Hubble Trouble: heir apparent back on track

Hubble’s $8BN successor, the James Webb Space Telescope (JWST) is back on track after being hit with multitudinous delays stretching back to early 2011.  The JWST will be the largest telescope ever sent to space and one of the most sophisticated pieces of technology ever created.

Over budget and behind schedule, the JWST is heading into an eventful year of testing & assembly as the four main components of the telescope arrived at the NASA Goddard Space Flight Centre in Greenbelt, Maryland.  In January, the telescope passed its final design milestone, the critical design review, where all systems were approved as functional.

Eric Smith, Washington’s JWST Deputy Programme Director for NASA, stated: “97% of the mass of the telescope is either built or on it’s way, paving the way for the manufacture of the telescope.” The delivery of the last primary mirror segment arrived on the 16th December 2013.

The JWST mission objectives are to search for the first galaxies or luminous objects formed after the big bang.  Furthermore, the mission will determine how galaxies evolved from their formation until now, whilst observing the birth of stars from their first stages to the formation of planetary systems.

The mission will also measure the physical and chemical properties of planetary systems, investigating the potential for life in those systems.

The JWST differs from its predecessor, the Hubble, because it uses infrared light in order to capture light from a longer wavelength band.  Because the universe is still expanding, the father away an object appears from Earth, the faster it appears to recede. This is known as the Doppler shift, and causes the wavelengths to stretch, or move towards the red end of the light spectrum. This does mean that the telescope can capture light from ancient, extremely distant stars and galaxies that could well be as old as the Universe.

The telescope is a work of genius. Engineered to work at temperatures lower than 50 Kelvin (-223 degrees), it is made from a composite graphite to cope with extreme temperature changes and to avoid contamination of images from heat radiation.  It also contains seven times the optics and collecting area of Hubble.

Instead of orbiting around Earth, the JWST will sit at the Earth-Sun L2 language point, 1.5 million km away.  At this point, Webb’s solar shield will block light from the Sun, Earth and Moon and ensure that the JWST can see back deep into the cosmos, potentially even to the beginnings of the universe.

Thomas Bamford

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