On NPR the other day, they said NASA chose Florida because they like being by the water in case of mishaps, and it helps to launch close to the equator. They also said that because of the earth’s rotation, the east coast is better because it gives the shuttle a little “boost.” I cannot wrap my brain around the last part. Wouldn’t the earth’s rotation give the same boost from anywhere on the globe (near the equator)?
Total layman here, but I venture a WAG: If the “boost” from the Earth’s rotation causes an eastward (relative to the ground) course of the spacecraft, then the boost helps bringing the spacecraft over the ocean if launched in Florida, which is obviously helpful. If launched on the West Coast, the same course would get it over inhabited land.
Well, it gets an eastward boost from wherever you launch it. Naturally, since Earth is giving you a little push in that direction for free, you’ll want to save the most fuel by accelerating further eastward — ultimately reaching an orbit that goes in the “counter-clockwise” direction when viewed from above the North Pole.
But if something goes wrong and you have to abort the mission in mid-ascent, you’d prefer it to happen over open ocean and not populated areas. Hence the preference for a Florida coast launch site, as opposed to California.
To get maximum boost from the Earth’s rotation, you also want the launch site as close the equator as you can reasonably get. Hence the preference for Florida over Maine.
The reason is range safety. Launching from Florida allows NASA to launch to the east, over water, avoiding populated areas. NASA does use Vandenberg AFB in California for launches into polar orbit. The European Space Agency uses French Guiana for similar reasons.
As China has demonstrated, you can launch from anywhere, including heavily populated areas, if you are willing to accept the casualties and property damage caused when an errant rocket lands on some unlucky town.
Guess it should have been obvious; makes sense now! Thanks folks!
If you launch in an eastward direction, the rotation of the Earth helps you, but if you launch westward, it’s a disadvantage. So if you want to launch eastward, and you want to launch over ocean in case of mishaps, then you have to start on the east coast.
They launch over the ocean for safety. Launching from Florida would give it the additional speed of the Earth’s rotation. They would have to launch from the West Coast after the launch angled over the ocean again and it would then be subtracting the speed of the Earth’s rotation from the rocket.
On a related note, it was once explained to me that the reason that Russian rockets all look “beefier” than American rockets is the fact that they HAD to be to get a similarly sized spacecraft into orbit from Khazikstan, which is apparantly a good bit farther from the Equator than Cape Caneveral is. Any plans for American and Russian spacecraft to meet in orbit also requires some PITA planning because of the difference in lattitude between launch sites.
In more detail: It’s easiest to launch into an orbit whose inclination is the same as your latitude. For orbits with a greater inclination, it’s harder, since you lose some of the advantage of the Earth’s rotation. And it’s almost impossible to launch into an orbit whose inclination is less than your latitude. So most Shuttle orbits have an inclination of 29 degrees, since that’s the latitude of Cape Canaveral. But the International Space Station has to be reachable by both American and Russian rockets, so they had to put it in a higher inclination orbit of 47.5 degrees (the latitude of the Russian launch sites). The Shuttles can reach this, but it’s more difficult, so only those Shuttles specifically intended to go to the ISS are launched into an orbit that can reach it. A shuttle crew couldn’t just spontaneously decide to stop in for a visit, once they’re in orbit.
Satellites intended for polar orbit were usually launched from Vandenberg AF base near Santa Barbara, CA. There you could launch toward the south and be launching over open ocean which, as has been said, is desirable in case of abort and to let the bossters fall into the sea.
The other main reason ESA uses French Guiana (Kourou) rather than somewhere in Europe itself is of course that it’s only about 5 degrees north of the Equator.
Note that Jules Verne, who usually tried to get the science right (ignoring the bullet as spaceship), came to the same conclusion as NASA and launched his fictional moonshot from Florida. This wasn’t just a coincidence.
Is there ever a reason to put a satellite in an opposite orbit (going clockwise when viewed from above the north pole)?