Sun, 25 Jul 2021
The increasing privatization of space travel has brought renewed interest in the potential for crewed spaceflights to the moon and Mars, with private ventures such as SpaceX and Amazon's Blue Origin setting their sights on some of the most ambitious spacefaring missions humanity has yet attempted. Many leaders in the field of aeronautics have expressed a desire to not merely land on the surface of Mars, but to establish a permanent human presence on the Martian surface.
Though the exploration and colonization of foreign worlds remains for now just a tantalizing fantasy, many scientists and engineers in both the private and public sectors are hard at work trying to determine how to bring the spacefaring aspirations of humankind into reality. But establishing a permanent human presence on a barren, freezing world 34 million miles from Earth is no simple task. Among the myriad hurdles that the task of interplanetary colonization presents, there are a few that are especially vexing for astronauts. The following is a list of the biggest impediments to realizing humanity's dream of reaching other worlds.
The task of establishing a permanent base on the red planet begins with actually landing on its surface. Even when Mars is at its nearest to us, it is still more than 100 times farther away from us than our moon. That means that getting to Mars will require far more powerful rockets than humans have ever launched into space. And covering this astronomical distance is made even more difficult by the added burden of all the additional equipment that will be required to not only make the trip with humans on board, but to establish a long-term base of operations on the Martian surface.
A wide range of equipment would be required for colonization, including facilities to produce food, water, energy, and breathable oxygen. All of this added weight requires boosters with far greater lift than anything NASA has constructed to date. Since no space agency has made a serious attempt at a crewed spaceflight to Mars, there are no precise estimates for how much power would be required to get us there.
SpaceX is currently in development of a fully reusable super heavy-lift launch vehicle capable of carrying over 150 tons of useful payload into space. To put that into perspective, the total mass of the Command Service Module, which was the spacecraft used during Apollo 11, the first crewed mission to the lunar surface, was 28,801 kg, or just under 32 tons.
If successful, this rocket, which SpaceX has dubbed Starship, will be the most powerful spacecraft constructed to date. Whether this level of power will be sufficient to achieve a crewed mission to Mars is yet to be seen, but there appears to be confidence on the part of SpaceX, as their current projections are to use Starship as the basis for their first projected crewed Mars flight in the year 2026.
NASA is also in development of a launch vehicle capable of lifting a payload of more than 100 tons into orbit. The project is being conducted in collaboration with Boeing and involves the construction of a launch vehicle known as the Space Launch System which is intended, among other purposes, to enable human crewed missions to Mars. This rocket will contain boosters capable of lifting over 130 tons. The first crewed mission is projected for 2023.
Water is the key ingredient to all life that we have yet discovered, so securing a reliable source of it is essential to establishing a lasting presence on another planet. Large-scale water purification systems will be essential in order to successfully maintain a Mars colony. However, for a resource as essential as water, it would also be highly advantageous to locate reservoirs of water locked beneath the Mars surface in order to sustain the colony in instances where water filtration systems break down, or the amount of clean drinkable water is insufficient to sustain the colony.
Though all evidence suggests that the surface of the red planet has been bone dry and intensely cold for the last several billion years, some evidence suggests that the moisture that existed on the surface of Mars in past ages may have seeped down through the ground and formed deep aquifers within the crust, and that those aquifers may still exist.
Researchers analyzing data obtained from the Opportunity Mars Exploration Rover, which launched in 2003 and touched down on the Martian surface the following year, discovered evidence of groundwater activity in the Meridiani Planum region. This is an area of Mars near the equator known for its rare formations of crystalline hematite. On Earth, this iron oxide compound has been known to form in hot springs and other standing pools of water. For this reason, many scientists have speculated that the Meridiani Planum environment could be host to ancient stores of liquid water just beneath the surface.
Pictures taken by the Mars Global Surveyor, which launched in 1996, also present compelling evidence for the presence of ground water in the upper levels of the Martian crust. The satellite took pictures of a series of large gullies on the Martian surface. Over the course of its mission, the research vessel catalogued several new formations emerging from these gullies, indicating the presence of ground water aquifers very near the surface of the Martian crust. An extensive analysis of the Global Surveyor's data by Dr. Thomas M. Donahue in 2001 at John Hopkins University concluded that the Surveyor's images strongly suggest "recent seepage of groundwater" from these large gullies. Moreover, the presence of high concentrations of atmospheric hydrogen suggests a series of chemical reactions "involving efficient exchange of water between atmosphere and crust now and in times past."
More recent observations from the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft, which was launched in 2013, and continues to collect atmospheric data from Mars' orbit, found high concentrations of molecular hydrogen in Mars' upper atmosphere, varying by season. This would indicate that there continues to be vast reservoirs of water trapped in the crust of Mars continuously escaping into the atmosphere, where it is then converted into hydrogen.
If indeed there are large quantities of water trapped within the Martian crust, it could serve as the foundation for a sustainable, long-term colonizing project. Water found on Mars would prove invaluable, not simply for drinking and agricultural purposes, but also as a fuel source for hydrogen gas powered equipment. Hydrogen fuel cell technology is a natural fit for space exploration, as it is far more efficient and longer lasting than its aging, environmentally wasteful alkaline counterparts.
On Earth, we must constantly exert our muscles in order to counter gravity, with certain muscle groups bearing the brunt of this burden to support the body against the inexorable downward force. These are called antigravity muscles. They include the calves and quadriceps, as well as the neck and back muscles. These are also the muscles predominantly responsible for maintaining an upright posture.
As with so many things in life, a lack of regular use causes these muscles to deteriorate and waste away. This poses a significant problem to prospective Mars explorers, as the red planet contains only about one-third of Earth's gravity due to its much smaller size and mass. This reduced strain eventually leads to a phenomenon known as muscle atrophy. This loss of muscle mass could severely limit the ability of astronauts to perform physically strenuous tasks once they re-enter Earth's gravitational field. This effect is more pronounced with more time spent outside of Earth's orbit, with potentially dire consequences for a crew stationed on Mars for an extended period.
The hazards associated with muscular atrophy go far beyond just the skeletal muscles. Research from the University of Texas Medical School and the University of Texas Southwestern Medical Center examining the effect of microgravity during space flights found that operating in an environment with gravitational levels far below that of Earth resulted in the deterioration of cardiac muscle which could, in turn, result in increased risk of cardiac arrhythmias.
Their findings suggested that "6 months of spaceflight would alter atrial size and atrial electrical function, thereby increasing the risk of AF (atrial fibrillation, the most common form of cardiac arrhythmia." Certain types of arrhythmia, such as tachycardia, are associated with increased risk of cardiac arrest and stroke.
Given that the most accurate estimate for the time needed for a space crew to reach Mars is roughly 7 months, this increased strain on the heart muscles from prolonged exposure to microgravity could pose a significant threat to astronauts' health.
Astronauts have found that the only way to limit the effects of progressive muscle atrophy is to engage in regular, intense physical activity combined with optimal nutrition. Scientists are still trying to determine whether the effects of muscle atrophy during long-duration space missions might taper off over time due to the body adjusting to the new low-gravity environment.
Some would suggest that a goal as auspicious as the exploration of space would preclude any obstacles as mundane as budget constraints, particularly after the success of the lunar landing of Apollo 11. Many had hoped that following the first successful crewed mission to the moon in 1969, NASA's budget would expand in line with a growing interest in space travel among the public. However, it is an unfortunate reality that governments must allocate their limited resources to a myriad of other critical functions before lofty goals such as space exploration can be considered.
The precipitous decline in NASA's budget relative to overall federal spending actually began several years before the first crewed lunar mission had been completed. According to the U.S. Office of Management and Budget (OMB), NASA's budget peaked in 1966 at 4.41% of total federal spending, then declined sharply every year until around 1980, where it has remained constant at roughly 1% of the federal budget. These cuts have impacted a number of NASA's programs, including those that are involved in Mars exploration.
In a meeting of NASA's planetary science advisory committee, Jim Watzin, director of NASA's Mars exploration program, stated that due to budget cuts in fiscal year 2020, NASA's Mars programs would suffer "austerity across the portfolio" and that "funding for extended mission longevity is limited".
There are many reasons why lawmakers have seen fit to cut NASA's budget over the years, but one of the most significant is the perceived lack of return on investment of NASA's spacefaring missions. Over the course of its tenure, segments of the public have expressed opposition to NASA funding, citing more pressing national concerns, such as education, medical care and national defense.
There may be a silver lining however. This decline in government funding for space travel has provided an opening for private sector forces to attempt to bridge the gap between humanity's ambition to explore the cosmos, and the budgetary concerns of the US treasury.
It is for this reason that private aeronautics firms such as SpaceX and Amazon's Blue Origin have sought to provide more cost-effective solutions for crewed space travel. A private company that is capable of operating on a positive cash flow and generating returns for stakeholders may have a greater chance of achieving a successful crewed mission to the red planet. These companies derive most of their profits from launching commercial satellites, which they hope, when coupled with private equity investment, will eventually provide the means to finance exploratory ventures such as a crewed mission to Mars.
There is an argument to be made about whether the greatest benefits of space travel can even be qualified in monetary terms. Some would argue that the true benefits of space travel transcend budgetary concerns, and that the urge to send humans to other worlds satisfies a more inherent need within all of us to explore and seek new horizons, that space exploration represents a kind of manifest destiny for all of humankind.
The obstacles to a crewed Mars mission are many and daunting. In addition to financial constraints, we must contend with the challenges of survival on an extremely hostile, foreign world. From the long-term effects of microgravity on our muscles, to the struggles of securing vital resources such as food, water, and fuel on a planet seemingly devoid of virtually all the necessities of life, the challenges of interplanetary space travel appear to be insurmountable. However, throughout our history on this planet, humanity has repeatedly demonstrated the will to overcome seemingly impossible odds, and some would say there is no more worthy challenge then to put a permanent mark on a world beyond our own.
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