The Hubble Space Telescope cost about $1.5 billion to build and place into orbit. From its first pictures, imaging teams realized there was a problem. It turns out the primary mirror was ground incorrectly. The curvature was not to specification, and as an image was analyzed from the center out, the clarity of the image fell off. Poor resolution at the edges of an image made analysis of anything little more than a point object out of the question.
The problem was traced to a null corrector at the mirror manufacturer's site. It was assembled with incorrect spacing in a component, and the null corrector was then used to check the mirror and guide grinding during the shaping of the surface of the reflector. The flaw in the instrument was translated onto the mirror.
A link to the Wikipedia article on the Hubble is provided. So is one to a N.Y. Times article on the glitch.
Incidentally, the Mars Rovers have been spectacularly successful, and continue operating a full six years beyond their expected mission lifespan. The question might be referring to the unsuccessful Mars Climate Orbiter, which was launched in December, 1998.