When scientists are looking into space, the more they can see, the easier it is to piece together the puzzle of the cosmos. The James Webb Space Telescope's mirror blanks have now been constructed. When polished and assembled, together they will form a mirror whose area is over seven times larger than the Hubble Telescope's mirror.
A telescope’s sensitivity, or how much detail it can see, is directly related to the size of the mirror area that collects light from the cosmos. A larger area collects more light to see deeper into space, just like a larger bucket collects more water in a rain shower than a small one. The larger mirror also means the James Webb Space Telescope (JWST) will have excellent resolution. That's why the telescope's mirror is made up of 18 mirror segments that form a total area of 25 square-meters (almost 30 square yards) when they all come together.
The challenge was to make the mirrors lightweight for launch, but nearly distortion-free for excellent image quality. That challenge has been met by AXSYS Technologies., Inc., Cullman, Ala. "From the start, AXSYS Technologies has been a key player in the mirror technology development effort," said Kevin Russell, mirror development lead at NASA's Marshall Spaceflight Center, Huntsville, Ala.
If the mirror were assembled completely and fully opened on the ground, there would be no way to fit it into a rocket. Therefore, the Webb Telescope's 18 mirror segments must be set into place when the telescope is in space. Engineers solved this problem by allowing the segmented mirror to fold, like the leaves of a drop-leaf table.
Each of the 18 mirrors will have the ability to be moved individually, so that they can be aligned together to act as a single large mirror. Scientists and engineers can also correct for any imperfections after the telescope opens in space, or if any changes occur in the mirror during the life of the mission. Each segment is made of beryllium, one of the lightest of all metals known to man. Beryllium has been used in other space telescopes and has worked well at the super-frigid temperatures of space in which the telescope will operate.
Each of the hexagonal-shaped mirror segments is 1.3 meters (4.26 feet) in diameter, and weighs approximately 20 kilograms or 46 pounds. The completed primary mirror will be over 2.5 times larger than the diameter of the Hubble Space Telescope's primary mirror, which is 2.4 meters in diameter, but will weigh roughly half as much.
"The James Webb Space Telescope will collect light approximately 9 times faster than the Hubble Space Telescope when one takes into account the details of the relative mirror sizes, shapes, and features in each design," said Eric Smith, JWST program scientist at NASA Headquarters, Washington. The increased sensitivity will allow scientists to see back to when the first galaxies formed just after the Big Bang. The larger telescope will have advantages for all aspects of astronomy and will revolutionize studies of how stars and planetary systems form and evolve.
The 18 mirrors have now been shipped to L-3 Communications SSG-Tinsley, Richmond, Calif. where they can be ground and polished.
After the grinding and polishing, the mirror segments will be delivered to Ball Aerospace in small groups where they will be assembled. Once the mirrors are completed, they will go to NASA's Goddard Space Flight Center, Greenbelt, Md., for final assembly on the telescope.
Upon successful launch in 2013, JWST will study the first stars and galaxies following the Big Bang.
X PRIZE today announced registration dates and rules changes for the $2 million Northrop Grumman Lunar Lander Challenge, which will require a vehicle to simulate trips between the moon’s surface and lunar orbit.
NASA, which signed a Space Act Agreement with X PRIZE before the first year’s competition for the Northrop Grumman Lunar Lander Challenge in 2006, will once again fund the prizes through its Centennial Challenges program.
X-ray bursts are among the most fascinating of astrophysical phenomena. Now, a new finding by a team led by University of Notre Dame astrophysicist Michael Wiescher will enable researchers to derive many more qualitative predictions about X-ray burst behavior and characteristics.
X-ray bursts are thermonuclear explosions in the outer atmosphere of accreting neutron stars. The accreted hydrogen and helium-rich material burns through steady fusion processes, heating the neutron star atmosphere toward the ignition point.
NASA's drive to return astronauts to the moon and later probe deeper into space achieved a key milestone recently when agency officials approved critical elements of a moon impact mission scheduled to launch in October 2008. NASA's unmanned Lunar Crater Observation and Sensing Satellite, known as LCROSS, will strike the moon near its south pole in January 2009. It will search for water and other materials that astronauts could use at a future lunar outpost.