Herschel is the fourth cornerstone mission of the European Space Agency’s (ESA) Horizons 2000 program. This next generation space observatory is scheduled for launch in August 2007 and will allow astronomers to study topics ranging from how the first galaxies were formed after the big bang to how stars are currently being formed in our own galaxy, the Milky Way. The spacecraft features a giant telescope with a primary mirror of 3.5m diameter, the largest mirror ever launched into space. The school-bus sized spacecraft will house three far-infrared and submillimeter instruments at temperatures just a few degrees above absolute zero. The sensitivity of the detectors at these low temperatures allows them to detect radiation from the farthest reaches of the universe. Appropriately, the mission is named after Sir William Herschel (1738 – 1822), the first astronomer to make observations in the infrared part of the electromagnetic spectrum.

Canada is participating in two of the three instruments onboard Herschel: SPIRE and HIFI. Professor David Naylor from the University of Lethbridge is leading Canada’s contribution to SPIRE, the Spectral and Photometric Imaging REceiver; Professor Michel Fich from the University of Waterloo is the Canadian lead for HIFI, the Heterodyne Instrument for the Far-Infrared. SPIRE can be thought of as a camera that operates at very long wavelengths well beyond the limit of human vision. Observations at these wavelengths provide astronomers with a unique tool to study the physical conditions of the early universe. The spectrometer part of SPIRE can be thought of as providing the camera with colour film, opening up another dimension in our study of the universe. With funding from the Canadian Space Agency (CSA) the University of Lethbridge team is providing hardware to evaluate the performance of SPIRE prior to launch, as well as data processing software and staff support for the operational phase of the mission. In return for these contributions, five associate scientists from universities and research institutes across Canada receive guaranteed observing time with the Herschel telescope for their own research. This team will study a wide range of astronomical problems including: understanding the distribution of matter during the early phases of our universe, tracing the evolution of active galaxies in our immediate neighborhood, and studying the early phases of star formation in our own galaxy.

The SPIRE flight model is currently undergoing performance evaluation at the Rutherford Appleton Laboratory, Oxford UK. This important test campaign represents the last window of opportunity to identify and remedy problems with the instrument design. While first results from the flight model tests have been impressive, the Canadian team quickly identified an unexpected feature in the data and traced it to a late modification in the optical design. Discussions are currently on-going as to what action can and should be taken to decrease the impact of this design feature while minimizing the risk to the project.

Canada’s involvement in the Herschel mission not only showcases Canadian expertise on an international space mission but also builds the infrastructure necessary for participation in future missions. Herschel will not be the last word on space-based far-infrared astronomy: NASA, ESA, and the Japanese space agencies are currently exploring options for future infrared space missions building on the pioneering work of the Herschel space observatory, and Canada is well positioned to play a significant role in these missions.

The details are being presented at the annual meeting of the Canadian Astronomical Society held at Université de Montréal in Montréal (QC) from 15 to 17 May 2005..


Professor David Naylor
Dept. of Physics
University of Lethbridge
Phone: 403-329-2426

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Picture captions:
Artists impression of Herschel Spacecraft.

Herschel Telescope Primary Mirror inspection at EADS Astrium, Toulouse, France.

Dr. David Naylor aligns the Canadian built Fourier transform spectrometer at the SPIRE test facility at the Rutherford Appleton Laboratory, Oxford, UK.