Introduction (Sona Popat)
The day is July 20th, 1969. Neil Armstrong, Buzz Aldrin and Michael Collins (Figure 1), the crew of the Apollo 11, land on the moon, and people around the world turn their eyes to the universe. A whole generation vividly remember the moment, with over half a billion people gathering around their TVs and radios, sitting enraptured as Neil Armstrong took the first step on its surface and said those famous words:
“That’s one small step for a man, one giant leap for mankind.”Neil Armstrong
Today, on the 50th anniversary of a day that changed the world, YSJ celebrates the Apollo 11 mission that allowed man to walk on the moon.
Historical Background (Jennifer Miess)
It all began in August, 1955. The Soviet Union reacted to the United States of America\’s announcement of artificial satellites in space by successfully launching satellite Sputnik 1 on 4th October, 1957. This marked the start of the Space Race, and the Soviet Union built on their success a few years later in April 1961, when Yuri Gagarin became the first human in Earth orbit. Soon things started turning around, and in the climax of the Space Race, the US made what is perhaps the best known human accomplishment of that time: the lunar landing of Apollo 11 on 20 July, 1969. We all learned about this in school, have books about it at home and maybe a dubious article doubting the correctness of the whole mission has crossed our way some day. Even children’s movies such as “Minions” won’t miss the opportunity to humorically point out the lunar landing was faked badly in a movie studio in the US. But as the term ‘Space Race’ indicates, this wasn’t just about science and research in two very different countries, but rather about showing off strategical power within the framework of the Cold War.
Digging deeper, we have to recognise 1930s Germany as the root of the Space Race, as at this time they were developing different kinds of rockets aiming for long-range cannons. Initially, nobody necessarily thought about their military use. But soon, having realised this exact potential, the weapons were used in World War 2 against the Allied forces who took advantage of the advanced technology and developed it further after Germany’s capitulation. With the beginning of the Cold War (1947-1991), the two former allies (USA and Soviet Union) started a severe political conflict marked by military tension, proxy wars and economic competition, dividing the world into “capitalist west” and “communist east”. The most dangerous weapon was the hydrogen atomic bomb and both parties tried to threaten the enemy with its explosive potential. But just as important as these aggressive demonstration of seemingly infinite power, ground-breaking scientific findings were just as important.
The Space Race fitted perfectly with the demand for something humans have dreamed of ever since: exploring the world around us, finally knowing how and maybe even why the universe exists. However, it wasn’t solely the intrinsic wish to gain knowledge and answer the questions only science fiction has thus far touched that led to the moon landing. Rather, it was the US fearing even more humiliation and embarrassment after the Soviets had launched their satellites and Yuri Gagarin. It was President Kennedy who decided to pursue the famous Apollo program, which endured various difficulties but finally led to the sought after success. While the Soviets were struggling with destroyed facilities, the US finally reached the moon surface. Namely Neil Armstrong, Michael Collins and Edwin “Buzz” Aldrin safely landed on the moon on 20th July, 1969 and were able to take several photos (Figure 2) to prove their arrival.
It isn’t clearly defined whether this was the end of the Space Race, but it’s safe to say that with the end of the Cold War and the decay of the Soviet Union, there was no longer the need for competition in spatial development and the countries decided to collaborate instead of battling for the sake of political power.
The People Behind Apollo 11 (Sona Popat)
The moon landing would not have been possible without the extraordinary work of the teams working at NASA to ensure the safety of the astronauts and the integrity of the systems being used on Apollo 11. In an interview for the Johnson Space Center Oral History Project in Houston, Texas, in 2001, Neil Armstrong praised all the people working on the project in a range of roles.
“When you have hundreds of thousands of people all doing their job a little better than they have to, you get an improvement in performance. And that\’s the only reason we could have pulled this whole thing off.”Neil Armstrong
Notable examples of those working on the Apollo 11 mission are Margaret Hamilton and Katherine Johnson, mathematicians who ensured the computers and equipment on board the spacecraft were programmed with the correct equations.
Margaret Hamilton (Figure 3), born 17th August, 1936, in Paoli, Indiana, graduated in mathematics from Earlham College. In 1960, she took a software development position at the Massachusetts Institute of Technology (MIT), and by 1965, was leading the software engineering division.
Hamilton developed software which allowed computers on board Apollo 11 to arrange tasks in order of their importance. Without this software, it is likely that the mission would have failed: before the lunar landing, alarms went off due to the computer being overloaded with unnecessary data from equipment which was less important at that moment, such as the radar. The software therefore allowed successful landing to occur, by enabling the computer to focus on the essential task of landing before processing other data.
Hamilton spoke of the success of her software in a letter to Datamation:
“If the computer hadn’t recognized this problem and taken recovery action, I doubt if Apollo 11 would have been the successful moon landing it was.”Margaret Hamilton
Hamilton was recipient of a ‘NASA Exceptional Space Act Award’ in 2003, celebrating the Apollo guidance software she created. This software was subsequently adapted for use in Skylab, the Space Shuttle, and the first digital fly-by-wire systems in aircraft, showing just how important her work was for space flight. In 2016, Hamilton was honoured again by being selected as a recipient of the Presidential Medal of Freedom, the highest civilian award of the United States of America.
Katherine Coleman Goble Johnson (Figure 4) was born on 26th August, 1918, in White Sulphur Springs, West Virginia. She graduated from West Virginia State College in 1937 with highest honours, earning a Bachelor of Science in Mathematics and French. In 1939, she was one of three black students, and the only black woman, in West Virginia’s graduate schools when the graduate schools were integrated. Johnson went on to work as a teacher in a black public school in Virginia.
\”I counted everything: the steps, the dishes, the stars in the sky”Katherine Johnson, talking about her childhood
Johnson worked for the Langley laboratory at what was then known as NACA (and now is known as NASA) from 1953. In 1960, she became the first woman in the Flight Research Division to receive credit as an author of a research report, when the report she co-authored with Ted Skopinski was published.
Working with engineers Al Hamer and John Young, Johnson provided trajectory work for the Lunar Orbiter Program. The Lunar Orbiter program involved five identical unmanned spacecraft launched in advance of the Apollo 11 mission, which scanned the surface of the moon to locate smooth level areas which would be suitable as landing sites for the moon landing. During this, 99% of the Moon was photographed with a resolution of 60 meters or better, and this was 10 times better than resolutions achievable via observations from Earth at the time.
The calculations Johnson wrote were used to sync Project Apollo’s Lunar Lander with the moon-orbiting Command and Service Module. These calculations were essential, as they allowed precise trajectory information to be obtained for the moon landing, resulting in the Eagle, the Apollo 11 spacecraft, to land in what was then dubbed the Tranquility Base.
In 2015, President Obama awarded Johnson the Presidential Medal of Freedom. Her story also features in the book Hidden Figures by Margot Lee Shetterly and its film adaptation of the same name, both released in 2016. These celebrate the contribution of female African-American mathematicians in NASA.
It is important to celebrate the work of the people working on the Apollo 11 project behind the scenes as their role was essential to its success, and the stories of Margaret Hamilton and Katherine Johnson continue to inspire women in STEM today.
Principles of Spaceflight (Shannon Rennie)
The nature of flight has evolved over human history. Our earliest knowledge of flight dates back to the 11th century where sulfur, charcoal and potassium nitrate were used to make gunpowder to propel rockets used in Chinese warfare. The beginning of spaceflight though, was marked by Robert Goddard’s launch of a liquid fuel rocket on 16th March, 1926. The rocket reached an altitude of 41 feet, the time of flight was 2 seconds and its average velocity was 60mph. Goddard was the first to make use of the idea that pressure differences within an engine can be used to provide thrust: otherwise known as a de Laval nozzle.
The de Laval nozzle (Figure 5) was initially developed by the Swedish inventor Gustaf de Laval in 1888 and is used in most modern rocket engines. The nozzle works by manipulating the properties of gases at both subsonic and supersonic speeds. Subsonic speeds (Mach <1) are those lower than the speed of sound, 343ms-1 at 20°C . Supersonic speeds (Mach >1) are those larger than the speed of sound. As the mass flow rate of the gas is constant, the speed of the subsonic flow increases as the nozzle narrows. At subsonic speeds sound waves propagate through the gas and where the cross-sectional area of the nozzle is at its minimum, the velocity of the gas increases significantly to become transonic. Transonic speeds (Mach 1.0) are those equal to or near the speed of sound. Then as the cross-sectional area of the nozzle increases, the velocity of the gas becomes supersonic. At this speed soundwaves will not propagate backwards.
Earth’s gravity was once a major problem for spaceflight, butcalculations by early astronomers and an understanding of Newtonian laws helped make spaceflight a reality. Rocket engines take advantage of Newton\’s third law which states that for every action force there is an equal and opposite reaction force. As the fuel combusts the temperature of the gas increases, which then increases the pressure the gas exerts and the kinetic energy of the gas particles. The gas expands and accelerates out of the nozzle at the base of the rocket producing a resultant force, causing the rocket to accelerate upwards. As fuel is consumed, the mass of the rocket decreases and therefore it increases in its acceleration as it rises. At the point where the centrifugal acceleration – the acceleration normal to the earth’s axis of rotation which points directly away from the earth – of its circular path is equal to the Earth’s gravity, the spacecraft will orbit the planet with its velocity parallel to the surface of Earth.
Space Medicine Sclerostin may have a Major Role in Astronauts\’ Bone Homeostasis (Roberto Parisi)
There are several health issues linked to modern spaceflight and many of them already have some available treatments which can be used to preserve the human body in conditions of microgravity. One of the first health implications of human spaceflight is the astronauts’ osteoporosis (a clinical condition characterized by the loss of bone mass resulting in a serious fragility of the skeleton) after space missions.
The correct development of the human skeleton, as well as its homeostasis, is closely related to physical exercise. It has been demonstrated that when human bones are subjected to continuous movements, osteocytes (osteoblasts (Figure 6) trapped in the extracellular matrix, incapable of proliferating) decrease the expression of the SOST gene coding for sclerostin. This substance is a monomeric glycoprotein which links to the LRP5/6 co-receptors involved in the WNT/β-catenin signalling pathway, responsible for the differentiation of osteoblasts.
The reduction in the number of osteoblasts results in the alteration of the BMU’s (Basic Multicellular Unit) mechanism of bone tissue homeostasis. In fact osteoclasts are responsible for the degradation of the bone tissue caused by the release of proteolytic enzymes such as cathepsin K, a potent collagenase capable of cleaving the triple helix of type I collagen fibers , and the extracellular matrix is restored by osteoblasts.
Since the beginning of the Space Race era, agencies like NASA have been conscious that the reduction of the gravitational forces would have had a great impact on the musculoskeletal system. Therefore, X-ray photodensitometries and blood tests for the quantification of Ca2+ were run in order to determine if there was an overall loss of bone density during the main space missions (e.g. Gemini VII, Apollo 7, Apollo 8, Apollo 9 and Apollo 11). Official results confirmed this hypothesis and similar outcomes were found by Russian scientists during the Soyuz and Mir missions. The two main effects of long-duration flight were found to be muscle atrophy and bone loss, which both have a particular impact on astronauts’ legs.
Nowadays there are several treatments in order to countermeasure the reduction of bone density. Artificial gravity is often used to contrast microgravity simulations and spaceflights. There are many studies, like A. Larson, C., 1969 and Dorais, G., 2016, that propose the creation of rotating space stations for the simulation of terrestrial gravity. This result can be achieved (and understood) thanks to Einstein’s explanation of the theory of equivalence which states that it is impossible (in particular cases, such as microgravity conditions) to distinguish between gravitation and centrifugation. Despite this, there are problems linked to the movement of the head and some parts of the human body which can induce nausea.
Bisphosphonates are also used to inhibit the osteoclastic reabsorption of the bone ECM (Extra-Cellular Matrix). In fact, thanks to their particular structure, which recalls the pyrophosphate group, they bind to the hydroxyapatite crystals present on the collagen fibers, avoiding the degradation of the extracellular matrix. Limitations associated with the assumption of bisphosphonates, include the irritation of the upper gastrointestinal tract as well as the scarce absorption mediated by the intestinal villi.
Conclusion (Roberto Parisi)
Spaceflight missions are becoming increasingly complex and they represent the only way to get directly in touch with the space surrounding our planet. There will be human missions to Mars in the 2030s and the first attempts to use fully reusable lift rockets are already scheduled. As science enthusiasts and students, during such an important anniversary, we pay tribute to all the astronauts who have trained with sacrifice and passion to bring humankind into the unexplored parts of the universe.
We would like to conclude our article with DeGrasse Tyson’s inspirational quote:
“I look up at the night sky, and I know that, yes, we are part of this Universe, we are in this Universe, but perhaps more important than both of those facts is that the Universe is in us. When I reflect on that fact, I look up—many people feel small, because they’re small and the Universe is big, but I feel big, because my atoms came from those stars.”DeGrasse Tyson
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About the Authors
Sona Popat (UK), Jennifer Miess (Germany), Shannon Rennie (UK) and Roberto Parisi (Italy)
Sona, Jennifer, Shannon and Roberto are all members of the Young Scientists Journal Team and collaborated to write this article in celebration of 50 years since the first moon landing. Sona is an Editor, Shannon is the Subject Ambassadors Lead, and Jennifer and Roberto are Ambassadors to Germany and Italy respectively.