There's a lot of technology required to get humans to Mars.
That's the main takeaway I come away with after talking to NASA's chief technologist, David Miller. It's a trite observation, to be sure—but having all the challenges laid out really hammers the point home.
"It's one of those things where there are so many things you can work on," he told me. "But you have to pick and choose, and you have to choose wisely."
Some of it you likely would never have considered. Take "water walls." Line your space shuttle with water and hey presto: you both help protect against radiation during the journey and transport a vital resource for your astronauts. "Water with hydrogen content absorbs radiation to some degree," Miller explained. "Seeing as you need to take water, maybe you could line the walls of your capsule with water. So it's used for drinking as well as shielding."
I spoke to Miller after he gave a talk with NASA's chief scientist, Ellen Stofan, at the Royal Institution in London. The pair discussed the US space agency's plans for human exploration of Mars, and what it'll take to meet President Obama's target of a manned mission to the Red Planet's orbit by the 2030s, followed by a Mars landing.
The longer they talked, the more challenges became clear, until the whole idea of sending people into space at all seemed ridiculous.
Stofan gave an overview of some of the scientific challenges such a mission presented—from radiation to potentially toxic dust—and Miller added insight into the kinds of tech we'll need to develop to overcome them. The main steps: "We have to be able to land there, we have to be able to live and work productively, and we also have to be able to return home."
In some ways we are already halfway to Mars with humans
Mars One might have visions of a one-way trip, but NASA is dead set on maintaining the option of getting its astronauts back. And as Miller put it in response to an audience member's question, "If we don't have the technology to come back, I don't think we have the technology to go."
From landing systems on a planet that has a very thin atmosphere to designing life support for a place where supplies will take months to arrive, there's a lot of tools to factor in. But Miller, who joined NASA this March from MIT's Space Systems Laboratory, told me it's not as far off as you might think.
"I think one of the things NASA does poorly is that we always talk about the challenges ahead, but we don't talk about the challenges that we've addressed," he said. "As I got to NASA and started looking at the programs, I saw that in some ways we are already halfway to Mars with humans. We are there with robots today, but we are halfway there with humans."
That's not to say the spaceship's already on its way, but the technologies necessary to keep a human alive through lift-off, landing, and beyond are making strides—though there are obviously still great challenges.
Miller used the issue of radiation as an example. Given the amount of time it would take to get to Mars—about eight months with current technology—and the danger posed to humans by exposure to galactic cosmic ray radiation, it's a big one on NASA's list of 30-something identified risks on the roadmap for human research.
"The thing is, I don't think there is one technology that is going to win the day," he said. "It's one of those things which you have to look at as a mix of technologies working together." This could mean everything from choosing to launch at solar maximum, when solar winds would help reduce the galactic cosmic ray effect, to coming up with novel ways to shield the capsule of the spacecraft like the water walls mentioned above.
Then there's the less high-tech approach of simply selecting for astronauts who are less susceptible to the effects of radiation, though that obviously carries its own pros and cons. And technology built with another primary purpose can also help: designing a rocket to get to the surface faster, for instance, would have the additional benefit of reducing exposure to radiation. "So if you can look at different techniques such as nuclear thermal propulsion that can shorten the duration of the journey, that helps as well," Miller said.
But all that is just to address the one problem of radiation.
Miller took me through a whirlwind tour of the major equipment that, hypothetically, would get me to Mars. First up is transportation, where unlike conventional shuttles, crew is separated from cargo so as to deal with their separate requirements and so you can use different propulsion techniques for each. NASA is exploring solar electric propulsion, a very fuel efficient but relatively slow method that could be used for cargo.
Humans, on the other hand, need to move quickly. But you might want to send up some cargo before they take off. "So maybe your landing system is already out at Mars before you send humans," Miller suggested. "Perhaps you have put down a habitat on the surface, so you can check it out to make sure it's all ready." Tools for in-situ resource utilisation (ISRU) could also be on the packing list, which would attempt to harness resources like water or oxygen from the site itself.
We have to be able to land there, we have to be able to live and work productively, and we also have to be able to return home
When you do send up a crew, they'll probably want more space than a simple shuttle given the extremely long-haul flight and the lack of leg room in most capsules. "There are a lot of ideas about inflatable habitats, which you inflate once you're up in orbit and are a nice way to create a nice interior room without a lot of mass or complexity," Miller said.
And once your intrepid space explorers are up there, you're going to need to keep them alive with whatever limited cargo is available. That means recycling resources (it's probably best not to think about recycling water too much). And, Miller noted, communications tech would be an important aspect, not only for operational purposes but because we'll probably want to televise the whole thing.
Finally, there's getting off the surface when you need to get people back. Think about the infrastructure required to launch a spacecraft from Earth; there's no handy spaceport on Mars right now.
It's a lot to take on, but NASA is working towards each of the issues on its chart of risks. We're not there yet, but in a roundabout way, each failure means a step forward.
In his talk, Miller showed the audience a video clip of a recent test of NASA's Low-Density Supersonic Decelerator, fondly known as the "flying saucer." This could be one way of helping land a vehicle on Mars. In June, the rocket-powered vehicle was flown into near-space from Hawaii, with the largest supersonic parachute ever flown on board.
All goes well—until the parachute inflates and pretty much immediately gets shredded into pieces. NASA didn't seem too put out with the result, with the principle investigator for the project later saying it was "such a blessing to this program" to get an early look at where they needed to redesign.
Miller told the crowd it was the type of thing he liked to see, if it was going to happen, in a technology test—not on the way to Mars.