Jonathan Amos is a science correspondent for the British Broadcasting Corporation.
A small rock fragment has hit the main mirror.
The mission's overall performance is not expected to be affected by the damage done to the observatory.
On July 12th, the first views of the universe will be released.
The images would be even more stunning because of what happened.
Sometime between 23 and 25 May, there was an incident.
The mirror segment known as C3 was struck, according to analysis.
Even the smallest particles can give a lot of energy when they collide with another object. The most significant event has been hit five times.
The open design of the telescope's mirrors makes them impervious to the kind of tubular baffles seen on other telescopes. The giant sun shield behind the reflectors allows them to maintain a stable temperature.
contingencies like this were incorporated into the choice of materials, the construction of components and the different modes of operation of the telescope.
The space environment includes harsh ultraviolet light and charged particles from the Sun, cosmic rays from exotic sources in the galaxy, and occasional strikes by micrometeoroids.
It was designed and built to perform its ambitious science mission after many years in space.
Engineers will adjust the positioning of the mirror segment to remove some of the distortion, but they can't remove all of it.
The Universe is being observed to show its capabilities. The pictures will be presented to the world.
The scientists want to see the first stars in the universe more than 13 billion years ago.
The telescope's big "eye" will be trained to look at the atmospheres of distant planets to see if they are hospitable.