Where does this come from, and can I check it?

A 2.2 micrometre error left every image blurred until astronauts fitted corrective optics. The figure is taken from NASA Hubble, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.

Is this really a space fact?

Yes. It sits on the Space shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.

What else can I read about it?

The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.

Mondo Knows Facts

The Hubble mirror was ground to the wrong shape

A 2.2 micrometre error left every image blurred until astronauts fitted corrective optics Hubble launched in 1990 with a primary mirror polished 2.2 micrometres too flat at the edge, about one fiftieth of a human hair. The error came from a miscalibrated test instrument rather than the mirror itself. A 1993 shuttle servicing mission installed COSTAR and four new instruments. It sits in Mondo's space collection, one of 200 facts that each trace back to the reference below.

Where this comes from

NASA Hubble

Facts that can change over time are reviewed and updated. If something here looks wrong, Mondo would rather know than be confidently incorrect.

Go further

Space & Astronomy trivia

More facts like this

The Hubble Deep Field uncovered thousands of distant galaxiesFocusing on a tiny patch of dark sky revealed deep cosmic history The space shuttle flew 135 missionsFive orbiters carried 355 people between 1981 and 2011 Venus Express circled the planet for nine yearsIt mapped winds, sulphuric acid clouds and the greenhouse far below Spectacles appeared in Italy in the late thirteenth centuryA Florentine sermon from 1306 mentions lenses made only recently Optical fibres trap light using total internal reflectionLight signals bounce inside glass cores without escaping through the outer boundary Light bends when transitioning between different transparent materialsRefraction alters the direction of light waves due to changes in propagation speed

Tags: hubble, optics, missions

The Hubble mirror was ground to the wrong shape: the short answers

Where does this come from, and can I check it?: A 2.2 micrometre error left every image blurred until astronauts fitted corrective optics. The figure is taken from NASA Hubble, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
Is this really a space fact?: Yes. It sits on the Space shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
What else can I read about it?: The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.