The Hubble Space Telescope resumed science observations on Friday after ground teams spent most of the last three weeks assessing the performance of a finicky gyroscope, NASA said.

The troublesome gyroscope is a critical part of the observatory’s pointing system. Hubble’s gyros measure how fast the spacecraft is turning, helping the telescope aim its aperture toward distant cosmic wonders.

Hubble still provides valuable scientific data for astronomers nearly 34 years since its launch aboard NASA’s Space Shuttle Discovery in 1990. Five more shuttle servicing missions repaired Hubble, upgraded its science instruments, and replaced hardware degraded from long-term use in space. Among other tasks, astronauts on the last of the shuttle repair flights in 2009 installed six new gyroscopes on Hubble.