Hubble to get an even bigger picture of the universal web

BY THE end of the year, the world's greatest telescope should see deeper into space and further back in time than ever.

If all goes as planned, it will detect events closer to the big bang, explore the "cosmic web" of galaxies and intergalactic gas that make up the large-scale structure of the universe, and reveal much more about how and when distant stars and planets were formed.

NASA scientists, engineers and astronauts are finalising plans for an October mission to repair and improve the Hubble Space Telescope.

The long-delayed mission will be the last for the Hubble, says NASA, but it will allow the telescope to perform at its highest level for the remaining five or six years of its operating life.

"This will be the first time ever that the instrument box is full," said a Hubble senior scientist, David Leckrone, last week. "We will have the most powerful imaging capability on Hubble ever, and possibly anywhere."

It is hard to overstate the importance of the Hubble and its insights into the evolution of the universe, the presence of dark matter and dark energy, and the existence of hundreds of planets orbiting distant stars.

Scientists said observations by the telescope had resulted in an average of 12 published discoveries a week for years.

"This is surely the most productive telescope in history," said Charles Mountain, director of the Space Telescope Science Institute at Johns Hopkins University.

The mission will be the fifth to the observatory that orbits almost 560 kilometres above Earth.

Launched with fanfare in 1990, the instrument cost more than $US3 billion (funded by NASA with contributions from the European Space Agency) but did not work initially because of an embarrassing mistake in its 2.4-metre mirror.

In 1993 the first repair mission in orbit succeeded in installing corrective optics that allowed the telescope to begin sending back spectacular and often awe-inspiring images.

In this final mission, two new instruments will be installed so the telescope can see across the light spectrum, from ultraviolet to optical and infrared, and explore the cosmic web in extreme ultraviolet frequencies.

Assuming the mission goes off as planned, the first new Hubble data and images are expected by early next year.