WE WILL CARRY OUT THESE AIMS WITH TWO ADDITIONAL LAUNCHES OF THE PAYLOAD DEVELOPED UNDER THE PREDECESSOR AWARD AND THE DEVELOPMENT AND FLIGHT TESTING OF THE NEW IFS INSTRUMENT. ALL WORK WILL BE PERFORMED IN A UNIVERSITY ENVIRONMENT WITH A LONG HISTORY OF POSTDOCTORAL AND STUDENT TRAINING IN UV ASTROPHYSICS HELIOPHYSICS AND PLANETARY SCIENCE. IN THE FIRST TWO YEARS OF THE PROPOSED WORK WE WILL FLY THE DUAL-CHANNEL EXTREME ULTRAVIOLET CONTINUUM EXPERIMENT (DEUCE) PAYLOAD TWICE: FIRST TO COMPLETE THE IONIZING RADIATION CENSUS OF LOCAL B STARS AND THEN TO OBTAIN THE FIRST EUV SPECTRA OF THE NEAREST MAIN-SEQUENCE STARS. OUR GROUP RECENTLY COMPLETED THE FIRST FLIGHT OF DEUCE TO OBSERVE THE IONIZING SPECTRUM OF ONE OF THE ONLY TWO B-STARS WITH SUFFICIENTLY LOW INTERVENING NEUTRAL HYDROGEN COLUMN: BETA CANIS MAJORIS. A NASA VEHICLE SUBSYSTEM FAILURE PREVENTED SUCCESSFUL TARGET ACQUISITION ON THIS FLIGHT SO IN YEAR 1 OF THE PROPOSED WORK WE WILL LAUNCH DEUCE TO RECOVER THE ORIGINAL SCIENCE MISSION. IN YEAR 2 WE WILL FLY DEUCE FROM AUSTRALIA TO OBTAIN THE FIRST 500 - 900 ANGSTROM SPECTRUM OF THE POTENTIAL EXOPLANET HOST STARS ALPHA CENTAURI A AND B. THE LONG-TERM STABILITY OF ROCKY PLANET ATMOSPHERES IS DRIVEN BY EUV RADIATION FROM THEIR PARENT STARS ALTHOUGH THIS QUANTITY IS ALMOST COMPLETELY UNCONSTRAINED BY DIRECT OBSERVATION. DEUCE WILL CONSTRAIN THE EXOPLANET CLIMATE MODELS USED TO INTERPRET THE FIRST ATMOSPHERIC SPECTRA OF EARTH-LIKE PLANETS THAT WILL BE OBTAINED IN THE COMING DECADES WITH JWST LUVOIR/ HABEX AND OTHER FORTHCOMING NASA MISSIONS.