Elon Musk : Commercial space flight wo n't be affordable without reusable rockets . CEO of SpaceX gives keynote at South by Southwest Interactive festival . Comment: `` If we ca n't make rockets reusable , the cost is just prohibitive . '' Musk also is CEO and chief designer at Tesla Motors , maker of electric cars .
Elon Musk : Commercial space flight wo n't be affordable without reusable rockets . CEO of SpaceX gives keynote at South by Southwest Interactive festival . Comment: Musk also is CEO and chief designer at Tesla Motors , maker of electric cars .