Advancing the Webb

Balancing its position between the Sun and Earth’s gravity, a next generation of Space Observatory is beginning to come off the drawing boards and onto the lathes and lens grinders of machine shops. Scheduled for launch in 2011, the Webb Space Telescope was officially named today after James E. Webb, NASA’s second administrator. Particularly sensitive to the infrared range of the universe, the telescope is part of large-scale international collaborations which also may enable imaging some kinds of extrasolar planets.

deep_hubble
This close-up of the large galaxy cluster Abell 2218 shows how this cluster acts as one of nature’s most powerful ‘gravitational telescopes’ and amplifies and stretches all galaxies lying behind the cluster core (seen as red, orange and blue arcs). Such natural gravitational ‘telescopes’ allow astronomers to see extremely distant and faint objects that could otherwise not be seen. A new galaxy (split into two ‘images’ marked with an ellipse and a circle) was detected in this image taken with the Advanced Camera for Surveys on board the NASA/ESA Hubble Space Telescope. The extremely faint galaxy is so far away that its visible light has been stretched into infrared wavelengths, making the observations particularly difficult.
Image Credit: NASA/ESA/Hubble

NASA’s James Webb Space Telescope (JWST) moved a major step forward with the opening of a state-of-the-art facility that will machine the observatory’s optical components.

The new facility houses advanced computer-aided manufacturing and metrology equipment that will shape JWST’s optical components to a high degree of accuracy. The components consist of 18 hexagonal beryllium segments for JWST’s primary mirror, measuring 1.3 meters from tip to tip, and other mirror substrates and support structures.

Fabrication in the facility will begin later this month and will be completed in 2007.

"Axsys Technologies’ new facility is critical to providing the lightweight beryllium mirrors that enable JWST’s large aperture," said Martin Mohan, JWST program manager, Northrop Grumman Space Technology. "The start of machining the beryllium blanks marks another key milestone accomplished on schedule for the JWST team."

Manufacturing the observatory’s mirror is a four-step process, which is being performed by a team led by Ball Aerospace. Brush Wellman compresses beryllium into large segments called "blanks;" Axsys Technologies machines the blanks; Tinsley Laboratories grinds and polishes the mirrors; and Ball incorporates the mirrors into optical assemblies and mounts them on the telescope structure. Manufacturing all 18 mirrors will take approximately four-and-a-half years.

At Axsys Technologies, machining and etching of the blank’s backside will reduce the mirror mass by 92 percent, from 553 pounds (250 kilograms) to 46 pounds (21 kilograms); machining of the front side prepares the optical surface for subsequent grinding and polishing. Earlier this year, Axsys Technologies started machining an engineering development unit (mirror prototype) to demonstrate its capabilities.

The observatory features a 6.5-meter (20 feet) aperture primary mirror that will be the largest deployable telescope ever launched. Beryllium, one of the lightest of all metals, was selected as the mirror technology for its demonstrated track record operating at cryogenic temperatures (around -400 degrees Fahrenheit) on space-based telescopes.

JWST will peer into the infrared at great distances to search for answers to astronomers’ fundamental questions about the birth and evolution of galaxies, the size and shape of the universe, and the mysterious life cycle of matter. In addition to distant galaxies, the longer infrared wavelengths are sensitive to galaxies that are intrinsically red, such as elliptical galaxies and galaxies that have red colors due to a high degree of dust absorption. A component of NASA’s Origins Program, JWST will reside in an orbit 940,000 miles from Earth at the L2 Lagrange point after its launch in 2011.

Timelines

1990
- Hubble Space Telescope launches aboard Space Shuttle Discovery, as Earth Orbiting Observatory

1994
- Hubble Space Telescope finds evidence of black hole in the center of M87
– Hubble Key Project begins studying Cepheid variable stars to better define Hubble Constant, and the size of the universe

The TPF
The Terestrial Planet Finder will search for Earth-like planets orbiting 250 of the closest stars.
Credit: NASA

1996
- Sidney van den Bergh and Gustav Tammann debate Hubble Constant and the scale of the universe

1998
- Jim Peebles and Michael Turner debate nature of universe and whether cosmology is solved

1999
- John Cowan confirms age estimates of globular clusters and universe by dating metal-poor stars
– Wendy Freedman and Allan Sandage debate Hubble Constant and the scale of universe

2001
- Hubble Space Telescope detects an atmosphere around an extrasolar planet

2002
- Chandra X-ray Observatory finds evidence for new matter in "quark stars", matter so dense it exceeds terrestrial nuclear material with 1.2 million degree temperatures

2003
- Final mission in NASA Great Observatory series, the infrared observatory, or Spitzer Space Telescope, finds evidence for organic molecules in intergalactic regions
Microwave measurements precisely date the Big Bang at 13.7 billion years ago, with a remarkable 1% error prediction

2006
- French COROT mission will look at 50,000 to 60,000 stars and should find a few dozen terrestrial planets and several hundred close-in gas-giant planets during a two- to three-year mission

2007
- Kepler, Extrasolar Terrestrial Planet Detection Mission, designed to look for transiting or earth-size planets that eclipse their parent stars [survey 100,000 stars]. Scientists expect to find thousands of planets, and perhaps 50 Earth-like candidates.
- Likely de-orbit for Hubble Space Telescope [date announced is highly fluid but assumes no planned shuttle visits from NASA]

2009
– Planned launch for Space Interferometery Mission (SIM)

2011
– Planned launch for NASA-ESA Next Generation Space Telescope, or NGST [James Webb Space Telescope], a near-infrared telescope that will succeed the Hubble Space Telescope.

2012-2015
- Planned launch for TPF and Darwin missions


Related Web Pages

Hipparcos Catalog
SETI Institute
How To Find An Extrasolar Planet
SIM (NASA’s Space Interferometry Mission
GAIA – The Galactic Census Project
FAME: Full-sky Astrometric Mapping Explorer
Habitability: Betting on 37 Gem
HabStars: Speeding Up In the Zone