Tartu Observatory Has True Assets

Tartu Observatory has had quite a few different names in the past, has been administrated by a number different institutions and even seen different regimes. Behind the name of the observatory are our employees who have kept the Estonian space science world class throughout all of the changes. Many of our colleagues have been working here for more than 50 years: Tõnu Prans, Mare Ruusalepp, former Director Tõnu Viik and academics Enn Saar and Jaan Einasto. Jaan, who recently celebrated his 90th birthday, has been a researcher at the observatory since 1952.

In April, Enno Ruusalepp, the only professional Estonian telescope engineer and our current Building Superintendent, had his 50-year work anniversary at the observatory. Enno is one of the few people who can tell the whole story about how the largest telescope of the Nordic countries got to the observatory. He is also the one to thank for everyone at the observatory being able to work at such a beautiful building with perfect working conditions.

The Only Telescope Engineer in Estonia

It is a fortune that the only constructor of optical devices ended up at the observatory. After high school, Enno got the chance to study at the institute of precision engineering in Saint Petersburg. The whole spectrum of optical instruments was focused on in the studies. "We were taught everything starting from microscopes to telescopes. Spectral instruments, spectrometers, microscopes – in the end, a regular magnifying glass is also an optical instrument," he says. The reason why Enno was sent to study at the institute by the National Economic Council of the ESSR, was that he was supposed to start working at a factory of optical devices that was planned to be built near Rakvere. By the time of Enno’s graduation, however, the plans had changed and there was going to be no factory. „Basically, I didn’t have a job,“ Enno recalls.

This is when physicist and apparatus engineering specialist Valdur Tiit offered Enno a job. At the time, an apparatus engineering complex was being built on the site of the current Tartu Science Park. "We met for the interview on April 1, 1969 under the university’s clock. I had to look for the clock for a while: I hadn’t gone to this university!" Enno laughs. However, because the observatory shared the institute with physicists, soon word started spreading that Enno – an optical engineering graduate – is working on a construction site. "The old Aksel Kipper whose bronze statue we have here on the wall of the building, called me in for an interview and asked if I would like to work in optics instead. He was the one who brought me here to work with the astronomers."

Our Big Telescope Is Doing Just Fine

Enno got to the observatory at the same time that the planning of the big telescope was kicked off. He has accompanied the telescope on its journey from the hole of the tower to nowadays. "The endless visits to the factory in Saint Petersburg with Tõnu Kipper and Lauri Luud who was the organizer of getting the telescope here," Enno recalls. "We had an UAZ van which had a driver who lives in Tõravere to this day. We would sit on the bus at 3 or 4 in the morning – it was bleak and cold – and drive to the gate of the factory in Saint Petersburg. The driver would stay and sleep in the van and us, at the factory, would examine, coordinate and argue with the constructors the whole day," Enno says. "At the end of the day we came out of the factory and the driver would start to drive back home."

The telescope, now about 45 years old, is still in good condition. "It isn’t poorly made at all. A telescope isn’t built for 20 years," Enno states. However, the good shape of the telescope requires constant care. The control system of the big telescope has been replaced and its mirror needs to be aluminated once every ten years. It is a long process: the telescope needs to be disassembled and the mirror that weights almost a ton lifted out. The next alumination should be done in two years.

It is also necessary to clean the mirror of the telescope. "The mirror will tarnishes with time because in our weather, it is cold-cold-cold and then suddenly the thaw comes. But massive mirrors don’t heat up as fast. There can even be icicles on the mirror," Enno describes. You can’t warm the mirror because it might break. This is why the telescope is provided with fans that help clean the mirror with air.

Telescope Left in Uzbekistan

Just like the telescope, Estonian climate also affects the researchers who are observing the sky with it. "You can see climate change from here. In the 70s, when the telescope started its work, we had about 100–110 clear nights in a year. Now we only have about 60–70," Enno admits. But Estonia isn’t the best place for observations regarding the location either. "In Chile, for example, there are observatories in the mountains and they have 365 clear days a year," he states.

Because of the peculiarity of the climate, the researchers of the observatory, headed by Jaan Einasto, started to dream about an observatory at their own southern base in a location with good astroclimate in the 70s. Our 1.5 telescope could be used to observe lighter galaxies, but it wasn’t suitable for observing weaker objects.

When searching for a location for the Southern base, Einasto and his team started to organize expeditions. Enno also participated in one of them. It turned out that there is a very good astroclimate in Suffa, located at current Uzbekistan. In July 1988, a telescope was taken there with a helicopter and a heated container was set up. However, soon the Soviet Union fell apart and its countries gained independence which ruined the whole plan. "We got a message from the President of Uzbekistan at that time saying that our expedition telescope and tiny house are a property of the people of Uzbekistan and we have no point of going back and getting them," Enno says. Thus, the container and telescope were left in the mountains.

From Transition Period to Nowadays

Estonia gained its independence as well. This brought along major changes in the work of the observatory, because although the country was free, there wasn’t much money. In 1992, Enno became the Building Superintendent of the observatory. Although Enno now thinks that the difficulties of that time have paid off, he remembers the hard times well. "We needed to heat the furnace but had no heating oil. I myself – I can speak Russian – went to Narva at the thermal power station’s oil factory to wrangle us some heating oil," Enno says. "We had a man in Elva who had privatized a tub for transporting oil. We paid him for transport and he went and got it. It was hard to organize everyday life."

An important turning-point was when Nõo Parish started to stand on its own two feet and took many responsibilities that had been the observatory’s before upon itself: the kindergarten, plumbing and heating. The observatory started to save money and, step by step, renovating the house with the savings. "I am glad that we managed to survive the tough times and manage everything by ourselves," Enno states.

In 2011 and 2012, the whole main building was renovated under the direction of Enno. The electrical system was completely replaced and ventilation was added to the building. The lack of the latter had been a real problem beforehand, especially on the side of the building which is exposed to the sun in daytime. "We made an experiment when I was young. We put an egg on a black fabric on the window sill. The egg was cooked in 15 minutes. The thermometer had been next to it: there was 80 degrees on the black fabric," Enno describes.

Timeless Interest

New assignments as Building Superintendent did not mean that Enno forgot all about telescopes. For example, in the beginning of the 90s he got a chance to learn in Munich at the German Museum with master restorers Ernst Ellinger and Reinhold Baumann. After that he himself restored the almost 200-year-old great Fraunhofer Refractor of the University of Tartu Old Observatory. The telescope had seen wars and been standing in unheated humid rooms.

But why has observing the sky been such an interest for the human kind that we can talk about 200-year-old telescopes? "A human, when he was still living in the cave, came out of the cave at night, scratched his belly and looked at the stars, wondering what they were. We have been interested in space since then," Enno discusses. "A human being is created that way: he wants to know what something is or how it works. You have to be curious."

Enno's colleagues know to say that he – no matter if the only telescope engineer in Estonia or the Building Superintendent of the biggest observatory – has done everything with his heart, although always stayed modest about his work. "I have been taught to do my job as well as I can. I have tried to live by that rule, no matter what the job is. And this is how I've managed."