Mars mission sequels
by Jeff Foust
|“Probably the most important thing that I want to convey in this presentation as that I think we’ve figure out how to pay for it,” Musk said.|
This year, when Elon Musk returned to the Congress in Adelaide, Australia, conference organizers were better prepared. They set out clear rules of where and when people could line up to get into the main hall for his speech, scheduled for effectively the end of the week-long event. An hour before the speech, the crowd started to orderly file its way through a maze of stanchions. By the time Musk took the stage, only about ten minutes after the scheduled start time, everyone had filed in and there were still a few seats available in the upper corners of the hall at the Adelaide Convention Centre.
Musk took the stage after a brief introduction by International Astronautical Federation president Jean-Yves Le Gall and launched into an update of his Mars mission architecture, with a revised version of his ITS, noting the vehicle was now known as simply BFR. (“B” stands for “big” and “R” for “rocket”, while “F” is left as an exercise for the reader.) A key difference, he argued, was in economics.
“Probably the most important thing that I want to convey in this presentation as that I think we’ve figure out how to pay for it,” he said.
This new BFR he described in his speech was somewhat smaller than last year’s ITS, but still extremely big. The vehicle’s diameter has shunk from 12 to 9 meters, reducing the number of Raptor engines in its first stage from 42 to 31. With fewer engines, each generating less thrust, the rocket’s liftoff thrust is “just” 10.8 million pounds-force, 40 percent of last year’s ITS.
Despite this reduction in size, the booster and its spaceship upper stage—both still reusable—can place 150 metric tons of payload into orbit (including 100 people) and return 50 tons back to Earth.
One thing Musk stressed in his presentation was the versatility of the BFR. Last year, the focus was almost exclusively on Mars, with only a passing mention of the ability of the ITS to visit other solar system destinations. This year, he showed the BFR launching satellites, supporting a lunar base, and even, at the end of his talk, performing point-to-point suborbital spaceflight for passenger transportation (something that attracted a lot of public attention, despite many clear questions about its economics, technical feasibility, and regulatory issues.)
Musk mentioned that versatility because it is central to that affordability he also mentioned. BFR, in his vision of the future, will take over everything SpaceX currently does, or plans to do, with its Falcon rocket and Dragon spacecraft.
“This is really quite a profound—I won’t call it a breakthrough, but a realization—that if we can build a system that cannibalizes our own products, makes our own products redundant,” he said, the company’s resources can then “be applied to one system.”
Musk foresees phasing out the Falcon and Dragon families and move all of the satellite launches and space station resupply missions currently handled by those vehicles. Some customers, he acknowledged, would be “conservative” and might want to stick with those vehicles for a while. “What we plan to do is to build ahead and have a stock of Falcon 9 and Dragon vehicles” for those customers until they’re comfortable with the BFR.
However, he emphasized that the future of SpaceX will be with the BFR. “All of our resources will then turn towards building the BFR,” he said, “and we believe we can do this with the revenue that we receive for launching satellites and servicing the space station.”
That transition will take several years. Work on the first BFR vehicle will start in the first quarter of 2018, he said, with the first vehicle “ready for launch in about five years.”
|“That’s not a typo, although it is aspirational,” he said when he showed a chart with a 2022 date of the first Mars landing.|
While his interest in supporting lunar base—seen by some observers as an effort to win support from the Trump Administration and its perceived, but not yet explicit, interest in a human return to the Moon—got a lot of attention, it was clear from his presentation that his primary interest still lies with Mars. His new plan calls for landing “at least two” cargo vehicles on the surface of Mars in 2022, followed by at least four vehicles, carrying both crew and cargo, in 2024.
“That’s not a typo, although it is aspirational,” he said when he showed a chart with the 2022 date. “But if not this timeframe, I think pretty soon thereafter.”
Critics will note that SpaceX’s schedules are often aspirational: the Falcon Heavy, for example, is now several years behind schedule, with a launch now planned for no sooner than the end of the year. Schedules for SpaceX’s Crew Dragon vehicle has also slipped. Thus, any schedules should be taken with a grain or two—or many more—of salt.
Also, for all of the emphasis he made on the affordability of developing BFR, there were few hard figures. He made no mention of the costs of developing the system or individual vehicles, or how often each vehicle can be reused, key to amortizing its costs. He also gave no firm figures for launch costs, beyond indicating that BFR would have a lower cost per kilogram of payload than any other vehicle.
After his speech, he posted on Instagram a video he showed at the conference illustrating the point-to-point use of BFR, in this case a half-hour flight from off the coast of New York to off the coast of Shanghai. “Cost per seat should be about the same as full fare economy in an aircraft,” he wrote. “Forgot to mention that.”
After he showed this video in stage, he wrapped up his talk. “If we’re building this thing to go to the Moon and Mars, then why not go to other places on Earth as well?” he asked. “Thank you.” And with that, he walked off the stage.
There was no question-and-answer session like after his talk in Guadalajara, and thus no opportunity for any zealous fans of Musk to proclaim their allegiance to him, but also no opportunity to drill down into deeper details. (The press kit for the Congress mentioned a press conference after his talk, but conference organizers said hours before the talk it was cancelled due to a “last minute commitment.” Other sources said that SpaceX had not actually agreed to hold a press conference in the first place.)
Lockheed Martin’s proposed Mars lander could support four people on Mars for several weeks at a time, and could be reused for multiple missions. (credit: Lockheed Martin)
Elon Musk was not the only person providing an update to Mars mission architectures at the conference that day. Six and a half hours before he took the stage, Lockheed Martin used the conference to discuss their plans for human missions to Mars, known as Mars Base Camp.
The concept, announced last year, remains in many respects the same: development of a spacecraft to travel to Mars orbit and back, using the Orion spacecraft and other components that exist today or under development. That plan would place a crew in Mars orbit—but not on the surface—as soon as 2028, the company claimed.
What Lockheed Martin added to the concept was a means to get astronauts to the surface and back. The lander, launched separately, is designed to carry up to four people to the surface on sortie missions lasting up to a few weeks at a time. The single-stage lander, powered by liquid oxygen and liquid hydrogen engines, is intended to be refueled and reused: up to three trips per Mars per stay in Mars orbit by the Mars Base Camp spacecraft, with a total lifetime of at least six missions.
|“The Moon has always been the gateway to get to Mars,” Chambers said. “The big focus is to make sure we don’t lose sight of Mars as we start to work the details of the Moon.”|
The lander has a striking aerodynamic shape, which the company said is designed to use the Martian atmosphere as much as possible to slow it down. In an interview prior to the presentation, Rob Chambers of Lockheed Martin said aerodynamics can handle about 80 percent of the change in velocity, or delta-V, needed for landing, with the engines handling the rest. (Musk, in his presentation, said that aerodynamics can take care of removing 99 percent of the energy of the BFR spaceship when landing at Mars.)
Lockheed Martin chose liquid hydrogen and liquid oxygen as propellants for the lander in part because of its performance. “The high efficiency is really important. It enables things like the lander,” said Tim Cichan, space exploration architect at Lockheed Martin, in the presentation.
Another factor, though, is their belief in the emergence of a “water-based economy” in space, with water available at the poles of the Moon and near Earth asteroids. That water, the company foresees, would be shipped to Mars, perhaps as part of commercial deals, to refuel the lander.
Cichan said later that the water that would be converted to liquid hydrogen and liquid hydrogen could be delivered to Mars orbit in any number of ways, ranging from direct transport from the Earth to extraction from asteroids. “As long as the water shows up, and it can be turned into propellant, we’re happy.”
The lander could also be used for missions at the Moon. The lander has enough delta-V in its current configuration to land and take off without refueling, even without the aerodynamic assistance it gets at Mars. The lander’s performance could be improved by removing some of the aerodynamic surfaces not needed for lunar landings.
With the lander generating power from its propellant supply while on the surface, rather than solar or nuclear power, Lockheed Martin believes it could operate even at permanently shadowed lunar craters, where the cold temperatures would actually be an asset for preserving its cryogenic propellants. “With the zero-boiloff-powered fuel system, the lander is extremely happy in the darkest craters on the lunar surface,” said Danielle Richey, advanced programs exploration architect at Lockheed Martin.
That dual-use design of the lander, Chambers said, is key to fitting into an exploration architecture that includes the Deep Space Gateway—which could be used to test the Mars Base Camp spacecraft—but also options for lunar exploration. “The Moon has always been the gateway to get to Mars,” he said. “The big focus is to make sure we don’t lose sight of Mars as we start to work the details of the Moon.”
Turnout at the hour-long talk—which did include written audience questions—was only a small fraction of Musk’s talk later in the day. Starting at 7:30 am Adelaide time certainly didn’t help, although it meant that the talk was mid-afternoon to early evening in the US. (A technical glitch, though, prevented a live webcast, with video available only after the talk ended.)
Both Lockheed Martin and SpaceX have the same goals in mind: humans on the surface of Mars. But the similarities between the companies end there. Beyond the obvious technical differences is a clear different in philosophy.
|Which approach is the right one? The answer might also well be neither.|
Lockheed Martin is proposing a largely evolutionary approach, leveraging existing technologies and systems to get people to Mars as soon as the late 2020s. It fits into NASA’s plans, and leaves room for contributions by both commercial and international partners, from delivery of water ice to Mars for the lander to development of modules for the Mars Base Camp vehicle.
SpaceX, though, is taking a revolutionary approach, casting aside what it has done in favor of a new, giant vehicle that could send humans to Mars even sooner, although with tremendous uncertainties about cost and schedule. SpaceX’s approach seems very much a go-it-alone one, with room for customers, but not for partnerships that might distract from the vision.
Which approach is the right one? Beware of anyone who is certain one or the other is the One True Way of getting people to Mars. With so many details, from engineering to economic, largely unknown about these systems, it’s premature to declare one the “better” approach than the other.
The answer might also well be neither: countless designs for human missions to Mars have foundered on the shoals of political, economic, and technical challenges, which might yet disrupt or doom SpaceX’s BFR and Lockheed Martin’s Mars Base Camp. At the very least, there is no shortage of bold ideas for these missions, but such ideas are just the start.