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?
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.
If you just stepped outside of ISS you’ll still be in an orbit around earth ( something something first law of motion) it would take you decades to loose enough energy to deorbit and if you survived that long without eating drinking shitting then good luck surviving the reentry.
Is that correct? I know there’s still a trace of atmosphere at the altitude the ISS orbits, and they need to occasionally make a burn to regain speed lost to friction.
At ISS altitude, it’s probably not decades to decay, but a few years instead.
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.
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
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.
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.
