Every week there seems to be a new hero in space. Last Friday, a week ago to the day, the entire world was celebrating the end of the Cassini mission to Saturn and its moons. The spacecraft, as planned, disintegrated on September 15, 2017 as it plunged into the Saturnian atmosphere, recording and transmitting images right up to its last cosmic breath. This week, the European Space Agency is celebrating the Herschel space observatory, which collected a rich trove of data concerning the formation of stars and galaxies. Herschel helped scientists uncover some of the best kept secrets in our Universe, and made them very happy indeed!

The space observatory Herschel was orbited on May 14, 2009 by Arianespace, along with its co-passenger Planck. These two high-tech jewels are still considered some of the most complex scientific satellites ever built in Europe. Herschel-Planck was a space exploration program conducted by Thales Alenia Space as prime contractor on behalf of ESA. The Herschel mission came to an end on April 29, 2013 after four years of loyal service in orbit – 10% over its initial life expectancy.

Dedicated to the exploration of the “cold universe”, Herschel was fitted with a telescope that featured a primary mirror 3.5 meters in diameter – twice the surface area of the mirror used on the Hubble Space Telescope. Herschel was the first spaceborne observatory to cover the spectrum between 55 and 672 µm (far infrared and submillimetric radiation), capable of detecting radiating objects at temperatures between 5 and 50 K (-268/-223°C). Placed in orbit around the Lagrange Point L2, at 1.5 million kilometers from the Earth, it was also the first telescope to detect emissions from cosmic dust, allowing it to observe fossil radiation (light) from some of the oldest phenomena in the Universe. Along with Planck, this observatory revolutionized modern astronomy, and gave scientists a better understanding of the distant Universe, as well as our own Solar System.

Planck in Thales Alenia Space's clean rooms © Thales Alenia Space

While Planck pulled off the daunting feat of photographing the Universe as it was 13.8 billion years ago, just 380,000 years after the Big Bang, Herschel allowed scientists to analyze and better understand the evolving lifecycles of stars, galaxies and other big structures in deep space. Both Herschel and Planck [whose mission came to an end in October 2013] generated unprecedented scientific discoveries. “So long Herschel… give my regards to your brother Planck!”