08 MAY. 2008
publication date
30414
Views
Herschel was the largest infrared space telescope ever launched. With its 3.5-m primary mirror, it was four times bigger than any previous infrared space telescope and almost one and a half times larger than the Hubble Space Telescope.
Herschel's primary mirror was the telescope's light collector. It captured the light from astronomical objects and directed it towards the smaller secondary mirror. The two mirrors worked together focusing the light and directing it to the instruments, where the light was detected and analysed, and the results recorded by the onboard computer.
Media modal
Space telescope comparison
The size of the primary mirror is the key to a telescope's sensitivity: the bigger it is, the more light it collects, and the fainter the objects it sees. It also determines the telescope's ability to distinguish fine details. The surface of the mirror is very important, too. It has to be precisely shaped and perfectly smooth, since the slightest roughness distorts the final image.
The mirror must be light and sturdy to withstand the extreme conditions of launch (when it will be shaken with a force several times that of Earth’s gravity), and the low temperatures of outer space; and any bump on its surface must be less than a thousandth of a millimetre high.
Media modal
Herschel spacecraft
This technological marvel was constructed almost entirely of silicon carbide. The primary mirror was made out of 12 segments brazed together to form a monolithic mirror which was machined and polished to the required thickness (about 3 mm), shape, and surface accuracy.
Media modal
Caroline and William Herschel: Revealing the invisible
The Herschels were pioneers of the systematic classification and investigation of the heavens. William Herschel was one of the first 'professional' astronomers, and discovered infrared radiation. His sister Caroline helped him to develop the modern mathematical approach to astronomy.
Observations: Seeing in infrared wavelengths
The Universe in infrared wavelengths is only one step removed from the familiar, visible Universe. It is the cooler objects that emit most strongly in the infrared.
The electromagnetic spectrum
Light, or electromagnetic radiation, comes in many forms. There are radio waves, microwaves, infrared light, visible light, ultraviolet light, X-rays and gamma rays, all of which form what is known as the 'electromagnetic spectrum'
Share this page
stay updated
Subscribe to our newsletter to receive the latest news, mission updates, and exclusive insights directly in your inbox. Be the first to know about our upcoming projects and breakthroughs.