David Kirtley, MSNW, LLC, Magnetoshell Aerocapture for Manned Missions and Planetary Deep Space Orbiters
The Magnetoshell deploys a simple dipole magnetic field containing a magnetized plasma. It is interaction of the atmosphere with this magnetized plasma that supplies a significant impediment to atmospheric flow past the spacecraft, and thereby producing the desired drag for braking. Frictional heating would no longer be of concern as the energy dissipation required to slow the spacecraft would be deposited into the plasma ions helping to maintain the Magnetoshell plasma while at the same time shielding the spacecraft itself from frictional heating. With the aeroshell now being composed of massless magnetic field, the transverse scale of the magnetic barrier can be as large as 100 meters while requiring no more than a gram of plasma. With the ability to rapidly and precisely modify the drag in varying atmospheric conditions, much larger forces can now be achieved at low risk, enabling very aggressive aerocapture maneuvers. By providing power in a pulsed manner, the thermal and power processing requirements can be kept modest and with conventional technologies.
In Phase I a full system was designed for Neptune and Mars missions. This analysis showed that a 200 kg, 2 m magnet could generate a 9 m radius Magnetoshell for Neptune aerocapture with a 21 km/s injection at a peak force of 150 N entirely removing the need for a TPS. At Mars, a 2.5 m magnet could generate a 21 meter radius Magnetoshell, providing aerocapture for a 60 metric ton payload removing the dedicated aerocapture TPS and saving $2 B for DRA 5.0. A transient analytic model was developed evolving the radial plasma parameters for a variety of plasma, neutral, and magnetic parameters. Finally, a stationary 1.6 meter argon Magnetoshell was fully demonstrated and a 1000:1 increase in aerodynamic drag was found. This experimental program definitively demonstrated a subscale Magnetoshell by eliminating electromagnetic interference, utilizing a dielectric torsional thrust stand, and placing all key electrical components under vacuum in the plasma environment. In addition, by decrease the dynamic pressure requirements while simultaneously shielding the spacecraft, heating during an Aerocapture maneuver could be reduced by 10,000X. In Phase II, the complete mission benefits of the Magnetoshell system have been proven.
They are working to prepare for low earth orbit cubesat test.
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Very intriguing.
If I were including this in a re-entry vehicle, I would still have an ablative shield for one-time use as insurance against failure of the magnetoshell and eat the weight penalty. However, the RV would be reusable thanks to this new technology.
I’ve asked this before, but never got an answer. Is it possible to shape the field, maybe like a wing? If so, can it be used to steer and remain at high altitude until most speed is lost?
And maybe more significantly, if the above is true, can it be used on conventional aircraft on earth? Imagine the weight savings if you replace the wings with a magnetoshell…
Wouldn’t the drag produced be proportional to the cube of the relative velocity?
What effect, if any, does this have on incoming radiation? It would be ideal if the same equipment protecting them from aerocapture heat also protected them from solar radiation beforehand.
So, this is essentially an unbreakable, heat-immune parachute. What is the minimum working speed? I assume it’s dependent on atmospheric density/speed. Would this work on Mars? if so then retrorocket braking could be used for just the final positioning. That would be great! Does anyone have the details?
I expect the biggest use for this would for things coming back to LEO from anywhere beyond LEO, or for things coming down to the earth from LEO.
So, an assumption: an atmosphere is required for this to work…so not for airless bodies like the Moon, Phobos, Mercury, etc. Second; at what density does the atmosphere overcome the ability of the plasma to “balloon out” and create drag? IMHO, that would dictate a lot of the capture scenarios considering mass/velocity of the object to be captured.
I followed some links at NASA, and found a few more details. But nothing on what velocity/altitude the system stopped working at. In the Martial atmosphere, it might work all the way to the surface, it’s pretty thin.
https://www.nasa.gov/sites/default/files/files/Kirtley_2012_PhI_PlasmaAerocapture.pdf
The chief advantage of this system is that it can produce significant, adjustable drag even at very high speeds, without being overloaded by the resulting heat. That lets them skip any burn at the other end of the flight, dissipate all the speed difference in the atmosphere. That’s some serious potential savings there. You’re still going to need retropropulsion for the actual landing.
Nothing on whether they can produce aerodynamic lift at the same time. That would be ideal.
Probably to get lift you’d need some sort of wing or lifting body shape to your magnetic field.
The hypersonic aircraft people are probably looking at this very hard.
The drag force on the magnet is stable. Higher density plasma will bend the flux more. The drag force is higher at higher higher velocity.