Reference

The telescopes that left Earth

Hubble, JWST, Chandra and the rest — with their real specifications, in the same units used for every telescope in this catalog. None of these are for sale. That is rather the point.

Hubble Space Telescope

2400 mm

A 2.4-metre mirror parked above the atmosphere in 1990, launched with a flawed figure, repaired by hand, and still returning science more than three decades later.

1990-04-24OperationalNASA / ESA

Chandra X-ray Observatory

An X-ray telescope whose mirrors do not face the sky at all — light skims across them at a grazing angle, which is why the two numbers you would normally ask for do not exist.

1999-07-23OperationalNASA (Marshall Space Flight Center; operated by the Chandra X-ray Center at the Smithsonian Astrophysical Observatory)

James Webb Space Telescope

6500 mm

A 6.5-metre segmented infrared mirror that had to be folded to fit inside a rocket, unfolded a million miles from Earth, and kept below 50 kelvin to see anything at all.

2021-12-25OperationalNASA / ESA / CSA

Nancy Grace Roman Space Telescope

2400 mm

The same 2.4-metre mirror size as Hubble, arranged to see a hundred times more sky at once — a survey machine rather than a portrait lens.

2026-08-30Not yet operationalNASA