From NASA’s upcoming Moon to Mars mission to Elon Musk’s ambitious plans to use a SpaceX Starship to eventually colonize Mars, the race to populate the Red Planet is already on. But before humans can visit Mars and set up any kind of long-term base there, we need to send out scouts to see the lay of the land and prepare it for manned missions.
The mechanical pioneers we’ll be sending to Mars in the coming years will follow in the tire tracks of explorers like the Curiosity rover and the Insight lander, but the next generation of Martian robotics will use sophisticated AI, novel propulsion methods, and flexible smallsats to meet the challenges of colonizing a new world.
Designing for the Mars environment
There are distinct difficulties in building machines which can withstand the Martian environment. First, there’s the cold, with temperatures averaging around minus 80 degrees Fahrenheit and going down to minus 190 degrees Fahrenheit at the poles. Then there’s the thin atmosphere, which is just one percent the density of Earth’s atmosphere. And then there’s the troublesome dust that gets kicked up in any operations on the planet’s surface, not to mention the intense radiation from the Sun’s rays.
These environmental conditions create problems for robotics, from temperature variations which cause mechanisms to expand and contract and so wear over time, to dust getting into gears which prevents the use of exposed lubrication.
NASA’s Curiosity rover, with its robotic arm built by Maxar to withstand the Martian environment. NASA
“It’s a very unique and extreme environment, even for space robotics,” said Al Tadros, VP of Space Infrastructure and Civil Space at Maxar Technologies, which is the company that builds the robotic arms for NASA’s Mars rovers. Maxar’s robotic arms must be able not only to survive this harsh environment, but also perform the tasks like digging and drilling which enable scientific investigations.
Another consideration is weight limitations. When a part has to be delivered to Mars via rocket, every single gram need to be considered and accounted for, and that requires carefully selecting materials. “A lot of what we do uses different types of aluminum,” Tadros explained. “We also use titanium and in some cases we use carbon fiber, depending on the application.” Other weight-saving tricks include hollowing out some sections that don’t need to be so structurally strong, such as the length of a robotic arm which could be made from honeycomb matrix composite tubes.
Letting robots explore on their own
When a rover has been delivered to the surface of Mars, it can start exploring. However, due to the distance from Earth, it’s not feasible for engineers to control rovers directly. Instead, the robots have a degree of autonomy in their explorations, with NASA exercising supervisory command.
“They can tell the rover to go five meters in this direction,” Tadros says as an example. If there’s a problem executing that command, the rover will stop and wait for more instructions. “It’s rather rudimentary in that sense. But in the future, the desire is to have autonomy on board so the rover recognizes ‘Oh, I was told to go five meters, but there’s a boulder here. I’ll go around in this direction because I know the terrain is open.’”
“We need communication networks on Mars, both between two points on Mars and from Mars back to Earth.”
With a map and local knowledge, rovers will be able to perform self-navigation. They will even eventually be able to perform science autonomously, so scientists would only need to specify a command like ‘find this kind of rock’ and the rover could locate and analyze a sample. This kind of autonomy is already being planned as part of NASA’s upcoming lunar mission with the VIPER rover, Tadros said. “It’s going to be doing rapid prospecting, looking at and characterizing the regolith and the rocks to look for ice and other materials.”
With robotics like VIPER and the Marscopter launching as part of the Mars 2020 project, we can expect machines to scout and explore Mars, finding out about local resources and hazards which will help or impede the survival of humans on the planet.
Building a Mars Positioning System
Knowing where humans can safely land on Mars and where they can locate the resources they need is the first step towards colonization. But the real difference between a visit and a long-term stay on another planet is a matter of infrastructure. From water to communications to building habitats, we’ll need to find a way to provide the basic necessities of life in a sustainable way.
A rendering of a smallsat powered by an Orbion plasma thruster. Orbion
One method for setting up early infrastructure is through the use of small satellites, or smallsats. “If you’re thinking of colonizing Mars, where the smallsats come in is setting up the infrastructure for the colony,” said Brad King, CEO of Orbion, a company creating more efficient propulsion systems for smallsats. “We need communication networks on Mars, both between two points on Mars and from Mars back to Earth. On Earth, we’ve solved many of these problems with orbiting satellites around our planet.”
Smallsats could fulfill similar functions on Mars, by setting up a Martian equivalent to GPS – we could call it the Mars Positioning System. They can also scout out the surface of the planet, preparing the area for the humans to come.
Getting from A to B
The issue is getting satellites from Earth to Mars in an affordable manner. Traditionally, craft have been moved through space via chemical propulsion – that is, burning fuel to create thrust. This is a great way to create large amounts of thrust, such as the thrust required for a rocket to leave Earth’s atmosphere and make it into space. But it takes a massive amount of fuel, to such a degree that the biggest part of modern rockets is simply the fuel tank.
A cheaper alternative for moving through space is electric propulsion, which uses solar power to shoot an inert substance like xenon out of the back of the craft. This method is highly fuel-efficient, allowing the traveling of long distances with very little fuel. The downside is that this propulsion method is low thrust, so it takes longer to arrive at a destination. Sending a craft from Earth to Mars using electric propulsion might take a handful of years, compared to chemical propulsion with which the journey would take in the region of six to nine months.
“We as humans can’t hear something going wrong there, but when you translate that into data over time, AI can spot those subtle changes in deviation from the norm.”
However, the principle doesn’t only apply to small unmanned craft. A distinct advantage of electric propulsion is that it scales up very efficiently: “Electric propulsion technology works better the bigger it gets,” King said. “In principle, there’s nothing limiting the scaling up of electric propulsion to very large, crewed missions. You just start to run into economic hurdles because you’re building Battlestar Galactica-sized craft to get there.”
Electric propulsion has been used in projects like the Japanese Space Agency’s Hayabusa craft, which recently visited the distant asteroid Ryugu. And there are more plans for electricity propelled craft in future projects, such as the power and propulsion element (PPE) module of NASA’s Lunar Gateway station which use solar electric propulsion and will be three times more powerful than current capabilities.
Riding the bus
Launching and landing on planets will still require chemical propulsion, but the journey in between could be made far more efficient. King suggests that a non-propulsive crew vehicle or cargo vehicle could be put into a cycling orbit that goes past Earth and Mars. “Then you can essentially send things up and ‘ride the bus’ to Mars, requiring no propulsion,” he explained. A similar system has already been used for the Kepler Space Telescope, which used very little fuel after its launch into a Earth-trailing heliocentric orbit.
Of course, getting from Earth to Mars is only part of the journey. Once a craft arrives at Mars, it needs to slow down and enter orbit. To slow a craft, there are typically two methods: using reverse thrusters which require fuel, and aerobraking. The latter is where a craft dips into the outer atmosphere of Mars, using the aerodynamic drag to reduce the vehicle’s energy enough that when it comes out of the atmosphere, it can enter orbit.
The concept of electric propulsion has been somewhat fringe for the past several decades, but with these new projects it’s moved into the mainstream. “Now it’s being applied on a large scale – it’s like the transition of air travel from propeller driven aircraft to jet aircraft,” King said.
Sensors and AI
So we can send robots to scout the surface and satellites to set up infrastructure. We could even move enormous constructions like habitats through space using minimal fuel through electric propulsion. But the challenges of Mars colonization don’t only occur when humans are actually occupying an on-planet habitat. One major issue is how habitats and structures can be maintained for the long periods during which they will be unoccupied. Planned projects like NASA’s Lunar Gateway station, for example, will likely only be occupied 20 to 30 percent of the time, and we can expect similar or even lower rates of occupancy for potential Mars habitats.
Off-planet habitats need to be able to monitor themselves and fix themselves, especially when the nearest human is millions of miles away. And for that, AI is required.
“I believe that colonizing Mars is not a technological issue, it’s an economics issue.”
A system recently launched to the International Space Station could provide the basis for AI habitat monitoring. Bosch’s SoundSee system consists of a payload containing 20 microphones, a camera, and an environmental sensor for recording temperature, humidity, and pressure. These sensors collect data about the environment, especially acoustic information, which can be used to flag up problems.
“If you imagine there is a leak in the station, not only would there be ultrasonic tones, but also a pressure loss,” Bosch research scientist Jonathan Macoskey explained. “If we see both a pressure loss and an ultrasonic tone and other factors, that’s a concrete way of identifying a problem.”
Of course, a leak in the ISS would be loud, obvious, and dramatic. But many machine failures, especially in unmanned environments, are due to a gradual degradation over time. AI can be used to sense these things, SoundSee principal researcher Samarjit Das said, not by adding more or better sensors, but rather by using sensor data more efficiently to search for subtle patterns.
“Machines don’t just break down immediately from good to bad,” Das said. “There is gradual wearing down over time. Think of a system you might want to monitor in the ISS like a treadmill. The gears inside slowly degrade over time as it’s used. We as humans can’t hear something going wrong there, but when you translate that into data over time, AI can spot those subtle changes in deviation from the norm.”
A photo taken by the Mar’s Curiosity rover in the Gale Crater. NASA/JPL/MSL
Don’t imagine future ships and habitats controlled entirely by AI though, or even worse a rouge AI like 2001’s HAL. “Sensors and AI won’t replace humans entirely and automate everything,” Das said. “AI is a line of defense.” Macoskey agreed: “We see AI as a tool that enables new things in the same way that the microscope enabled humans to look at microscopic organisms.”
Colonizing Mars is possible
With all these environment and logistical difficulties, it might seem as if sending humans to Mars at all is a long shot, let alone establishing any kind of permanent or semi-permanent base there. Although these are serious challenges, solutions do exist in the form of AI, robotics, and propulsion methods which are being tested now for use in future space projects.
“I believe that colonizing Mars is not a technological issue, it’s an economics issue,” King said. “If we had the resources to spend, we know what needs to be built and we know how to build it. But the number of dollars or euros that it takes to do that is daunting.”
With sufficient funding, we do have the knowledge to begin setting up communication systems, enabling transportation, and building habitats on Mars. King is confident that it could even happen within our lifetime: “Given unlimited resources, we could set this infrastructure up in a decade.”