Why do spacecraft reenter at such high speed?

The Columbia flew 27 missions before a failure on the 28th. In order to slow down the rocket enough for it to not be on fire you would need as much fuel as you would need to take off, meaning you would need another big ass orange fuel take and you would need to increase the size of the original one to boost the additional weigh of the new one. Simply making more durable ceramic plates would be a far better solution then trying to slow down like that.

won't you just bounce off the atmosphere if you go too slow? I recall hearing that somewhere

it would reenter if it were to slow down. it just stays in orbit because it is fast. if you slow down you loose altitude so they slow down and loose altitude at the same time in the most efficient way.

I forgot about that.

True.

I think it depends on your speed and angle of attack

I guess. But, damn.... Mach 26

Just play Kerbal Space Program and you'll understand why

Is too poor for PC

That's a shame

They could definitely be going slower. The issue is that you have to get going so damn fast to even stay in orbit, and by the time you're in orbit you've already used up almost all of your fuel. Slowing down takes fuel, and that is fuel that would simply be too much effort to bring along.

2 Dudes in 1951 found that heat load experienced by an entry vehicle was inversely proportional to the drag coefficient, i.e. the greater the drag, the less the heat load. If the reentry vehicle is made blunt, air cannot "get out of the way" quickly enough, and acts as an air cushion to push the shock wave and heated shock layer forward

A spacecraft must have maximum value of deceleration low enough to keep the weakest points of its vehicle intact but high enough to penetrate the atmosphere without rebounding

A steep re-entry causes a very high heating rate but for a brief time, so
the overall effect on the vehicle may be small. On the other hand, shallow
re-entries lead to much lower heating rates. However, because heating con-
tinues longer, the vehicle is more likely to “soak up” heat and be damaged

To reduce atmospheric effects, and improve our accuracy, we
want a trajectory that spends the least time in the atmosphere. So we
choose a high re-entry velocity and a steep re-entry angle

Most programs limit maximum deceleration
and maximum to certain values. Thus, we could still expand the re-
entry corridor by decreasing Vre-entry or γ. This change would give us a
larger margin for error in planning the re-entry trajectory and relieve
requirements placed on the control system. Unfortunately, for most
missions, Vre-entry and γ are set by the mission orbit and are difficult to
change significantly without using rockets to perform large, expensive
∆Vs.

So basically theres a ton of reasons and wikipedia.org/wiki/Skip_reentry is a better idea than using some retrograde rocket like a kerbal faggot would

Also space shuttle on reentry generates enougj btus to heat a home in colorado for 41 years

If you slow down to much before reentry your reentry gets to steep and you literally explode because your reach the dense atmosphere to fast.

Bleeding off speed at high altitude while remaining the altitude is the way to go.

not running ksp with rss/ro
not playing with 200 mods to make it look like real
not sending 7 satellites at once to Jupiter

faggot

How the fuck are you even posting this?

KSP runs just fine on laptops. A cheap $200 laptop can run KSP.

It's easier to just use the atmosphere to break since you don't have to bring that much propellant with you.

serious question, why don't shuttles release some kind of disposable sail-like thing to take the blunt of the drag when they reenter? wouldn't that be much safer than taking it all straight to the face?

>(they're not just floating in space, but flying/(actually falling), around it as fast as they could possibly fall.)

Is there a terminal velocity in orbit?

There's a very simple way of explaining this.

If you take the coefficient of your mom's vaginal effluence and multiply it by gorilla coprophagy, you get jizz covered dolphin shit.

too fast and you escape orbit, too slow and you fall to the planet, ideally you fall just fast enough to keep the distance constant

that had potential but you ruined it at the end

No.

>use RSS/RO
>mechjeb landing guidance gets altitude very wrong
Fuck it all.

> IIRC the Orion reentered at like 20,000 MPH. That's mach 27. It was turning atmospheric gasses into PLASMA.
That's true of any orbital re-entry. You need to go that fast to be in orbit. Re-entry involves slowing down just enough that you drop into the atmosphere; atmospheric drag provides the rest of the deceleration.

When you launch something to low-earth orbit with a rocket, most (~70%) of the fuel is spent on delta-V, i.e. moving fast enough horizontally to orbit, with the minority spent on achieving altitude and overcoming drag. If you wanted to decelerate significantly before re-entry, it would require a similar amount of fuel.

tl;dr: not going to happen unless someone invents propellant-less propulsion (e.g. meme drive but with rocket-like levels of thrust).

>serious question, why don't shuttles release some kind of disposable sail-like thing to take the blunt of the drag when they reenter?

Because it would immediately burst into flames.

I rmember there WAS an idea of a disposable balloon in "2010: the year we make contact" that the "Alexi Leanov" spacecraft used to aerobrake on arrival to the jovian system in roder to enter a stable capture orbit around the gas giant.

I don't know how feasable this idea is in reality, but it HAS been thought of before.

A "Drouge Chute" or simmilar parachute deployed behind the space shuttle would literally burst into all consuming flames AND rip right off of it's mounting brackets the second it was deployed...

the space shuttle is going at something like 17 kilometers per second on re-entry, and has to use the atmospheric drag to slow down, otherwise it would need to take as much fuel with it to slow down as it used to lift off into orbit.

I use a kindle.

All I can afford. And I didn't even pay for it.

No you just burn, you may have heard it from deep space reentry but it s about the angle, if it s to steep you burn otherwise you just have an ellyptic orbit around and you get bounced angain into space

What materials are OK with space reentry?

For fucks sake a "One Ring"" from LOTR can theoretically survive being dropped in a volcano!

Tungsten is hardcore.

Wood:
newscientist.com/article/mg14619738-300-space-oddities/

It turns to charcoal and ablates away taking heat with it.

whatever the soyuz escape hatch is made of:
universetoday.com/13820/soyuz-capsule-hatch-nearly-failed-and-crews-lives-were-on-a-razors-edge/

Because the shuttle was designed in 1970s and because the aerospace industry is very cautious. In addition analyzing thin flexible structures at hypersonic speed is difficult

It could work though. A large area means more drag at higher altitudes and less heat load.

There is a name for these things, ballutes

solarsystem.nasa.gov/docs/54_rohrschneider.ppt.pdf
well if the heat load is lower then it won't burst into flames

A spacecraft reenters at such high speeds because it's already going REALLY fast. When in orbit, gravity doesn't just go away. The crew in the ISS right now are feeling the exact same gravity as we are here on the ground. They are just falling towards Earth at such an angle they miss the earth every time (thus creating an elliptical path). And the reason it gets so hot and the need for thermal protection arises, is because of friction and drag. You can go more in depth with aerodynamics with drag and all, but in physics, friction is a pain in the ass. You can do so many theoretical calculations that would play off perfectly, but we live in a universe where friction exists. And yeah, when you're walking at 5 Km/h air moves right past you. But think about when you're in a car. When you roll down the window at 80 Km/h and stick your arm out, your arm gets pushed backwards because air is scraping past your arm (known as drag). So imagine all of that happening at 32,000 Km/h!

Not really, it's just that if you were moving at a different velocity you'd be in a different orbit. There is a maximum velocity, though - faster velocities correspond to higher and higher orbits, and if you're going faster than escape velocity the orbit goes out to infinity and you fly off into space.

It was ruined by not replying to anyone.

Going to space isn't just about going up and down. You have to go sideways really really fast or else you'll just fall back down.

Once you get going really really fast you have to slow down if you want to get back down.
You can either use a giant rocket like the one you used to get up to that speed in the first place to slow down again, or you can use a small amount of thrust to dip into the atmosphere and let friction do the work for you.
Friction of course has the side effect of heat. Turns out a heat shield weighs a lot less than a giant rocket.

Until we invent a reactionless or extremely efficient engine with high thrust, we're stuck with aerobraking and heatshields.