# "Cigar-shaped satellite" from early days of spaceflight — details?

In Kleppner and Kolenkow’s An Introduction to Mechanics (1973), the authors relate the following story:

They go on to explain why this occurred (summary: angular momentum is conserved; kinetic energy gets lost due to centrifugal “kneading” of satellite; and for a given angular momentum, spinning around axis with higher moment of inertia results in lower kinetic energy.)

My question is the following: does anyone know if this actually happened? If so, what was the name of the satellite in question, and when did this incident occur? Kleppner & Kolenkow don’t provide any details other than the quote above. I’d love to be able to cite this as an example when I’m teaching the subject, but I’m a little worried that this just one of those science & engineering urban legends that get repeated in each generation of textbooks but are never adequately confirmed. (See also: the effects of the Coriolis force during the Battle of the Falkland Islands.)

Looks like this guy saw it - or something like it:

But no one seems sure what it was - some suggestions are that it was echo 1 deflated:
http://en.m.wikipedia.org/wiki/Project_Echo

What doesn’t seem to jive with your source, but thought I’d throw it out there anyway

I was just reading up on this this morning. The US’s first satellite Explorer 1.

Cool - that definitely seems like it is it - also seems close to the date of the posted I mentioned - so it probably answers his question too.

From reading up on it this morning, it seems that when the spin was imparted along the long axis, this generated an angular momentum Iw. What happened was that it started precessing with a new moment of inertia J and new angular velocity v such that Iw = Jv (conservation of angular momentum) and while J>I, v<w and Jv[sup]2[/sup] was at a minimum.

Heinlein must have been so embarrassed. :rolleyes:

This, I’ve argued, is why the Discovery ended up flipping end over end in the movie 2010. The bearings in the internal rotating centrifuge must’ve eventually seized up from lack of maintenance, which set the whole ship spinning about its long axis, and eventually it ended up flipping end over end.
I used K&K my freshman year. Years later I had Dan Kleppner teaching me advanced mechanics.

That must be it. Thanks for the info!

I believe ACC explained it at some length in the book, almost exactly as you’ve put it. The force from the carousel slowing down was transferred to the whole ship. IIRC, he describes *Discovery *as going through an amazing series of gyrations as they power up the centrifuge section again.