LONDON, ENGLAND - MAY 20: Members of the European Association of Space Explorers (L-R) Ernst Messerschmidt, Sergei Krikalev, Helen Sharman, Claudie Haignere, Anatoli Artsebarski, and Viktor Afanasyev are presented with a cake as they celebrate 25 years since Ms Sharman's mission into space hosted at the Science Museum on May 20, 2016 in London, England. Ms Sharman became the first Briton into space and the first female astronaut to visit the Mir space station in 1991, as part of Project Juno, a UK-Soviet cooperative programme. (Photo by Jack Taylor/Getty Images)

LONDON, ENGLAND - MAY 20: Members of the European Association of Space Explorers and the crew from the Soyuz TM-11 mission : (back row L-R) Jean-Pierre Haignere, Viktor Afanasyev, Ernst Messerschmidt, Anatoli Artsebarski, Sergei Krikalev, Claudie Haignere, Franz Viehbock, Dumitru Prunariu, Aleksandar Aleksandrov, Jean-Loup Chretien and (front row L-R) Jean-Francois Clervoy, Michel Tognini, Helen Sharman, Andreas Mogensen and Reinhold Ewald pose at an event to mark 25 years since Helen Sharman's space mission hosted by the Science Museum on May 20, 2016 in London, England. Ms Sharman became the first Briton into space and the first female astronaut to visit the Mir space station in 1991, as part of Project Juno, a UK-Soviet cooperative programme. (Photo by Jack Taylor/Getty Images)

LONDON, ENGLAND - MAY 20: British astronaut Helen Sharman poses at an event to mark 25 years since her space mission hosted by the Science Museum on May 20, 2016 in London, England. Ms Sharman became the first Briton into space and the first female astronaut to visit the Mir space station in 1991, as part of Project Juno, a UK-Soviet cooperative programme. (Photo by Jack Taylor/Getty Images)

This handout picture taken and released by the Turkish Presidential press office shows Turkish President Recep Tayyip Erdogan (4L), Prime Minister Ahmet Davutoglu (4R), Chief of the General Staff of the Turkish Armed Forces Hulusi Akar (3R), Prof. Dr. Aziz Sancar (3L), his wife Gwen Sancar (L), President of the Court of Cassation Ismail Rustu Cirit (R) and Minister of Science, Industry and Technology Fikri Isik (2R) standing during a ceremony for the Professor Aziz Sancar, Turkish Nobel Prize in chemistry, at the Anitkabir (Ataturk's mausoleum) in Ankara, on May 19, 2016. / AFP PHOTO / TURKISH PRESIDENTIAL PRESS OFFICE / KAYHAN OZER / RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT "AFP PHOTO / TURKISH PRESIDENTIAL PRESS OFFICE / KAYHAN OZER" - NO MARKETING NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS KAYHAN OZER/AFP/Getty Images

This handout picture taken and released by the Turkish Presidential press office shows Turkish President Recep Tayyip Erdogan (2L), Prime Minister Ahmet Davutoglu (3L), Chief of the General Staff of the Turkish Armed Forces Hulusi Akar (4L), Prof. Dr. Aziz Sancar (L), President of the Court of Cassation Ismail Rustu Cirit (4R) and Minister of Science, Industry and Technology Fikri Isik (5R), President of the Turkish Council of State Zerrin Gungor (2R), President of the Constitutional Court Zuhtu Arslan (3R) and Minister of National Education of Turkey Nabi Avci (R) standing during a ceremony for the Professor Aziz Sancar, Turkish Nobel Prize in chemistry, at the Anitkabir (Ataturk's mausoleum) in Ankara, on May 19, 2016. / AFP PHOTO / TURKISH PRESIDENTIAL PRESS OFFICE / KAYHAN OZER / RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT "AFP PHOTO / TURKISH PRESIDENTIAL PRESS OFFICE / KAYHAN OZER" - NO MARKETING NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS KAYHAN OZER/AFP/Getty Images

US President Barack Obama arrives to award the National Medal of Science and the National medal of Technology and Innovation to 17 scientists at the White House in Washington, DC, on May 19, 2016. / AFP PHOTO / Nicholas KammNICHOLAS KAMM/AFP/Getty Images

US President Barack Obama speaks before awarding the National Medal of Science and the National medal of Technology and Innovation to 17 scientists at the White House in Washington, DC, on May 19, 2016. / AFP PHOTO / Nicholas KammNICHOLAS KAMM/AFP/Getty Images

US President Barack Obama waves after awarding the National Medal of Science and the National medal of Technology and Innovation to 17 scientists at the White House in Washington, DC, on May 19, 2016. / AFP PHOTO / Nicholas KammNICHOLAS KAMM/AFP/Getty Images