dr. squyres tell us what types of planetary science missions does the unique capability of the space launch system, this new big rocket, that is evolvable in size, what does that provide? >> like dr. kennel i am excited about what we can do with an asteroid. i was recently part of a four member nasa crew. i was the one non-astronaut on the crew that conducted a two-week long mission of the aquarius mission in your home state of florida simulating the kinds of extra vehicular activity tools and equipment for what we use for exploration of an asteroid and it got me very excited about what a human scientist, explorer could do in an asteroid on a mission by sls. i think most importantly a heavy lift capability is essential. i'm a big fan of robotic exploration. i'm a member of the science team for the curiosity mission but with our magnificent curiosity rover can do in a day you can do in about 45 seconds, and you know what our magnificent opportunity rover has done on mars and eight and a half years you could do in a good week, week and a half, something like that. so what humans can do in the

dr. steven squyres who is the professor of astronomy at cornell, dr.es kennel, chair of the space studies board of the national academies and mr. jim maser, president of pratt and whitney rocketdyne. so, dr. squyres, we'll start with you. >> all right. well, senator nelson, thank you very much for the opportunity to appear here today. my name is steve squyres, and my title is gold and smith professor of astrongny at cornell -- astronomy at cornell university. a central focus of the nasa authorization act of 2010 was the development of two crucial and highly-capable elements of a deep space exploration system. the space launch system and the o rye oncrew vehicle. nasa's development of both is well underway, passing successful test firings of sos's cryogenic upper stage and the delivery of the first orion command module to kennedy space center. what will these vehicles be used for? president obama has called for sending humans to an it's royce by 2025. these are grand goals, and they're broadly consistent with the goals that were expressed in the 2010 au