[HN Gopher] Neumann Drive: A Pulsed Cathodic Arc Thruster for Sp...
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Neumann Drive: A Pulsed Cathodic Arc Thruster for Spacecrafts
Author : LastNevadan
Score : 55 points
Date : 2023-12-19 10:33 UTC (1 days ago)
(HTM) web link (neumannspace.com)
(TXT) w3m dump (neumannspace.com)
| dang wrote:
| We changed the URL from https://ts2.space/en/australian-firm-
| pioneers-molybdenum-fue..., which points to this.
| tevon wrote:
| This whole post excitingly reads like star wars.
|
| Can someone with an electrical or physics background help
| translate what this means "Our propulsion system uses a cathodic
| arc discharge powered by a capacitor bank"?
|
| I take it it uses capacitors to release larges amounts of
| electricity on a given period, thus producing plasma which
| creates propulsion?
| blacksmith_tb wrote:
| That looks like it, I take it the "solid state" aspect of using
| a metal rod as the source of material to ionize is the main
| claim to fame here. It does mean 'refueling' is easy, just pop
| another rod in (easy if you happen to in orbit nearby, that
| is). The suggestion that you could make new rods from asteroids
| etc. is cool, but there's quite a gap between theory and
| practice still...
| imglorp wrote:
| > make new rods from asteroids etc
|
| The Etc includes dead hardware in Earth orbit: that's a
| smaller gap than mining asteroids. Maybe not molybdenum but
| probably lots of magnesium, titanium and aluminum.
| throwawaymaths wrote:
| It's like an ion drive. Here's the steps:
|
| 1. Start with a metal rod.
|
| 2. Remove one atom from the rod.
|
| 3. Remove electron from atom.
|
| 4. Now that the atom is charged, shoot it out the back of the
| engine really fast using electrical repulsion.
|
| 5. Shoot the electron out the back (using a different pipe) so
| that the exhaust doesn't come back at you due to electrostatic
| attraction.
|
| 6. Now you have the rod, with one less atom. Repeat. A whole
| ton of times.
|
| Steps 2&3 might happen simultaneously, not entirely sure the
| mechanism but generally an electrical arc is violent, it will
| spallate and ionize a few atoms here and there.
|
| Not having a tank is huge, and the first ionization energy of
| many metal ions is far far lower than noble gases, which are
| what is commonly used in normal ion drives
| throwup238 wrote:
| That looks awesome! The photo of the plasma discharge from the
| solid molybdenum fuel rod in the datasheet is worth looking at
| [1], perfectly illustrating the "Centre-Triggered Pulsed Cathodic
| Arc" that is the basis for this thruster.
|
| The ion and hall effect thrusters that this drive would replace
| require a propellant tank to hold xenon, krypton, iodine, etc. so
| integrating them is a bit of a pain in the ass. Anyone know how
| the mass stacks up though? Hall effect thrusters from Busek have
| a (much) higher power/mass ratio but that doesn't include the
| propellant tank.
|
| [1] https://neumannspace.com/wp-
| content/uploads/2023/09/Neumann-...
| xoa wrote:
| > _Anyone know how the mass stacks up though?_
|
| I haven't been able to find that yet, but even if significantly
| worse this may still have an important big upcoming space. In
| the upcoming Starship era, economics is going to play a
| historically huge new role in space, just as it does in
| Starship itself where many of the design and material decisions
| are optimized around cost and simplicity, even at some
| performance penalty, vs the old space total focus on perf. A
| drive that performs worse, but is much easier and cheap, could
| be useful alongside the others in some roles when you can throw
| 100+ tons at a problem at <$200/kg to LEO, or even <$100/kg.
| axus wrote:
| Good data sheet!
|
| I wonder where it fits on this table:
| https://en.wikipedia.org/wiki/Spacecraft_propulsion#Table_of...
|
| Also looked at this table:
| https://en.wikipedia.org/wiki/Ion_thruster#Comparisons
|
| The weight on this one looks really good, not even counting the
| lack of propellant. I'm going to guess that has a downside,
| that the total impulse is limited by how small the fuel rod is.
| mikewarot wrote:
| >the lack of propellant
|
| The molybdenum rod IS the propellant. It eventually ends up
| out in space.
|
| I'm only aware of one propellantless thruster, and I'm
| waiting to see if it works aboard Barry-1[1] It uses electric
| power in an entirely closed drive, generating 1 milli-newton
| of thrust. It should be switched on in a month or two.
|
| [1] https://celestrak.org/NORAD/elements/graph-orbit-
| data.php?CA...
| dmichulke wrote:
| > That looks awesome!
|
| "Power overwhelming" comes to mind
| deepfriedchokes wrote:
| Plasma welders in space.
| ortusdux wrote:
| https://en.wikipedia.org/wiki/Electrical_discharge_machining
| vcg3rd wrote:
| I read that as A Newman (John (Cardinal)) Drive: A Pulsed
| Catholic...and had to click.
| ortusdux wrote:
| Would this be a viable option for maintaining extra low earth
| orbits?
| paulvnickerson wrote:
| All hail the Holy Cathodic Arc Thruster!
|
| _Downvote me all you want, heathens, I don 't care!_
| HankB99 wrote:
| I was looking for the Epstein drive.
| jtriangle wrote:
| I wonder why they're using Molybdenum instead of just lead. All
| of the thrust comes from throwing atoms out of the thruster, so,
| throwing something denser makes sense in my mind... surely
| there's a reason?
| kelnos wrote:
| Maybe it's harder to strip atoms from a lead cathode, and/or
| harder to strip one of its electrons?
| dexwiz wrote:
| Density doesn't mean anything at the ion level. Yes, lead has a
| higher atomic mass, but at the end of the day it's about
| momentum and energy. If they can shoot a Mo2+ out twice as fast
| as Pb2+, it's about them same.
| hgomersall wrote:
| I'm sure they spent loads of time thinking about their website,
| but I find these webpages that reveal information only when you
| scroll to them really annoying. I find it such a distraction from
| trying to digest the content I generally give up, like I just
| did.
| robin_reala wrote:
| Hit the reader mode button in the address bar? All the info's
| there in Firefox at least. Safari seems to have trouble with
| it.
| jamiek88 wrote:
| Wow this could be a real game changer in the new / commercial
| space paradigm.
|
| Perhaps lower ultimate performance but much easier logistics and
| reuse.
| RcouF1uZ4gsC wrote:
| Notice that this is not the Newman Drive which is A Pulsed
| Catholic Arc Thruster
|
| https://en.m.wikipedia.org/wiki/John_Henry_Newman
| p1mrx wrote:
| > We have found that refractory metals such as molybdenum make
| excellent propellants, and recycled aluminium alloys can also be
| used. Exceptions include mercury and gallium, tin, bismuth and
| lithium (due to their low melting points), cadmium and
| technetium.
|
| Oh darn, I was hoping they'd found a use for all my spare
| technetium.
| dallas wrote:
| I'm a little out of touch with the space-related investment right
| now in Adelaide, so I hadn't heard of these guys, but as soon as
| I saw that airport photo on the main page I knew where they were
| based! :)
| linker3000 wrote:
| First thing that came to mind was how much rf noise as does this
| thing generate, and might it be an issue for comms?
|
| Nothing I could see in the docs or FAQ.
| api_or_ipa wrote:
| Very cool. I love seeing development in commercial non-chemical-
| propellant technologies.
|
| Question about the total impulse. For ND-500+, they claim up to
| 250kNs of total impulse and a wet mass of 10-20kg. Assuming a
| spacecraft mass of about 100kg, and a fuel payload of 10kg,
| that's only about 2000m/s dV. Not enough to go to Mars, but
| enough to extend an LEO mission or to send a tug to deorbit space
| junk.
|
| Anyone know how much one of these might cost?
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(page generated 2023-12-20 23:00 UTC)