THIS PROPOSAL COVERS DR. DAVID VANIMAN'S ACTIVITIES AS A CO-INVESTIGATOR FOR THE CHEMIN MINERALOGICAL INSTRUMENT WHICH IS PART OF THE INSTRUMENT SUITE ON THE MARS SCIENCE LABORATORY (MSL) ROVER CURIOSITY DURING THE EXTENDED MISSION PHASE THROUGH 2019 AND INTO 2021. THE PROPOSAL INCLUDES CONTINUING SUPPORT FOR STEVE CHIPERA AS WELL AS COVERAGE FOR DR. PATRICIA CRAIG AS A CHEMIN POST-DOCTORAL RESEARCH SCIENTIST. DR. VANIMAN WAS A NAMED CO-I ON THE ORIGINAL CHEMIN INSTRUMENT PROPOSAL SUBMITTED TO THE MSL MISSION ANNOUNCEMENT OF OPPORTUNITY AND HIS INCLUSION WAS VALIDATED AT THAT TIME BY DR. MICHAEL MEYER MARS PROGRAM SCIENTIST AT NASA HEADQUARTERS. IN THE INTERVAL BETWEEN CHEMIN'S SELECTION AS AN MSL PAYLOAD ELEMENT AND THE LAUNCH OFMSL (PHASES A-D OF THE INSTRUMENT PROJECT) DR. VANIMAN WAS SUPPORTED THROUGH CONTRACTS ADMINISTERED DIRECTLY FROM THE MARS PROGRAM OFFICE AT THE JET PROPULSION LABORATORY DURING WHICH TIME HE WAS MADE DEPUTY PI OF CHEMIN. IN THIS CAPACITY DAVID VANIMAN HAS HAD EQUAL AUTHORITY AND RESPONSIBILITY TO THE CHEMIN PI DR. DAVID BLAKE. DURING PHASE E OF THE INSTRUMENT PROJECT (MISSION OPERATIONS) VANIMAN'S ACTIVITIES HAVE BEEN SUPPORTED THROUGH COOP AGREEMENTS ADMINISTERED THROUGH AMES RESEARCH CENTER. IN 2017 THE DEPUTY PI WERE TRANSFERRED TO ELIZABETH RAMPE OFNASA-JSC AND VANIMAN TRANSITIONED TO CO-I STATUS; THIS TRANSITION WAS AGREED TO BY MICHAEL MEYER MARS PROGRAM SCIENTIST AT NASA HEADQUARTERS. THE DUTIES AND OBLIGATIONS OF CHEMIN CO-I'S FOR THE PRIME MISSION WERE DELINEATED IN THE CHEMIN EXPERIMENT OPERATIONS PLAN (JPL D-36918) "CHEMIN EOP" OR "EOP" AND PUBLICATIONS LISTED THEREIN. THESE DUTIES AND OBLIGATIONS HAVE WORKED WELL DURING THE PRIME MISSION AND THE FIRST AND SECOND EXTENDED MISSIONS AND WILL BE MAINTAINED INTO THE THIRD EXTENDED MISSION.