for you to survive the journey. If you could somehow spray the oxygen to get you close enough to Earth to use the parachute and land safely, how would you do it?
Edit: and how much oxygen would it take to spray, would you need to use to oxygen to slow your decent? This is assuming the amount of oxygen you have would be the same amount required before you naturally deorbited like a junk satellite or something. So like, you don’t have any food so you wouldn’t make it that long, but that’s how much oxygen you magically have…. Could you make it out alive? And how?
Edit 2: one of you has a cool clipboard and space pen that astronauts have that you can do math with.
Edit 3: one of you is a stoner.
Edit 4: if the space station was in geosynchronous orbit, could an astronaut jump down off of it?
You’re going much too fast to hit the earth, you’ll miss it and continue in orbit. To deorbit, you’ll need a lot of things to throw in the other direction, like the oxygen from your magic tank. You’d need about a full rocket full of oxygen (~170 tons) to slow down, probably more because the exit velocity would be slower than a rocket.
The other issue with this scheme is you’d slow down too slowly. You’ll start getting slower and lower, but you’d start to get into the atmosphere, which because you’re still going so fast would cause you to not have a great time. So your magic oxygen bottle will also need a massive tube off the end of it, maybe a couple meters in diameter.
But if you had your magic infinite air tank with a huge tube off it, theoretically you could get back down to earth safely with just it, a space suit, and a parachute.
Jumping off the ISS wouldn’t cause you to de-orbit—it would just put you in a slightly more elliptical orbit that would eventually intersect the ISS again.
And if you did get into an orbit that took you down into the atmosphere, no parachute would save you—parachutes are for slowing to a safe landing speed from terminal velocity, not from orbital velocity. You’d need to go through atmosphere too thin to fill a chute, but still fast enough to burn you up.
Right but we have the oxygen. Which direction should we jump? If we jumped forward we wouldn’t run into it again but we could get further away faster if we jumped away I think
Orbits are all about speed, not height. To deorbit, you need to reduce your speed at the highest part of your orbit. This will lower the lowest part. You jump off the back. You would need to jump FAR harder than your legs are capable of though.
Unfortunately, the sheer speed will kill you, without shielding. As you hit the air, you are going so fast, the air can’t get out of your way. You compress it ahead of you, that heats it up. It gets hot enough to melt most metals. The air will cook you, long before you get slow enough to use your parachute.
For comparison, terminal velocity (max speed you reach falling) is around 200km/h. Orbital velocity is 7km/s or around 25200km/h.
No. Jumping forward increases your elevation at the far orbit. Jumping back decreases it. But you’d end up back on where you jumped in one orbit either way.
The intersection point of your orbit would be fixed in space, but because you have added or removed energy from yourself, your orbital period will be slightly different. When you come back around, the station will be a little bit ahead or behind where it was last orbit.
With each subsequent orbit, this gap would grow until you’re on completely opposite sides of the planet at the intersection point, and then it would shrink. Eventually, the difference would come back around to zero and you would hit the station.
In theory, anyway. In reality, perturbations in your and the ISS’ orbits would almost ensure you never hit it again for a very long time, if ever.
The answer to this depends on how much the magic device with the oxygen weighs.
Also just going to set aside anything to do with sky diving and space suits and having friends and everything else that I don’t know anything about.
I only know this from playing Simple Rockets on android but basically you direct your thrust in the direction you’re moving in order to reduce your velocity, and you’ll fall down to earth.
Think of an orbit as the balance between falling towards earth and zipping past earth. If you fly past too fast then you just fly past and maybe the gravity pulls you a bit but not much. If you fly past too slow the gravity pulls you down to earth and you crash. If you fly past at the same speed you fall towards earth the two directions balance out and you end up just spinning around earth.
Therefore, If you’re in a stable orbit on the space station, and then you slow down, you’ll start to fall down towards it instead of “falling” around it in an orbit.
If you only slow down a little bit you’ll start moving towards Earth but you’ll be moving way too fast for an unshielded human to enter the atmosphere without burning up.
You’d have to slow yourself down, by directing thrust towards the horizon you’re headed towards, enough so that you’re not going fast enough to burn up.
Whether or not you can slow down enough, quickly enough, depends on how much thrust your magic device can provide and how much that device makes you weigh.
The weight of the device let’s say is 20 bananas and so that makes 2 fit astronauts and a stoner. Nobody knows why the stoner was on the space station to begin with.
20 bananas
Americans will truly use anything but the metric system
If you fall straight down so I guess that means straight down is still like 24000 mph or whatever the earth is rotating… but if you slow yourself down would you still burn up?
The issue here is that the ISS is travelling about 17,500 mph. Even if you somehow stopped yourself immediately (watch The Expanse to see what happens what happens when someone traveling very fast sudden comes to a complete stop) I think you would be falling too fast by the time you hit the atmosphere to fall safely. Heat starts being an issue over mach 1 and you’ll be moving much fast than that. An unshielded astronaut suit would burn up quite fast in those conditions.
Would it help if the station was in geosynchronous orbit
Then it would be even higher up and you would be going even faster on re-entry
Nope. You would hit the atmosphere moving even faster
The only reason things burn up when they enter the atmosphere is because they’re moving so fast that the friction from the air generates too much heat.
So yes, if you slow yourself down enough then you could just float down like a feather in the wind.
I have no idea how fast is too fast.
I think it would be cold I don’t know would a human size piece of space debris burn up?
Everything burns up regardless of size. Big things might not finish burning by the time they hit the ground.
You need either enough thrust to slow you to ~mach 2, or a heat shield to do the same by aerobraking.
It’s called aerobraking for a reason: you’re using friction to turn kinetic energy into heat to slow down, but that heat goes into the air and your heat shield instead of brake pads and rotors.
If you fell straight down from the height of the orbit of the ISS, by the time you reached the thicker parts of the atmosphere, you would be travelling at around 2 km/s. Unprotected, this is enough energy to raise your temperature by 500 °C, but not all of that energy would actually go into you so you would be a little bit cooler. But suffice it to say, if you have to get off the ISS without a capsule, you’re cooked.
It seems difficult to have enough bottled oxygen to deorbit yourself, but maybe doable.
The MMU backpack units on the space shuttle had a total delta v of ~30 m/s. You need about three times that amount to deorbit from ISS. So imagine you need 3 MMUs give it take worth of expendable propellant oxygen, and you can do it. (The MMUs used nitrogen, but for this purpose oxygen is pretty much the same.)
After you deorbit, you will of course burn up on re-entry with no heat shield. But it might be conceivable to design a personal heat shield surfboard.
You could also avoid the whole burning up things by braking a lot more during the deorbit maneuver. But instead of 100 m/s, you need to slow down by more than 7000 m/s. That’s quite a few more MMUs worth of gas. But if you do that, then you’re essentially making a free fall jump from space, which has more or less already been demonstrated.
Edit:
To address the linked article in some way: each astronaut on the station has a dedicated seat on a capsule to come back down in an emergency. Usually, it’s the same space capsule you came up on, but not always. Those are maintained ready to go at all times, and the astronauts can be back on the ground in 60 minutes whenever they need to. These spacecraft can be operated to splashdown by astronauts alone with no ground assistance, if needed.
A freefall from space has not been demonstrated. The 40 km jumps done are well below the 100 km Karman line (accepted as the definition of space, but it’s mostly an on-paper thing) and much lower than the 400-600 km orbit of the ISS. The thing about these jumps is they begin at ~0 km/h already in or just above where the atmosphere is significant. If you fall from significantly higher than this, you have a lot of altitude in freefall and the atmosphere is so thin that you won’t slow down enough for it to matter, leading to a very high speed entry into the lower atmosphere.
Baumgartner’s top speed was Mach 1.25. If you fell from the ISS, your speed when you got to where he began his fall would be around Mach 6-8.
What is it that makes you “burn up” on reentry? Is any of that avoided if you can decelerate yourself from going sideways… apologies I don’t know what to call it but you are like a baseball at that point going sideways across the yard relative to flat ground on earth I think.
Edit: that’s really cool though if you are saying we only need a few backpacks of oxygen to burn ourselves up though
It’s friction with the air.
You’ve experienced a strong guest of wind, now multiply that by 700x. At some point the temperature of the air is meaningless. The impact of you on those air particles gives them soo much energy they get white hot and radiate heat as energy, thereby heating you up. Like standing next to a fire.
The energy that makes you burn up is your own kinetic energy. The “small” deorbit burn slows you down just enough to touch the atmosphere, but you’re still going nearly full speed: 7200 m/s. Around 30,000 km/hr.
If you slow down more in space, so that you enter the atmosphere at low speed, you don’t burn up. But you need a whole lot more backpacks to handle the full speed. It’s cheaper and burns less gas if you use the air to slow down.
Do rockets aim straight up as they try to leave earth, why don’t they burn up on exit too
By the time they’re going fast enough, they’re high enough they don’t have much air to worry about. (And they do have an angle over too, not just straight up)
Missiles do go more or less go straight though the atmosphere horizontally. Most are slower than what we’re taking about, but hypersonic missiles get close to rocket speeds. And they do need big heat shields to keep from melting immediately.
Rockets do not aim straight up when they are leaving. They go straight up for a few seconds, and then they tilt over in the desired direction to pickup speed.
They don’t burn up on the launch because they time the tilt over maneuver so that they get above nearly all of the atmosphere before they start picking up serious speed.
…what??? What does that have to do with the link? You would die in atmosphere.
I was trying to link to a comment in the thread
Someone made a random post and it’s Saturday night and I think I can ask anything here the article is political I guess or about current events let me know if I need to redo the post and how to link to comments… should it be a screenshot of the comments instead maybe so you can’t see the original post?
I’m on mobile watching a popped out video, I missed the comment! Apologies.
That said, probably wouldn’t live
Are you the stoner? One of you can be Neil degrass Tyson? That physics dude… Astro or even heck it could be Stephen hawking or anyone you probably need Superman to be one of the friends present okay we have to assume the people are strapped together and can hold the magic device lol no X-men, unless is that cool marvel guy who is like the flash in the dc universe
What?
Im trying to answer my question but I’m obviously not smart enough