Reentry Question

[CZoom]

Hello everybody,

Although this is my first post, I'm a fan of Orbiter, and I visit this forum quite often. I have a question relating to atmospheric reentry, would greatly appreciate your thoughts on this.

Why does the Space Shuttle perform such an aggresive reentry? I would think that if you spread the reentry process through a couple of hours (instead of a couple of minutes), the thermal protection system will have much more time to lose heat by radiation. That means that the TPS would reach lower temperatures, and maybe you could use a lighter TPS system. No? :hmm:

 

[dgatsoulis]

You may find this page useful.

 

[Tommy]

The short answer is that the tiles aren't heat-proof, only heat-resistant. The tiles conduct heat quite slowly, and can be extremely hot on one side and still safe to touch on the other - for a while. Eventually, heat does transfer through the tile causing a condition called "heat soak".

A shallower re-entry will mean lower peak temperatures, but will subject the shuttle to high temps longer than the tiles can protect it.

There are some other reasons as well, but this is one of the biggest reasons, and it's something no vessel in Orbiter currently models.

The Skylon was designed for a slower re-entry and features a ceramic aeroskin that is seperated from and insulated from the inner hull/aeroframe. Also, left over cyrogenic propellants (H2 ans O2, IIRC) can be used to cool the inner hull if needed.

 

[Urwumpe]

Also, you should add, that the Shuttle can't glide like that - if you try to fly much more shallow, you will loose lift and descend steeper and hotter during the final parts of reentry. The trajectory it really flies is a compromise between heating rates and staying under control.