On Tuesday evening, in South Texas, SpaceX launched its Starhopper test vehicle for the second time. During this test, it flew much higher than last month, nearly straight up to 150 meters. Then, under the power of a single Raptor engine, the vehicle smoothly moved laterally for about 100 meters before a controlled descent and touchdown in the center of a landing pad.
From a technical standpoint, the test was impressive, demonstrating the thrust and vector control of the new Raptor engine. This was the first time a large rocket engine burning liquid-methane propellant made a significant flight, and it appeared to be mostly, if not entirely, successful. SpaceX engineers can take confidence from this test as they move into finishing their builds of Starship orbital prototypes in Texas and Florida later this year.
The test may have had more political significance, however. SpaceX seeks to demonstrate that Starship is a viable vehicle for NASA to consider flying astronauts to and from the Moon and other destinations. Visually, the flight of the stubby Starhopper was arresting: it took off in a cloud of smoke and landed in the reddish——dust it kicked up at the landing site.
Some politicians may be beginning to notice. Earlier this month, a spokesperson for Ted Cruz, a Republican senator from Texas, told Ars, “With regard to the SpaceX’s Starship, the senator and his staff have been following the developments closely and are excited about the vehicle’s prospects and the economic activity and innovation that is occurring as a result in Texas.”
The timing may have been coincidental—but about one hour after SpaceX tested its Starhopper vehicle, NASA’s Marshall Space Flight Center tweeted three photos of a replica of its Space Launch System rocket being loaded into a test stand at Mississippi’s Stennis Space Center.
“Technicians are lifting and installing a replica of the @NASA_SLS core stage in preparation for the SLS Green Run test,” the Alabama-based NASA center tweeted. Marshall manages development of the SLS rocket.
NASA has spent about $230 million to renovate and modify the B-2 test stand for this Green Run test-firing of the SLS rocket’s core stage. The rocket itself has been under development since 2011, at a cost of about $14 billion and counting. The first test-firing of the rocket may occur next year at Stennis.
By contrast, the SpaceX Starship program has been moving rapidly. Construction of the Starhopper test vehicle—affectionately nicknamed the “Flying Water Tower” because of its appearance—only began in mid-December 2018. Engine tests began a few months later, with the first 20m flight test in July, followed by Tuesday evening’s 150m hop.
SpaceX has now learned what it could from Starhopper, and it will proceed with full-size, suborbital prototypes for Starship that could make test flights later this year. The actual Starship vehicle, which will launch from Earth as the second stage of the under-development Super Heavy rocket, may take flight some time in 2020 or later, depending on prototype testing.
A step toward Mars
It is easy to dismiss Starhopper for its slap-dash construction or the fact that it only flew 150 meters. After all, what does such a test accomplish?
Perhaps an analogy can be found in SpaceX’s Grasshopper test program. For the Grasshopper test, a Falcon 9 first-stage fuel tank that had been used for qualification testing was modified with landing legs. From September 2012 through October 2013, the company flew the vehicle several times to an altitude of up to 744 meters above its site in McGregor, Tex. This may have seemed similarly showy and shambolic—only less than three years later the company had landed Falcon 9 rocket first stages successfully on land and sea after trips to space.
From this standpoint, Starhopper’s two flights should be seen as steps toward a vehicle with potentially revolutionary capabilities, including landing and taking off propulsively from distant worlds including the Moon and Mars. SpaceX may not get there. This project may be too difficult, or it may require too much funding. But betting against a company that works as hard, fast, and with as much urgency as this is unwise.