion of an ISEP marshalling yard would offer an opportunity to bypass the old problem, and realize the benefits of atmospheric trawling. 

Parameters

What are the environmental parameters of the new problem?  First-pass:

To minimize the temperature inside the trawler inlet, one might scoop where the atmospheric temperature is lowest:  at 90 km, ~150-200 K.  Even so, the scoop’s compression shock would be hot:  600-900 C.

Some compression energy dissociates O2 and N2, producing atomic oxygen and nitrogen.  Atomic oxygen reacts with polymers, so heat shielding or other inert coatings must be applied to all polymer surfaces.  Fortunately the temperature is not high enough to ionize much, so at 90 km the trawler can maintain radio contact with the marshalling yard.

At 90 km the spacecraft’s split flaps should have good control authority, to maintain nose-forward orientation without expending propellant.

Pressure is ~0.2 Pa, density 3.4E-6 kg/m3, O2 mass fraction 23%.  Therefore an inlet of 100 m2, having capture efficiency of 90%, can fill the 860-ton LOX tank in 3 weeks.

How might the trawler be structured?

Conceivably a SpaceX ITS cargo ship could be fitted out at the marshalling yard with a trawler “kit”:  a tethered fabric inlet and cooler/compressor system.  The inlet would feed gas into the cooler, inside the cargo bay.  The cooler would feed a centrifugal compressor that separates LOX from gaseous N2, and then feeds LOX into the zero-boil-off (ZBO) unit’s LOX line, to fill the tank.

A trawler kit might look something like this:



In this modified SpaceX image the open cargo bay sports a trawler kit, in blue.  The inlet is defined by the layer of fabric connecting the two halves of the hinged fairing.  Inside, an inflated dual cone plug compressor maximizes the pressure and mass at the end of the inlet. 

The cone tip provides an attachment point for the tether, perhaps an interconnected hoytether, which extends 160+ km to the marshalling yard.  The marshalling yard lowers and lifts the trawler by the tether, using a pass-through gripper-wheel mechanism such as that proposed for the ISS in Vas et al. 2000.

Tether and inlet might be fabricated from 3M Nextel ceramic textiles, which have been used on space shuttles. 



These flexible ceramic products resist atomic oxygen and have both low thermal absorptivity and high emissivity.  They also benefit from “heat treating” at 900 C, which “improves the chemical resistance, anneals the stress from the fiber, and increases the modulus or stiffness of the fiber”, according to the product technical reference guide
 
To cool and liquefy O2, one might adapt Reaction Engines’ SABRE technology, as presented in Davies et al. 2015. 




 
The SABRE pre-cooler has been designed to cool Mach 5 air at 25 km, lowering it from 1000 C to 123 K. 


 
The SABRE turbo-compressor, or centrifugal compressor, has been designed to compress the cooled air to 14,000 kPa.  Heat from the pre-cooler drives the compressor, for high efficiency.

The trawler scenario presents different operating conditions of course.  Inlet air is cooler, inlet pressure is lower, and the final compressor output temperature and pressure are lowered to produce LOX (temperature around 80 K with pressure slightly above 150 Pa).   LOX flows over the diffuser surface into the manifold collector, where it’s pumped into the ZBO LOX line for storage in the LOX tank.

The compressor’s temperature and pressure hold N2 in gas phase.  N2 could pressurize the dual cone plug.  Notably, drag at this low altitude (10-20,000 N) is too great to be countered with ion engines, so the remaining nitrogen would not be used for propulsion.  It could be circulated as a supplemental coolant, before venting. 

As it happens, I had opportunity recently to meet with a Reaction Engines engineer and discuss adaptation of SABRE hardware to LOX trawling.  His initial impression was that the requirements were not a great challenge; they could be met with relatively minor modification of existing SABRE hardware.  So perhaps SABRE provides a first, known reference point for consideration of alternate coolers and compressors.  One option to explore:  adapt the compressor of the ZBO system to take over the role of the SABRE turbo-compressor, to perform both ZBO compression and trawler turbo-compression with the same hardware.  (N2 removal would be a new task for a ZBO compressor.)  Or vice versa.

Power

Electric pumps could run off ITS deployable solar panels, and ITS batteries at night.  However solar panels would need to be augmented with something akin to a hinge joint at the base, to rotate each panel unit parallel to the flight path and minimize drag.  Otherwise total drag on the vehicle could become excessive.  Alternately solar panels might be deployed from the cargo bay, behind the inlet.

Trawler Fleet

This basic configuration might allow two SpaceX trawlers to operate concurrently, with drag not exceeding the marshalling yard’s drag-compensation thrust.  However, conceivably an additional, much larger solar panel could be unfurled from each trawler, trailing behind, to provide greater electric potential and current.  Current electrons (PV + ionosphere electrons) would be directed up the tether through conductive strands, to give additional electrodynamic thrust; reducing orbit-averaged trawler deceleration, or, ideally, zeroing it out.  Notionally ISEP “needles” could be added to the trailing panel (which is likely much longer than the spacecraft itself) to apply torque and lift, so as to maintain the panel’s low-drag, edge-on orientation.  Likewise, the terminal 20 km of tether could be designed not as a hoytether but as a thin tape, with ISEP needles added for electrodynamic torque.  ISEP would hold that tether segment edge-on, minimizing tether drag where it would otherwise be very great.
 
If drag-canceling methods were successfully implemented, the marshalling yard could deploy trawlers without concern for drag.  It could deploy as many trawlers as might be supported concurrently by tether mechanisms, as a “trawler fleet”.



Refs

Davies, P., Hempsell, M., & Varvill, R. (2015). Progress on Skylon and SABRE. IAC-15-D218.

Vas, I. E., Kelly, T. J., & Scarl, E. A. (2000). Space station reboost with electrodynamic tethers. Journal of spacecraft and rockets, 37(2), 154-164.

Voronka, N. R., Hoyt, R. P., Slostad, J., Gilchrist, B. E., & Fuhrhop, K. (2006). Modular spacecraft with integrated structural electrodynamic propulsion. NASA Institute for Advanced Concepts.
« Last Edit: 02/15/2020 07:54 pm by LMT »

Offline LMT

  • Lake Matthew Team
  • Senior Member
  • *****
  • Posts: 2351
    • Lake Matthew
  • Liked: 424
  • Likes Given: 0
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #40 on: 05/06/2018 05:00 am »
Debris Scooping





Spatial density of cataloged objects and cross-sectional area flux of cataloged objects are both relatively low, in the notional altitude range of trawler and marshalling yard operations (90-250 km).

Notably, the cataloged-object cross-sectional area flux at the marshalling yard altitude of 250 km (green) is roughly 10% of the flux at the ISS altitude of 400 km (red).  This flux gives the km3 marshalling yard an annual impact probability on the order of 0.01 (a risk mitigated with ISEP debris avoidance maneuvering).

At trawler altitude (90 km), the object flux and impact probability are practically nil.

Refs:

Englert, C. R., Bays, J. T., Marr, K. D., Brown, C. M., Nicholas, A. C., & Finne, T. T. (2014). Optical orbital debris spotter. Acta Astronautica, 104(1), 99-105.

Kessler, D. J. (1989). Orbital debris environment and data requirements.
« Last Edit: 05/06/2018 05:09 am by LMT »

Offline LMT

  • Lake Matthew Team
  • Senior Member
  • *****
  • Posts: 2351
    • Lake Matthew
  • Liked: 424
  • Likes Given: 0
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #41 on: 05/10/2018 04:01 pm »
Countering Trawler Drag with PV "Flower Petals"

A trawler at 90 km could trail a string of solar panels having lift/drag ratio ~5:1, but I think the panels could be deployed more effectively at the "Terrestation" base perimeter, where panel lift is not needed and panel drag would be negligible.  The base perimeter also offers greater insolation.  Moreover, panel mass would be minimized, with panels unfurled under centripetal Mars g, so that panels require no significant structural mass.  These would be extremely thin, lightweight PV "flower petals", as it were.

IMM PV panels with BOL rating of ~3 kW/kg could be feasible in this configuration.  Applying Voronka et al. 2006, it seems one cargo payload of these panels could give the megawatts required to counter drag for one SpaceX trawler.

Update:

The quantum dot solar cell of Zhang et al. 2018 has mass-efficiency of 15.2 kW/kg, about a 5x improvement over IMM PV.  This raises the possibility of packaging a SpaceX trawler kit, with scoop, cooler/compressor, tether and all required drag-compensation PV panels, as a single SpaceX cargo payload.

Refs

Voronka, N. R., Hoyt, R. P., Slostad, J., Gilchrist, B. E., & Fuhrhop, K. (2006). Modular spacecraft with integrated structural electrodynamic propulsion. NASA Institute for Advanced Concepts.

Zhang, X., Öberg, V. A., Du, J., Liu, J., & Johansson, E. M. (2018).
Extremely lightweight and ultra-flexible infrared light-converting quantum dot solar cells with high power-per-weight output using a solution-processed bending durable silver nanowire-based electrode Energy & Environmental Science.

« Last Edit: 05/15/2018 04:26 pm by LMT »

Offline Comga

  • Senior Member
  • *****
  • Posts: 6466
  • Liked: 4572
  • Likes Given: 5136
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #42 on: 05/10/2018 04:35 pm »
If the thruster ISP is 2000 s then that is an exit velocity of ~19600 m/s vs ~8000 m/s orbital velocity
which suggests 8000/19600 or at least 41% of the front of the satellite has to be intake to cancel
drag.

Anyone see any flaws in this logic?

Something like that seems plausible. It's going to constrain your solar panel pointing a lot.
In principle, you may be able to effectively steer the ions, which helps if you don't solely want to use it for drag cancellation.

Given the shape of GOCE, this seems pretty reasonable.
Imagine this engine mounted in back, like the 3rd engine on a DC-10.
Vector the thrust through the CG.
Perhaps invert to have it on the nadir surface.

PS  This thread has diverged into "Advanced Concepts" at best.
Shouldn't we keep this on the title concept and leave out SABRE, multi-kilometer thethers, BFR, orbital debris removal, and the like?

What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline LMT

  • Lake Matthew Team
  • Senior Member
  • *****
  • Posts: 2351
    • Lake Matthew
  • Liked: 424
  • Likes Given: 0
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #43 on: 05/10/2018 04:46 pm »
Shouldn't we keep this on the title concept and leave out SABRE, multi-kilometer thethers, BFR, orbital debris removal, and the like?

You might choose to limit the thread to scooping without storage.  In that case, SpaceX Trawler systems might fit better under "SpaceX BFR - Earth to Deep Space".

Offline indaco1

  • Full Member
  • **
  • Posts: 283
  • Liked: 64
  • Likes Given: 37
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #44 on: 09/13/2018 04:29 pm »
This 3d deserve more attention, after all. 

I add some thougts about a neglected planet.  If scooping works maybe we've found a work for Venus: gas station. Venus could be the best place in the solar system to procure reaction mass.


Solar constant at Venus is 2.58 kw/m2, Earth 1.35 kw/m2, Mars 0.58 kw/m2.  Almost twice power density by PV panels compared to 1 AU, not bad.   
Transit time and launch windows frequency to Venus are significantly better than to Mars.
Delta V from Low Venus Orbit could be a little worse than Mars, because it's a deeper gravity well, but it could be better than Earth for many destination orbits, including part of cislunar space.
According to literature I've found, it's just 0.28 km/s of delta V between Earth and Venus Escape/Capture orbits. Of course astrodynamics is not simple: ITN, aerobrake, Lagrange Points and other tricks are possible.

Assuming Low Venus Orbit speed is 7.2 km/s the energy required to accelerate to that speed 1kg of atmospheric gas is almost 26 Mjoule. 
A 20% efficient solar panel at 2.58 kw/m2 irradiance produce 515 w/m2 that, in theory, could accellerate to orbit 0.025 grams per second ie 1kg in about 50k seconds. 1.7kg per square meter in a day. 630kg in a year. It's a lot.
This is a very theoretical upper limit of course: no termal loss, no drag, nothing bounce back, ejected/captured mass ratio is infinite (maximum propulsive efficiency).  In the real world an atmosphere scooper, even if it works, will be much less efficient.
Eg: if mass accelerated for propulsion to balance momentum loss is equal to captured mass theoretical energy requirement is doubled (If I'm not wrong with basic energy and momentum conservation laws. Mass accretion should not change the balance, it's a variable mass system but speed is constant, balance of forces is zero, no veichle acceleration).

A Venus scooper could use a solar syncronous terminator riding orbit.  Solar panels are kept vertical and parallel to motion to minimize drag and have sunlight 100% of time.
The dark side of panels could be used for CO2 storage and radiators with no need of other shades: as gas has to be compressed and refrigerated we need an heat sink. The intake and the "molecules trap" probably could be integrated with solar panels.
To keep the veichle vertical and panels always facing the sun just require rotating it once per each Venus year.
Solar syncronous orbit at Venus, that is not oblate, is a little more difficult than at Earth and require  propulsion.
But an atmosphere breathing ion engine is already required for drag and momentum compensation and attitude control.
It's impossible to guess scooper total production of mass for the expected lifespan. Maybe wear is an issue.


Usage, storage and transport of the matter collected:

CO2 could be more useful in space than O2/N2.   You can make a decent rocket bipropellant by CO+LOX.  Here an old but still good 3d about it:  https://forum.nasaspaceflight.com/index.php?topic=21544.0
Venus atmosphere also contains a possibily useful 3.5% of nitrogen, eg. you can make something close to breathable air. Not very healty with no water.

Low Venus Orbit to capture/escape orbit delta V is about 3 km/s. For descent aerobraking is possible.
For ascent, if atmosphere breathing ion propulsion on elliptic orbit is not workable (as likely) it is still possible to use part of collected reaction mass using chemical CO-LOX and/or electrical thrusters. Possibly the same veichle/tug will transport CO2 from low Venus orbit and travel were needed to tow another spacecraft.


Another property of CO2 could be very useful:  with a proper solar shade it could be kept solid in void at any useful distance from the Sun including Venus orbit.   Maybe there are issues I still can't see but maybe this could simplify storage and dramaticaly increase mass ratio of veichles.
A thiny but big bag full of CO2 snow (solid) attached to a small veichle with a small engine could allow an extremely high mass ratio.  CO2 required for engine is sublimated and headed to plumbing just adding the proper amount of heat inside the bag.
It sounds stupid but for now I can't see reasons it could not work.
The bag has not to be very robust: quite low acceleration and very low pressure. It just has to be gas tight, radiation and void resistant.  The bottleneck for a "CO2 bag tug" performances is probaby mass and power of solar panels. Off course mass ratio is inside the inverse exponential of the rocket equation, so increase it is not that effective as increasing isp, when high delta V is required.  But for many mission it's not required.  Electric or hybrid electric/chemical low isp propulsion could be easier and less energy demanding and more useful than an high isp ion engine when reaction mass is abundant and power and time is scarce.  High thrust of a chemical rocket allows more efficient trajectory.  I wonder if electric-pump feed cycle rockets could be used for orbital maneuver, not just for launch. See: https://en.wikipedia.org/wiki/Rutherford_(rocket_engine).
A deep space electric pump cycle CO+O2 rocket, where thrust to mass is not so important, could be optimized to add more electric energy before combustion to augment a little isp or, even more important, increase design margins to minimize wear and improve reusability if possible.

Furthermore carbon is not just volatile. Pure or combined it could be used for many feature rich building materials. Nice if the scoopers and spacecrafts, eg. structure and engines, could be partially made by ISRU carbon.



Just to mention:

Last and very theoretical note for a far future very similar to never. Venus atmosphere (unlike Earth and Mars) has not to be considered a scarce resource to preserve.
You can scoop as you want, on Venus. If it even will be possible to deplete Venus atmosphere, it will be good. Make Venus surface similar to Venus 50km altitude and you have something very similar to Earth, let alone the lack of water.  Even better if it was possible to take part of the CO2 to Mars.
I'm not very interested in terraforming, removing Venus atmosphere by scooping could be even more unrealistic than other methods, eg. freezing it. But it's worth to mention.

Just for fun I calculated how long it takes to remove 4.7×10^20 kg of CO2 from Venus using one or more scoopers with a total area of 10000 km2 (10^10 m2) that is about the same area of Jamaica o Cyprus.  If I'm not wrong it takes not less than 74 million years at theoretical maximum efficiency :-)

Non-native English speaker and non-expert, be patient.

Offline sanman

  • Senior Member
  • *****
  • Posts: 5975
  • Liked: 1312
  • Likes Given: 8
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #45 on: 10/26/2018 01:34 am »
I wanted to ask if there is a practical mass range for satellites to use air-breathing electric propulsion.

Can electric air-breathing propulsion be scaled up or down across the board for a wide range of satellite masses?

Can it be used on smallsats, including even nanosats?

Or is this type of propulsion only suitable for heavier satellites? What's the threshold for mass?
« Last Edit: 10/26/2018 01:34 am by sanman »

Offline speedevil

  • Senior Member
  • *****
  • Posts: 4406
  • Fife
  • Liked: 2762
  • Likes Given: 3369
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #46 on: 10/27/2018 12:59 am »
I wanted to ask if there is a practical mass range for satellites to use air-breathing electric propulsion.

Can electric air-breathing propulsion be scaled up or down across the board for a wide range of satellite masses?

Can it be used on smallsats, including even nanosats?

Or is this type of propulsion only suitable for heavier satellites? What's the threshold for mass?

If you are talking about a concept similar to the 'ion ramjet' - which uses the engine to provide a thrust to counter the drag, it works better for large satellites - as the drag (and power requirements) depends on the frontal area, but satellite volume goes up (for the same shape) by the cube, not the square, meaning something with eight times the mass only has four times the area, so you need 1/4 of the mass to be engines and panels, compared to the smaller satellite.

At some point, even if you do things like point the solar panels backwards along the airstream, you're going to end up as you go smaller with the whole thing being engine and panels.

This can be traded off somewhat with altitude - if you raise the altitude till your drag is a tenth, then your required amount of thrust is a tenth, and you can have a considerably smaller satellite able to counteract that drag as a minimum.

Offline ChrisWilson68

  • Senior Member
  • *****
  • Posts: 5266
  • Sunnyvale, CA
  • Liked: 4992
  • Likes Given: 6459
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #47 on: 10/27/2018 01:05 am »
+ Self filling oxygen depot (to reduce the number of refueling flights or fill up station tanks)
+ with a little stretch, a full on surface-to-orbit airplane

The second really isn't plausible at all.
This technology is several orders of magnitude too low thrust, and doesn't really scale meaningfully.
Once you get to perhaps to 70km or so the plasma physics changes, and you can't simply accellerate the gas in the same way.

Flying 'slowly' to orbit, you require hypersonic lift, which only comes with really high amounts of drag.
This means your heatshielding problems get orders of magnitude worse, as well as your power requirements being utterly ridiculous.

JP Aerospace and their Ascender design begs to differ, but they are the epitome of slow boat methods. Then again, they haven't gone bankrupt either...

"Someone is trying to do it" is not a valid argument against a sound, logical argument based on well-understood physics.

Offline SciNews

  • Full Member
  • ****
  • Posts: 812
  • Romania
  • Liked: 737
  • Likes Given: 6
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #48 on: 11/21/2018 05:24 pm »
The first aeroplane propelled by ionic wind

Offline tyrred

  • Full Member
  • ****
  • Posts: 920
  • Seattle
  • Liked: 750
  • Likes Given: 20640
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #49 on: 11/22/2018 08:50 am »
The first aeroplane propelled by ionic wind


This is exciting.  Doesn't it belong in a different thread, though?

Offline Asteroza

  • Senior Member
  • *****
  • Posts: 2836
  • Liked: 1084
  • Likes Given: 33
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #50 on: 11/22/2018 11:16 pm »
This is exciting.  Doesn't it belong in a different thread, though?

The core technology for this came out of and extends work at MIT from around 2010 or so, related to air breathing ion thrusters for VLEO sats to reduce propellant requires for stationkeeping/orbit maintenance for a VLEO path. A recent VLEO example was GOCE, a dart shaped sat which used a xenon thruster and was thus propellant limited, and another one called SLATS that had solar panels set up like wings but used xenon propellant.

A proper air breathing ion engine, either similar to the configuration on this aircraft using exposed cathode/anode wires (more suitable to the SLATS shape), or a proper ion ramjet (more suited to a nacelle shape like GOCE), would be a substantial game changer for VLEO sat operators, particular the communications megaconstellations if they are trying to extremely reduce latency (perhaps targeting latency sensitive services like gaming, remote VR teleops, and high frequency trading businesses).

Offline indaco1

  • Full Member
  • **
  • Posts: 283
  • Liked: 64
  • Likes Given: 37
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #51 on: 12/17/2018 11:27 am »
Just another idea that suggests how atmospheric scooping could change the game, if it works.

Refill a LOX depot at LEO by Atmospheric Scooping.

Dock a reusable second stage (eg. BFS/Starship) and relox it to enable a much longer reentry burn and a low velocity reentry with reduced TPS requirements.

LOX is the heavy part of propellant, (eg  BFS old design 240000 kg CH4, 860000 kg  LOX) so additional CH4 at launch is not so expensive in terms of payload penalty.

« Last Edit: 12/17/2018 11:36 am by indaco1 »
Non-native English speaker and non-expert, be patient.

Offline Spaniard

  • Member
  • Posts: 73
  • Liked: 6
  • Likes Given: 1
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #52 on: 12/17/2018 02:34 pm »
Just another idea that suggests how atmospheric scooping could change the game, if it works.

Refill a LOX depot at LEO by Atmospheric Scooping.

Dock a reusable second stage (eg. BFS/Starship) and relox it to enable a much longer reentry burn and a low velocity reentry with reduced TPS requirements.

LOX is the heavy part of propellant, (eg  BFS old design 240000 kg CH4, 860000 kg  LOX) so additional CH4 at launch is not so expensive in terms of payload penalty.

It seems even easier than scooping. Because with a high elliptic orbit reenter into space is mostly guarranteed. It's only about suck enough oxigen while in the atmosphere that later ion propulsion bring positive absortion of the spacecraft. So, technically we could "mine" the atmosphere more easily than from moon, for example. As you said, refuelling could be methane from Earth plus "mined" oxygen.

And perhaps it's even possible to mining water vapor successfully. That's mean hydrogen propulsion only with Earth atmosphere "mining".

Sound easier than real mining of Moon or asteroids, although are combinable so perhaps in the future, water and carbon could be produced from asteroids/comets captured.

But for starting, it sounds "easy", lower cost barrier, at least compared with deploy of conventional mining operations on Moon or asteroids.

Offline edzieba

  • Virtual Realist
  • Senior Member
  • *****
  • Posts: 6105
  • United Kingdom
  • Liked: 9333
  • Likes Given: 39
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #53 on: 12/17/2018 02:56 pm »
In order to ramscoop any useful quantity of O2, you would need to compensate for the apogee drop from that braking manoeuvre. That means either you need a rarefied airbreathing engine of sufficient thrust to overcome that drag (and enough excess thrust to collect some extra atmosphere to scavenge additional O2 from), or drag up enough propellant in the first place to use a rocket engine to keep your apogee up (in which case you may as well skip the scoop and just transfer that propellant instead!).

Offline sanman

  • Senior Member
  • *****
  • Posts: 5975
  • Liked: 1312
  • Likes Given: 8
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #54 on: 12/17/2018 03:45 pm »
In order to ramscoop any useful quantity of O2, you would need to compensate for the apogee drop from that braking manoeuvre. That means either you need a rarefied airbreathing engine of sufficient thrust to overcome that drag (and enough excess thrust to collect some extra atmosphere to scavenge additional O2 from), or drag up enough propellant in the first place to use a rocket engine to keep your apogee up (in which case you may as well skip the scoop and just transfer that propellant instead!).


If not Earth, then could you do this around Venus, where there's higher solar flux and slightly less gravity to fight?

How would the performance margins around Venus compare to those around Earth?


Another thing I was thinking of, was scooping Helium-3 from Uranus/Neptune using this method. That stuff could be quite the precious commodity down the road, if nuclear fusion takes off. It might be easier than trying to strip-mine it from the lunar regolith.

Since solar flux out there is much lower, perhaps any recovered Helium-3 could itself be used as the power source for the ion engine. That might afford much wider performance margins.
« Last Edit: 12/17/2018 03:48 pm by sanman »

Offline Spaniard

  • Member
  • Posts: 73
  • Liked: 6
  • Likes Given: 1
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #55 on: 12/17/2018 04:08 pm »
In order to ramscoop any useful quantity of O2, you would need to compensate for the apogee drop from that braking manoeuvre. That means either you need a rarefied airbreathing engine of sufficient thrust to overcome that drag (and enough excess thrust to collect some extra atmosphere to scavenge additional O2 from), or drag up enough propellant in the first place to use a rocket engine to keep your apogee up (in which case you may as well skip the scoop and just transfer that propellant instead!).
True but i could be in theory.
We are assuming a ion engine that it could use oxygen and/or nitrogen. And technically you could send this ion faster than the incoming speed. The key is capture as much wind as you could to avoid extra drag. So, probably need some kind of ion wind compression and capture.
Ion engine could be turned on more time than in the atmosphere (in fact, it could scape the atmosphere time if it means some kind of technical problem although I didn't see anyone.
So it's not need to make so strong force to compensate the drag on the "atmosphere inmersion". All propulsion time counts.

It only needs enough efficiency to have positive capture on the process.

Offline dror

  • Full Member
  • ****
  • Posts: 730
  • Israel
  • Liked: 245
  • Likes Given: 593
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #56 on: 12/17/2018 06:57 pm »
What about scooping at aerobrake?
Space is hard immensely complex and high risk !

Offline indaco1

  • Full Member
  • **
  • Posts: 283
  • Liked: 64
  • Likes Given: 37
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #57 on: 12/17/2018 08:08 pm »
A scooper will have a bypass ratio somehow similar to turbofans.

Part of ions are accelerated for propulsion, part of ions are collected.

Low bypass scoopers will be more energy hungry, because less mass used for propulsion translates in lower propulsive efficiency.
« Last Edit: 12/17/2018 08:10 pm by indaco1 »
Non-native English speaker and non-expert, be patient.

Offline dror

  • Full Member
  • ****
  • Posts: 730
  • Israel
  • Liked: 245
  • Likes Given: 593
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #58 on: 12/19/2018 06:49 pm »
Here's one major problem.  If you dip your perigee into the atmosphere, the drag is going to decrease your apogee.  And your next perigee is going to be back in the atmosphere again.
...trim
Let's say a spacecraft aerobrake at Mars/Earth.
Could it scoop some of the atmosphere while braking?
If it aerobrakes into an elliptical orbit, can it scoop some mass while circulating its orbit?
Space is hard immensely complex and high risk !

Offline dror

  • Full Member
  • ****
  • Posts: 730
  • Israel
  • Liked: 245
  • Likes Given: 593
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #59 on: 07/31/2020 11:32 am »
Scooping without storage

https://www.universetoday.com/147240/earth-observation-satellites-could-be-flown-much-lower-than-current-altitudes-and-do-better-science/
Quote
But it might be the case that a propulsion system is needed to counteract the drag. There are solutions on the horizon for that, especially in the form of Atmosphere-Breathing Electric Propulsion (ABEP.)

Though the atmosphere is very thin in VLEO, it’s still there. The oxygen in that environment can act as a propellant for ABEP systems. The problem is the low density.

The ESA is working on an Air-Breathing Electronic Thruster, an ion drive that uses the atmospheric oxygen as a source of ions, with a satellite’s electrical power system providing the electricity. By doing that, the system doesn’t need to carry any xenon propellant, instead harvesting the atomic oxygen in VLEO.

The problem, again, is the low density of that atomic oxygen. The ESA is developing a special intake for their thruster that would collect and compress the oxygen, making it viable as a propellant. The system has been tested successfully in simulated VLEO conditions.


Pic 1
Generalised concept of an atmosphere-breathing electric
propulsion (ABEP) system. Image Credit: Crisp et al, 2020.

Pic 2
A drawing of an air intake collector for use on electric air thrusters on satellites. Image Credit: ESA/VKI/Politechnico di Milano
« Last Edit: 07/31/2020 12:02 pm by dror »
Space is hard immensely complex and high risk !

Offline LMT

  • Lake Matthew Team
  • Senior Member
  • *****
  • Posts: 2351
    • Lake Matthew
  • Liked: 424
  • Likes Given: 0
Re: Refueling Ion Drive from Atmospheric Scooping
« Reply #60 on: 08/02/2020 04:22 pm »
Generalised concept of an atmosphere-breathing electric propulsion (ABEP) system.

Evaluation of various air-breathing concepts in Schönherr et al. 2015.

Refs.

T. Schonherr, K. Komurasaki, F. Romano, B. Massuti-Ballester, G. Herdrich, Analysis of atmosphere-breathing electric propulsion, IEEE Transactions on Plasma Science 43(2015) 287–294.

Tags:
 

Advertisement NovaTech
Advertisement Northrop Grumman
Advertisement
Advertisement Margaritaville Beach Resort South Padre Island
Advertisement Brady Kenniston
Advertisement NextSpaceflight
Advertisement Nathan Barker Photography
0