About ice cubes, polar explorers and the search for neutrinos

How does an ice cube become a giant telescope? The answer to this is given by the American physicist Francis Halzen, who coordinated the construction of today’s largest particle detector in the history of mankind. “If you want to construct a detector weighing a billion tons, then you simply have to find a place where nature has already constructed this for you.”

The place? The Antarctic, more precisely, the South Pole. The detector? Goes by the name of “IceCube”, in German “Eiswürfel”. What sounds as if you could easily hold five of these in your cupped hand, involves somewhat different dimensions at the South Pole: the ice cube has an edge length of one kilometre and thereby a volume of one cubic kilometre. There are 4,800 sensors in it which are evenly distributed over 80 holes.

Together with approximately 300 physicists from 12 countries, this exceptional ice cube is searching for neutrinos – ghost particles, “cosmic long-distance runners”, hence, tiny, subatomic particles which can tell us a great deal about how the universe functions. But which are, however, extremely difficult to find.

The race to the South Pole...

It’s said today that it’s easier to reach the International Space Station ISS than the South Pole. Yet the Antarctic and the South Pole have been places of longing for explorers since the end of the 19th century. The era with the modest name “Golden Age of Antarctic Exploration” extended into the early 1920s; in the English-speaking area this is also known as the “Heroic Age”. The first impetus for the exploration of the Antarctic came from Sir John Murray at the Royal Geographical Society in London as early as 1893; he wanted to “resolve the outstanding geographical questions still posed in the south”.

The first expedition which supposedly heralded the start of the “Golden Age” was, however, that of the Belgian Adrien de Gerlache with his “Belgica” in 1897. De Gerlache and his crew (including Roald Amundsen, among others) spent the winter south of the Antarctic Circle, since their ship was trapped in pack ice. 

This made it possible, though, for them to be the first people to collect data in the Antarctic all the year round.

The Belgian was followed by the most diverse expeditions from Great Britain, Sweden, the German Reich and many other countries; these started moving south in the subsequent years to promote research on the Antarctic. Two of these expeditions should be mentioned here, namely those who actually made it to the South Pole: the Norwegian expedition led by Roald Amundsen and the British one led by Robert Falcon Scott, who competed against each other in the legendary “Race to the Pole” between 1910 and 1912. (Spoiler: the Norwegian Amundsen won and, moreover, returned alive to tell us all about it.)

... and a toast to the sledge dogs

Amundsen’s participation in this race was actually due to a coincidence. His real goal – the - North Pole - had been reached in 1909 by the Americans Frederick Cook and Robert Peary, respectively (at least they claimed this convincingly). While looking around for an alternative goal, he heard about an old rival, the Briton Robert Falcon Scott, and his expedition to the South Pole. Within a short space of time, Amundsen acquired a ship (the “Fram”, which had belonged to the famous polar explorer Fridjof Nansen), a crew and equipment. With the aid of 52 sledge dogs, Amundsen wanted to become the first person to reach the South Pole. However, only two people knew about this plan: his brother (who was supposed to go public with this news after the former’s departure) and his captain (who had to be let in on the secret due to navigational aspects). Otherwise, no one knew about this, not even the crew, since Amundsen hoped to gain an advantage over Scott here with his secrecy. Moreover, he didn’t personally like Scott.

 But when the “Fram” reached Madeira, Amundsen could no longer keep his plans a secret. He sent a message to Scott and, finally, Amundsen’s brother went public with the news. The race to the Pole had officially begun. Roald Amundsen won this on 14th December 1911 when he reached the South Pole first. He had overcome 1,400 kilometres of ice, snowstorms and crevasses. To mark the occasion, he and his companions each ate a piece of seal meat in the tent which they had erected and decorated with a Norwegian flag and a pennant from the “Fram”. In addition, on their departure four days later, Amundsen left two letters for Scott with the request to send these on for him if he should not survive the return journey.

Robert Falcon Scott found the letters exactly one month later on 18th January 1912, but couldn’t play his role as a postman – he died on the return journey. In the end it was bad planning with regard to equipment and provisioning which tragically caused the expedition to fail.

Amundsen was cheered on his return to Norway and his achievement respected internationally. By contrast, the British press blamed Amundsen for Scott’s death and took the view that his expedition was deceitful and unsporting. Finally, the situation escalated when Amundsen was a guest at the Royal Geographic Society in London and its honorary president drank a toast not to Amundsen, but to the latter’s dogs: “I therefore propose three cheers for the dogs.”

45 years later: Polheim becomes the Amundsen-Scott South Pole Station

Roald Amundsen’s camp “Polheim” was the first at the South Pole and was also to retain this unique feature for the next 45 years. It was not until the International Geophysical Year in 1956 that a group of America Navy pioneers reached the Pole again, this time from the air, to begin with the preparations for constructing the Amundsen-Scott South Pole Station. Since its opening in 1957, the station, which is situated on the ice sheet at an altitude of 2,835 metres, conducts research on the Antarctic.

Today there are 85 research stations in the Antarctic, half of which are also occupied during the winter. The fields of research comprise everything: from geophysics and astrophysics up to glaciology, meteorology and astronomy. The German Kohnen-Station, built in 2001, is used for the European deep ice core drilling project EPICA (European Project for Ice Coring in Antarctica), which wants to reconstruct the climate of the Atlantic sector in the Antarctic in the past one hundred thousand years. In 2019 there was almost an encounter of the third kind near this station: interstellar iron from a stellar explosion was found here by researchers from Munich.

The neutrinos being searched for, mentioned at the beginning, are also of interstellar origin. Unfortunately, they do not react willingly with matter, which makes it difficult to find evidence of them and requires gigantic telescopes to be able to catch a glimpse of the rare moments of a reaction. Ultimately, the IceCube was successful: the first non-terrestrial high energy neutrino was sighted in 2013. A short blue flash of light in the Antarctic ice, a great moment for science.

Sources and links

Atlas Obscura „IceCube Research Station“: https://www.atlasobscura.com/places/icecube-research-station (Letzter Zugriff 23.01.20)

Wikipedia „IceCube“: https://de.wikipedia.org/wiki/IceCube (Letzter Zugriff 23.01.20)

Webseite of the IceCube South Pole Neutrino Observatory: https://icecube.wisc.edu/about/overview

heise online „Erstmals Quelle von Hochenergie-Neutrino lokalisiert“: https://www.heise.de/newsticker/meldung/Erstmals-Quelle-von-Hochenergie-Neutrino-lokalisiert-4109091.html

Deutschlandfunk „Eiswürfel mit Weitblick“: https://www.deutschlandfunk.de/eiswuerfel-mit-weitblick.676.de.html?dram:article_id=24230

Wikipedia „Amundsen-Scott-Südpolstation“: https://de.wikipedia.org/wiki/Amundsen-Scott-S%C3%BCdpolstation

Wikipedia „Forschungsstationen in der Antarktis“: https://de.wikipedia.org/wiki/Forschungsstationen_in_der_Antarktis

Wikipedia „Kohnen-Station“: https://de.wikipedia.org/wiki/Kohnen-Station

Wikipedia „Polheim (Camp)“: https://de.wikipedia.org/wiki/Polheim_(Camp)

Wikipedia „Amundsens Fram-Expedition“: https://de.wikipedia.org/wiki/Amundsens_Fram-Expedition

Wikipedia „Südpol Erforschung“: https://de.wikipedia.org/wiki/S%C3%BCdpol#Erforschung

Wikipedia „Goldenes Zeitalter der Antarktis-Forschung“: https://de.wikipedia.org/wiki/Goldenes_Zeitalter_der_Antarktis-Forschung

BR „Wettlauf zwischen Amundsen und Scott zum Südpol“: https://www.br.de/themen/wissen/antarktis-amundsen-scott-suedpol-100.html

Welt „Der Wettlauf zum Südpol brachte Ruhm und den Tod“: https://www.welt.de/kultur/history/article13751343/Der-Wettlauf-zum-Suedpol-brachte-Ruhm-und-den-Tod.html

Welt der Physik „Das übersteigt meine kühnsten Erwartungen“: https://www.weltderphysik.de/gebiet/teilchen/news/2018/moegliche-neutrinoquelle-aufgespuert/