The Hubble Space Telescope was designed to be upgraded and repaired throughout its life.
And after its launch in 1990, this fact became very important.
When Hubble’s first pictures came back to Earth, they didn’t look quite right.
The images were blurred and out of focus,
because Hubble's primary mirror had been ground too flat.
In 1993, Hubble’s first servicing mission was launched:
They installed Wide Field and Planetary Camera 2, which compensated for the mirror’s imperfection.
Astronauts also added the Corrective Optics Space Telescope Axial Replacement, or COSTAR.
It almost acted like a pair of glasses for the primary mirror, fixing the image focus
for the rest of Hubble’s science instruments.
They also installed new solar panels, and replaced failing gyroscopes and magnetometers
so that the telescope’s orientation could remain accurate.
After Servicing Mission 1’s completion, Hubble was able to fulfill its original expectations
and much more.
Without it, Hubble and NASA may not be where they are today more than 30 years later.