Patch Conic Orbits and travel in simple terms.(soon)
A simple space lesson for 3rd Graders (you will need a flashlight, basketball, baseball or racket ball, a string, and many volunteers). It is a good thing to teach the next generation about the universe they might explore!
Faster than Light Navigation 101 by B. Meyer
When you stare at the night sky and see the point of light that is a heavenly body of some type, you are actually looking back in time.
For example, lets say I saw the star Sirius. What we see here on Earth is actually light from Sirius system that left 8.6 years ago (Sirius is 8.6 light years away).
SO if I had a starship that could instantly jump from Earth orbit to my observed Sirius, I would actually end up where Sirius WAS 8.6 years ago.
What I would actually have to do to get to where Sirius actually is at the current moment is something like this (assuming I don't have a library of all the current positions and motions):
Similified Look and See Navigation (one way of finding where I really need to go):
Outbound: What I need to do before leaving the comfort of Earth orbit (or where-ever)is to watch my target star for a while,
taking very careful measurements (using other stars as references) of its position relative to my current position.
After enough measurements I can now estimate the shape of the target star's path relative to me, modelling it in a computer program (via some interesting differential equations, this is why
it is good to get a background in calculus :0)
Depending on my errors, I may want to jump some of the distance to my target, repeat my observations to refine my model, then jump again until get near the target star system.
Return Trip (oh, you WANTED to get back to Earth, right?): Assuming you decide to stay a while at the Sirius system (or whatever target you chose), simply reversing your path may not be a good idea.
In your absence from the yellow light of our middle aged star Sol, Sol and its captive planet Earth, have also been moving relative to your current position at Sirius!
You may want to start those observations as soon as you arrive, assuming you know what Sol looks like 8.6 light years away (not a big deal if you kept track of Sol's characteristic spectrum for 8.6 years
before you left Earth. At Sirius you see Sol as it was 8.6 years (minus your time at Sirius) ago.
A real slick space pilot would have gotten a real good fix on Sol relative to other stars visible from Sirius for a long period, then reversed your model, and corrected it using current observations from Sirius.
If not, repeat all the steps used for the Outbound leg, and make lots of intermediate jumps to get you home.
FYI, you may want to also look for things to run into (or more likely shine too much radiation on you) that may be at your jump arrival points.
P.S. If you think this sounds easy, look for transcripts from the Apollo missions, and how much effort it was to use a similar technique just to go from Earth to the Moon and back.
Figure 1: Simplified Problem of FTL travel to distant bodies
