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Quaoar

Member

Registered: 2013-12-13

Posts: 665

Ablative structural hull for one-way entry vehicles

SpaceX Starship, designed for entering in Earth and Mars atmosphere many times, will have a steel hull, covered with PICA-3 tiles: very sturdy and thermal resistant, but also quite heavy.
I don't know if it is possible to conceive a much lighter pure reinforced carbon-carbon monolithic starship, covered with ablative PICA-3 tiles (or it will be too expensive).
I would like to explore the feasibility of an ablative structural hull, for a one-way spaceship like a cargo or a habitat designed to land on Mars surface and remain there forever: instead to built a steel hull and cover it with ablative tiles, why not to study some kind of fiber reinforced ablative hull economically molded like a GRP saiboat?

Is it feasible?
And if so, which material could be the best candidate for that purpose?

Last edited by Quaoar (2022-02-08 14:24:35)

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 29,433

Re: Ablative structural hull for one-way entry vehicles

The repair material for the shuttle comes to mind for possibly a shield that would be of a lighter mass as to land a higher payload mass means we can not add it to the shell or shield that lands the payload.

kbd512

Administrator

Registered: 2015-01-02

Posts: 7,862

Re: Ablative structural hull for one-way entry vehicles

Quaoar,

The only practical way to do this is with inflatable or deployable fabric heat shields.  Those are designed for single-use and, incidentally, also how I intended to land people and cargo on Mars after their one-way trip to Mars.  The reentry vehicle will start in LMO aboard the orbiting large interplanetary transport ships, use retro-propulsion to reenter, and then use retro-propulsion again to soft-land on the surface of Mars.  This scheme minimizes the vehicle mass, negates much of the mass and energy requirement associated with ISRU propellant production to go back and forth between Earth and Mars, and drastically simplifies logistics.

Maybe we can use LOX/LCO as our bi-propellant, made from processed and separated CO2 stored during the transit from Earth to Mars, so that we don't need to fully recycle 100% of exhaled CO2.  We can also save and store a small quantity of CH4 from human excrement to set light to the LOX/LCO propellant to assure ignition.  Since we must have last-second retro-propulsion to soft-land, it may as well be waste products that we would otherwise discard or have to devote more energy to, in order to fully recycle it back into breathable O2.