Originally posted by sonhousePointing the rockets downwards, to the surface of Mars, is totally in vain.
Is it possible to show how much force (choose your own units, Newtons, Kg, Tons, whatever) or thrust continuously applied like maybe a rocket on a circumferential railroad, constantly pointing to Mars or some like technology to provide Mars facing thrust, how much thrust is needed to keep it in a steady orbit?
Originally posted by sonhouseBut first you have to slow down its rotation to zero, or to a bounded rotation. In that way you can attach your propulsion device fixed to its ground.
Ok, backwards then. I was thinking the wrong vector, eh.
Originally posted by FabianFnasThat is the question, how much thrust? I guess the thrust could be minimized by the fact you have a few million years in which to act so if you had to do it in one year, you would clearly need 7.6 million times the thrust if you could do it in 7.6 million years, whatever that would turn out to be.
But first you have to slow down its rotation to zero, or to a bounded rotation. In that way you can attach your propulsion device fixed to its ground.
Now it's time to fire her up, and let her fire, feeding her with fuel, until you get high enough orbital energy.
Originally posted by sonhouseI don't know about the thrust but it is possible to clculate the power (in watt/horsepower/whatever).
This piece suggests Phobos will crash into Mars in 10 million years but will reach the Roche limit of about 7000 Km from the center of mars, 3620 Km above the surface, in about 7.6 million years and be torn to bits by tidal forces.
So here it is: Say it's a coupl hnology to provide Mars facing thrust, how much thrust is needed to keep it in a steady orbit?
Originally posted by David11335,000 hp. Ok. I think 1 hp is the energy needed to lift 555 pounds one foot in one second or 32 Hp to lift 555 pounds at one G.
I don't know about the thrust but it is possible to clculate the power (in watt/horsepower/whatever).
If I'm not mistaken it's not 3.13m per year but 0.313m per year.
The total energy (Potential+kinetic) of Phobos is -GMm/(2r), where G is the gravitational constant, M and m are the masses of Mars anf Phobos, r is the distance between their centers. Calcul ...[text shortened]... second, so the effective power of the engines must be 26 megawatt or about 35000 horsepower.
Originally posted by sonhousehttp://en.wikipedia.org/wiki/Tidal_acceleration
35,000 hp. Ok. I think 1 hp is the energy needed to lift 555 pounds one foot in one second or 32 Hp to lift 555 pounds at one G.
I guess that 35K hp would have to be continuously applied forever to keep it in that same exact orbit, or double it to 70,000 hp to make it go UP 313 Cm/year?
What bugs me is why is it not a stable orbit? Aren't the satellites i ...[text shortened]... rth at some small rate, an inch a year or something. What is making the difference for Phobos?
Originally posted by sonhouseIt would be stable if there were no outer forces in action. And there are lots of them acting on the satellite. Solar wind, radiation, other bodies, like Jupiter, etc.
What bugs me is why is it not a stable orbit?
Originally posted by David113Yes, I've read the article. Well written but old stuff.
Not true. Read the wikipedia article.
Originally posted by David113Very interesting article. One thing that fascinated me, the estimate of the energy in the lunar/Earth tidal effect: almost 4,000,000 megawatts! Too bad we can't tap into that somehow!