How to Fly A Spaceship to the Space Station


#1

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#2

Is speed related to altitude?

Why Mars? Is this another moon thing where we will prove that we can do it, then never go back again?


#3

I see those headphones, and immediately want to know what’s on the playlists.


#4

Generally, but it depends on the direction you’re going, what altitude you’re measuring, and what your speed is in relation to…

Orbital mechanics can be such a fun bit of brain-bending. I’ve also always loved how orbit is pretty much the ultimate application of “throw yourself at the ground and miss”.


#5

Of course, if you’ve played Kerbal Space Program (or heck, I’ve just played its cheap-o, but still very fun, mobile knockoff, SimpleRockets) then you’ve taught yourself what a Hohmann Transfer is, even without knowing its name.

It’s amazing how quickly orbits start to make sense once you’ve played with them, even though they still seem unintuitive. Blasting the thrusters while at the perigee of an orbit makes the orbital path expand away from you like inflating a long balloon. Blasting them at the apogee makes the ballon expand into a circle again. And if you ever want to go back down to Earth, you need to use a long, long burn backwards to kill all that incredible momentum you have.


#6

Agreed! I try to explain the concept to friends and I still haven’t found a good analogy.


#7

With orbital mechanics one has to use the word “typically” a lot. To go faster without burning fuel you drop down closer to the gravity source and thus move into a faster orbit. But how do you drop down into a shallower orbit? By putting on the brakes and firing a thruster forward.

You then fire the thrusters behind you to move forward and move into a higher orbit and slow down, the tricky bit is then matching orbit of something that might be on an elliptical orbit and not a perfect circle.

Why Mars? Because we have a pretty good handle on the Moon. Because let’s figure out the rest of these places near us and maybe we can solve some geologic questions in the universe. Right now all our field studies of our solar system are of the Earth and the Moon. And we’ve figured out part of the Moon comes from the Earth and vice versa, so we’re really just looking at knowing about one and a half things. But what’s over there, on that other place? Curiosity can help us out a lot but eventually you have to send someone who’s not going to take a day of data transmission to get the instruction to pick up that rock to bring home.


#8

Have you tried Osmosis? Many of the levels in that game include orbital mechanics.


#9

I did try it, and while it was a really neat game I didn’t feel the orbital mechanics were as strong as SimpleRockets. Maybe it’s just the difference of seeing the planned orbit as you make a maneuver, but I feel you’re making a lot more interesting decisions when trying to accurately dock with something, or land on the moon with enough fuel left to decelerate and not crash.

Osmosis was definitely cool, though.


#10

Sounds nice in a scientific eutopia when man kind’s needs are being met, but I wonder if this funding might be more useful in other applications right now?
I am also not thrilled that a lot of the NASA experience and advances find their way down into weapons.


#11

Other people are hedging and saying “generally.” I’ll say a definite “yes.” You cannot remain at one orbit (altitude) and move faster or slower. Moving faster or slower means changing orbits.

Any orbit is directly tied to a specific speed. To change speed you change orbit, and visa versa.

Now, when the Soyuz is docking with the ISS, during that last phase it looks like they are in the exact same orbit and moving relative to each other (i.e. the Soyuz is slowly approaching the ISS, moving up, down, left, right), and while that’s almost the case, the Soyuz is still actually making minute changes to it’s orbit (and therefore altitude) every time it makes a tiny adjustment.


#12

And pacemakers and microwaves and advanced materials for baby toys and more dependable mechanical systems and so on until you end up at the advancement of the human goddamned spirit for about half a percent of the US budget.

Cut the defense department’s 17.7% first. Let’s just eliminate Homeland Security (as the FBI is still out there) and save 1.5%.

Yes, shooting things into space costs money and lives. But I’ll tell you right now that we’ll never meet the utopia with all the needs met and this at least provides a positive return on investment both financially and in creating Happy Mutants of all curious and interested stripes.


#13

Yeah, you are right, there are a lot more things needing to be cut before space exploration.

As for militarization, maybe we can convince the government that education and healthcare would be good for the war machine they would get more attention.


#14

It would be great if we could even get them to realize that investing in the infrastructure would be helpful in both creating jobs and fixing up the place. Win-win.


#15

For myself, at least, the “generally” was at least partially because orbit wasn’t specified. The question is really dependent on the frame of reference you’re using. Pedantic, I know, but physics in space can be confusing enough even when you have all of your terms defined.


#16

Actual rocket scientist, here. The bit about “slower than but faster than” is wrong. Orbits that are lower have both a shorter period and a higher velocity. The circular speed is inversely proportional to the square root of the orbital radius (and thus decreases with altitude), and the orbital period is proportional to the 3/2 power of the orbital radius (and thus increases with altitude). So, the Soyuz, in a lower orbit than the ISS, has a higher velocity and shorter period. In other words, both the angular and linear velocity of the Soyuz are greater than the ISS. Also, when he says, “now we’re a little higher and a little faster,” this is demonstrably incorrect. The higher you go, the slower you go.

In this video, it looks like they did that thing where you make an error once and just keep repeating it.


#17

Orbital mechanics: “Well, it depends…”


#18

Orbital mechanics are simple nowadays.
1-Strip real national space capability and keep remaining capability with pork projects to bribe legislative districts to vote incumbent.
2-As next generation is being implemented give up all manned space capability.
3-Use sketchy frenemy with sketchier leadership as you ride to G$ space station.
4-End up stuck paying for the rocket program of frenemy as it slides back to cold war enemy who again begins to use nuclear threats.

It really didn’t help that even after the Challenger disaster we pretty much kept the does everything kinda badly Shuttle prestige project unchanged, it was as much a gift to Von Braun’s Nazi era vision of space exploration as any. Space planes and runway landing are great and probably the future, look at the little USAF spaceplane, but the 80s through 90s manned NASA effort should have been several spacecraft and Apollo launch capability should have been retained for many missions including saving Skylab.
I wish more nations and corporations would move ahead on maned space and man rated rockets like China has done, despite the expense. By pushing space tourism forward even the most selfish .01% can contribute to an economy of scale for manned space.


#19

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