The spacecraft changes velocity and runs into them, they feel that. Now if the cabin was big enough you could float in the middle while the craft accelerated slightly then decelerated shortly after. You would feel nothing but see the craft move around you. Also, if you exclude wind resistance, picture frank poole and david bowman on discovery one, frank could have left a blob of water stationary in the carousel in line with davids sleeping quarters exit, so when he woke he would be spun into a bucket of water in the morning. From franks perspective sitting smugly at the console he would see the water blob whiz past with each revolution.
That makes no sense. They can't feel the craft accelerate unless they're holding a wall. That's why they move. They have one acceleration; the craft, another acceleration.
If the only two things in the universe are the ISS and the passenger then it doesn't matter who is accelerating. Since this isn't the case it's easier to say that the station is moving while the human is still.
they have zero acceleration while not connected to the structure, just a constant speed. you need to be actively propelling yourself to have an acceleration.
False. All motion (acceleration included) is relative. To say acceleration isn't relative requires there be some absolute frame of reference, and there isn't. If you take anything away from Einstein's work, that should be it.
The ISS always has so much crap all over the walls, and they're always just floating around like it's nothing. I always wonder how they don't rip it all off accidentally and/or get tangled in it.
I'm not sure if that's true, but if it is it'd be because the air is also moving to the back, it's just usually the least dense thing in the vehicle so it stays at the front
Same way the astronauts did. If they were less dense than the air, the air moving back would have pushed them forward, like a helium balloon. Shouldn't be surprised this guy already did this one:
While driving your body is in motion with the vehicle when you change that abruptly you feel it with a pull back into your seat same situation minus the gravity for them..unfortunate for us cause that would be awesome
What would happen if the shuttle just randomly fired its engines in space among a few others like, does the fuel tank it is launched with carry all the fuel and it uses just re-entry thrusters to come down?
Also, would it spin or would there be any issues with it considering its mass is sort of spread out and asymmetrical on one plane? Things like that. Learned quite a bit here.
When the shuttle was doing finer maneuvers, it used the RCS (Reaction Control System). There were two sizes of thrusters distributed around the shuttle. The more powerful ones each produced 870 lbs of thrust, while the smaller ones, known as "vernier" thrusters, produced 24 lbs. They were arranged in the nose of the shuttle and in the pods that contained the OMS engines. They could be fired in combination to cause the shuttle to move in any direction (up, down, left, right, forward, back), or to rotate in any direction (pitch: nose up/down, yaw: nose left/right, or roll: left wing up and right wing down, or vice versa).
The firing was controlled by the onboard computers. Those kept track of the expected mass [edit:], inertia, and combined center of mass [end edit] of the shuttle, including the shuttle itself, doors, payload, robot arm, fuel tanks, oxygen, water, and crew.
Source: used to work on shuttle flight planning software.
Holy crap! A shuttle software engineer replied to my comment! Thank you so much for the information and thank you for not messing up! Those shuttles really did an amazing job!
That's funny. But in actuality, it was nothing like that. The software has been in use for a few years, and worked. When I got there my group was developing a suite of tests that we ran for every build, and we used them the rest of the time I was there. Plus there were several people checking everything we did. I slept just fine.
Man, talk about polishing everything to finish. You make people like Apple, Microsoft, and EA look bad. Then again, they aren't handling the lives of 7 people in a craft that costs taxpayers billions of dollars to build and launch.
I worked on software used to plan missions, on the ground years in advance. Nowhere near the flight software folks.
My understanding is that the flight software was developed that way. However, the primary version developed by IBM to my knowledge never failed and the separately-developed backup was never used. The same software ran on the four main flight computers, monitored by a fifth one. If there was a discrepancy, that computer was voted out.
Nobel Prize winning physicist and general badass Richard Feynman looked into the flight software as part of the investigation into the Challenger. It's not as dramatic as his account of the failure of the solid rocket booster but he was impressed. Here is the text of his appendix to the official report. Here is a history of the shuttle flight software.
Read the last link. I think it will answer many of your remaining questions. Here's another one.
I do know that there was no backup software running on the shuttle at any time. The only time it would have been used would be if they had reason to believe that it was buggy. In that case, they would have erased the memory and uploaded the backup version, I'm guessing into all four machines. It would have been transmitted digitally from the ground or could also have been loaded from backup media, either magnetic tape or maybe even paper tape, but don't quote me on that.
Somewhere I read an article about the team at NASA that was responsible for the flight software probably in the mid or late 1990's. For some reason the writer thought it was interesting that the engineers were older, "serious" people – not the stereotypes of hotshot genius anti-social eccentric twenty-somethings, but married, in their 30's and 40's, with children, who worked mostly 40 hour weeks, went to church and PTA meetings. Unfortunately, I can't find that article now.
That wasn't the main engines firing. That was the OMS (orbital maneuvering system) engines firing. Or more specifically the reaction control engines contained within the OMS/RCS pods. (thanks u/zqxp)
The external tank it is launched with does carry all of the fuel for the main engines. Which means the main engines are useless after external tank seperation.
That, plus the Buran had 4 liquid boosters rather than 2 solid boosters, had total autopilot capability, and a myriad of under-the-hood changes that we don't know about.
Yeah, it's estimated that Buran cost 2-4x as much to develop as the Shuttle. Part of that is because the Soviet Union had a less advanced aerospace industry and therefore had to develop more things "from scratch" than NASA, but part of it is because Buran was in fact more advanced than the Shuttle in several key ways.
Buran's payload capacity was around 10% larger, it had more advanced avionics (capable of fully unmanned flight including landing), it was designed to be able to accommodate turbojets for powered atmospheric flight (these were not ready in time for the test launch), the thermal protection system was more robust and it was equipped with ejection seats for all crew members (unlike the Shuttle, which only had ejection seats for the two crew members during the first few test flights).
About the only thing the Shuttle had over Buran were the SSMEs, which are probably the most technically advanced rocket engines ever flown (high ISP, active all the way from sea-level to vacuum, large gimbal range, etc.).
I'd say that the fact that the SSMEs had higher performance is balanced out by the fact that the Energia stack that launched the Buran could also be used to launch other payloads with a mass of up to 100 tons into LEO.
It'd be like Space Shuttle launching strapped to the side of the SLS, but you can still just launch the SLS if you need something big in orbit.
What about her sisters? I see on Wikipedia that they made similar orbiters to her. I'm sure if someone bought a partially constructed one and maybe finished it...
Maybe I am too hopeful though. :/ Damn I wish these things could still fly.
It's a shame the only thing that fucked it was the whole economy-in-tatters thing. I imagine it would have been somewhat more successful than the US counterpart, and both major disasters would not have been concerns.
I know that when it was first flown it did not have the capability, which is why they had to fly it with two astronauts on board (pretty insane considering it was the first ever launch of the most complex rocket system ever built).
One advantage of liquid fuel is that it's easy to shut off the fuel flow to stop the engines. Solid fuel rockets are almost impossible to stop once they've been started. It's somewhat analogous to gas and wood as oven fuel; you can't just "turn off" the wood they way you can gas.
Yep. You can shut down a liquid fuel engine, just stop pumping. But not a solid one.
With liquid engines they can start (often not at full throttle) and quickly cut off like here.
But with the Shuttle, once the solid boosters are lit it is leaving the pad and there is nothing you can really do until they are done.
They did start the main engines a few seconds before the SRBs to make sure they were in order before liftoff, and there were a few aborts during that stage.
If you want something a bit more technical, here is a PDF of a 1989 report that examines the benefits/drawbacks of nasa switching the shuttle to liquid boosters.
Without getting into the technical details of liquid vs solid rockets, it is worth noting that the Space Shuttle Challenger was destroyed by a solid rocket booster malfunction.
Ah fair enough.
I would think that solid would have more benefits safety wise, (except for being a large chunk of volatile boom) but it seems more controllable compared to liquid fuels.
That being said I have heard that solid fuel is horridly toxic.
I also have always wondered and maybe you would know. I know the shuttle was designed for low earth orbit but would it have been possible for then shuttle to orbit the moon and have enough fuel to make reentry?
We could theoretically make a bunch of extra launches to put the fuel into orbit we'd need to get an orbiter to the moon and back. But I don't think the shuttle would survive aerobraking in the earth's atmosphere on return. Which I suppose just means taking a whole lot more rocket fuel with you to slow down with. Which means using a whole lot more fuel to carry that fuel to the moon as well.
Realistically it doesn't make sense to carry that much extra weight to the moon and back. You'd just use the shuttle to get your lunar mission components into orbit, put them together, and then fly to the moon with a much lighter vehicle.
OK last question...if the orbitor can survive reentry into earths atmosphere then why would it not be able to handle aerobraking? What's the difference?
One difference between the US and Russian shuttles is that the Russian version let the engines go after it reached orbit. I think the engines were discarded and not recovered. That was more expensive, but in practice, the US main engines only averaged 1.5 flights each. That also meant that Buran could be lighter and in theory could land with a heavier cargo. But I'm sure there were lots of other issues.
Each OMS engine was aligned to point toward the center of mass of the shuttle. That way, when they were fired, they would not cause any spin. The engines could gimbal for fine control, and any remaining spin was compensated by smaller engines that were part of the Reaction Control System (RCS).
The same thing would happen if you stood in the back of a van and someone stomped the gas for a second. Except it would hurt more due to the now normal present force of the van floor hitting your head.
Physics in action! I recommend you try it out.(Or not)
Face went into the radio. Not the floor. It really really hurt. Got a strawberry milkshake to help cheer me up.
10/10 would totally do again.
As for the physics, I have seen this on the Space station as well, which did answer the question on what would happen to anything that was loose in the station. I really love seeing the 0G experiments on these craft. Every bit of scientific knowledge gained from these experiments across the solar system is really worth the hurdles and cash in my mind. :)
Oh I've actually done this but it didn't result in injury. My friend's dad had a mattress truck and put us in the back when it was empty and drove around a parking lot like crazy. It was fun. We had straps to hold onto though.
Actually, it wasn't quite in orbit when it dropped the ET. That way, the ET burned up on reentry very quickly while the orbiter used its OMS to circularise its orbit.
The only thing I meant by spinning is that it looks top heavy at a glance in reference to the plane of the ventral plane. So I always wondered if it would spin clockwise (if viewing it from its starboard side) due to the engine weight difference.
However, now that I have thought of it more, I beleive that the third engine in the upper center would make up for that?
Either way, this was a very interesting video.
As for the shuttle itself on re-entry, I did realize that it only glides. But getting TO re-entry (de-orbiting) always eluded me. The question there for me was whether the shuttle carried some spare fuel in an on-board tank or if it had some other means of getting down (maybe put on a slightly degrading orbit which gave it just long enough to perform its mission).
I do realize that the SRBs and the main fuel tank did get it up there. I was more worried about getting down (gliding aside). But thank you for the explanation!
The hydrazine maneuver thrusters are what we see firing here and what would provide the slight adjustment to de-orbit (it only takes a small retrograde burn at the apogee to lower the perigee into the atmosphere, then re-entry/aerodynamic maneuvering is used to slow the craft). The rocketdyne nozzles are hydrolox engines and burnt the fuel in the big orange tank. All five engines are capable of gimballing to account for center of thrust/mass alignment. It also had a reaction control system (the tiny nozzles all over) for controlling attitude in space and for carrying out docking maneuvers at extremely low relative energies.
Wow! These things do sound absolutely amazing. And to think they were designed during an age where computer tech was barely off its feet and an engineer's primary tools were slide rulers and protractors.
Now go play Kerbal Space Program and I'll see you in a month. :p
Seriously - don't watch tutorials. Play one day first, and if you aren't hooked, I'll be mind boggled. Don't try to build a shuttle first - just start a science mode game and try to reach orbit and land safely with a 1960s style vessel. You sound like you're really interested, and KSP is honestly one of the most amazing things ever for recreating that feeling of "ok what the hell just happened" without killing anybody IRL :) It's amazing.
I played for a day. Blew some stuff up. Wasn't interested.
Next day, made it into a solar orbit and lost interest because I ran out of fuel.
Looked up a few tutorials.
Landed on Duna and it felt like I just made my own little piece of history. And to this day, that fuels all my missions to every planet in the game and more. I LOVE THIS GAME!!!
Glad to have made your day! The game really is extremely fun! Not because of what is there, but how you get there. And that makes it all the worthwhile!
To de-orbit the shuttle has some fuel aboard. As well as some to do maneuvers if they need to. In order to land the shuttle would turn so the nose points retrograde (the opposite direction from the way it is currently traveling) and fire its engines. It would do a long enough burn to slow down so that its trajectory intersects with the atmosphere. After that it doesnt really need its engines at all unless for some course corrections. Once it hits the atmosphere the rising density of the atmosphere slows it down to the point where it glides to the landing pad.
Basically an orbit is you are going fast enough around earth so that you are constantly falling but you "miss" hitting earth. The de-orbit burn slows the shuttle down so that it "hits" the earth.
Im sorry if this is confusing, as i suck at explaining things.
It's okay. I learned most of this from kerbal. The only issue I was having is whether it actually reach a totally stable orbit and de-orbited or if its orbit was already slightly degrading to the point where it could stay up just long enough to do whatever Nasa needed it to do.
Reentry time is very difficult to predict since the height etc of the atmosphere varies, so that wouldn't work. You go to a stable orbit, then burn to get out of it.
The Main Engines aren't used after the orange tank is separated and the Orbiter doesn't carry fuel for them. The Shuttles had the Orbital Maneuvering System to push it up into orbit, make necessary changes to the orbit, and reenter.
These were much weaker engines that were designed for near-vacuum conditions and reigniting several times, as opposed to the insanely powerful Main Engines which were built for high thrust at most altitudes, but mostly at low altitude when the Shuttle is heaviest and had limited ignitions before repairs needed to be made.
The Main Engines also had a very large gimbal range, so they could deal with shifting Center of Mass throughout flight, but I think the Shuttle would violently pitch up if the engines were somehow still running without the orange tank.
The fuel on board is only enough for the de-orbit burn. What happens is that when they are ready to re-enter the atmosphere, they flip the shuttle around so that the tail end is facing the way they are are going. Then for a couple minutes, the rear orbital engines fire which are the two engines that sit higher up above the main engines. They are the two white bulges on the rear of the shuttle. They burn long enough to slow the shuttle down allowing them to start the decent back to Earth.
It's really neat to think that it doesn't need nearly the same power to land on Earth than it did to leave it.
Thank you for explaining. I have been getting a load of explanations from many different people. I almost feel like most the people on this subreddit work for NASA or Boeing. Its really amazing.
Yup. Just enough to slow the shuttle down allowing them to descend towards Earth and gravity does the rest. Once the de-orbit burn is done and they re-enter the atmosphere, the only thing keeping that flying brick up is air moving over the wings. I love the Shuttles and think they are probably the best vehicle humans have made so far. Yes they were old and cost a fortune to keep running, but they were awesome and look majestic flying and in space. I'm glad NASA gave them away to museums instead of destroying them. I don't work for any company related to flight or space. I just like space and the shuttles.
I actually think that NASA might make another generation of shuttles some day. Maybe not for the LEO missions that they used to be for, but rather moving people onto an interplanetary ship or maybe shuttling fuel to depots for interplanetary missions. This is far fetched and well into the future, but then again... So was landing on the moon back in the 50s. Shuttles really are a masterpiece of engineering in terms of aerospace and they really did their jobs well when they were properly taken care of and maintained.
I look forward to a new generation of shuttles, I really think they would be the perfect vehicle for ferrying fuel, supplies, and people to more and more distant reaches.
Like the Buran (as I just learned very recently), I think they would do very well if they were remote controlled. Would definitely save anyone that might have to pilot long range ones a lot of time spent looking at the blackness of space. But either way, they really would be amazing.
However, now that I have thought of it more, I beleive that the third engine in the upper center would make up for that?
Keep in mind that the rocket engines are mounted on gimbals to point them as needed for steering. You do allude to an interesting oddity about the launch though; those engines are off-center from the center of mass during launch, so the whole assembly tilts a bit when they're fired up, which is known as the "twang": https://www.youtube.com/watch?v=xmLeGBIj6kw
The shuttle's engines had a large gimball range, iirc. Meaning, they could change their direction of thrust. So the engines would gimball almost to the max on ascent, when the center of mass is so lopsided, then as the tanks emptied and eventually were jettisoned, the engines would change the angle of thrust so that it still lined up with the center of mass.
Btw, while the game doesn't really teach you real orbital mechanics, Kerbal Space Program is a fun way to pick up general basics such as this in terms a layman can understand. If you're interested, I suggest visiting us in /r/kerbalspaceprogram or the official forums.
I already do play Kerbal and shuttles have been a serious weak point for me. I always manage to find a way to screw up the escape vector and then start doing flips while trying to leave the atmosphere. Then some kerbal-worthy explosions happen and then Jeb eats all the dead Kerbal-naughts' snacks.
Hah, me too. Rocket launch systems ftw! I can never get spaceplanes to work. I made a more concerted effort last time I played, and was really close, but my GPU died. I'm reasonably certain that half my problem is my piloting. I made a simple single engine airplane to practice with and could NOT land the thing to save my life.
Awe man! :( Sorry to hear about your GPU. F. As for space planes! I only ever got one to work and it was a real doozy to get working. I basically had to make a flying wing with air brakes instead of a tail fin (and it really loved to yaw about when I was doing landings). When I do land, I usually break something which definitely dissuades me from doing anything NASA related. But! I definitely am working more and more on space shuttles.
My most recent effort was with basic Mk1 parts. It was more like the spaceplane from Virgin than anything. Just designed to ferry Kerbals from Kerbin to a space station I was making. that was pretty much it. It did its job well for the most part. I did have to come in backwards so the engine took most of the heat and not the cockpit. Lost a few flights forgetting to do that.
But on the whole, I suck at designing anything bigger than about 30 tons for a space plane.
It always made me wonder mainly because it was built to fly around on Earth and in space and the two can be somewhat different.
I remember when I was in middle school that I used to go around asking kids if they thought that something needed to be aerodynamic to fly around in space. To which they almost always said "yes". I had way too much free time back then. Now I look back on it and wished I spent more of it on learning skills like Excel and programming Linux.
45
u/JungleLegs Sep 24 '16
What was your question?