Why does a plane going up from Earth into space not need heat shields?

The shuttle or any other plane coming from space to the Earth needs heat shields; otherwise it would burn up. But why is the heat not a problem when they are going up from Earth into space?Why does a plane going up from Earth into space not need heat shields?The atmosphere is densest closest to the Earth and thins at high altitudes. The shuttle and rockets launching from the ground accelerate as they climb. They reach their highest speeds at altitudes where the atmosphere is thin and friction is minimal. The same craft returning to earth are already travelling at very high speed and as they travel downward through the atmosphere friction increases to the point where the spacecraft would melt or burn.Why does a plane going up from Earth into space not need heat shields?
This is because during accent into space the air pressure is less the higher one goes.



The inverse is true during decent, as the vehicle approaches earth the air pressure, i.e. the density of the molecules become greater, thus causing greater friction, increasing as the altitude drops. The effect of the increasing air resistance upon decent is dealt with by the heat shields.



On accent into space from earth the atmosphere becomes thinner, therefore the surface of the vehicle has time to cool sufficiently, negating the use of heat shields, even at very high speed (on earth 11.2km/s or 40320km/h).



Also one must account for the effect of gravity on a descending body since it will also increase the rate of acceleration, until the maximum velocity is reached for the falling object (i.e. when the air resistance is sufficient to counter the effect of gravity, causing acceleration to be zero). When the object under goes the acceleration in increasingly dense atmosphere, the conditions are extreme and heat-shields are needed to protect the vehicle.Why does a plane going up from Earth into space not need heat shields?Because while it is in the dense part of the atmosphere, it is still moving relatively slowly. By the time it's moving really fast, it's already high enough that the atmosphere is extremely thin and doesn't pose a serious problem. By comparison, on reentry, the atmosphere itself is used to slow the spaceship down, so it necessarily encounters a huge amount of resistance. In other words, the relations between speed and height for the two parts of the trip are not the same.Why does a plane going up from Earth into space not need heat shields?
Everybody is pretty much on track here. During ascent, a rocket does not reach it's peak speed until after it clears the dense atmosphere. But during reentry, it is still traveling very fast at this dense point.



An example: rub your hands together slowly. You don't feel any heat. But if you rub your hands together really fast, you should feel some heat. It's the same thing with the Space Shuttle during launch and reentry, just on a larger scale.Why does a plane going up from Earth into space not need heat shields?No need to tack on orbit a lot if one did not fly to a star. Ship can have 0.5c and no see that by eyes (accidentally).Better to braking on East and not to be on side then.Accelerometer must show zero ( as originally was been). One case on every 360 degree will be accident even with shilds.Why does a plane going up from Earth into space not need heat shields?
Speed. The shuttle comes down a lot faster than it goes up. Speed creates friction. Friction

generates heat.Why does a plane going up from Earth into space not need heat shields?
I'm guessing there's a big difference in speed. Less speed, less friction, less heat.