> as lemmas

1931 Proc. IRE 19 1534 The complications introduced into the transmitter led to the decision to limit the problem for the time to radio tracking.

1992 S. P. Maran Astron. & Astrophysics Encycl. 421/2 Radio tracking of the spacecraft yielded a precise radius for the planet that showed Mercury to be a more perfect sphere than either the Earth or Mars. A search for mercurian moons proved futile.