�鶹��Ժ

Artemis mission signals new era of discovery

On April 12, 1961, with a soaring “Poyekhali!” from cosmonaut Gagarin and a boom from a Vostok-K rocket engine, humanity abandoned its status as an exclusively terrestrial species and launched its way towards the stars with the first human to leave the atmosphere. From the first missions carrying humans on suborbital space flights to the Apollo program landing 12 astronauts on the surface of the Moon, the 1960s and 70s brought about an unprecedented era of progress in rocketry, spaceflight, and the next frontier of human exploration. It was a time when we truly reached for the stars and the barrier between science and science fiction felt practically nonexistent. What was next? A permanent Moon colony by 1980? Mars by 1990? And then, just as soon as it had started, it was over. No human has visited another world since.

Subsequent decades brought robotic landers to Mars, Venus, Saturn’s moon Titan, and even a few asteroids and a comet. Probes have visited all of the eight planets, and even Pluto has been visited by a probe that was launched shortly before it lost its own planetary status. Other missions such as the Hubble and recently launched James Webb Space Telescopes have brought both an immense amount of information about our universe and stunning views of the cosmos. Manned space exploration has continued in the form of several permanent space stations and other programs like the Space Shuttle missions. However, humans have yet to venture beyond low Earth orbit since the Apollo 17 astronauts left the Moon in 1972. There was barely a decade between the first manned spaceflight and our first visit to another world, yet in the nearly fifty years since our last trip to our celestial companion, not one person has left the orbit of Earth. It’s time to change that.

Artemis, Greek goddess of the hunt and twin of her brother Apollo, is humanity’s return to the Moon after five decades of absence. This endeavor, a collaboration between NASA and several international space agencies, will continue and expand upon the work the Apollo program began a half-century ago, sparking a new age of exploration and study of the universe and our place in it. Of course, before we do that, we have to actually get there. The Apollo missions used the Saturn V, a colossus taller than the Statue of Liberty weighing in at 310,000 pounds. Even though its last launch was in 1973, it is still the most powerful rocket ever launched with approximately 7.6 million pounds of thrust. The new Space Launch System (SLS) surpasses that by a cool 1.2 million pounds of thrust. When it is launched, it will be the most powerful rocket the world has ever seen. This rocket will be the principal launch vehicle for the Artemis program, carrying infrastructure, cargo, and of course, astronauts to the Moon.

So why does the SLS need so much power? Artemis differs from Apollo in that Artemis is designed to establish a permanent settlement on the Moon, allowing astronauts to live and work on the surface for up to a month at a time, rather than just a few days. This requires the transportation of a significant amount of infrastructure to the Moon so as to enable such long stays. Part of this infrastructure is the Lunar Gateway station. In the Apollo missions, when the spacecraft reached lunar orbit, two of the astronauts descended to the surface in the Lunar Module while one astronaut remained in orbit on the Command Module. The Lunar Gateway station is like a permanent Command Module, staying in lunar orbit so that astronauts who are coming from Earth or returning from the lunar surface can resupply and refuel. It also allows astronauts to live and work in lunar orbit, letting them perform experiments that wouldn’t be possible on Earth. 

The next step is getting down to the lunar surface from the Lunar Gateway. This aspect of the mission is called the Starship Human Landing System (Starship HLS) and is being developed by SpaceX. The Starship HLS acts like the Lunar Module from the Apollo missions; it takes astronauts from lunar orbit to the surface, sustains them while on the surface, and returns them to orbit. Because the Starship HLS can use the Lunar Gateway as a base of operations, it is capable of supporting astronauts on the surface for a longer period of time than the Apollo Lunar Module could, as it can return to the Gateway station for refueling and resupply. This makes it possible to bring more advanced technology and infrastructure to the surface than what was possible on the Apollo missions.

Perhaps the most exciting aspect of Artemis, the Artemis Base Camp, is unfortunately the most uncertain. It is scheduled to be established sometime near the end of the decade, and in its current form consists of three main parts. The first part is the main habitat for the astronauts, a combined home and office that will allow up to four astronauts to live and work on the Moon for a month at a time. The next part is the Lunar Terrain Vehicle, an unpressurized car that astronauts can drive while wearing their spacesuits. They will be able to use this vehicle to travel more than 12 miles away from their base of operations. The Apollo missions brought something similar to the Moon, called the Lunar Roving Vehicle, whose iterations in Apollo 15, 16, and 17 drove a combined 56 miles on the lunar surface. There is also the Habitable Mobility Platform, a pressurized rover that would allow astronauts to drive on the surface of the Moon without wearing their bulky spacesuits. This would act as a mobile home and significantly expand the operational area of a lunar mission by eliminating the restriction on travel time caused by the need to carry oxygen in the astronauts’ spacesuits. 

Any permanent base on the Moon would need to be able to power itself; constant refueling missions would be costly and inefficient. Many spacecraft and rovers use solar panels, and the Artemis Base Camp will be no exception. However, the nature of the Moon’s orbit and rotation makes depending on sunlight for power rather complicated. The Moon is tidally locked with Earth, which means that the same side of the Moon always faces towards Earth, so a day on the Moon is the same length as its orbital period around the Earth, or about 27 Earth days. This means that about half of the time, any particular spot on the moon will be in darkness and unable to collect any power from solar panels. Prolonged lunar nights pose another danger as well: the intense cold can be dangerous to electronics and equipment—as well as human life.

To mitigate some of these effects, NASA plans to establish the Artemis Base Camp at Shackleton Crater. Named after the explorer who was famous for his own expeditions to Earth’s south pole, Shackleton Crater is located at the south pole of the Moon. A location like this has several benefits. Due to its polar location, the crater receives sunlight differently than most other places on the moon. “Both poles of the Moon contain regions where the Sun literally never shines. This is a result of the Moon’s orientation relative to the Sun: its spin axis is always within about 1.5° of being perpendicular to the Sun’s rays. As such, craters and other depressions near the poles will be naturally shielded from sunlight. Interestingly, the same effect creates areas of nearly perpetual sunlight, typically on the summits of mountains and crater rims,” says CU professor and planetary scientist Dr. Paul Hayne. Both the light and dark regions are useful. The illuminated regions can be used to collect sunlight for solar power, and the unlit regions have their own precious resource: water. “NASA’s selection of landing sites near the lunar south pole stems directly from the desire to investigate and utilize ice in the [permanently shadowed regions],” said Hayne. “Water at the lunar poles could be a vital resource. Human missions will need it for drinking water, bathing, and even producing rocket fuel. Robotic missions could also benefit from gathering water and other chemical compounds that could be useful for a variety of industrial processes necessary to build and maintain infrastructure.” Although living near a region in perpetual darkness doesn’t sound ideal, having access to this water could be a huge step towards establishing a permanent settlement on the Moon. At any rate, if power is still an issue and solar panels just aren’t enough, NASA is working with the U.S. Departments of Energy and Defense to develop a nuclear fission reactor capable of producing 10 kW of power that could be brought to the moon.

Clearly, landing humans on the moon—in any capacity, much less to the extent we are attempting to do with Artemis—is an arduous task. The immense investment in resources and manpower required for such a program may cause some to ask, “why are we spending so much time and money trying to land people on the Moon, something that we already did?”. There are several answers to this question. For one, we are far from having exhausted all that the Moon can teach us. “Scientifically, the lunar poles could be a treasure trove of information about the Moon and the rest of the solar system. As the Earth and Moon careen through space, they encounter water, dust, and debris in interplanetary space. Most of this space junk is burned up in Earth’s atmosphere or vaporized in hypervelocity collisions on the lunar surface. However, the permanently shadowed cold traps at the Moon’s poles could retain a relatively intact record of water delivery to the Earth-Moon system. Volcanic eruptions early in the Moon’s history could also be recorded there. Collecting samples from the lunar poles would enable a forensic analysis of how water moves around the solar system,” said Hayne. According to Dr. Jack Burns, CU professor and director of the Network for Exploration and Space Science “other goals include doing low frequency radio observations of the early universe from the radio-quiet lunar far side [and] finding ancient rocks to understand the bombardment history of the Moon.” But it is also true that one of the most important things about the Artemis program doesn’t really have anything to do with the Moon at all. Artemis is serving as a trial run for our next challenge: Mars. 

A manned mission to Mars is an entirely different beast than a mission to the Moon. There are significantly longer travel times, a huge amount of radiation exposure, and at least 30 million extra miles between the astronauts and help if something were to go wrong. The entirety of Apollo 17 took less than two weeks, while any manned mission to the red planet is likely to take at least a year. To even attempt a Mars mission, we need to be sure that all of our technology and infrastructure will be able to perform in peak condition during a months-long trip to Mars, on its surface, and for a months-long trip back. There will be no material assistance from Earth and a significant communications delay if there are any problems. If there are problems, they could be deadly. During the Apollo 13 mission, one of the Command Module oxygen tanks exploded while en route to the Moon, causing significant damage to many spacecraft systems and causing the astronauts to abort the mission. Such an event while on the way to Mars would almost certainly be a death sentence for the crew. Artemis is a way for us to test and refine our current technology and to develop new technology so that when we do make that next step towards Mars, we are able to do it safely and with full confidence in our abilities and technologies. “The Moon is where we will learn to explore in a sustainable fashion. It is both a stepping stone to Mars and a scientifically exciting doorway to understand the history of the formation and evolution of the Earth and the Moon,” said Burns.

So Artemis is an important step towards Mars. That’s great, but why should we go to Mars? Why are we spending so much money and so many resources on trying to get there? Firstly, there is much to be gained scientifically from a mission to Mars. One of the most important questions a mission to Mars could help answer pertains to our own origins; where did life come from? “It’s a good place to look for the possibility of life. Mars was once (billions of years ago) covered with liquid water, like the Earth, before the atmosphere thinned. Microbial life might have started there,” says Burns. However, our push towards Mars is for more than scientific data. 

The reason why we are going to Mars is the same reason why we climb mountains, why we sailed across oceans, why we dived to the deepest depths of the ocean, and why humans first ventured out of the cave and into the unknown. It is in our nature to push the boundaries, to go where nobody has gone before, and Mars is the next step. As engineers, we like to see results. We don’t leave things to our imaginations. We want to design something, test something, build something, and then see it in action. For far too long, manned space exploration has remained dormant, a series of what-ifs and what-could-have-beens. However, for the first time in many of our lifetimes, manned exploration beyond low-Earth orbit is stepping out of the realm of science fiction and into reality. It’s a good time to be alive and looking skyward. It’s a good time to be an engineer. Let’s get to work.