ADMIN: This thread was split from the Rocketry thread for being off-topic and for giving us a number of different things to think about. It is based on the membership of a "pmb" who joined and said they are a specialist in relativity, and they claim to have done work for a NASA project. CluesForum invites you to read on, in order to see if you can learn anything about this special specialist on special relativity that NASA apparently hired. -HP
Since there are 522 posts I didn't think it would be a good way to spend my time reading all of them. I just skimmed through them.Selene wrote: Hi Pete, welcome to Cluesforum. Have you read quite a bit before registering?
Can you point me to one?Selene wrote: On satellites ("geostationary" and others) there's a separate thread where you find info on how to obtain the huge amounts of satellite data and signals (including your DirectTV) we receive on Earth.
As a physicist I know that such a thing is quite literally impossible. The laser beam would be so week after traveling only a mile that it'd be impossible to detect it after another 250,000 miles. Perhaps you're thinking of sunlight bouncing off the regolith? You're confusing bouncing a radar beam with bouncing a laser beam. They are radically different problems due to the radically different wavelengths.Selene wrote: As a physicist you also should know one doesn't need a 50x50 cm mirror to bounce back signals (radio waves, lasers or sunlight) from the surface of the Moon; the celestial body itself reflects signals easily, otherwise they wouldn't be able to do so before the Apollo "moon" missions (1963 the Soviets did it and radio wave bouncing was done already in 1946 (!) and you wouldn't be able to see a thing at nights with (full) Moonlight...
That's not a problem. There's heat shielding to take care of that. You've made a lot of statements here but have you ever made any calculations to back up your qualitative assertions?Selene wrote: As a physicist you know that material properties are highly T-dependent, so a "rocket" in "space" would have the problem that ~50% of the surface (sun-lit) suffers from very high T's (due to radiation) and the other half or even more of the "rocket" would suffer near-zero T's.
What's there to know? Matter is composed of atoms and molecules. The composition of the matter in those terms determines the conductivity. How exactly that's done is very hard to calculate and requires someone who specializes in that field. Not all physicists know all branches of physics. I'll look into it though.Selene wrote: Take the thermal conductivity for instance. Could you as physical expert make a calculation on how this works?
Those aren't the kind of problems that a physicist studies or solves. Those are done my physical chemists. See: https://en.wikipedia.org/wiki/Physical_chemistrySelene wrote: 50% aluminium rocket surface @ -let's say- +270 C and the other part at -NASA-claimed- -270 C, or some mere 3 K!
What effect should those extreme conditions have on the rocket and everything inside it, you think?
My specialty is relativity.