Want to send something to space? Get in line. The demand for rides off Earth is skyrocketing, pushing even the busiest spaceports, like Florida’s Kennedy Space Center, to their operational limits. Orbital launches worldwide have more than doubled over the past four years, from about 100 to 250 annually. That number is projected to spiral further up this decade, fueled by an epic growth spurt in the commercial space sector. To relieve the congestion, some mission planners are looking to the ocea...