I’m going to be very disappointed if the rockets top out at 65mph.
In: Planetary Science
Because, as most people, you imagine space as something vertical, where as it’s something way more ‘horizontal’, with speeds and such.
It’s also the reasons launches happen near the equator, where they can already use Earth’s rotation speed, which would be next to zero near the Poles, for example.
You should try Kerbal Space Program. I had about 100 hours into the game, largely toying with builds, before attempting docking with a satellite.
I had landed on the ‘moon’ and even other planets before. Which was much easier due to their gravity.
The process of matching up with a satellite is *crazy*. I had to watch several youtube videos to understand how to do it. And it was so tedious that I only ever did it once.
I mean they could get there a lot quicker if they wanted to crash into it at incredible velocity.
Imagine a race car going around a round track at 100mph. You are in the middle of the track. You could just run straight at the car but that would be bad. To catch it softly you would need to start driving around the track behind it slowly catching up.
Because it’s moving very fast, it’s not stationary. Matching orbits takes time and you can’t really just gun it towards the station, that will just put you in a much higher orbit and take you farther away. You need to establish an orbit that’s almost the same as that of the station but ever so slightly lower so that you’re going faster to catch up, or if it’s behind you, higher so that it catches up to you. Then you have to wait until you’re close enough to burn towards the station and dock. Given the complexity of this 4 hours is actually not that long.
Since the numbers involved are absurd to the human mind let’s divide them all by 100 and construct a scenario closer to daily life.
It might take under a minute to reach train tracks 4 km (2.5 miles) away but you obviously can’t just aim for a head on collision with a TGV or similar. Neither can you jump out and grab on to a train moving at 280 km/h (174 mph) relative to you.
You could drive straight up to the tracks, turn parallel to them, and catch the train. That’s pretty wasteful in time and fuel consumption.
Ideal is approaching in an arc where you reach the trains speed once you’re parallel to the tracks. The downside to this is timing. You can only go when the apex of the arc will coincide with the train going past.
One thing I haven’t seen mentioned is that ISS was somewhat optimized for Russian launches as, without Buran, they didn’t have as much capabilities as the Americans. It’s possible that a new space station could be made that’s faster for Dragon to reach than ISS.
Think of it like you’re standing in the middle of a big race track. A car racing around that track might only be 1/2 mile away at any point but it’s still going to take more than the 3 to 4 minutes it takes you to run to the track surface. The car is always going around the track (like the ISS orbiting the earth) and you’ll have to find some way to keep up with it.
In real life this means launching at a specific time, going into a slightly lower orbit that is slightly behind the ISS (which counterintuitively takes less time per orbit meaning you’ll slowly catch up), then carefully syncing your orbit to the ISS while you get closer and closer. To go back to the race car analogy, that would be like leaving the pit lane just as the car crosses the start/finish line, getting up to speed just behind it, and slowly pulling up next to it after a few laps.
That’s not how it works.
The ISS is moving at about 7 km/s around the Earth.
If you just go straight up to the ISS you’ll hit it with about 7 km/s of velocity.
You need to match its trajectory and position.
There are lots of ways to do this, just the most efficient way is to get into a lower orbit (lower means faster and vice versa) than your target and wait until the perfect timing to make a burn and raise your orbit such that when you reach the apex of your trajectory, your in more or less the same position as your target while having a small relative velocity which you then cancel out when your nearby.
You can minimize the time you’re waiting, by launching when the target is overhead, but the ISS is in what’s called an inclined orbit meaning that its orbit is at an angle relative to the equator.
In simple terms, this means that you must launch when the trajectory is overhead, otherwise your trajectory won’t line up with the target’s. However, this means that, in practice, you only get one chance per day since the Earth is turning while the trajectory stays in place.
Since you only get one chance per day, you can’t really be picky about the position of the ISS meaning that the process I described earlier takes significantly longer.
If the ISS and the launch site were on the equator you could launch whenever you want since the ISS’s trajectory is always overhead and you could theoretically get there in a matter of minutes if you time it right and are okay with doing things inefficiently.
probs cause its running away really fast and ya need to get to the point where you are orbiting at the same velocity
If youre watching a NASCAR race from the infield (the open grassy place in the middle of the racetrack where all the big RVs pand such park). The cars driving by are only a few hundred yards away from you. You could walk to the location they are in just a minute or so. But to “get to” them (i.e. to catch up to them so that you could “dock” with them or something) you not only need to get to the same location as them, but be going the same SPEED as them. So even though they are “close” to you, it takes awhile to catch up to them, even if youre driving a pretty fast car yourself.
Latest Answers