Last month, SpaceX tested a "hopping" Falcon 9 rocket as part of its Grasshopper program. It was a standard first stage with a single Merlin-1D engine in its tail instead of the usual 9, and landing legs added on. The hop was all of six feet, but was the first step in the companys plan to give its boosters the ability to launch payloads into orbit and then land robotically so they can be refueled and launched again. Instead of plunging back to Earth and being destroyed as it does now after completing its part of the job, each of the Falcon 9s two stages would fly back to Earth in a controlled maneuver, using reserve propellant to make a gentle touchdown on retractable legs.
Reusable orbital flight could bring airline-style operations beyond Earth. Its all about reducing the very high cost of leaving the planet. Imagine throwing away an airliner every time you fly across the Atlantic and you get the idea of the current state of orbital transportation. (Spacecraft like the shuttles are reusable, but the rockets that launch them to orbit are not.) Each flight has to pay for an entire vehicle, putting the trip out of reach of all but government programs, big corporations, and the wealthiest individuals.
But if the cost of a vehicle could be spread across multiple flightsthe more the betterspaceflight could become much, much cheaper, perhaps opening the door to truly routine, reliable access to space.
"The end point would be the costs of the propellantsand kerosene and liquid oxygen arent particularly expensive propellantsplus whatever nominal operational costs it would be to prepare the vehicle and launch it," says Futron Corporation space launch analyst Jeff Foust. "You might be able to get costs down to the low millions of dollars per flight." Compare that to the $50 million to $60 million per flight cost today, says Foust, and we could see all sorts of new business opportunities open up.
"Its widely excepted that very large reductions in priceorders of magnitude or moremove us into a different regime, where there are a whole lot of new users of space whose business plans become practical," says Jeff Greason, president of XCOR Aerospace and a member of the White House-appointed Review of U.S. Human Space Flight Plans Committee.
Just what those business plans would be is anyones guess, since theres no sure way to find out until the capability exists. Foust likens the situation to the early days of the personal computer industry. "When people were developing PCs in the 70s and 80s, they werent thinking about a lot of the applications that we use them for now because no one had thought about what happens when computers become low-cost, ubiquitous, and networked," he says.
A hint of whats possible comes from the realm of suborbital spaceflight, where reusable vehicles in development are already attracting customers in the form of space tourists paying anywhere from $95,000 for a ride on XCORs Lynx vehicle, to $200,000 on Virgin Galactic and Scaled Composites SpaceShipTwo. That market simply didnt exist before SpaceShipOne proved the feasibility of reusable suborbital vehicles in 2004.
Greason sees a kind of virtuous cycle driving prices down. "If we suddenly have $500-a-pound launch, once the economy got used to that and all the new businesses that would use $500-a-pound launch came into being, a lot of them would be very cost sensitive," he says. "All of a sudden space would be like every other facet of the economy and thered be a lot of competition to get the prices down, because if you got the price down, youd make more money."
In the area of unmanned orbital flight, for example, Foust sees lower launch costs bringing an increased market for space-based imagery. "You can imagine putting up a constellation of satellites that could provide basically 24/7 imaging of any particular point on the planet," he says. Currently, commercial providers of such imagery can afford to launch only a couple of satellites each, requiring a days-long wait for one to pass over a spot of interest. "If youre able to put a constellation up, you could have almost real-time imagery, depending on lighting and clouds and so on."
From a technical standpoint, reusable orbital vehicles should be doable. The Space Shuttle, after all, reused all but the big external fuel tank it needed to get to orbit. But high development costs, extensive maintenance requirements, and months-long turn-around times drove the Shuttles per-launch cost to $1.5 billion.
The SpaceX grasshopper may well be on the right track to reusable orbital flight. But to bring about the spaceflight revolution the company seeks, the system will have to cost less to develop and achieve much shorter turn-around times than the Shuttle, Foust says. He figures that turnarounds of several days to one week ought to give it a good start.
Michael Belfiore is the author of Rocketeers: How a Visionary Band of Business Leaders, Engineers, and Pilots Is Boldly Privatizing Space, and is a frequent PM contributor.