Sir William Herschel. Photo: ESA

Astronomers from around the world met in Toledo, Spain, earlier this month to discuss new scientific objectives for Europe's next-generation infrared space observatory. By the time the workshop was over, the telescope had a new name and redefined mission goals.

On December 12, the opening day of the three-day conference, ESA's Far Infrared and Submillimeter Telescope (FIRST), was re-named the Herschel Space Observatory in honor of Sir William Herschel.

Herschel first discovered infrared light on December 12, 1800, exactly 200 years before the announcement was made.

The German-born British astronomer and musician described that the differently colored filters through which he observed the Sun allowed different levels of heat to pass. He performed a simple experiment to study the "heating powers of colured rays", splitting the sunlight with a glass prism into its different constituent rainbow colors and measured the temperature of each color.

"It strikes me that we are at a key scientific conference devoted to the next ESA infrared space mission, gathering together many 'infrared pioneers' 200 years after a famous musician and astronomer discovered that by placing a thermometer in the remote part of the solar spectrum, where apparently there was no light, he could detect heat. What we call now infrared radiation. This meeting marks two events: the beginning of a very promising utilization of FIRST, and the adoption of a new name for the telescope: Herschel Space Observatory," ESA science director Roger Bonnett said as he announced the new name.

During the remainder of the workshop, 200 astronomers from varying backgrounds redefined the scientific objectives of the Herschel telescope. "This is the kind of input we need," Goran Pilbratt, Herschel Project Scientist, said of the meeting. "We want to make sure that we use the precious observing time for the most profound problems."

Some plans for Herschel that were developed at the Toledo conference were derived from lessons learned during the mission the European Infrared Space Observatory, or ISO. For example, a goal set forth during the workshop was to use Herschel to study how the original galaxies and stars in the Universe formed. That objective was already on the agenda for Herschel, but the worldwide support shown in Toledo adds to ESA's confidence in that plan.

Artist's Impression of the Herschel Space Observatory. Photo: Royal Astronomical Observatory/ESA

However, other priorities not listed on Herschel's original agenda were devised at Toledo. One such plan calls for Herschel to search for chemical compounds, most notably water, in the void reaches of the Universe. Ewine van Dishoeck of Leiden University in the Netherlands, an authority in space chemistry, had this to say about the Herschel's proposed search for water:

"Herschel will continue the search for water in space, as initiated by ISO. It will give us an in-depth knowledge about how much water there is, its distribution and formation."

To sum up the premise for searching for water, he said, "Herschel will provide us with a much better understanding of the chemistry of the Universe."

Other program goals much closer to home that were forged at the Spanish conference included the studies of both comets and asteroid-like objects in the Kuiper Belt, which is located beyond the orbit of Neptune.

Therese Encrenaz of the Paris Observatory in France said that Hershel will help in the study of the history of our solar system. Comets remain almost completely unscathed since the time they were formed during the solar system's beginnings.

Herschel proposals also include the identification and studying of so-called trans-Neptunian objects in the Kuiper Belts, situated well outside the orbit of the planet Neptune. These space rocks are similar to asteroids in composition and shape, and may number up to 10,000, only 300 of which have been located by Earth-based or space-based observatories.

Currently scheduled for launch on February 15, 2007, aboard an Ariane 5 rocket, the Herschel Space Observatory will be positioned at the L2 LaGrange point located around 1 million miles from Earth where the gravity influence between the Earth and the Sun is uniform.

With NASA building the 3.5 meter telescope and Europe contributing three science experiments and most likely the spacecraft bus, Herschel will operate for a minimum of three years, with approximately two-thirds of that viewing time available to the astronomy community outside of ESA and NASA.

Herschel will ride into space along with the Planck mission. Once in space, the two probes will separate and enter their respective orbits around the L2 LaGrange point.