Saying goodbye to the "Herschel" telescope

The space telescope ended its journey as planned after four years of operation * The European Space Agency is considering launching it into deep space or crashing on the moon

The 18th century British astronomer William Herschel signed some of the most important discoveries in astronomy, including the discovery of infrared radiation and the planet Uranus. Herschel's memory has been immortalized in the European Union space telescope that bears his name, and yesterday he completed his mission. "Hershel" was launched 4 years ago. "His main tasks were observations in the far infrared range, that is, at very long wavelengths," explains Professor Hagai Netzer from Tel Aviv University. "These are observations of what is known in our language as 'cold regions', primarily places where new stars are formed all the time."

Accelerated birth of stars

Herschel was a very large telescope, 3.5 m, which allowed him to observe enormous distances of more than ten billion light years. "He discovered star formation at a tremendous rate that occurs in almost all regions of the distant universe," says Netzer. "They are formed at a rate 100 times faster than in very bright bodies, and 1000 times more than in our galaxy. Such observations help to explain, for example, the evolution processes of galaxies."

No helium for the moon

As mentioned, Herschel finished his journey as planned. Observations at his wavelengths require cooling his instruments to a temperature close to absolute zero, which necessitates the use of liquid helium, and now, when the helium runs out, it is no longer possible to operate the instruments. "Unfortunately, the next device will probably be built by Japan and European countries only at the end of the decade, or at the beginning of the next decade," says Prof. Netzer, who was a partner in the work with the telescope. "Herschel will not have a replacement in the coming years, but he did so many things that many scientists will continue to study the data he collected."

What will happen to the telescope now? The European Space Agency will be forced to divert it from orbit around the Earth, fearing that it will crash into our planet. Among other things, the possibility of launching it into deep space or causing it to crash - on the moon - is being examined.