Passive shielding

This isn't really the magnet blog, so I'll relay Space Startup News who knows better. He's talking radiation-shields. To replace his overview, here is one from 2025.

What appears to have inspired our boy is Zenno. They announced a few weeks ago they'd loaded Supertorquer on "Starburst-1". The latter is Portal Space, which rideshares Transporter-18. Present plan: Falcon-9 next month. Portal are trying to shift sats between MEO and GEO, which engine they grandiosely term "Supernova".

Zenno's Supertorquer in this, confusingly termed a "flagship", is the actuator for this ship. It's a superconductor: a passive magnet at 3,500 A·m. Contrast, the usual passive shielding of lithium-hydrates which then add to the dry mass. SSN points out that superconductors are now a commodity, made more-or-less cheaply. (This is because of the work done in the fusion field. If those customers go away, as they well might, this application will keep superconductors in business.)

Although the Zenno magnet be passive it must be kept below 100 K or so. The mission is going to use power (by solar), if nothing else for the "TRL11" diagnostics also on board. It is in fact sun-sync so will be in daylight for a full year. Basic thermodynamics will heat up the chassis, and that heat is not going to be blowing propellant all the time. One assumes radiators will be brought.

Portal's aim is to use Earth's magnetic field for control authority. That's the "torque" part, to turn itself about. This leaves, for propellant, only shifting orbits. I imagine it also simplifies the design as the engine(s) shouldn't need gimbals (the solar and radiators get their own torque). In a future when sats might use the spicy-meatball for higher I_sp, any improvement on shifting cargo about is good.

Naturally the torque part works only over planets with dynamo. Such include the four big'uns, plus Mercury and Ganymede-why-not. We gotta start somewhere so, Earth it is.

This mission already-excellent hasn't even got to SSN's stake in it. Zenno want to test how well this magnet, which again is passive so always-on, keeps out the radiation. That can help scale to such human-rated habitats as can't bury themselves under regolith. Thinking here not so much of longterm space-stations outside Van Allen (Jensen imports regolith - and hydrates), as the shuttles to/from those stations or, perhaps, the stations-under-construction. Meanwhile all those LEO stations are likely going to stay lightweight (so micrograv) so will need the shields too. So much for those BVDs!