Like Musk's SpaceX, Boeing is focused on building out the commercial space sector near earth as spaceflight becomes more routine, while developing technology to venture far beyond the moon.
The Chicago-based aerospace giant is working with the National Aeronautics and Space Administration to develop a heavy-lift rocket called the Space Launch System for deep space exploration. Boeing and SpaceX are also the first commercial companies NASA selected to ferry astronauts to the International Space Station.
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Musk last week welcomed competitors as he unveiled a SpaceX craft that would dwarf the workhorse of Apollo missions of a half-century ago, hauling 100 travelers to Mars with cruise-ship-style amenities.
"The goal of SpaceX really is to build the transport system. It's like building the Union Pacific railroad," Musk told a space conference, as he laid out a plan to bring travel to Mars to a mass market with tickets priced one day as low as US$100,000.
Boeing built the first stage for the Saturn V, the most powerful U.S. rocket ever built, which took men to the moon. Nowadays, Muilenburg sees space tourism closer to home "blossoming over the next couple of decades into a viable commercial market." The International Space Station could be joined in low-earth orbit by dozens of hotels and companies pursuing micro-gravity manufacturing and research, he said.
"I think it's a fascinating area for us," he said.
Muilenburg said Boeing will make spacecraft for the new era of tourists. He also sees potential for hypersonic aircraft, traveling at upwards of three times the speed of sound.
Boeing and Lockheed Martin are among the space heavyweights developing experimental aircraft that could fly U.S. travelers at speeds right out of a science fiction movie.
Lockheed's Falcon Hypersonic Technology Vehicle 2 is being designed to zip through the sky at Mach 20 (about 13,000 miles per hour), flying between New York and Los Angeles in 12 minutes. Boeing's X-51A WaveRider, which relied on its own shock waves for compression lift, reached Mach 5.1 in 2013.
Costs will need to drop substantially before these experimental spacecraft can be seriously considered for commercial use, Muilenburg said.
"That business model isn't closed yet. At some point it will," he said. "The future of innovation has to include not only the technology, but economic viability."