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Space telescope

An observatory placed in orbit so it can look outward without the Earth's atmosphere blurring, absorbing or brightening what it sees.

Why it matters

The atmosphere is not a neutral window: it smears fine detail, blocks most infrared and ultraviolet light entirely, and adds a background glow. Putting the instrument above it is the only way to observe at those wavelengths at all, which is why the wavelength a telescope is designed for largely decides whether it must fly. The price is that nothing can be repaired by hand once it is out there, so a space telescope is built to a standard closer to a spacecraft than to a ground observatory, and a deployment failure is usually final.

In our data

Telescopes take up far more of our coverage than of our launch manifest: only 1 of the 350 missions we track is classified as a space telescope launch, yet observatories are among the most-written-about subjects across our 688 published articles. It is the clearest case on this site where public interest and industrial volume point in opposite directions.

Missions we track
Where we use it
Not to be confused with

A ground-based observatory, which can be far larger and is serviceable, and an Earth-observation satellite, which carries similar optics pointed in the opposite direction - down rather than out.