Eyes on the Cosmos -European Space Agency's Hawk 1 & Hubble's Successor

NASA and the European Southern Observatory are creating new space-exploration instruments that will provide astronomers with next-generation tools to explore faint light from the most ancient, distant objects of our Universe.

Scientists and engineers at NASA have have created and successfully tested a set of algorithms and software programs which are designed to enable the 19 individual mirrors comprising NASA's powerful James Webb Space Telescope, Hubble's successor, to function as one very sensitive telescope when it goes in orbit in 2013.

Europe's flagship ground-based astronomical facility, the European Southern Observatory (ESO) Very Large Telescope (VLT) high in Chile's Atacama Desert, has been equipped with a new 'eye' to study the Universe. The ESO, more formally the European Organization for Astronomical Research in the Southern Hemisphere, is composed and supported by twelve countries from the European Union plus Switzerland. Created in 1962, it is famous for building and operating some of the largest and most technologically advanced telescopes in the world, such as the New Technology Telescope (NTT), which was one of the telescopes which pioneered active optics technology, and more recently the VLT, consisting of four 8-meter class telescopes.

In 2005, ESO astronomers captured the first picture of an exo-solar planet, 2M1207b, orbiting a brown dwarf 260 light-years away.

Working in the near-infrared, the new camera - dubbed HAWK-I (High Acuity, Wide field K-band Imaging) saw first light on July 31, 2007. It covers about 1/10th the area of the Full Moon in a single exposure, and s uniquely suited to the discovery and study of faint objects, such as distant galaxies or small stars and planets.

Hawk-1 provides an international team of astronomers with incredible resolution (0.1 arcseconds per pixel, which is basically what Hubble can do) and a wide field, peering at a field 7.5 arcminutes square. The VLT, houses an 8 meter mirror (for comparison, Hubble’s mirror is 2.4 meters across, less than 1/10th the area).

After its launch in 2013, he Webb Telescope will settled into its vantage point about one million miles from Earth. Periodically thereafter, the orientations of the telescope’s 18 primary mirror segments and the position of the secondary mirror will have to be adjusted to bring light from the universe into focus. Through a process called "Wavefront Sensing and Control," or WFSC, software aboard the observatory will compute the optimum position of each of the 19 mirrors, and then adjust the positions, when necessary.

"This major technological accomplishment, which built on the legacy of software algorithms used to fix the Hubble Space Telescope and align the Keck telescope, is a major step forward in the development of JWST." said John Mather, Senior Project Scientist on the Webb telescope at Goddard and the 2006 winner of the Nobel Prize in Physics.

The Webb Telescope's 18 primary mirror segments cover a combined total area of 25 square meters (approx. 30 square yards) and a diameter of 6.5 meters (approx. 21 feet). This will allow scientists to clearly focus on very dim objects that we can't see now.

The WFSC system is put to work when the telescope takes digital pictures of a star. It then processes the images through mathematical algorithms to calculate the mirror adjustments required to bring the stellar image into focus. When the individual mirrors are properly aligned, the Webb Telescope will be able to obtain extraordinarily sharp images and detect the faint glimmer of a distant galaxy.

During Hawk-1's first light this August, varied astronomical objects were observed to test different characteristics of the instrument. For example, during one period of good atmospheric stability, images were taken towards the central bulge of our Galaxy. Many thousands of stars were visible over the field and allowed the astronomers to obtain stellar images only 3.4 pixels (0.34 arcsecond) wide.

HAWK-I takes images in the 0.9 to 2.5 micron domain over a large field-of-view of 7.5 x 7.5 arcminutes. This is nine times larger than that of ISAAC, another near-infrared imager on the VLT that went into operation in late 1998. ISAAC has shown how deep near-infrared images can contribute uniquely to the discovery and study of large, distant galaxies, and to the study of discs around stars or even very low mass objects, down to a few Jupiter masses.

"Until the availability of the James Webb Space Telescope in the next decade, it is clear that 8-m class telescopes will provide the best sensitivity achievable in the near-infrared below 3 microns," explained Mark Casali, the ESO scientist responsible for the instrument.

HAWK-I will also be very well suited for the search for the most massive stars and for the least massive objects in our Galaxy, such as hot Jupiters. But HAWK-I will also be a perfect instrument for the study of outer Solar System bodies, such as distant, icy asteroids and comets.

Posted by Casey Kazan.