Jupiter Mission – Holiday
From the Captain’s log USS Discovery, Tue Dec 25, 2012 00:08:30 GMT
It’s Christmas day. The first of several that we will spend out here in deep space. Last week mission control had us record a Christmas special called “Christmas in deep space” that is to be broadcast today.
Ralph, Hal and I exchanged the expected rounds of “Merry Christmas” and talked about what it’s like to spend Christmas farther away from home than anyone in history. We also recorded messages to family and friends to be transmitted back home. Because of the special, their holiday messages to us were recorded and sent to us two weeks ahead of time.
It was done that early not only because of the usual production work involved in such things but also because of the increasing delay in communications.
At our present distance which is a little over 110.5 million miles (and getting greater at the rate of approximately 70,843 miles per hour) it takes a bit over ten minutes for the radio signal to travel from Earth to us and another ten minutes for our replies to arrive there.
We arrive at that figure by taking our distance from the Earth and dividing it by the speed that radio communications travel which, for all intents and purposes is the speed of light. (this is not always true but it’s close enough for this calculation)
The basic formula is one you learn in grade school.
time = distance divided by speed
time delay in seconds = distance from Earth (currently 1.189au which converts to 110,524,550 miles) divided by 182,000 miles per second (the speed of light)
As we get farther from Earth this time delay in communications will get longer. It is one of the reasons that we have so many redundant systems as well as literally tons of spare parts, tools and supplies for doing repairs. We are very much on our own out here and every possibility had to be planned for no matter how remote that possibility might be.
I have been asked to give a simplified explanation of how far away we are and how much farther we have to go. I made a graphic of our orbit and Jupiter’s orbit and used it with the following;
To help visualize the distances involved the yellow circle in the graphic is Jupiter’s orbit around the sun. The place where the green ellipse meets the yellow circle is where we will meet up with Jupiter.
The solid yellow line shows where Jupiter is in that orbit now. The green ellipse is our orbit and the solid green line shows our current position in that orbit. Years from now we will use a similar orbit to return to Earth.
As you can see Jupiter will travel almost a quarter of the way around it’s orbit by the time we get there. We are a little under a fourth of the way to the point where our two orbits meet. Even moving at our incredible speed of over 70,000 miles per hour we have over a year to travel before we get there.
Some may look at that graphic and think that it would be faster to travel in a straight line. The answer is that it would be faster. Unfortunately to do that would require more fuel for acceleration and braking than a hundred ships like Discovery could carry. In fact, any ship that could carry that much fuel would be have so much mass no rocket engine we can build could move it faster than a snails pace.
Filed under: Short Stories
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