"We use femtosecond laser pulses. We scan the skin and we get signals from the skin, particularly fluorescence, as well as another signal called second harmonic generation. So with these two signals we can build up images and get a precise look into the skin with a high resolution.

"The resolution is a factor of one thousand [times] better than ultrasound. So now you get the information without taking biopsies; normally you slice them, you stain them, and then a pathologist would look through these sections. Now you can get this information in seconds, labor free and with this fantastic resolution," said Koenig, adding that applications include in vivo histology for early cancer diagnosis and determining effects of skin ageing.

Koenig, who is also chief executive officer of German company JenLab, with facilities in Jena and Saarbrucken, was asked by the European Space Agency (ESA) to use their femtosecond laser technology for their 'Skin B' project, which the space agency says is aimed at understanding "skin ageing mechanisms which are slow on Earth [therefore nearly impossible to study efficiently] but very much accelerated in weightlessness".

"NASA and ESA - the European Space Agency - came to us and asked, 'is it possible to also look in the skin of astronauts? Because we want to know if there's any ageing process going on or what kind of modifications happened to astronauts as they work for six months out in space'. Because many astronauts complain about skin problems," said Koenig.

So far, Koenig and his team of researchers have scanned three astronauts before and after a trip into space; Italians Luca Parmitano and Samantha Cristoforetti, and Germany's Alexander Gerst.