Since the launch of the Falcon Heavy rocket in February, NASA has been faced with some uneasy questions about the affordability of its own Space Launch System rocket. By some estimates, NASA could afford 17 to 27 Falcon Heavy launches a year for what it pays annually to develop the SLS rocket, which won’t fly before 2020. Even President Trump has mulled over the high cost of NASA’s rocket.
On Monday, during a committee meeting of NASA’s Advisory Board, former Space Shuttle Program Manager Wayne Hale raised the issue. After a presentation by Bill Gerstenmaier, NASA’s chief of manned spaceflight, Hale asked whether the space agency would be better off with the cheaper commercial rocket.
“Now that the Falcon Heavy has been flown and demonstrated, the advertised costs for it are quite low,” Hale said. “So there’s a lot of people asking why don’t we just buy four or five or six and do what we’re supposed to do without building this big, heavy rocket and putting things together like we did with the space station?”
In response, Gerstenmaier pointed Hale and other members of the advisory committee — made up of outside space experts who provide non-binding advice to the space agency — to a map he showed earlier in the presentation. This map showed the payload of the Space Launch System in various configurations in terms of mass sent to the moon.
“It’s a lot smaller than any of these,” Gerstenmaier said, referring to the Falcon Heavy’s payload to TLI, or “trans-lunar injection,” which basically means the amount of mass that can be extracted from low Earth orbit. broken and sent into lunar orbit. In the chart, the SLS Block 1 rocket has a TLI capacity of 26 tons. (The map also includes the more advanced Block 2 version of the SLS, with a 45-ton capacity. However, this missile is at least a decade away and will require billions of dollars more to design and develop.)
SpaceX has not publicly disclosed the Falcon Heavy rocket’s TLI capacity, but for the fully replaceable version of the booster, it will likely be somewhere between 18 and 22 tons. This is a value roughly between the vehicle’s published capacity for geostationary orbit, 26.7 tons, and Mars, 16.8 tons.
Gerstenmaier then said that NASA’s exploration program requires the unique capabilities of the SLS rocket. “I think it’s still going to be high-volume monolithic pieces that need some sort of SLS power to get them into space,” he said. “Then Falcon Heavy can play a role for routine maintenance and cargo delivery, perhaps with smaller crew vehicles than Orion. [Jeff] Bezos can play a part. What United Launch Alliance has talked about may play a role.”
“and”, not “or”
After this, Gerstenmaier reiterated NASA’s standard position regarding the SLS and much cheaper commercial launch solutions – that there is room for everyone in the industry. “I don’t see it as an ‘either/or;’ I see it as an ‘and’,” he said. “We’re trying to build a plan that uses SLS because of its unique capability of large volumes and large single masses in one launch. The cargo capacity is quite amazing with SLS. You can launch a large part of the gateway in one flight; where it would take multiple flights, I’m not sure you could even break some of those pieces into those smaller pieces to get them on a smaller rocket.”
One difficulty with Gerstenmaier’s answer to Hale’s question is that, in fact, NASA doesn’t yet have “large, monolithic pieces” that can only be launched by the Space Launch System. The cornerstone of his exploration plans for 2020 is the Lunar Orbiting Platform-Gateway, a small space station for orbiting the moon. The first piece of this station, a power and propulsion module, will be launched in 2022 aboard a commercial rocket.
Beyond this power element, NASA is in the early stages of requesting and accepting designs for the other components of this “gateway,” including airlocks and residential areas. These could, in theory at least, be easily designed to fit within the mass and size constraints of a Falcon Heavy or other planned commercial launch vehicles. Potentially, this would save NASA billions of dollars and allow it to spend significantly more money on exploration activities.