A Deeper Look into AI and Space: Mars Rovers
“Mars is there, waiting to be reached.” — Buzz Aldrin
This is Part 2 of a blog series. Click here to see the Introduction or Part 1.
Sometimes called the Red Planet, the dusty, cold, and rocky world of Mars has been an area of considerable interest for scientists. Mars is the fourth planet from the sun and, compared to Earth, is smaller and colder, and its atmosphere is thinner. Although divergent in these factors, the geologic processes of the two planets are surprisingly similar, and it is believed that Mars was once warmer and wetter. Because of this presumed past, as well as because of its proximity to Earth and favorable (compared to other planets) temperatures, many space missions have been dedicated to exploring and understanding Mars. In fact, Mars is the only planet we have sent rovers to probe.
The USSR began sending spacecrafts to Mars in the mid-1960s, though all were unsuccessful. It was actually NASA’s 1971 Mariner 9 that became the first artificial satellite of Mars. Since then, many different types of spacecrafts have been sent to Mars, some successful, others not. In this post I will be focusing on rovers. Rovers are planetary exploration devices that are primarily designed to explore and investigate other planets. Since Mars contains lots of rocks and minerals, scientists can use rovers to interact with and sample the rock’s chemical mixture, ultimately giving them insight into the history and changes to the environment. Trying to acquire this information, NASA has successfully launched and landed four rovers: Sojourner (1996–97), the twin rovers Spirit and Opportunity (2003–4), and most recently Curiosity (2011–12). NASA also just launched a new rover, Perseverance, and we are waiting and hoping for yet another successful landing.
Launched on November 26, 2011, the Curiosity rover landed on Mars at Gale Crater on August 6th, 2012. Its mission was and continues to be “to search areas of Mars for past or present conditions favorable for life, and conditions capable of preserving a record of life”. In order to complete its mission, Curiosity is loaded with high tech equipment such as a Geology lab, a rock-vaporizing laser, and lots of cameras. With six wheels and four motors, Curiosity can turn in place and in arcs. In addition, its great suspension system enables it to drive over uneven terrain with all the wheels on the ground. In order to determine driving locations, arm or part movement, and mechanism use, Curiosity uses Navigation cameras up high and Hazard-avoidance cameras down low. It also has a computer that maps the terrain, specifying areas to avoid. All these functions and mechanisms were designed specifically to aid the rover’s success and survival. Two of the most important and interesting tools that I am doing to discuss in depth are SAM and the ChemCam.
SAM, or Sample Analysis at Mars, is a tool composed of three instruments: a gas chromatograph, a quadrupole mass spectrometer, and a tunable laser spectrometer. Together, these three instruments work to search for and measure levels of carbon, oxygen, and other elements associated with life. The process and instruments work as follows. Samples of rock or soil are heated in ovens present in SAM. The samples are then vaporized and fed into the gas chromatograph. Inside this instrument, the gases are separated into similar groups and again fed into the mass spectrometer. Here, the different gases and their corresponding masses are identified. Lastly, the gases make their way into the laser spectrometer where the different isotopes are measured to look for things like water vapor or the cause of methane production (life or geologic processes).
Although SAM is located inside the rover, the ChemCam, or Chemical Camera sits on top of the rover and is used to identify the chemical and mineral composition of a target (rock or soil). The ChemCam is made up of four main parts: a telescope, a camera, a laser, and a spectrograph. The telescope is used to center the camera that takes pictures of rocks. Curiosity then uses an AI system called AEGIS to choose which rock to analyze. Once chosen, the telescope is again used to center the laser, which zaps the target. The contact between the sample and laser creates plasma (extremely hot gas made of free-floating ions and electrons). The spectrograph then records the light or the spectrum of plasma, showing the chemical composition of the initial target. In essence, from 20 feet away, the ChemCam can identify the kind of rock, determine the composition and the abundance of all chemical elements, measure the effects of weathering (process of disintegration) on the rock, and provide visual assistance for drilling of rock cores. This information is critical in helping to map and understand Mar’s terrain and geologic process as the chemicals present in different areas can tell us a lot about the history of the planet.
AEGIS, the artificial intelligence system used by the ChemCam, is an important part of the sampling process as it helps decide the rock from which to draw samples. A signal sent from Earth takes around 4–24 minutes to reach Mars depending on the distance between the planets. This long waiting time makes automating the rover crucial to saving valuable time. In order to maximize their efforts, scientists have a set criteria for interesting rocks depending on terrain and properties. However, because of this waiting time, it would take far too long for information on each rock to be sent back in order for the scientists to choose which rock to sample from. Instead, they use AEGIS, Autonomous Exploration for Gathering Increased Science. AEGIS uses an algorithm called Rockster, which attempts to identify discrete objects by a combination of edge-detection, edge-segment grouping and morphological operations (image processing operations that adjust pixel values based on surrounding pixels). The way it works is that the algorithm scans the image for edges of objects, and then defines or ‘finds’ rocks. Next, it determines properties such as size, shape, brightness, and distance from the rover. Finally, it ranks the rocks from most to least interesting and then has the laser vapor the most interesting one. This AI system has been very successful and has increased much needed data. Before this system was put in place, rovers were just blindly sampling rocks. The effects of the shift to this algorithm were tracked in a study that found that the rover hit a target of interest 93% of the time versus the expected 24%.
Curiosity has been operating on Mars for around eight years, and, although no traces of living organisms have been found yet, it has been highly successful. One thing that Curiosity found was that the radiation levels on Mars are similar to those experienced by astronauts on the International Space Station. This is good news for the eventual transition from rovers to humans as radiation is always a possible concern. Related more to life on Mars, just seven weeks after touchdown, Curiosity found an ancient stream-bed that once flowed with water. This discovery strengthens the idea that Mars may have been habitable at some point as we have generally found on Earth that if there is water, there is life. Additionally, in 2013, Curiosity became the first rover to drill into a rock and collect samples of another world. This event occurred in the John Klein outcrop where the rover drilled 2.5 inches into the Martian soil. Curiosity analyzed this sample and found some of the key chemical ingredients for life (sulfur, nitrogen, hydrogen, oxygen, phosphorus, and carbon). Overall, the Curiosity rover has done wonderful work, returning over 49,000 images to Earth. Even with the upcoming arrival of a new and more advanced rover, Curiosity will continue to be integral to our exploration and understanding of Mars.
The newest NASA rover, Perseverance, was launched on July 30th, 2020 from the Cape Canaveral Air Force Station in Florida. Set to land at Jezero Crater on February 18th, 2021, its main mission is to “seek signs of ancient life and collect rock and soil samples for possible return to Earth”. Created just eight years after Curiosity’s landing, the Perseverance rover is equipped with new and improved technology like zoomable cameras (MastCam-Z and others), a weather station that provides daily and seasonal reports (RAD), and laser and X-ray instruments (SuperCam and PIXL). Outdoing Curiosity, Perseverance uses a new technology called terrain relative navigation to be able to self drive and build a map of the Martian landscape. Perseverance also uses an improved AEGIS with the updated SuperCam. The SuperCam is basically the same as the ChemCam, but has some more advanced features such as being able to take colored pictures. Perseverance also has a new device, Planetary Instrument for X-ray Lithochemistry (PIXL), that looks for traces of past microscopic life. PIXL is a precision X-ray device located on the rover’s arm. Powered by AI, it analyzes rocks for different chemical compositions by shooting X-ray beams at the target. PIXL is primarily used to zoom in on tiny features of rock or soil to find changes in textures and chemicals, specifically looking for signs of life. So, you might be wondering, what is the difference between PIXL and the SuperCam? Basically, the main difference is that PIXL takes measurements close up and actually looks for signs of ancient microbial life, whereas the SuperCam takes measurements from afar and looks for signs that or conditions in which life could exist.
Two more new and exciting technologies present on Perseverance are microphones and MOXIE. As a result of several successful missions to Mars, scientists have been able to recreate and simulate conditions on Mars. However, sound is the last of the five senses still utterly unknown about Mars. Only two of NASA’s Mars spacecrafts have carried microphones — the Mars Polar Lander and the Phoenix Lander. Unfortunately, the former mission failed, and in the latter, a flaw was discovered in the device containing the microphone, and it was never turned on. The Perseverance rover will carry two microphones to record the first Martian sounds. Additionally, these microphones not only will provide scientists with the thrill of auditory perception on Mars, but the sounds of the rover itself should be useful to engineers trying to solve problems with the motors or wheels. The second intriguing new piece of equipment, MOXIE, is a carbon dioxide to oxygen converter. To do this, MOXIE first collects carbon dioxide from the atmosphere. It then electrochemically splits it into oxygen and carbon monoxide. These molecules go through purity analysis and then are finally released into the atmosphere. MOXIE is important as about 95% of Mars’s atmosphere is carbon dioxide. If we could turn this carbon dioxide into oxygen, we could make Mars more habitable to humans while also removing a barrier to sending human astronauts to Mars.
One of the most pioneering technologies aboard Perseverance is the Ingenuity helicopter. Weighing around 4 pounds, Ingenuity will test the possibility of flight on Mars. Because the atmosphere is so thin, it offers very little lift, and, therefore, the helicopter must be lightweight with larger and faster rotor blades. Engineers spent a long time designing, building, and testing Ingenuity and are hoping for groundbreaking results as the first flying craft on another planet. Ingenuity is fully autonomous as it must decide how to best keep itself warm and charged at night. It also must navigate completely on its own as the signal wait time between Mars and Earth is too long. To do this, the scientists have given the helicopter a flight plan and programmed the system to figure out how to complete the plan based on its surroundings. The Ingenuity autonomy system consists of a navigation camera, a laser altimeter (to map the terrain), and an accelerometer gyroscope package called an inertial measurement unit (the accelerometer measures acceleration and the gyroscope measures turning speed). The presence of Ingenuity on this mission is a big deal not only because it should result in flight on Mars. It can also scout ahead and explore places rovers cannot travel to, and all the while take aerial images with a 10x higher resolution than the satellites we have orbiting Mars. If successful, Ingenuity could open up a whole new range of exploration possibilities on Mars.
Because Perseverance has not landed yet, there is no information or data about its success or findings, but nevertheless, there is still much to talk about. Perseverance has a similar mission to Curiosity, but also has the task of setting up samples to be retrieved by future missions. Although rovers have great capabilities, they can only do so much, and are stuck with the equipment they have. Perseverance is tasked with the initial retrieval of samples that will later be brought back to Earth for detailed analysis. This process is called sample caching and is composed of three steps. First, Perseverance must find rocks of interest. These include rocks that have been formed or altered by water, rocks that contain organic molecules, and volcanic and other rock samples for geologic record. Second, Perseverance must collect and seal samples. The rover will use a coring drill to collect about two inches in a test tube. The tube (around 15 grams) will then be tightly sealed and placed in a storage rack. Finally, Perseverance must carry and cache the samples (expected to be around 30). The drop sights for the samples will be determined by the mission team as they must choose strategic locations for future missions to retrieve and return them.
Hopefully all will go well with the Perseverance rover, and we will be able to gather ground-breaking data. Who knows, maybe someday we will see colonies on Mars. Until then, NASA will continue its hard work, constantly improving technology and launching updated spacecrafts. To read about NASA’s other latest technology as well as possible future applications of AI in space, keep an eye out for part 3…
Caroline is a Student Ambassador in the Inspirit AI Student Ambassadors Program. Inspirit AI is a pre-collegiate enrichment program that exposes curious high school students globally to AI through live online classes. Learn more at https://www.inspiritai.com/.