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Greek astrophysicist explains Messenger mission to Mercury

Stamatis Krimizis continues to explore the universe with the excitement of a child gazing at the stars, even though he has already enjoyed a lengthy and distinguished career.

The latest achievement by the Chios-born astrophysicist and his associates is NASA?s Messenger mission to Mercury, which has just celebrated two months in orbit around the planet nearest to the sun.

The 55-million-kilometer journey from Earth to Mercury took the Messenger spacecraft about six-and-a-half years, but achieving this journey required some pioneering technology, according to Krimizis.

?Mercury is very close to the sun. Its surface temperature is 426 degrees Celsius, while the magnitude of the solar radiation is 11 times higher than it is on Earth,? the scientist, who was in Athens to deliver a lecture, told Kathimerini. ?We designed a special sun shade, under which the spacecraft can be safe at a temperature of 30 degrees Celsius.?

The design of the Messenger space probe and of the mission, as well as its overall supervision, is a project being run by the Johns Hopkins University Applied Physics Laboratory, of which Professor Krimizis is the director. The temperature was not the only challenge the team faced, as the spacecraft also had to be very light and still be able to carry the fuel needed to make its journey. To this end, the team built a titanium gas tank and when the 1,100-kilogram Messenger took off, 600 kg of that weight was fuel.

So far, Messenger has successfully orbited Mercury 100 times. It can descend to a distance of 500 kilometers from the planet?s surface, but it cannot stay there for too long due to the risk of overheating.

?We activate the instruments when Messenger is near the surface,? explained Krimizis. ?It takes a lot of skill to navigate it, because if it becomes exposed to the solar radiation it will last just 20 minutes.?

What has the exploratory spacecraft discovered so far?

?First of all,? said Krimizis, ?we discovered the biggest basin [or crater] in our solar system, with a diameter of 1,550 kilometers. We have also recorded signs of older volcanic activity, such as solidified lava. Mercury has a low-pressure atmosphere, which means it is subject to harsh solar wind, as well as a strong magnetic field, though this is something we already knew.?

In spite of this great achievement, Krimizis isn?t willing to rest on his laurels. ?Our next project concerns an approach to the sun and its study from as close as possible,? he revealed. ?This is a massive technological challenge as the temperatures are huge. But as I?ve already explored eight planets in our solar system, I have now set my sights on the sun.?

What drew this boy from Vrontados on the island of Chios to pursue studies in astrophysics at the universities of Minnesota and Iowa in the USA and to become part of the avant-garde of space exploration? ?Exploring the unknown, producing new knowledge and answering some of the most fundamental questions, like how the solar system was formed, where we came from and where we are going,? he said.

Krimizis is also a member of the Athens Academy, the Greek National Council of Research and Technology, and president of the International Academy of Astronautics.