Re-entry Heat

Here are my geeky questions of the day:
I recently read an article about a private company that hopes to take passengers up for short space rides in what was described as a 'souped up lear jet.'

Will these private space ventures to take people to the edge of space have to cope with the same sorts of re-entry heat that space capsules and the space shuttle deal with? Or do they deal with far less heat because they re-enter at far lower speeds? And, if the heat is so much less for a low speed reentry, is it possible to slow a spacecraft like the shuttle down enough before it enters the atmosphere so that reentry heat is reduced? 8O

Hi Lee,

I'm certainly no expert on this subject but I think the discussions are entertaining. I am sure there are some trained physics folks around here who know far more than I.

<>

As long as these private ventures stay within the atmosphere they will not reach speeds that will generate the same heat that a space vehicle experiences during re-entry. However, they may get hot during flight. According to Wikipedia, "the SR-71 Blackbird jet could fly continuously at Mach 3.1 while some parts were above 315°C (600°F)." Of course, once outside the atmosphere,(in space) there is no heating due to the friction of the air.

It is my understanding that the heat of re-entry results from converting the kinetic energy of the space vehicle to heat. This is what provides the necessary braking action to slow the vehicle. It could be done with a rocket engine prior to re-entry but it would take a similar amount of fuel to slow the vehicle as it did to accelerate it in the first place. Also keep in mind that if a space vehicle is not moving forward, it is going to fall straight towards the earth. That might make the landing a little tricky.


dan

Thanks Jarno and Dan. Your answers make a lot of sense. When I first heard about the commercial passenger spacecraft feathering upon re-entry like a badmitton shuttlecock, I thought it was pretty swift. But, you guys have confirmed that it's actually a little slow! 8)