JWST versus Hubble

The James Webb Space Telescope is due to launch in October 2018, ushering in a new era of observation that will enable us to look at the early Universe.

But how will it compare with the current king of orbiting observatories, the Hubble Space Telescope? Ben Skuse investigates.

Find out more about how the James Webb Space Telescope will change our understanding of the Universe in this month's BBC Sky at Night Magazine, out 18 May!

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An illustration showing how the Chandra X-ray Observatory and the Hubble Space Telescope’s Great Observatories Origins Deep Survey compares with the power of the James Webb Space Telescope. JWST will be able to gaze into the early Universe and observe the period during which the first stars were being born.
Credit: NASA/ESA and Ann Feild (STScI)

Unlike Hubble – which mainly looks at the part of the electromagnetic spectrum we can see as well – the James Webb Space Telescope (JWST) will primarily see in the infrared.

These longer wavelength observations will enable JWST to reach farther back in time to the formation of the first galaxies, deeper inside dust clouds where stars and planetary systems are forming, and will offer the chance to analyse the atmospheres of distant potentially habitable worlds that may harbour life.

The price for such insights is high – an estimated $10 billion lifetime cost. 

For that you get a 25 m2 gold-coated beryllium mirror, four advanced cameras and detectors, a spacecraft bus and sunshield, Ariane 5 rocket, and seven years of the lives of the best minds in NASA and the European and Canadian space agencies.

But how will JWST compare with Hubble? Find out in our facts and figures below:


The Hubble Space Telescope

The Hubble Space Telescope floating in Earth orbit (Credit: NASA / STScl)

Cost to launch: $4.7 billion

Orbital distance from Earth: 570km (orbits Earth)

Imaging wavelength coverage: 0.1 - 2.5 microns (mainly around the ultraviolet/visual/infrared band)

No. of science instruments: 5

Diameter of light-collecting mirror: 2.4m

Size of spacecraft: 13.2 x 4.2m (the size of a lorry with a trailer)

Total payload mass: 11,110kg

How far the telescope can see: 400-600 million years after the Big Bang

Operational lifetime: 27 years and counting


The James Webb Space Telescope

An artist's impression of how the JWST will look once it has been launched (Credit: Northrop Grumman)

Cost to launch: $7.998 billion

Orbital distance from Earth: 1.5 million km (orbits the Sun)

Imaging wavelength coverage: 0.6 - 28 micrometres (from near-infrared to mid-infrared)

No. of science instruments: 4

Diameter of light-collecting mirror: 6.5m

Size of spacecraft: 22 x 12m (the size of a 737 aircraft)

Total payload mass: 6,200kg

How far the telescope can see: 200-275 million years after the Big Bang

Operational lifetime: 10 years and counting


Find out more about how the James Webb Space Telescope will change our understanding of the Universe in this month's BBC Sky at Night Magazine, out 18 May.

 

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