Space Trail: Newsletter Challenge (July 2014)

Choice, for speed and/or less energy consumption.

Vector calculation.

Also makes return to Earth more easy.

Makes the pass on the Moon closer.

Where is the gravity centre of Earth/Moon constellation? How dynamic is that centre?

I'd go because it is not possible to run on that ellipse. And it would not make sense after all.

Not sure but I think it is to take the craft through the lagrangian point where the craft moves from the earths gravity field into the moons gravity field.

http://en.wikipedia.org/wiki/Lagrangian_point

Regards JD.

Such a trajectory allows the vehicle to return to Earth without using fuel.

Just a couple other comments to this: Orbit #1 can (obviously) be tweaked to provide the 'free return' to Earth, in case an abort is needed; but so can orbit #2. Orbit #2 also yields a higher speed when the spacecraft hits the atmosphere, which is more dangerous. So #1 is the natural choice.

Dear CR4 colleges, I request your excuse in advance for any mistake in my knowledge.
The space craft tragectory around the Earth's orbit (West -East) is first to be stabilized from eliptical to circular motion. Again elliptical trajectory needed for jettisoning the payload on to the Moon's orbit. Now this elliptical motion with foci as Earth and Moon, the space craft trajectory makes "distorted figure EIGHT" (the motion of the space craft around moon is opposite of the direction around earth).

I agree, it's to prevent slingshot effect thereby preserving fuel.

And on the other hand, NASA had insisted for years that it was required to take three days to rendezvous with the ISS and now we do it in 6 hours, so maybe this isn't as cut and dried as one might think.

Just saying.....

Another reason: Transfer to lunar orbit is on this side of the moon, not the far side where communication is lost.

follows the lowest gravityfield

rounds the moon clockwise or anticlockwise?

"rounds the moon clockwise or anticlockwise?"

That sort of depends on your observational frame of reference.

Too!

Gravity Assist to take advantage of the large mass of the earth as well as the moon as compared to a spacecraft.

"The figure eight path allows the spacecraft to remain almost equidistant from the centers of the earth and the moon."

To 'remain' equidistant from the centers of the Earth and the Moon?

You gotta be kidding.

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Agreed.

Provided answer is nonsense.

Half of last month's 'correct answer' was flat wrong. The 'correct answer' to that buoyancy CQ sometime back was a flight of fantasy. There've been a bunch, but the 'correct answer' to this month's CQ surely wins the Governor's Prize for The Most Nonsensical Answer On Record. Take a look at it: it is complete and utter nonsense.

When the authors of these CQs don't check their work and come up with these nonsensical answers, it just leaves participants wondering "Why did I even bother?"

That is exactly what myself and others are wondering right now. Why did we bother? Truly? We take the time to work these out; is it unreasonable to expect the author to do the same, maybe maybe even have someone check his/her work before publication? Peer-review: Top-tier science journals do that; it is why they are Top-Tier science journals.

"The figure eight path allows the spacecraft to remain almost equidistant from the centers of the earth and the moon."

You've got to be kidding. For starters, somebody please tell that author what 'equidistant' means? Please? We'll take it from there.

-e