Astrophysics Question ??

Question

Due to the Earth's rotation, surface objects are actually moving with high velocities. What
fraction of the Earth's escape velocity is obtained by an object placed at the Earth's equator?
Ignoring weather as a factor, is it better to launch a rocket to the Moon from the equator or
a pole? Does direction matter? Explain your answer.

Answer 1

That is exactly why all nations with space agencies have their launch facilities as close to the equator as possible. NASA has KSC here in FL and ESA has someplace on the northeastern tip of South America.
To realise why, you have to do a thought experiment. If you did this for real, you'd probably hurt someone or damage something. Anyway...
Imagine your going down the highway in your car. You hold a rock out the window and release it. Don't throw it, just let it go. To you it will appear to fall down and back from you. However, to someone on the side of the road it will appear to arc forward with the car, but lose velocity. It already has kinetic energy when released--the kinetic energy of the car. Since the circumference of the earth at the equator is approx 24,000 miles and it takes approx 24 hours for the earth to rotate once on its axis, the ground at the equator is moving along at approx 1,000 miles per hour. The closer the launch facility is to the equator, the more of this kinetic energy the rocket will have at launch, thus requiring less energy to achieve orbital or escape velocity. Launching from either of the poles would require enormous amounts of energy and would be too cost prohibitive. Also, instead of fighting its momentum eastward, it's better to keep it going easterly after launch. The ground has already thrown it that way.

Answer 2

At the equator Earth's rotational velocity is about 1,000 mph so it makes sense to launch from any site closest to the equator. Since the Earth rotates from west to east the launch direction would be best towards the east.

Answer 3

Actually, it -does- make a difference. That's why we launch from the east coast. The circumference of the Earth is about 24,900 miles and it rotates in 24 hours so the speed at the equator is 24,900/24 = 1037 miles/hr. If you launch to the east, you pick up about 1037*cos(lattitude) miles per hour due to the Earths rotation from west to east. At Cape Kennedy, that's about 898 mph.

Doug

Answer 4

yes it is easier to launch a rocket from the equator due to obtained velocity from the rotation of the Earth
that is why we launch our space shuttles at the southern most tip in the U.S. which is Florida
Hawaii is actually farther south and closer to the equator but it is too hilly and bumpy to create a one mile long landing way and a giant landing pad

Answer 5

Yes direction and location matters. The equator is - relitavely speaking - rotating faster than at the poles. Launching in the direction of rotation (easterly) is beneficial.

Answer 6

You have it right. That is why NASA launches shuttles to the east. It gives the shuttle a 1,000 mph boost because that is the direction the earth rotates.