Quote from: Asteroza on 07/26/2016 11:56 pmNot sure if this is a tangent, but how applicable is this for an e-sail spacecraft that is doing interplanetary insertion?Quote from: dkirtley on 07/26/2016 08:06 pmFor 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.pdfWhat's the expected failure mode of MAC above 18km/s?
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.
Quote from: Impaler on 07/25/2016 08:33 amdkirtley: 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?
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?
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.
Anyone have other weird missions fit in this kind of velocity range?
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.
David Kirtley of MNSW discusses his research on magnetoshell aerocapture for manned missions and planetary deep space orbiters #NIAC2017
Was there anything new for the NIAC 2017 session? https://twitter.com/cant_HALT_me/status/912439326860070912QuoteDavid Kirtley of MNSW discusses his research on magnetoshell aerocapture for manned missions and planetary deep space orbiters #NIAC2017
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?
Quote from: qraal on 10/27/2017 11:01 amHere'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.
NASA says it’ll provide resources for a University of Washington research team that’s 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 NASA’s 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. UW’s team, for instance, has been paired up with Langley Research Center in Virginia.
Fascinating tech! Is there any feasibility in using a magnetic heat shield in the lower atmosphere for maglev launched payloads?If so, it seems like it could solve perhaps the biggest issue with developing a mass driver from the ground on earth.Everything I can find on the subject is for re-entry, not the other way around.
too much power required
Quote from: 3DTOPO on 10/08/2018 12:49 amFascinating tech! Is there any feasibility in using a magnetic heat shield in the lower atmosphere for maglev launched payloads?If so, it seems like it could solve perhaps the biggest issue with developing a mass driver from the ground on earth.Everything I can find on the subject is for re-entry, not the other way around.too much power required