Balloon Stellar


NGO Tim Stellar has the mission of gathering people who are interested in space exploration, promotion of astronomy and astronautics, popularisation of science, creative thinking, teamwork and non-institutionalised upbringing and education of children and young people.

“Balloon Stellar” is a competition open to all high schools in Croatia, with the full support of President Dr Ivo Josipović, the Croatian Ministry of Science, Education and Sports and the Mayor of Zagreb. The main idea is that high school students design and make experiments, which will later be launched into the stratosphere by special balloons.

Purpose Of The Competition:

Promotion of Science in the Republic of Croatia, by encouraging:

  • Creative thinking among young people
  • Interest in science and education
  • Educational development of gifted children and young people
  • Inter-institutional cooperation among schools and developing a sense of teamwork
  • Creating a “healthy” environment, quality school education, and the smart use of free time
  • Awareness of natural phenomena and environmental values of Earth

Terms of Competition

The competition involves launching balloons with high school experiments into the stratosphere, at altitudes up to 30 km. An unlimited number of teams, from any high school, can apply for the competition. Teams must fill in the official application form and attach the required documentation in order to participate in the competition. Members of the expert committee will determine the top 20 teams that will participate in the competition. The selection of the teams that will enter the competition is based on the originality of the idea and the quality of the designed experiment.

Basic information

Country: Croatia

Coordinator: Tim Stellar,

Programme: Other

Project Acronym:

Target groups: secondary school students

Topic: Aeronautics, Astronautics, Astronomy, Computer science, Electronics, Energy, Engineering, Physics, Education


Contact person: Marin Tomičić, marin.tomicic (at)

Technical Requirements

Weight of the individual experiments with battery should be maximum 150g. If there is a need for a deviation from the default weight, it is necessary to forward the request to an expert committee so they can analyse the exception. In the case of an approval, they will notify all the teams in the competition. Expected temperature range during flight is -60°C to +40°C, and the pressure at the altitude of 30 km is around 1/100 of atmospheric pressure. Due to the extremely cold temperatures Team Stellar advises the use of lithium batteries when making the experiment. All teams will make experiments in a manner that does not endanger the flight or other experiments. Experiments must not contain explosives, acids, easily combustible materials, animals, etc. For additional precautions, experiments should be able to resist a wind speed of 10 m/sec. Depending on height attainment, the expected duration balloon flight is from 2.5 - 4 h.

After the launch, the teams will analyse the data collected during the balloon flight and write the final report. All this time they have to document their work and activities on specially designed pages opened for every team on social networks.

Creative Workshops

The teams which enter the competition will get the chance to attend two rounds of creative workshops. The first round of workshops entitled “Stratospheric Explorations” will be run by Uroš Todorović Mikšaj, who has the academic title Master of Science in Electrical Engineering, course Radio Communication. The second round of workshops entitled “Moon Habitat” will be run by Bosiljko Đerek, Maths and Physics Teacher and Scientix Ambassador for Croatia. Workshops do not affect the competition and do not suggest the experiments, they are here to inspire and encourage the participants to develop their own ideas.


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