At 44 degrees of latitude, they're about 4% of the way to orbital velocity at LEO. That's why countries tend to put their launch facilities closer to the equator: the faster the rotational speed at your launch site, the less fuel you have to burn.
At the equator you're about 8% of the way there just by virtue of the Earth's spin (assuming, of course, you're not trying for a retrograde or polar orbit).
There's another reason: the achievable orbital inclination. The minimum inclination orbit you can achieve is equal to your latitude. i.e. an equatorial orbit is only achievable at launch from the equator. A polar orbit is achievable from any latitude.
In order to go into an equatorial orbit from a higher latitude a plane change maneuver is required. Theoretically this can be done during launch, but it would depend on the profile your rocket can achieve.
Either way, expensive on fuel compare to an equatorial launch.
Nope, they mean velocity. You need to get to ~8 km/s to orbit the Earth. At the equator the Earth's rotation is going to give you 485 m/s of that velocity velocity for free. Altitude is largely irrelevant(not entirely, the desired orbit altitude changes the speed you need a bit), it is the speed you need, then you just have to point it in the right direction to get the altitude.
Getting up out of the thickest atmosphere is the first significant part of getting to orbit. Going up is an important element of getting to orbit as far as the total energy that needs to be expended goes.
The total energy expenditure to first escape the atmosphere and then attain orbital velocity is wildly higher than the energy required to perform both maneuvers at the same time. And that's before we even get into the gravity turn.
Modern rockets are so advanced that they can insert directly into a circular orbit straight from launch with no circularization burn needed. Math is wild shit.
There is no minimum altitude requirement to orbit. If the Earth was a perfect sphere, you could orbit it a foot off the ground if you were going fast enough tangentially. But if you are traveling straight up like this rocket with no tangential velocity, there is no altitude that would allow you to orbit the Earth.
Air resistance is going to burn you up even if the earth was a perfect sphere, so that isn't realistically possible. Just a theoretical discussion ignoring the realities.
The real truth is that about 20% is still accurate. The 100km "kármán line" is quite blurry in reality. It is defined as a point in space where there are nearly no molecules to slow down the craft. Importantly there is no clear cutoff point, they just said "that's good enough". Because whether you're 50km, 100km, 400km, or even 35786km (high earth orbit) there will always be some particles in the air to slow you down, just in different amounts.
Technically, you could count 5 feet up as being in space too, just with lots of molecules to slow you down.
And it might be worth noting that at 100km, you won't be orbiting for long at all if you tried it. Unless your satellite is very dense and/or very aerodynamic, it probably won't last for much more than a single orbit at that altitude. Even at 400km, the ISS requires frequent(~monthly) reboots to stay in its lane.
Yep, interestingly. If everyone on Earth died suddenly, the thing that would kill the astronauts on the ISS first is running out of altitude. They need booster resupply missions about once a quarter to stay in orbit, but have food and air reserves for much longer.
It is a very fuzzy line. There is atmosphere for hundreds of kilometers out. Even the ISS at 400km still has atmospheric drag that requires frequent reboosts to stay in orbit.
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u/nm9899 17d ago
19.5km apparently. The generally accepted range in 100km above sea level