If I'm right (and who knows, I just may be), that applies to a single body in an eliptical orbit. When the orbiting body is closer (ie the earth and the sun), it moves faster, when it's farther away it slows down, but in any given period of time (t) it will sweep and equal arc area. Whether or not you can apply it to two distinct bodies, I don't know. ----- Original Message ----- From: "O'Reilly John E NORC" To: Sent: Monday, March 26, 2001 4:37 PM Subject: Re: [OT]:Mir > If I remember right from college (university for those of you outside the > US), there was something about the area of the arc the orbiting object > sweeps out in a given amount of time is constant and based on the masses of > the two bodies. Basically, if you take the radius of the orbit r, multiply > by the angular velocity a / t , it is constant. r * a / t is constant. So, > as you increase r, the angular velocity decreases, and vice versa. I'm sure > there are hundreds of other equations that can be derived from this, but I > haven't touched this stuff in 7 years. > > On a similar note, the reason that NASA launches from Florida is that > launching to the east coast takes advantage of the rotation of the Earth. > It is also closer to the equator, which spins faster. If they were to > launch from the west coast, they would have to launch over my apartment. > Or, if they launched the space shuttle to the west, they would have to lose > about 50,000 pounds of payload to get into orbit. > > John > > -----Original Message----- > From: Barry Gershenfeld [mailto:barry@ZMICRO.COM] > Sent: Monday, March 26, 2001 1:01 PM > To: PICLIST@MITVMA.MIT.EDU > Subject: Re: [OT]:Mir > > > >From: "Matthew Mucker" > >> Actually, I think this is backwards. I'm no expert, but after > >> reading Gene Krantz' autobiography, I reacll that NASA had > >> lots of problems with stuff like this until they realized > >> that at a lower orbit, a body must revolve around the earch > >> much faster to keep it in orbit. Any experts out there who > >> can clarify? > > >Object of mass m rotating around a gravitation field of strength 'mu' > >so-called Earth: > >Centigugal force = m * V * V / R (V is velocity and R the > >radius) > >Weight = mu * m / ( R * R ) > (snip) > >Jeszs Gonzalo > > In english: At a higher orbit you are traveling faster. As in, > if you were standing still and watched it go by. (So-called, > linear velocity). But at the same time, it takes longer to > complete an orbit, so it "goes around" slower (so-called, > angular velocity). > > This is a favorite story of mine, because the best and brightest > missed the point the first time. Not that I knew anything, I > read about it in the paper back then, and I hope I remember > it right. > > On one of the early Gemini flights they did a rendezvous experiment. > As I recall, a lot of the Gemini program was aimed towards working > out all the particulars about rendezvous-and-docking for the > subsequent Apollo (moon shot) program. This flight predated > the later docking with other capsules, adapters, Russian > ships, etc. What they did was to put lights on the booster > stage which remained in orbit (or near-orbit) along with the > flight capsule. Early in the mission they practised the > rendezvous maneuver with this booster. It didn't work. > Basically the complaint was "the more I tried to catch > up with it, the farther away it got". So they went home > and did some head scratching, and presumably looked at > those formulas again, and said, "Oh...now we get it". > > Essentially you slow down, drop to a lower orbit, which > lets you swing ahead of the thing you want to catch up with. > > Orbital mechanics is interesting. > > Barry > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body > > -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body