The far-infrared spectrograph SAFARI, on-board the joint European-Japanese space telescope SPICA (the next step after ESA’s Herschel mission), will provide the most sensitive view ever of the cool, obscured universe. By cooling the telescope to below 8 K its thermal background emission is decreased below the level of the weakest astronomical background. With this low background SAFARI with its latest generation, ultra-sensitive, detectors can look far deeper into space than was possible ever before. SPICA is the only facility at competing sensitivity that fills the gap in the wavelength domain between the other great observatories, the James Webb Space telescope and the ALMA radio observatory – only with SPICA/SAFARI we will complete the view on the star-formation history of our universe.
SAFARI will be used to study the basic processes of formation of celestial bodies, ranging from planets to stars and galaxies, resulting in a better understanding of the formation history of our own solar system and of the stellar content of our universe. The large majority of these objects are enshrouded in dust, and only the infrared radiation can escape – an infrared facility like SAFARI/SPICA provides the means to investigate their properties and evolution. The faintest far away galaxies have a brightness of one ten-billionth of that what the human eye can see. Only with the extremely cold SPICA mirror and the ultra-sensitive SAFARI detectors the very weak infrared emission from these distant galaxies can be detected. By observing many hundreds of such galaxies spanning the most active epochs of galaxy formation in the universe, their evolutionary histories can be unequivocally established.
The extremely sensitive Transition Edge Sensors (TES) whose development has been spearheaded by SRON scientists are at the heart of SAFARI. Many years of development have resulted in a detector performance that is rivalled only in a few institutes around the world. To achieve this extreme performance the sensors must be cooled down to about 50 milli-degree above absolute zero. In addition the structure and electronics around the detectors will also need to operate at such low temperatures, and must be well isolated from the warmer spacecraft around them. The cryomechanics involved is one of the other necessary key technologies in which SRON also has long and leading experience. Because of this extensive experience, SRON has been asked to lead the international consortium that aims to implement the SAFARI instrument.
The development and implementation tasks, and thus cost, for SAFARI are shared among the consortium partners. SRON’s primary role lies in project coordination and overseeing the system aspects, major partners in the project are Spain providing the optics and mechanical structure of the instrument, France providing the cooler and detector read out system and the US providing most of the detector units. As is generally the case for space observatories, access to observing time for the general astronomical user community is granted through ESA in a peer-reviewed proposal process. All observatory data eventually will become publicly accessible after a proprietary period of ~1.5 years.