The sequence of rhythmic sounds echoed through the Great Hall of Técnico – Alameda campus, causing almost two hundred heads to turn immediately. The Morse code message, which translates to “VVV, ISTSat-1” (the satellite built at Técnico and currently orbiting the Earth to “indicate that everything is fine”), marked the beginning of the morning on 8 October 2025, during World Space Week, setting the tone for a talk about satellites and space exploration. The session inaugurated the 3rd season of the initiative “Explain it like I’m 5 – Science talks at Técnico for curious children and adults”, the first to take place entirely in person.
In front of this “small” audience, João Paulo Monteiro, a professor at Técnico and researcher at the Institute for Systems and Robotics (ISR-Lisboa), prepared to answer the question “How does a satellite work?”. Children’s arms in the air, even before the professor began to talk, showed that curiosity was already in orbit.
The Great Hall, usually occupied by university students, was filled with children’s voices, stifled laughter and hurried footsteps. In the air, the sound of backpacks being put down and the squeak of small shoes on the floor mingled with the anticipation that always precedes a discovery. Around 180 children, from 1st to 4th grade, gathered for what would be their “first class” at Técnico.
“This is the type of satellite we work on at IST NanosatLab”, explained the researcher, showing a replica of ISTSat-1, the first nanosatellite built entirely in Portugal to be launched into space. “What is the purpose of a satellite?” he asked, posing another challenge to the audience’s imagination. The answers came in chorus, mixing assumptions and certainties. As he described how these instruments aid in communications, weather forecasting and Earth observation, the students leaned forward, following every word as if watching a launch.
As images of Earth from space were displayed, João Paulo Monteiro explained that satellites communicate through antennas, and it is in the control room where researchers “talk” to them. “The only way to understand what the satellite is saying is through a computer that translates its signals”, he explained, amidst questions coming from all sides of the room. This is how they receive the Morse code message “…- …- …- / .. … – … .- – .—-“ from ISTSat-1.
“How do you see a satellite with a telescope?”, “How long does it take to make a satellite?”, “Why do people have to wear suits when they build satellites?”. In the session open to children, each answer led to new questions, and the enthusiasm seemed to defy gravity. The conversation followed the path of a mission: from idea to construction, from Earth to space.
To provide a more tangible understanding, João Paulo Monteiro described the extreme conditions faced by ISTSat-1 in orbit, taking the audience on a brief imaginary journey beyond the Earth’s atmosphere. He explained that thousands of kilometers above the surface, temperatures can vary between very high and extremely low values in an environment without air and sound. It was in this challenging environment that the small Portuguese satellite began operating, orbiting at approximately 30,000 kilometers per hour.
He also said that the satellite, which passes “four times a day over our heads”, is expected to remain in space for between 10 and 15 years, and that its development required a decade of work by students and researchers at Técnico. “Satellites don’t fly like airplanes”, he emphasised when asked how they stay in space. “They are in an airless environment, and it is Earth’s gravity that keeps them orbiting the planet”.
“How do you know so much?” someone in the front row asked, raising laughter in the audience. João Paulo Monteiro smiled and replied that knowledge comes from study, research and experience accumulated over the years, showing that science is built step by step.
The session ended with the projection of a photograph featuring the team responsible for the project, along with Paxi, ESA’s education mascot, readily recognised by many participants. The image prompted a talk about cooperation and teamwork. “To launch a satellite,” the researcher explained, “you need time, collaboration, and a willingness to learn” — the same essential ingredients that make any scientific project possible.
Amid questions, laughter and demonstrations, science took on a tangible form for an audience that listened with the same amazement as those discovering space for the first time. At the end of the morning, the buzz returned to the Great Hall, now filled with enthusiastic voices repeating new words – ‘orbit’, ‘solar panel’, ‘rocket’ – which seemed to float like small satellites in the memory.
In the coming months, another six researchers from Técnico will take the stage to address new questions related to the science and research projects they are conducting. The “Explain it like I’m 5” talks, organised by Técnico and aimed at primary school children, seek to bridge scientific research and society by promoting dialogue between scientists and children.
Upcoming sessions:
12 November 2025, 10 a.m. – “Como funciona um laboratório que pode viajar na palma da mão?” – Vania Silvério (INESC-MN)
14 January 2026, 10 a.m. – “Para que serve a radiação?” – Joana Madureira (C2TN)
6 February 2026, 10 a.m. – “Sabiam que há cidades onde cada gota conta… e outras onde todas as gotas se perdem?” – Filipa Ferreira (CERIS)
18 March 2026, 10 a.m. – “Qual é a magia dos comboios?” – Hugo Magalhães (idMEC)
29 April 2026, 10 a.m. – “Universo – Infinitamente grande ou Infinitamente pequeno?” – Pedro Abreu (LIP)
13 May 2026, 10 a.m. – “Podemos medir a música?” – Diogo Oliveira e Silva (CAMGSD)
