Author Topic: Magnetoshell Aerobraking & Aerodynamics  (Read 43831 times)

Offline Hanelyp

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #40 on: 05/24/2014 06:30 PM »
At least some variants of magnetic plasma shell would have a character of compressing in response to the atmosphere they pass through, presenting less drag area when passing through a higher pressure atmosphere.  Which would be very good for aerocapture through uncertain atmospheric density.

Offline JasonAW3

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #41 on: 05/26/2014 04:20 AM »
http://nextbigfuture.com/2013/06/magnetoshell-concept-proven-for-braking.html#more

If I understand the article correctly, this would act something like a Plasma Parachute in the upper atmosphere.

Yeah, that's the analogy we use a lot. It works reasonably well.

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But if the Payload is actually in front of the Magnetized Plasma effect, wouldn't it too need some form of TPS?

It depends, but not exactly. While it's true that having the spacecraft inside the magnetoshell provides an extra level of protection versus atmospheric heating, just increasing the effective drag area means you can get the same amount of braking higher in the atmosphere, where the lower density means much less heat flux.

Instead of a ballistic coefficient of 250-500kg/m^2 that you see for capsules or the shuttle, or 25-50kg/m^2 that you get for a HIAD system, you can potentially get ballistic coefficients less than 1-5kg/m^2 with a properly designed Magnetoshell with the right bells and whistles...Potentially much less than 1kg/m^2...

Take their Mars aerocapture design. Compared to a 5m radius heatshield that you could theoretically get on an SLS-type vehicle, you could get a 20m radius magnetoshell using their design, and possibly as much as 40-50m radius magnetoshell using some reasonable tricks we've thought of since they did their paper. You're talking about an areal density somewhere between 16-100x lower than you could get with a traditional heat shield (and probably still 4-25x more than you could get with a HIAD. That means that for the same desired drag, you can do a pass where the density is 16-100x lower than you could with the traditional heatshield or 4-25x lower density than you could with a HIAD. Heat flux goes linearly with the density, so depending on the details, and the knobs twisted, even if your MAC coil is trailing on a tether, you still might not actually need TPS.

Oh, and that 20-50m radius magnetoshell can be made with a payload that fits into a 5m EELV fairing...

~Jon

Jon,

Sounds like lots of advantages there.

With such low ballistic coefficients, could this be used for de-orbiting stuff from a high-ish LEO? Does sound just what F9US would need for recovery.

Also, for Mars capture... I believe this is frowned upon for crew because of risk of atmospheric variability.

This technology sounds like you could target a middling coefficient for expected conditions, then adjust it on-the-fly to ensure exactly the required capture?

Perhaps use same trick for decreasing the landing ellipse of direct entries?

I'm wondering if an element of lift is available by shaping the magnetic field?

Cheers, Martin

Sounds more like an excellent system for doing aero capture.
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Offline TrevorMonty

Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #42 on: 05/26/2014 04:49 AM »
Sounds like it can be used on more delicate spacecraft eg SEP tugs. If plasma field is big enough would protect solar panels from airstream?

Offline jongoff

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #43 on: 05/26/2014 04:14 PM »
Jon,

Sounds like lots of advantages there.

Yeah, if this stuff works as advertised (and as preliminary proof-of-concept tests MSNW has done in a ersatz arcjet tunnel indicate), I could really see this becoming a key piece of how things are moved around in space.

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With such low ballistic coefficients, could this be used for de-orbiting stuff from a high-ish LEO? Does sound just what F9US would need for recovery.

MAC only works at fairly low altitudes (85km on the low end up to maybe 150-200km at the high end), which means you have to get the perigee low via some other means. But once you've done this, you can bleed off a lot of velocity on the way in. How much will depend strongly on details. :-)

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Also, for Mars capture... I believe this is frowned upon for crew because of risk of atmospheric variability.

This technology sounds like you could target a middling coefficient for expected conditions, then adjust it on-the-fly to ensure exactly the required capture?

Perhaps use same trick for decreasing the landing ellipse of direct entries?

One of the things we and MSNW want to demo with the MAC demo cubesat is the ability to actively vary the magnetoshell drag area to effect real-time drag modulation. Which would enable exactly what you're suggesting. There will obviously need to be some further research to optimize the guidance targeting of such a system once we have some data on how well it performs at full scale, in space, compared to theoretical models. But yeah, this is one of the capabilities we're trying to get to.

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I'm wondering if an element of lift is available by shaping the magnetic field?

That's less clear. The only way I can see to get an off-axis thrust is if you could somehow control the average velocity vectors of magnetoshell ions immediately prior to charge exchange. That might be possible, but I'm not a plasma physicist.

~Jon

Offline jongoff

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #44 on: 05/26/2014 04:15 PM »
Sounds like it can be used on more delicate spacecraft eg SEP tugs. If plasma field is big enough would protect solar panels from airstream?

Potentially yes. I think the key is that by lowering the ballistic coefficient, you can produce the same drag at a much lower dynamic pressure, even ignoring any effects of the magnetoshell on the flow of atmosphere around the spacecraft. The magnetoshell's ability to redirect particles is hopefully of secondary importance.

~Jon

Offline Asteroza

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #45 on: 05/26/2014 11:13 PM »
I'm wondering if an element of lift is available by shaping the magnetic field?

That's less clear. The only way I can see to get an off-axis thrust is if you could somehow control the average velocity vectors of magnetoshell ions immediately prior to charge exchange. That might be possible, but I'm not a plasma physicist.

~Jon

Is this partially because you are using a single field, creating a uniform balloon effect, to create a drag anchor? How feasible is it to make the field "lumpy"?

Online MP99

Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #46 on: 05/27/2014 07:48 AM »
Jon,

Thanks for the clarifications.

Cheers, Martin

Online dkovacic

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #47 on: 06/24/2014 12:40 PM »
Jon

in your blog entry you mentioned 250Wh battery and 1kW power. I assume that the peak power will be mainly used for plasma generation during the magnetoshell formation. How long would that phase last? And what power requirements do you expect during the magnetoshell maintenance period?

If I understand the concept well, you would use PV to charge the battery during several orbits and then perform up to 15 minutes breaking operation.


Offline jongoff

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #48 on: 06/24/2014 01:58 PM »
In your blog entry you mentioned 250Wh battery and 1kW power. I assume that the peak power will be mainly used for plasma generation during the magnetoshell formation.

Actually most of the power is for the electromagnet coil, the plasma generator should be a much lower fraction of the power.

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How long would that phase last? And what power requirements do you expect during the magnetoshell maintenance period?

If you look at their NIAC final report that I linked to, for most aerocapture/aerobraking applications, you're only in the altitude band where MAC works for ~2-3min. Once you're out of that band, you may as well shut the thing down. If you're trying to do magnetoshell aeroentry, my very un-optimized BOTE analysis suggests you might be looking at more like 5-6min of "on time".

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If I understand the concept well, you would use PV to charge the battery during several orbits and then perform up to 15 minutes breaking operation.

Actually, for the current MAC demo concept we weren't planning on charging the battery using the PV cells. That could change by the time we go to flight, but our baseline concept was to use the battery like an electron fuel tank, where we'd only get ~10 "passes" before the battery is used up. For normal MAC operations, you'd be right, but this is just a "keep it as simple as possible" tech demo. Plus we'd be starting form a low enough altitude, that one battery worth may be all we can get anyway before the thing slows down enough to reenter.

~Jon

Offline dodo

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Offline jongoff

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #50 on: 07/10/2014 02:15 AM »
The project featured in New Scientist:

http://www.newscientist.com/article/mg22329763.100-magnetic-bubble-may-give-space-probes-a-soft-landing.html

Yeah, a few of the details got garbled in translation, but overall it's good to get press.

~Jon

Offline TrevorMonty

Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #51 on: 12/16/2014 01:26 AM »
Hi Jon

When is this mission due to fly?


Offline Katzen

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #52 on: 12/16/2014 07:50 PM »
Just a question if anyone can answer this. adding together the weight of the magnet, weight of power supply and storage,  would it be simpler and lighter to make a carbon fiber or fiberglass reinforced mylar parachute? Some sort of way to control the size wouldn't be hard. The force total on the magnetic brake was maximum 10N and a area of 100m according to IEPC-2011-304 paper. It doesn't say mass of the system though.
 I'm thinking something like 100 grams a square meter will be 1000kg for a 100m parachute to use the upper atmosphere. That arbitrary number for mass is heavy, but it illustrates the point in that the mass of the parachute for high altitude braking might be lighter than a magnetoshell.

I am of course also thinking the parachute will be durable enough to handle hypersonic atmosphere due to the low pressure and density of the atmosphere.

please feel free to shoot this down like a paper airplane over a AA battery.

Offline TrevorMonty

Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #53 on: 12/16/2014 09:15 PM »
Just a question if anyone can answer this. adding together the weight of the magnet, weight of power supply and storage,  would it be simpler and lighter to make a carbon fiber or fiberglass reinforced mylar parachute? Some sort of way to control the size wouldn't be hard. The force total on the magnetic brake was maximum 10N and a area of 100m according to IEPC-2011-304 paper. It doesn't say mass of the system though.
 I'm thinking something like 100 grams a square meter will be 1000kg for a 100m parachute to use the upper atmosphere. That arbitrary number for mass is heavy, but it illustrates the point in that the mass of the parachute for high altitude braking might be lighter than a magnetoshell.

I am of course also thinking the parachute will be durable enough to handle hypersonic atmosphere due to the low pressure and density of the atmosphere.

please feel free to shoot this down like a paper airplane over a AA battery.
The magnetoshell is designed to reduce or eliminate a heat shield during reentry or aerobraking. Parachutes can't be used for reentry, the forces are to great.

 NB this experiment is using a cubesat to test technology, if it works it could be used on larger vehicles eg planetary probes,  2nd stages, OTV.

Offline Katzen

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #54 on: 12/17/2014 08:29 AM »
okay I think I got this mixed up with a different aerobraking system which is used as a end of life system rather than travel aerocapture.
http://www.clyde-space.com/video/lets_put_brakes_spacejunk_problem

I skimed through this paper where I got the idea of a parachute. Though it seems to be more of a sail than parachute.
 http://www.google.de/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0CCgQFjAB&url=http%3A%2F%2Fmsnwllc.com%2FPapers%2FMAC_IEPC-2011-304.pdf&ei=tUqRVLuLJMP0OrXcgcAN&usg=AFQjCNFuMwdi_giJcbhQwEciWL9r_eAZJA&sig2=McUdQ72w7uOeSl_BDVo2WQ

 I would not think of a parachute as a retry method but using the thin upper atmosphere for aerobraking might still be useful.

Online MP99

Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #55 on: 12/17/2014 09:05 AM »
Just a question if anyone can answer this. adding together the weight of the magnet, weight of power supply and storage,  would it be simpler and lighter to make a carbon fiber or fiberglass reinforced mylar parachute? Some sort of way to control the size wouldn't be hard. The force total on the magnetic brake was maximum 10N and a area of 100m according to IEPC-2011-304 paper. It doesn't say mass of the system though.
 I'm thinking something like 100 grams a square meter will be 1000kg for a 100m parachute to use the upper atmosphere. That arbitrary number for mass is heavy, but it illustrates the point in that the mass of the parachute for high altitude braking might be lighter than a magnetoshell.

I am of course also thinking the parachute will be durable enough to handle hypersonic atmosphere due to the low pressure and density of the atmosphere.

please feel free to shoot this down like a paper airplane over a AA battery.

See the illustration in post #1. Since there is a plasma involved, temps will be very high.

Ultimately, this will be dissipating a huge amount of kinetic energy in a small amount of time. The beauty of doing it magnetically is that the magnetic field restrains the plasma without having to contact matter. It takes extreme measures to enable matter to survive contact with the plasma of re-entry, IE a heatshield.

cheers, Martin

Offline dkirtley

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #56 on: 12/31/2014 05:25 AM »
Martin,
Exactly the issue. For Aerocapture, the forces are not the primary concern, its the heat and control. The hypersonic incoming gas particles deposit massive amounts of energy into the thin upper layer of physical heat shields resulting in heating, vaporization, and worse, sputtering (atoms ripped off above a few eV). A plasma can take the incoming kinetic energy, in fact when the energy is high enough it in theory it will actually help fuel and inflate the Magnetoshell. We also like the idea that you can dial in the force by adjusting the magnetic field based on the actual planetary conditions when you arrive (i.e. the duststorms on Mars).
We see this as a companion to traditional heatshields. The Magnetoshell to capture, the heatshield to enter and descend. In total the system is much lighter.
This last year MSNW built up CubeSat compatible plasma injectors, power supplies, and magnet systems. Here is a picture of a Magnetoshell being generated by a 20 W plasma injector in a 6U CubeSat 'simulator' hanging in our vacuum facility.
Enjoy!
-David

Offline Elmar Moelzer

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #57 on: 01/07/2015 04:36 PM »
Very cool, David!

Offline TrevorMonty

Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #58 on: 01/07/2015 04:47 PM »
Martin,
Exactly the issue. For Aerocapture, the forces are not the primary concern, its the heat and control. The hypersonic incoming gas particles deposit massive amounts of energy into the thin upper layer of physical heat shields resulting in heating, vaporization, and worse, sputtering (atoms ripped off above a few eV). A plasma can take the incoming kinetic energy, in fact when the energy is high enough it in theory it will actually help fuel and inflate the Magnetoshell. We also like the idea that you can dial in the force by adjusting the magnetic field based on the actual planetary conditions when you arrive (i.e. the duststorms on Mars).
We see this as a companion to traditional heatshields. The Magnetoshell to capture, the heatshield to enter and descend. In total the system is much lighter.
This last year MSNW built up CubeSat compatible plasma injectors, power supplies, and magnet systems. Here is a picture of a Magnetoshell being generated by a 20 W plasma injector in a 6U CubeSat 'simulator' hanging in our vacuum facility.
Enjoy!
-David
When is the demo cubesat mission due to fly.

Offline Burninate

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #59 on: 06/03/2015 07:19 PM »
Let's say I have a ~1000 ton titanium alloy cylinder (good to ~600K) with a pointy end on one side and engines on the other, 15 meters diameter by 75 meters height, on an Earth-Mars Hohmann transfer orbit.

I want to do a direct entry at Mars pointy end forward because the engines are bad with pressures in this direction (not necessarily true, but for the sake of argument...).  I want it to eventually be moving at <1km/s relative to the ground, engine-end forward.

Is MAC capable of that sort of thing?  What sort of mass & volume of MAC should I expect that to require, as a ballpark estimate (1T, 3T, 10T, 30T, 100T, 300T)?  What power & weight laws does MAC obey while scaling to large sizes?  At what sort of velocity does it cease to be effective?

Secondarily:  Can one MAC unit be reused on a multi-phase EDL, with aerocapture, two or three aerobraking passes, and then an EDL?  Or would it have to pop out a new unit every time?
« Last Edit: 06/03/2015 07:21 PM by Burninate »

Tags: aerocapture