Can a Palladium Foam Parachute Slow Down a Spaceship Traveling at 0.4c?

[AllanR]

Ship is traveling at .4c.

It is medium sized, about 1500 tons displacement.

One way I want to slow down is using a parachute of sorts to use the drag from the interstellar medium. This doesn't have to be the majority of the deceleration, just a small part. A percent a year is fine.

What I was thinking making it from palladium foam. The idea is to catch the hydrogen and with a momentum transferring tether, slow the ship. I'm thinking the chute would be out for years and cover a very large area. (it might have to be brought in periodically to flush the hydrogen ).

How large would something like this be, in area and thickness? And how massive as well? Is palladium foam a plausible material?

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[anuttarasammyak]

Hello. Density and mass of interstellar medium are given, we can do estimation any way.

 

[DaveC426913]

I think you would probably find a better engineering analogy with a solar sail.

Maximum area, minimum thickness, minimum mass. You're not trapping the interstellar medium; you're just stealing its inertia and then letting it go. There's no reason for it to be thicker than a handful of micrometers.