human
Something wrong here! exclaimed the doctor.
gpt
She has no attraction for us.
human
Well, how do you explain this? I asked.
gpt
You say the whole projectile weighs only two pounds toward Phobos, when, just a short time ago, I weighed nearly eight pounds myself on the scales.
human
True enough! he cried;
gpt
He began figuring rapidly, and then exclaimed:
human
We weigh one hundred and thirty pounds toward Mars, and only two pounds toward the satellite. Small wonder that we could not make a landing, with Mars pulling us away sixty-five times harder than Phobos attracted us! But this is very strange! I remember no mention of this in any of the astronomical writings, and it is as easily calculable on Earth as it is here. Moreover, this must cause everything that is loose upon Phobos to fall upon Mars. The great planet is tugging at everything the satellite has with a force sixty-five times stronger than her own!
gpt
Now, I am afraid those figures won't do, Doctor, I put in.
human
For, if what you say is true, what prevents the whole satellite from tumbling into Mars at once?
gpt
She would do so were it not for centrifugal force. The speed with which she whirls around the planet must just balance the force with which he attracts her, and thus she is kept in her orbit. But stones and loose things on this side of her centre are attracted more strongly by Mars than they are repelled by the whirling, so they must all have fallen to the planet. That is why the surface was perfectly barren. If Phobos always keeps the same side turned toward Mars, there may be rocks and soil on the outer side, and we could land there with a positive current; but we could not see the great planet, as I had hoped.
human
I have had quite enough of this moon-chasing, I said;