CHENNAI: Based on last year's GSLV Mark III 's experimental flight, modifications have been done to solid rocket S-200 motors to change dynamic pressure and forces and ground tests have been done, a top ISRO official said today."When we flew the launch vehicle last time based on actual test, the solid rocket which was there -S 200 motors- there also certain changes had to be done," ISRO Chairman AS Kiran Kumar told reporters here.Such changes were needed "to change dynamic pressure and dynamic forces that occur during the atmospheric regime," he added.Sharing the developments over GSLV Mark III with reporters on the sidelines of Hindustan University 's convocation here, the top official said "those changes have also been incorporated and ground tests have been conducted on those modified rockets and so, that way we are quite on track for GSLV Mark III (launch)next year."ISRO successfully tested the atmospheric re-entry of a crew modul and studied flight validation and atmospheric flight regime of its heaviest launch vehicle GSLV Mk III on December 18 last year.Stating that ISRO was planning to launch GSLV Mk-III by December next year, he said,"for GSLV Mark III launch the target is December 2016 and a second launch December 2017."On the Mark III cryogenic engine development, it has been going on "very successfully," and ISRO has done "more than 21 different tests including long duration test," he said."Actually in the launch, it is supposed to work for about 635 seconds to put the satellites in orbit, now we have tested the engine for not only that period but also for an extended period for about 800 seconds." These tests have been done on one engine and "now we need to repeat it on another hardware and those activities are in progress," he said.An important aspect about cryogenic engine is that it is totally indigenous development, he said."The various tests that we have gone through so far is simulated prior to test and tests have validated, giving us great confidence that the entire technology in terms of basics the engineers and scientists have understood the mechanism."Asked about damages over Rs 4,000 crore awarded to ISRO's commercial arm Antrix by an international arbitration court and its fallout, he declined to comment.Earlier, university Vice Chancellor S Ramachandran conferred honorary degree 'Doctor of Science' to (Honoris Causa) to Kiran Kumar. The ISRO chief gave away degrees to students including 58 gold medalists.