The Herschel Mission

The Herschel Space Observatory, formerly known as FIRST, is an ESA Cornerstone mission. It is designed to provide imaging spectroscopy and photometry in the spectral range of 80-670 μm. It was launched on May 14, 2009 and orbits the Sun-Earth L2 Lagrangian point.


The instruments aboard Herschel are cooled by an on-board supply of liquid helium. The cryogen supply limits the planned lifetime of the spacecraft to 4 years.

Although other submillimetre facilities exist (e.g., JCMT) or are planned (e.g., SOFIA, ALMA), HERSCHEL has a number of unique features:

• a large (3.5 m), low-emissivity (0.01), passively-cooled (80 K) telescope;
• the complete absence of atmospheric absorption and emission, allowing complete access to this poorly explored spectral range; and
• a large amount of high quality observing time.

These features will provide unprecedented submillimetre sensitivity, enabling HERSCHEL to explore some of the most fundamental questions of modern astrophysics:

• the statistics and physics of galaxy formation at high red shift;
• the statistics and physics of star formation in our own and nearby galaxies;
• study of the interaction between stars and the interstellar medium at all stages of the stellar life cycle; and
• formation and evolution of our solar system.

The HERSCHEL payload consists of three instruments:

• The Heterodyne Instrument for FIRST (HIFI). HIFI will provide extremely high spectral resolution over selected ranges between 480 and 2700 GHz.
• The Photoconductor Array Camera and Spectrometer (PACS). PACS will provide photometry and spectroscopy over the range 80-210 μm.
• SPIRE will provide photometry and spectroscopy in the 200-670 μm range.

HERSCHEL is an observatory-class mission. Accordingly, one-third of the total observing time is reserved as Guaranteed Time for the instrument and mission teams. The remaining two-thirds of the total observing time, the Open Time, are available to the astronomical community at large by the conventional procedure of proposal submission and peer review.