Author Topic: Magnetoshell Aerobraking & Aerodynamics  (Read 43517 times)

Offline dkirtley

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #120 on: 07/27/2016 11:18 PM »
Not sure if this is a tangent, but how applicable is this for an e-sail spacecraft that is doing interplanetary insertion?

For an Earth type atmosphere, we think the lower limit where this technology works well is 8 km/s and the upper limit is 18 km/s.

A prototype e-sail uranus / gas giant mission assumes about 30km/s entry velocity and expects to survive that with a high mass fraction heat shield - https://arxiv.org/pdf/1312.6554v2.pdf

What's the expected failure mode of MAC above 18km/s?

For the deep planets where the atmosphere is Hydrogen and Helium (rather than N2), the upper limit is much higher, 40+ km/s. If the incoming velocity is too high, your particle collisions ionize, rather than charge exchange. You'd still get alot of drag, but the dynamics of the plasma gets much more complicated as you sweep up large amounts of atmosphere and loose energy to the ionization processes.

Offline Solo

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #121 on: 07/28/2016 08:01 PM »
Thanks David! That sounds like a fun project.  If you haven't already, you should talk to Michael Mauel at Columbia Univ. about his dipole confinement research.  Also, the FRC guys (Tri-Alpha, John Slough at Helion) deal with magnetized plasma blobs fired into neutral gas (probably a bit too fast, I saw 1 million mph quoted on the Helion site). I'm guessing you are familiar with their work already though.

Right, I was assuming the coil would be mounted around the perimeter of the conical capsule.  The disadvantage there is that you need shielding both on the top and bottom of the craft, though. (Assuming the mean free path of the ions before a charge exchange collision is longer than the bounce time in the mirror field.) I guess it depends on how much reduction you get in the heat load due to (a) the reduced peak heat flux (b) any improvement in the dissipation of the energy into the escaping particles instead of into the craft.  The 'parachute' coil would improve (b) for sure.  Probably a trade-off in terms of engineering to make sure it deploys correctly, gets power, cooling, etc.

Offline lamontagne

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #122 on: 07/28/2016 08:30 PM »
dkirtley:  Any thoughts on what the upper limits of entry velocity if any that such a system could handle when scaled up, or any upper limit on how much velocity can be bleed off in a single aerocapture pass through a planetary atmosphere such as at Earth or Mars.  Are limits more likely to be G loads on the vehicle and it's squishy contents or some limitation in the devices ability to exert a braking force?

The limit is actually a lower limit. These particular physics effects only work above a certain energy. A good way to think about it is two slow moving particles just bounce off each other (excitation), if they are moving faster they can actually swap an electron (charge exchange), and if they are moving faster still they can knock an electron entirely off (impact ionization). For an Earth type atmosphere, we think the lower limit where this technology works well is 8 km/s and the upper limit is 18 km/s. There will still be drag effects below and above these velocities, but we don't know how well it would work yet. Our mission studies we are focused on the really high delta-V missions, like interplanetary orbit insertion and lunar/Mars return missions.

You definitely still have the G-force and dynamic pressure issues (and squishy payloads), but because your 'shell is so much bigger than a standard physical aeroshell, you can do the same total braking maneuver at higher altitude and over a longer period. In theory, 10X lower peak forces and 1000X lower heating.

Anyone have other weird missions fit in this kind of velocity range?
I have a few weird missions:

How much could we save on mass (not crew) transportation to Neptune or Uranus?  And would it be advantageous in one direction or the other?  Can we basically transform a fly by mission into a stop at mission?

Another fun possibility would be the hypothetical planet 9.  If this is a form of gas giant, then might we use this to stop at the planet rather than do a quick fly bye like New Horizons did over Pluto?

Another is a SEP mission to Mars; could the large area allow us to use aerobraking on a relatively fragile vehicle such as a SEP transport?

And for my personal interest, (and rather off thread, sorry) are mini magnetospheres as radiation protection devices still an active field or has that application been abandoned?

Offline Elmar Moelzer

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #123 on: 07/29/2016 01:54 AM »
Also, the FRC guys (Tri-Alpha, John Slough at Helion) deal with magnetized plasma blobs fired into neutral gas (probably a bit too fast, I saw 1 million mph quoted on the Helion site). I'm guessing you are familiar with their work already though.
David is the CEO of Helion Energy, which is sort of a spin off of MSNW LLC :)
John Slough is the president and Director of Research at MSNW LLC.
« Last Edit: 07/29/2016 01:57 AM by Elmar Moelzer »

Offline Elmar Moelzer

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #124 on: 08/25/2016 05:35 AM »
Great NIAC presentation by David Kirtley earlier today, showing their progress and future plans for the Magnetoshell Aerocapture:
http://livestream.com/viewnow/NIAC2016/videos/133838016
His presentation starts about 50 minutes into the video.
« Last Edit: 08/25/2016 05:36 AM by Elmar Moelzer »

Offline guckyfan

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #125 on: 08/25/2016 06:22 AM »
Very interesting and promising technology. They are talking now about a 6U cubesat to demonstrate it in space.

Offline redliox

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #126 on: 09/08/2016 07:36 PM »
How much power does MAC require?  I've read through as much of this thread as I could and still don't have a specific answer.  Something on the level of kilowatts seem to be implied.  If that's the case I see problems but I also get hints there are variables not unlike how aerocapture itself has to deal with the variables of air pressure and density.

Assuming killowatts, that's slightly steep for a probe to spit out.  With solar power, it'd be a piece of cake at Venus and (with slightly more difficulty) Mars to get this.  However, at Uranus and Neptune, where the need to bleed off speed to enter orbit is in greater demand of this tech, sunlight isn't an option.  The average output for a standard RTG is just over 200 watts per unit; and there's factoring in plutonium decay which (using info on New Horizons' RTG) is about 5% powerloss every 4 hours.  I don't think a mission lofting enough plutonium to output a full kw would be launched; Cassini and Galileo both received protests for their 500+ w supplies.

On the plus side, I've seen commentary here about how, like with regular aerocapture, the setup only needs to be on for a matter of minutes to function.  That would make the power supply problem easier to handle; there have been suggestions for the Europa lander to give it a chemical generator (said by commentators here, not the mission designers bear in mind); in the case of a Neptune mission my concern would be if it would expire like a car battery does after ~6 years v.s. the likely 9 years of flight.

Mainly I'm curious how much power MAC needs; any other fresh news on it would be a bonus.
"Let the trails lead where they may, I will follow."
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Offline qraal

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #127 on: 09/10/2016 12:01 AM »
Anyone have other weird missions fit in this kind of velocity range?

How about a "Snowbank Orbit" mission to Planet Nine? Cruise speed 165 km/s, to aerocapture into orbit?

Offline jongoff

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #128 on: 09/10/2016 03:13 AM »
How much power does MAC require?  I've read through as much of this thread as I could and still don't have a specific answer.  Something on the level of kilowatts seem to be implied.  If that's the case I see problems but I also get hints there are variables not unlike how aerocapture itself has to deal with the variables of air pressure and density.

Assuming killowatts, that's slightly steep for a probe to spit out.  With solar power, it'd be a piece of cake at Venus and (with slightly more difficulty) Mars to get this.  However, at Uranus and Neptune, where the need to bleed off speed to enter orbit is in greater demand of this tech, sunlight isn't an option.  The average output for a standard RTG is just over 200 watts per unit; and there's factoring in plutonium decay which (using info on New Horizons' RTG) is about 5% powerloss every 4 hours.  I don't think a mission lofting enough plutonium to output a full kw would be launched; Cassini and Galileo both received protests for their 500+ w supplies.

On the plus side, I've seen commentary here about how, like with regular aerocapture, the setup only needs to be on for a matter of minutes to function.  That would make the power supply problem easier to handle; there have been suggestions for the Europa lander to give it a chemical generator (said by commentators here, not the mission designers bear in mind); in the case of a Neptune mission my concern would be if it would expire like a car battery does after ~6 years v.s. the likely 9 years of flight.

Mainly I'm curious how much power MAC needs; any other fresh news on it would be a bonus.

Kilowatts and big Lithium-Ion batteries. You only need them to operate for ~5-10min at a time typically, so you can trickle charge them from something with lower power levels like a solar panel or RTG.

~Jon

Offline Joffan

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #129 on: 10/11/2017 02:26 AM »
Was there anything new for the NIAC 2017 session?

https://twitter.com/cant_HALT_me/status/912439326860070912
Quote
David Kirtley of MNSW discusses his research on magnetoshell aerocapture for manned missions and planetary deep space orbiters #NIAC2017
When I say "Jump!", you say "To which orbital inclination?"

Offline eriblo

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #130 on: 10/14/2017 02:55 PM »
Was there anything new for the NIAC 2017 session?

https://twitter.com/cant_HALT_me/status/912439326860070912
Quote
David Kirtley of MNSW discusses his research on magnetoshell aerocapture for manned missions and planetary deep space orbiters #NIAC2017

I haven't kept up enough to know whats new but the presentation is the first 25 min of the day 1 part 4 stream. They've started testing the plasma injector and deployable magnet coil for their 3U Phase II LEO CubeSat Demonstrator and will assemble and test it in a vacuum chamber in the coming year (as well as continue their modeling work).

Offline qraal

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #131 on: 10/27/2017 11:01 AM »
Here's another mission design request for MAC. Flying to Jupiter on a fast elliptical orbit (a~5.2) with a re-entry speed of 60.7 km/s. Relative velocity is thus 48.2 km/s. Want to shave off ~1.5 km/s, thus exiting at 46.7 km/s (59.2 km/s relative to the stars) to enter a highly eccentric ellipse. Can the Magnetoshell do the mission?

Offline matterbeam

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #132 on: 10/27/2017 11:47 AM »
Here's another mission design request for MAC. Flying to Jupiter on a fast elliptical orbit (a~5.2) with a re-entry speed of 60.7 km/s. Relative velocity is thus 48.2 km/s. Want to shave off ~1.5 km/s, thus exiting at 46.7 km/s (59.2 km/s relative to the stars) to enter a highly eccentric ellipse. Can the Magnetoshell do the mission?

Equation at the equator adds a non-negligible +/-12km/s to the relative velocity.
toughsf.blogspot.com

Offline qraal

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #133 on: 10/28/2017 11:43 AM »
You mean Jupiter's 10 hour rotation rate? Yeah. Means it's moving at 12.5 km/s at the equator. Thus, relative to the stars, one re-enters at 60.7 km/s, but relative to the clouds your speed is 48.2 km/s. Capiche?

Here's another mission design request for MAC. Flying to Jupiter on a fast elliptical orbit (a~5.2) with a re-entry speed of 60.7 km/s. Relative velocity is thus 48.2 km/s. Want to shave off ~1.5 km/s, thus exiting at 46.7 km/s (59.2 km/s relative to the stars) to enter a highly eccentric ellipse. Can the Magnetoshell do the mission?

Equation at the equator adds a non-negligible +/-12km/s to the relative velocity.

Offline dkirtley

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #134 on: 10/31/2017 07:06 PM »
You sure you want a Jovian entry and not a direct Europa(n), etc? What is your final orbit/mission/intercept? Roughly how big of a payload? We are looking at minimum energy, 500 kg direct into Europa missions now.
Thanks!

Offline Joffan

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Re: Magnetoshell Aerobraking & Aerodynamics
« Reply #135 on: 12/04/2017 11:06 PM »
News on another step in this technology:

https://www.geekwire.com/2017/uw-team-wins-nasas-nod-small-satellites-magnetic-braking-systems/

Quote
NASA says itíll provide resources for a University of Washington research team thatís working on a concept to put small satellites in orbit around other worlds using magnetic interactions.

The concept, known as magnetoshell aerocapture, is one of nine university-led technology development projects winning NASAís backing under the Smallsat Technology Partnerships initiative.
:
The nine newly selected teams will have the opportunity to establish a two-year cooperative agreement with NASA, through which each university will receive up to $200,000 per year. As part of the agreement, NASA researchers will collaborate on the projects. UWís team, for instance, has been paired up with Langley Research Center in Virginia.
When I say "Jump!", you say "To which orbital inclination?"

Tags: aerocapture