Considering all the horrible ways that either humans or otherwise could end life on Earth, the idea of inhabiting another world seems pretty nifty. The only issue with that is we need oxygen and for our soft squishy skin to not get fried by intense sunlight. So, the prospects of getting off our planet for any indefinite amount of time outside the confines of some spacecraft seems grim. However, humans have proved that they can have some impact on the environment, so is it possible that we could sculpt, or “terraform”, a planet into one that is suitable for humans to live on?
In short, yes, but it is a rather complicated process. The first issue is that if whichever planet we choose to adapt does not have a strong core that spins fast then the magnetosphere would be too weak, or nonexistent, to sustain any atmosphere conducive for housing life. According to a Planetary Science Vision 2050 Workshop in 2017 we possess the current technology to artificially build a magnetosphere around a planet, but it requires giant rings that circumnavigate the world. Other ideas include building magnetic shields at some point between the planet and its sun to provide just enough blocking to mimic an Earth-like magnetosphere. Once the magnetosphere is established on most worlds volcanism will contribute to a build up of a greenhouse effect and global warming will start. If that world has water, which it probably does if it’s in the inhabitable region, the water will start to melt and finally provide a habitat suitable for microorganisms.
After only a few extremely expensive scientific endeavors that did not fail at all the world could finally support some plants and small animals after a few hundred years. For reference, the estimate to make Mars inhabitable for humans is about 1,000 years.
In 2003, NASA launched the Mars Exploration Rover mission, dropping the Spirit and Opportunity rovers on Mars in January 2004. Although their planned mission lifetime was 90 days, both rovers far exceeded this. Spirit lasted 20 times longer than this, traveling almost 5 miles before sending its final message to Earth on March 22, 2010. Spirit’s discoveries included evidence that Mars was once much wetter as well as data that helped scientists understand the wind of Mars. It also found chemical evidence in rocks that the atmosphere of Mars was once much thicker than it is today. Opportunity, one of NASA’s biggest successes, came to the end of its mission after approximately 15 years of exploration. Not only did Opportunity last 60 times longer than expected, it also traveled more than 28 miles before its last transmission was received on June 10, 2018—a feat that no other vehicle has achieved on the surface of another world. During its mission, Opportunity made many discoveries about Mars, including evidence that an area of Mars had once contained water for a period of time with conditions that may have been able to sustain life. Although it is sad to see the end of the mission, Spirit and Opportunity’s discoveries have not only helped us to better understand Mars, but have contributed to our understanding of how to better operate rovers on Mars.
Titan is one of the biggest moons in the solar system, and is the most similar object to Earth. The icy world is second in size to Jupiter’s Ganymede and is larger than the planet Mercury.
Titan is very unique in that it is the only moon to have a dense atmosphere. Like Earth, the atmosphere is made up of mostly nitrogen, except this moon also has methane. Standing rivers, lakes, and seas can be found on Titan; the only other place this is found is on Earth. There is also an earthlike cycle of liquid evaporating to clouds and raining back down to the bodies of water. Lastly, Titan has a very similar tilt as the Earth which results in seasons, but because of Saturn’s long revolution around the sun, seasons last about 7 Earth years.
Astronomers think that Titan formed early in the formation of the solar system. Titans nitrogen isotope ratio is similar to comets in the Oort Cloud, and was formed in the same nebula that the Sun was formed in. Titan is also thought to have 5 primary layers of rock, a shell of water ice, salty liquid water, an outer crust of water ice, and a final layer of organic molecules of sand and water. Source
The Periodic Table, showing the origin of each element. Note how many are formed by different stellar processes. Source: user Cmglee at Wikimedia Commons
You may be familiar with the Periodic Table, which lists every type of atom (referred to as ‘elements’) in the universe. Each of the elements is formed by combining subatomic building blocks in different ways.
One of the most important element-creating events in the Universe was Big Bang nucleosynthesis, the period about 10 seconds to 20 minutes after the Big Bang when most deuterium (hydrogen-2) and helium were produced, along with some lithium-7. That process is represented as blue on the chart above.
Most every other element is created by fusion of lighter elements into heavier elements in stars. It’s a complicated story, but here’s some highlights:
Stars about size of the Sun or smaller rely on the proton-proton chain, which (as you may be able to guess from the name) fuses protons and groups of protons together to produce helium-4. The carbon-nitrogen-oxygen cycle also produces helium from hydrogen in larger stars.
A plethora of other processes produce heavier elements, and most require the immense heat and pressure of large or dying stars to occur. See the Wikipedia page on stellar nucleosynthesis to learn more!
Stargazing is awesome! But sometimes, the night sky is not visible due to light pollution. In cities like Nashville, a common type of light pollution is “sky glow”. Sky glow is the brightening of the entire night sky, especially in populated areas. The light pollution around Nashville inhibits our view of zodiacal light, airglow, and many of the Messier objects.
How can we reduce sky glow? One method for cities to reduce skyglow is to reduce uplighting and excess / wasteful light through shielding or cutoff lights. For other tips, check out this blog by Mara Bermudez.
Shielded Lights
Light fixtures prevent light from immediately scattering in the atmosphere. Many fixtures also aim the light towards the ground, reducing glare and providing better ground visibility. Light shielding also reduces unwanted lighting on other people’s property, called light trespass.
Cutoff lights focus light towards the ground similarly to shielding fixtures. The amount of cutoff determines how much light gets distributed at or above the horizontal. Cutoff lights have many benefits, including focused light for better surface visibility, and less uplighting, which is wasteful and the excess light scatters in the atmosphere.
Many of the street lights at Vanderbilt University are non-cutoff, as shown in this picture on the Vanderbilt admissions page of downtown Nashville. This type of light pollution contributes to the skyglow around Nashville.
Contrary to popular belief, Earth’s climate has not always been the same; just in the last 650,000 years there has been several cycles of temperature rise and fall due to small changes in Earth’s orbit and the amount of energy Earth receives from the Sun. However, in the past 50 years, Earth’s climate has changed dramatically, and scientists predict this rapid change in climate to be the result of human activity within the past century with greater than 95 percent probability . Satellites orbiting Earth have enabled scientists to collect many different types of information about our planet’s climate on a global scale while allowing scientists to pinpoint the direct cause for this drastic change in Earth’s climate. Many scientists can agree that the main cause of this warming trend is due to the human expansion of the “greenhouse effect”, where Earth’s atmosphere traps heat radiating gases which in turn causes a global temperature rise. Certain gases, such as carbon dioxide, methane and nitrous oxide, trap heat in Earth’s atmosphere. While these gases have always been present in Earth’s atmosphere, the burning of fossil fuels such as coal and oil has dramatically increased the amount of greenhouse gases in our atmosphere, as carbon dioxide levels have risen from 280 parts per million to 400 parts per million over the past 150 years . While the consequence of changing the natural composition of our atmosphere are difficult to predict, certain effects seem likely such as:
. An average increase in Earth’s temperature.
.Warmer conditions resulting in more evaporation and precipitation, causing some regions to be wetter and other to be dryer, therefore resulting more a extreme climate.
.A larger greenhouse effect will warm oceans and melt glaciers, resulting in sea level rise.
.Higher temperatures and shifting climate patterns may change the areas where certain crops grow best.
There are four major factors affecting long-term climate change: changes in axis tilt, changes in reflectivity, solar brightening and changes in greenhouse gas abundance. Small gravitational tugs from the Moon and other planets can cause the tilt of a planet’s axis to change over long periods of time, therefore changing the angle that sunlight hits Earth resulting in global climate change. Due to the fact that the Earth’s axis tilt has not changed in the past 150 years, it is evident that changes in axis tilt is not the cause of our current climate change. Similarly, a change in a planet’s reflectivity, due to factors such as increased cloud cover, has remained relatively constant over the past century therefore does not contribute to our present global warming. Theoretical models of the Sun also tell us that the Sun has gradually brightened with age, therefore increasing the amount of solar energy reaching Earth. Studies have shown that solar variability has played a vital role in past climate changes, such as a decrease in solar activity is thought to have triggered the last Ice Age over 7,000 years ago. However, it is evident that the current climate change cannot be explained by changes in solar energy due to several reasons. Since 1970, the average amount of solar energy received by Earth has remained relatively constant. Similarly, if global warming were caused by increased solar energy, then scientists would expect to see warmer temperatures in all layers of the atmosphere. Instead, they have observed cooling in the upper atmosphere and warming in the lower atmosphere, which is a result of greenhouse gases trapping heat in the lower atmosphere. Finally, climate models that include solar energy are unable to reproduce the observed temperature rise over the past century without including the effect of a rise in greenhouse gases. Therefore, it is evident that the dramatic climate change we are experiencing now is due to increased abundance of greenhouse gases in our atmosphere, and the data points to mankind as the cause.
Climate change is real! Believe it! There is hope, though. Debunk the myth, tell your neighbors of this pressing issue and and as a global community we can come up with ways to reduce our carbon footprint and save our planet.
The Sun generates energy by fusing hydrogen into helium due to a process known as nuclear fusion. Fusion occurs within the Sun because the plasma in the solar core is full of hot gases that collide with one another at extremely high speeds. In most cases, electromagnetic repulsion forces deflect the nuclei of the two atoms preventing collisions, however, if the nuclei collide with sufficient energy, they can fuse together to form a heavier nucleus. A force known as the strong force binds protons and neutrons together in atomic nuclei, is the only natural force that can overcome the electromagnetic repulsion between two positively charged particles. In order for nuclear fusion to occur, the two charged nuclei must be pushed close enough together for the strong force to overpower electromagnetic repulsion.
The high temperatures and pressures in the Sun’s core are what allow nuclear fusion to occur. High temperatures provide atoms with more energy which in turn causes atoms to move faster therefore increasing the probability of collisions occurring. The high pressure on the Sun’s core is important for nuclear fusion because without it the solar core would explode into space, therefore halting all nuclear reactions.
The overall reaction of nuclear fusion proceeds through several steps known formally as the proton-proton chain. This chain of reactions begins with two protons fusing to form a deuterium nucleus consisting of one proton and one neutron. The deuterium nucleus then fuses with a proton to produce a helium-3 nucleus made of two protons and one neutron. Finally, two helium-3 nucleus combine to form a helium-4 nucleus consisting of two protons and two neutrons, releasing energy in the process. This energy produced from nuclear fusion provides the energy necessary for live to thrive on Earth. If the Sun were to suddenly halt all nuclear fusion this would be detrimental for all living organisms on Earth. There is a reality to this statement, though: the Sun will eventually run out of fuel to perform nuclear fusion and then it will die. Our Sun is currently halfway through its fuel reserves, so in 7.5 billion years our ancestors will have to come up with another way to provide energy for Earth, or they will have to move to a another solar system. Yikes! Thank goodness this will not happen any time close to my lifetime so I will not have to deal with this problem.
A sample model of the Voyager spacecraft and gold record contained within.
Voyager 1 is the only human made object existing outside of the heliosphere of Earth. The Voyager space probes represent a level of exploration not seen since the era of European explorers, and in many ways exceed the ambition of those brave individuals. Aspects of the Voyager mission have been designed to last for an eternity, such as the golden records inside of both Voyager probes with information about humanity and the location of the planet Earth. Other aspects of the Voyager probe have time limitations – such as the decaying plutonium that supplies their electronics with power. By 2030 at the very latest, both probes will be unable to communicate with their handlers. Every calculation made by the probes brings the date of their death closer.
A team of NASA engineers has been working for the 40-plus year length of the mission to conserve as much power in the probes as possible. The knowledge required to operate the probes has become less and less abundant as the probes have sped away from our globe. Only a few long-tenured individuals at NASA have the experience required to operate the probes in an efficient way. The continuation of the Voyager mission to 2030 will require experienced individuals to forgo retirement. This issue provides a unique look at the issues of space exploration: projects must be designed to have length longer than the lifespan of their designers. Processes must be put in place to constantly train new employees, developing them into the future project executives in charge of mission maintenance. In the future, design of spacecraft and their missions must accommodate the fact that mission length will span multiple lifespans. Hopefully, with careful planning, missions will have life beyond their creators, enabling exploration of a much larger region of space.
It all starts with the Sun. As the Sun rotates on its axis, magnetic field lines are twisted and jumbled around which cause sun spots, or regions on the suns surface of cooler temperature created by magnetic flux. These sun spots spew out plasma and solar winds creating the aurora that we see; the stronger the solar winds, the more intense the aurora is. Particles coming from the sun are drawn to the North and South poles because of their magnetization. As the particles come in, they interact with the different gases in the Earths atmosphere to create different light. Oxygen collides with the particles at lower altitudes, creating a green light. Higher altitudes produce red light which takes more energy as the air is less dense. Source
These lights have been studied for millennia, even dating back to the French Lascaux cave which show paintings of the event. Galileo was the one who named them, taking Aurora from the Goddess of the Dawn and Boreas, a Greek word meaning wind of the north. The lights can be seen in Canada and other northern countries like Sweden and Norway. When the flares are stronger they can be seen in northern England and even as far south as New England, which was recorded to be see in the 1700s. Source
I kept hearing about the Oort Cloud during this unit, so I wanted to do some more research on it. The Oort Cloud intrigues me because it is theoretical, meaning that we have not actually observed it empirically.
In my last post, I talked about the Voyager missions. In another 300 years, the Voyager space crafts will reach the Oort Cloud. Now the Oort Cloud is thought to be so massive that it would take 30,000 years for the Voyager space crafts to pass through them.
The article I read gave very nice information regarding the Oort Cloud. The Oort Cloud was named after Jan Oort, who in 1950 hypothesized its existence. Again, the Oort Cloud has not been physically observed, but it is largely accepted by the scientific community. Inside the Oort Cloud, there may be trillions of objects greater than a kilometer wide. Comets are thought to have originated from the Oort Cloud. While short-term comets, comets with a orbit of a few hundred years are thought to come from the Kuiper Belt, long-term comets, comets with a orbit of a few thousand years, are thought to come from the Oort Cloud.
The Oort Cloud captures my attention because it seems so mysterious. I wish the Voyager missions would survive long enough to relay information about the Oort Cloud, but that may be another mission for another day.
Depiction of the Oort Cloud Picture from Space Facts
