Meet NASA’s Greek “Planet Doctor”

Thanasis Economou is the creator of NASA's APXS
Thanasis Economou has been described as the “Planet Doctor,” since almost all space missions carry an instrument he developed to help analyze the composition of our neighboring planets.

Since the Pathfinder landed on Mars in 1977, until now that Rosetta is shadowing comet 67P / Churyumov-Gerasimenko, the Greek astrophysicist at the University of Chicago, has supplied each spaceship with a small but miraculous instrument examining the chemical composition of celestial bodies.

The Greek scientist who has also received an award by NASA for his longtime contribution to space research, has created APXS, an instrument used in the Rosetta, similar to the one that was on Pathfinder and tested for reliability.

The Alpha Particle X-Ray Spectrometer (9APXS) is a device that analyses the chemical element composition of a sample from the scattered alpha particles, and fluorescent X-rays after the sample is irradiated with alpha particles and X-rays from radioactive sources.

The small instrument currently analyzes the chemical composition of comet 67P / Churyumov-Gerasimenko, helping scientists understand exactly what comets are composed of and how they were created.

“We estimate that this comet is composed of a mixture of dust and frozen water, frozen carbon dioxide and some other elements observed in rocks on the Earth, such as silicon, aluminum, iron, magnesium,” Economou said.

Learning about the exact composition of planets will help the scientific community obtain a more complete picture of the creation of planets and the solar system.

Over the last days, the Rosetta has come closer than 40 km from the comet, about 300 million kilometers from the Sun.

Contribution to Greece

In 2010, Economou proposed building an astronomical observatory near his childhood home in the province of Grevena in Greece.

After a childhood marked by war and dislocation, Economou left Greece in 1948

“I left together with 200 other kids from our village in order to escape the consequences of the civil war that was raging in Greece at that time.”

Economou completed high school and college in Czechoslovakia, receiving his doctoral degree in physics from Charles University in Prague in 1964.