Quote from: jongoff on 05/24/2014 02:53 amQuote from: JasonAW3 on 05/23/2014 07:22 pmQuote from: xanmarus on 06/12/2013 09:15 amhttp://nextbigfuture.com/2013/06/magnetoshell-concept-proven-for-braking.html#moreIf 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.QuoteBut 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...~JonJon, 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
Quote from: JasonAW3 on 05/23/2014 07:22 pmQuote from: xanmarus on 06/12/2013 09:15 amhttp://nextbigfuture.com/2013/06/magnetoshell-concept-proven-for-braking.html#moreIf 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.QuoteBut 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
Quote from: xanmarus on 06/12/2013 09:15 amhttp://nextbigfuture.com/2013/06/magnetoshell-concept-proven-for-braking.html#moreIf I understand the article correctly, this would act something like a Plasma Parachute in the upper atmosphere.
http://nextbigfuture.com/2013/06/magnetoshell-concept-proven-for-braking.html#more
But if the Payload is actually in front of the Magnetized Plasma effect, wouldn't it too need some form of TPS?
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?
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?
Quote from: MP99 on 05/24/2014 11:53 amI'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
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.
The project featured in New Scientist:http://www.newscientist.com/article/mg22329763.100-magnetic-bubble-may-give-space-probes-a-soft-landing.html
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.
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