SMARTER STRATEGIES

James Webb Space Telescope Smarter Than Hubble

R. Colin Johnson | Date: 05-05-11 | Comments

The stunning images taken by the Hubble Space Telescope will be like sketches compared with improved images to be delivered by the James Webb Space Telescope, the world�s next-generation space observatory.

The James Webb Space Telescope will outperform the Hubble's single mirror by focusing the light from 18 separate mirrors onto a single sensor, enabling ultra-high-resolution observation of the most distant objects in the universe.

The main scientific goal of the James Webb Space Telescope will be to peer back into time, imaging the oldest galaxies in the universe, hopefully stretching back to original light from the "Big Bang." Everything about the design and deployment of the James Webb Space Telescope has been optimized for this task�from its 18 interlocking hexagonal mirrors to its positioning in synchronous orbit with Earth around the sun.

The James Webb Space Telescope's mirrors undergoing cryogenic testing (Source: NASA)

First off, the James Webb Space Telescope will solve problems faced by the Hubble Space Telescope, which is orbiting just 350 miles above us, bathing it in infrared radiation (heat) from Earth, moon and sun, as well as causing logistical problems in aiming it. The James Webb Space Telescope, on the other hand, will be positioned almost a million miles further from the sun than us, in synchronous orbit with Earth. As a result, a single heat shield can immerse the telescope in a shadow where infrared from the sun, Earth and moon never reach it. Also, the telescope can be easily aimed outward to observe distant galaxies without any nearby objects obstructing its view.

Secondly, the James Webb Space Telescope will not try to be all things to all scientists, like the Hubble Space Telescope, which has both visible light and infrared sensors.

The Hubble's 8-foot mirror (left) will be supersized on the James Webb Space Telescope, where 18 separate 5-foot segments collect six times more light. (Source: NASA)

Instead, the James Webb Space Telescope will be dedicated to the higher-resolution imagery possible with infrared images, giving it a better chance of achieving its goal of imaging the oldest galaxies in the universe. The James Webb Space Telescope uses 18 interlocking hexagonal mirrors, because there is no launch vehicle for a single mirror measuring 21 feet. Together the mirrors, which were recently polished at the cryogenic temperatures of space (minus 400 degrees), will gather more than six times more light than the Hubble Space Telescope.

The James Webb Space Telescope is a project of the U.S. National Aeronautics and Space Administration (NASA) with international collaboration from the European Space Agency (ESA) and the Canadian Space Agency (CSA) and 15 other nations. It is on schedule for deployment in 2014 atop an Ariane 5 rocket manufactured by Astrium (under the authority of the European Space Agency and the Centre National d'Etudes Spatiales). The James Webb Space Telescope will be positioned 930,000 miles on the far side of Earth, where it will revolve around the L2 Lagrange point. There it will remain in synchronous orbit with Earth around the sun for at least five years running scheduled observations, but like the Hubble, scientists hope it will keep operating for at least a decade.