# Measuring and analyzing the tumble of space debris

How well or accurately can we measure the tumble of space debris?

I know that we can make ground-based measurements based on light curve data acquired by telescopes. Can tumble be measured from radar data?

What percentage of space debris do we already have tumble data for?

Primarily, I am wondering if there are currently any space-based methods for analyzing tumble.

• @Uwe I don't think tumbling is necessarily periodic, though I'm sure you can probably still figure out the motion making assumptions about the shape and reflectivity and gauging the principal moments of inertia. Commented Jun 22, 2021 at 16:38
• @RogerWood If there is conservation of angular momentum, how tumbling may be non periodic ?
– Uwe
Commented Jun 22, 2021 at 20:36
• @Uwe I don't underand this very well, but, despite the conservation of angular momentum and rotational energy, the axis of rotation can still wander around within the body and the rpm can change (see Tennis Racket Theorem). The wandering around with respect to the body is called the "polhode" and it is periodic. But the wandering around of the axis with respect to fixed space (the "herpolhode") is not generally periodic. See also en.wikipedia.org/wiki/Poinsot%27s_ellipsoid Commented Jun 23, 2021 at 2:32
• I did some more digging. It seems the best tumble/rotational data comes from AIUB in Switzerland. They have a database of light curves for about 400 pieces of space debris throughout LEO, HEO, and GEO. They also catalogue some GLONASS objects. Silha et. al did a phenomenal study on it. Here's the link: sciencedirect.com/science/article/pii/S027311771730786X#b0025 Commented Jun 23, 2021 at 12:32
• @JonathanL. excellent! It's always okay to answer your own question in Stack Exchange. If you feel it's only a partial answer just mention that in the beginning.
– uhoh
Commented Jun 24, 2021 at 0:04