by Frozen moons, hot stars, search for life-friendly conditions, exoplanets, galaxies moving away from each other as the universe expands, future journeys into the universe’s past, new missions. The amazing quest to explore the universe not only fires the imagination but opens new avenues for scientific research and for all of humanity.
On the occasion of World Space Week, which is celebrated every year from 4 to 10 October – the dates defined by the launch of the first artificial satellite, Sputnik, on 4 October 1957, and the date of entry into force of the UN Treaty on space, October 10, 1967 – We discussed current and future space challenges with Ioannis A. Daglis, president of the Hellenic Space Center (HSC) and professor of Space Physics at the University of Athens.
Despite the fact that there are no “Chinese walls” in space research, we have divided scientific efforts into three parts: first, those related to Earth, our common home; Second, those concerning the solar system. third, the universe beyond. Voyages to distant celestial bodies may excite us more, but about 90% of space exploration involves the region around Earth.
“Space is a platform for observing our planet and developing a number of critical services that affect and facilitate our daily lives: communications, navigation, weather forecasting,” says Daglis. “The economic activity carried out by states and businesses is intense. Already more than 4,500 satellites are in orbit around the Earth and there are another 2,500 that are inactive. Great technological leaps have been made, but we are looking for solutions aimed at further improvements,” he adds.
To meet Greece’s needs, the Hellenic Space Center seeks to improve the 10×10 meter resolution provided by the European Earth Observation Program (Copernicus). “It is good, but not good enough for our national needs. HSC is developing a national satellite imagery program with a resolution of 3×3 meters, a factor of 10 improvement,” says Daglis. “Also, observation satellites are in relatively low orbits, 500-2,000 kilometers up, in order to provide good spatial resolution. But since they orbit the Earth continuously, they do not provide the continuous coverage of geostationary satellites that orbit 36,000 kilometers above the surface and hover continuously over the same area of our planet. Obviously, the resolution of images from such a height is much lower. The space industry is trying to combine information obtained from both these types of orbits.”
The new era brought by plans to launch large fleets of satellites by private companies will bring new challenges, but also risks, notes Daglis. “Continuous launches will, in the long run, put a strain on the space ecosystem. Congestion will increase the risk of collisions between satellites, resulting in space debris, which in turn could seriously damage or completely destroy other satellites. We have to face the issue and regulate. It takes a long time to inform the global conditions on the mutually beneficial use of space at the UN level. “The European Space Agency (ESA) has provided an excellent model by requiring each launch proposal to set out a comprehensive plan for mission completion, including the ‘retirement’ of the spacecraft,” he says.
Higher goals
At a second level, within the solar system, higher goals are set. “One primary direction is to explore a semi-alien world, such as Mars, which is considered the only celestial body with at least a theoretical ability to host humans. Of course, this is a long shot. A second line of exploration targets the icy moons of Jupiter and Saturn, which are of great interest to astrobiology because of the possibility that they may harbor some kind of life beneath their icy surface. It is something that we cannot rule out, for example in Europa or Enceladus, since on Earth itself we discovered life in great ocean depths, in conditions that we previously considered prohibitive”, Professor Daglis notes.
In 2023, ESA will launch the JUICE probe (Jupiter Icy Moons Explorer) which will make detailed observations of Jupiter, the gas giant, and three of its four largest moons (Ganymedes, Callisto and Europa) that are thought to have water below the ice surface.
“The magnetic field measurements in Europa can only be explained by the rotational motion of the salt water. On Enceladus, a moon of Saturn, jets of water have been recorded. NASA is already considering future missions aimed at drilling into Europa’s ice,” explains Daglis.
Another research pursuit in our solar system is to better understand the Sun-Earth system and the interaction of the two bodies. “We have made great progress, but we want to go even further. For example, we want to predict space weather, space storms, just like we do on the Earth’s surface, which will greatly help the safety of missions and satellites,” notes Daglis.
In the infinite universe beyond the solar system, the driving force of human exploration is primarily the fundamental scientific questions about the universe. “Our spacecraft have reached an infinitesimal part of the universe. We have been surprised by how many old galaxies we have discovered. The universe is much older than we thought.
We get our information through photons, from the whole spectrum of electromagnetic radiation and, finally, from gravitational waves. Now we have increasingly clear images of distant celestial bodies, from long ago. The James Webb telescope has helped a lot. it was also able to detect, for the first time, the atmospheres of exoplanets, i.e. planets outside the solar system,” says Daglis.
Earth on the Moon
Our last question is about humanity’s first space station. Why is a mission to the moon being prepared again? “First of all, we can launch heavier spacecraft to Mars or elsewhere more easily than the moon. Also, the Moon contains valuable minerals, such as rare earths. And, of course, there’s always the lure of taking a walk on the moon.”
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