Comments on: Traversing the Cosmos — With a Little Help from My Friends (Pt II)

By: Ryan Upton

Ryan Upton — Sun, 11 Jul 2010 16:26:46 +0000

What if your spaceship travels back in time close to the big bang era. Moves a small distance without effecting anything. Then travels back to the present day. In this way you could move large distance across the universe and you wouldn’t even have to break Einsteins rule of ‘no faster then light travel’.

By: Kevin Grazier

Kevin Grazier — Wed, 07 Jul 2010 19:08:49 +0000

You are correct, and I have edited that to read: ““So consistent with our previous statement “pass behind to gain speed/pass ahead to lose”, if Phaeton approached Neptune as in the diagram, they would be catapulted out of the Solar System and onto Eridani.” – KRG

By: J. R.

J. R. — Wed, 07 Jul 2010 16:56:52 +0000

It seems there is a bit of confusion with your wording.

“For a gravity assist in the real world, a spacecraft passes behind a planet (as above) to gain speed/kinetic energy, and behind to lose it.”

and

“So consistent with our previous statement “pass behind to gain speed/pass behind to lose”, if Phaeton approached Neptune as in the diagram, they would be catapulted out of the Solar System and onto Eridani.”

You said ‘pass behind’ all instances… Wouldn’t you need to pass ahead of the planet to lose speed?

By: Nekura

Nekura — Wed, 07 Jul 2010 00:48:51 +0000

What would you recommend as a good introductory book to read more about orbital mechanics? I’ve always been curious about it, like how getting to Phobos would be much easier then getting to Mars itself, but only find equation dense papers when I try to look stuff up online. And I have some mistaken ideas, like, I though that slingshot maneuvers stole rotational energy from a planet, rather than orbital energy, or that thrust/break maneuvers at aphelion/perihelion would change the height of the other, making dropping into the sun really easy. Reading bits and pieces doesn’t give a whole, connected picture.

Thank you
Nekura