ISABELLA MORISON
Calgary, AB
Edited by Nico Werschler
INTRODUCTION
Many of us have wondered if we are the only life in the universe, or if other creatures lurk beyond. On Earth, life thrives, though many factors are needed for this. Where our planet is in relation to the sun is one of these factors. The Goldilocks Zone, or more scientifically “the Circumstellar Habitable Zone”, is the region or area around a star that can maintain liquid water, and is neither too hot or too cold (Goldilocks World's, n.d., National Geographic). There are potentially habitable planets which are terrestrial with conditions that are roughly like those of earth, and, thus, are candidates for supporting life. In 2013, astronomers reported that there could be as many as 40 billion earth-sized planets orbiting the sun like stars or red dwarfs in their habitable zones in our galaxy, the Milky Way (Who’s Out There? Shreeve, Jamie, March, 2019, National Geographic).
There are probably other types of life on another planet in our galaxy, but that would most likely be microscopic cells. More complex life was made by a single cell creature eating another cell creature, but the creature that was eaten stayed alive and thus they could form things like you and me (One Strange Rock, Aronofsky, Darren, 2018). But that took millions of years. What I want to know is if there is other earth like life out there. Many factors are needed to support life, and one of those factors is gravity. My research question is: What percentage of planets in the goldilocks zone would have enough gravity to sustain earth-like life?
HYPOTHESIS
Based on the lack of small planets around Earth's size that scientists have found so far, I think that the percentage of planets that have the right mass to sustain earth like life will turn out to be around 15-20%. For a while I was thinking about 50-60% as most resources only tell you about the possibly habitable planets (they are quite exciting in comparison to non-habitable planets). This project aims to inform us on whether we have the potential to live elsewhere if we meet our demise driven from our own technological advancements and the detriment that discretely accompanies it. Future projects may emerge from this one, such as the possibility of finding other life in space, and maybe a research project on the planet Proxima Centauri b, and the ups and downs of living there.
EXOPLANETS
An exoplanet (extrasolar planet) is a planet outside our solar system. Exoplanets orbit around their own star, though, in special circumstances, the star can be shared with another exoplanet (Who’s Out There? Shreeve, Jamie, March, 2019, National Geographic). The first evidence of an exoplanet was detected in 1917, but was not recognized as such. It was confirmed in 1992, and was followed by the confirmation of another exoplanet, which had been detected in 1988 (Who’s Out There? Shreeve, Jamie, March, 2019, National Geographic). As of December 1st, 2019, there are 4,135 confirmed exoplanets in 3,073 systems, with 673 stars having more than 1 planet orbiting them (Who’s Out There? Shreeve, Jamie, March, 2019, National Geographic). There are many methods of detecting exoplanets. Some exoplanets were imaged using telescopes, though others have been found via transit photometry and radial velocity methods (F.J. Ballesteros, A. Fernandez-Soto, and V.J. Martínez.Astrobiology.May 2019).
GRAVITY & HUMAN SURVIVAL
Humans can only survive in 4 and a half times the earth's gravity. If the force of gravity is greater than that, the gravitational pull will cause our blood to pool in our legs and other extremities, or our bones might break, or we will be pinned helplessly to the ground (Allen, M September 20, 2018, What’s the Maximum Gravity We Could Survive? Discover). Interestingly, humans are capable of standing on a planet with as much as 90 times the Earth's mass, though if we were to start running, the stress on our bones as they flex and bend increases by a factor of ten due to the greater mass of the planet, but we could in fact run on a surface with ten times the Earth’s gravity before our bones start to crack. If we were squatting on a planet with five times the Earth's mass, even an elite athlete would not be able to move from a seated position.
WHY GRAVITY IS IMPORTANT IN THE SEARCH FOR EARTH-LIKE LIFE
When looking for planets that have the ability to sustain earth like life, the mass of the planet matters. All planets are believed to be formed by a process of competitive cannibalism in a disk of material around a star. Small pieces of dust collide and grow, and end up devouring their neighbors as they grow larger and larger. Their ability to consume all matter around them increases, resulting in an acceleration of their growth. If a planet swells to more than ten times the size of Earth, before their core ignites, they will become a gas giant (Horner J., Nicholson B., & Carter B, January 5, 2015, What makes one Earth-like planet more habitable than another?). The more massive a planet, the more massive an atmosphere it can acquire and maintain. An object or planet of too small a mass will not have enough gravity to maintain an atmosphere. But the mass of a planet, in terms of its ability to sustain life, only matters if it is in the habitable (Goldilocks) zone in the first place, of course.
BIOSIGNATURES
With more powerful telescopes, scientists are able to determine if a planet holds an atmosphere, and even the type of gases in that specific atmosphere. Each chemical compound absorbs a unique set of wavelengths of light, so different gases appear as different colors. Certain gases, such as oxygen, carbon dioxide, or methane, are associated with life, and can be identified through their individually-unique spectra. Scientists can see the colour of as the light shining from the star the planet orbits travels through its upper atmosphere or reflects off of the planet. This allows them to identify the gas (Who’s Out There? Shreeve, Jamie, March, 2019, National Geographic). In short, a planet leaves its spectral fingerprints in the starlight passing through the its upper atmosphere – termed ‘biosignatures’.
GRAVITATIONAL LENSING
Using the gravity of a large object in space, we are capable of bending light, similar to the effect seen through a magnifying glass (Who’s Out There? Shreeve, Jamie, March, 2019, National Geographic). The object pulls light into one focal point, allowing us to see what is on the other side in detail, as long as a telescope is positioned there. Using this technique makes it possible to view stars, galaxies, and possibly galaxy clusters. This technique (Gravitational Lensing) has been proven in science using our own star (the Sun). Gravitational Lensing has the potential to vastly increase the depth of knowledge we have about space and find exoplanets that, similar to Earth, have the capability of supporting life.
FINDING LIFE
One biological fingerprint that is of particular interest in space exploration and planetary search is that of oxygen. Oxygen reacts and bonds with almost anything on a planet's surface. Even more exciting would be to find both oxygen and methane. This is because the two constantly undergo a destructive chemical reaction, so there must be a constant reproduction occurring. On Earth, plants and certain bacteria produce oxygen, though we should not limit the search to just oxygen and methane. For example, not all life requires oxygen to remain viable. Some of the most important things in life only require a liquid medium, energy, and the right amount of heat (such that the liquid medium does not evaporate or freeze (between 0℃ and 100℃). All scientists need to look for is an excess amount of gas that should not be there. In these instances, this would indicate that there must be a system responsible for producing the gas. Another biosignature to look for is near infrared light or the so-called “red edge”. Plants reflect these wavelengths, so if you find those, you may have found evidence of extraterrestrial forests or other foliage. Near infrared light has a longer wavelength than that of normal light, so it is invisible to human eye but easily detectable using an infrared telescope. Unbeknownst to us, however, is that vegetation on other planets may absorb a unique wavelengths of light: there could be black forests on one planet, and or blue forests on another. This is all part of the mystery.
BREAKTHROUGH STARSHOT
An ambitious space exploration program called “Breakthrough Starshot” initially invested 100 million dollars to send tiny probes on a 20-year journey to the home of the rocky planet Proxima Centauri b, the nearest star cluster (Who’s Out There? Shreeve, Jamie, March, 2019, National Geographic). But even lightweight probes need fuel, and the further a device goes the more fuel it needs. The solution they propose is to launch it from an orbiting satellite and propel it with earth-based lasers. Each probe has one chip, each weighing five grams or less. This chip performs the job of navigation, computers, and cameras. Here is each step of the probes journey:
The first step of the probe's journey begins in a satellite in a low orbit around Earth, which houses thousands of the probes. When a probe is released, it automatically unfurls its sails.
Nearly a billion lasers on Earth are directed at the probe released. This creates a pulse with the power of 100 gigawatts, lasting several minutes.
Those few minutes are enough for the probe to accelerate to one-fifth the speed of light. It journeys into the vacuum of space and continues gliding.
After a voyage of twenty years, the probe arrives at Proxima Centauri. During this whole process, it takes photos and records a range of data.
The probe beams the information it collected back to Earth using a laser embedded in its chip. Each transmission takes about four years to reach the Earth. The first probes will be called Niñas, Pintas, and Santa Marías. This project is still on the drawing board.
TECHNO SIGNATURES AND THE RARITY OF ALIEN COMMUNICATION
SETI (Search for Extraterrestrial Intelligence) is a non-profit organization which searches for extraterrestrial beings who might be trying to communicate with us (Who’s Out There? Shreeve, Jamie, March, 2019, National Geographic). Thus far, their search has not found anything. I think this is because if life on another planet has the technology to detect us, then why try to communicate with us? We think our species is pretty technologically advanced, but compared to life with such technology, we would be like a bunch of ants, and who would try to contact them? What we should be looking for is extraterrestrials just going about their own business intelligence in a way we might not understand but can become aware of. Scientist approach this problem by looking for techno signatures. Techno signatures are signs of technological activity. Some of the most obvious techno signatures would be ones that we have produced ourselves. For one, if another civilization was using laser propulsion to help things sail through space, beacons would be visible to the edge of the universe. Another techno signature to look for is the signature of chlorofluorocarbons (non-toxic non-flammable chemicals containing atoms of carbon, chlorine, and fluorine) in an atmosphere of aliens who went extinct by harnessing technologies that lead to their own destruction. If we are to uncover civilizations like these, we could learn from them. But we could learn a lot more from life-forms that actually survive these, or similar events. The megastructure is a solar array around a star (for us it would be our own sun), which would generate enough energy each second to supply our energy demands for a million years. If a civilization accomplished this, it might provide some hope for us. Although the first signal of life elsewhere in space feels quite close, we may never encounter alien life.
CONCLUSION
In 2014, scientists determined that of the 1,780 confirmed planets beyond our solar system, as many as 16 were located in their star’s Circumstellar Habitable Zone (Who’s Out There? Shreeve, Jamie, March, 2019, National Geographic). From the research presented here, I have come to the conclusion that the percentage of planets that are in the habitable zone is 0.89%, though this does not count the planets that are the right size for life. I found this by dividing 16 by 1,780, which was 0.00898876, then multiplying that by 100, and the product turned out to be 0.8988764. I rounded this up to get 0.89%. This is the percentage for only a small portion of our galaxy. I conclude that the number of planets scientists have found since then has changed quite a bit in 6 years - humankind has been finding planets quite rapidly - but the percentage would have stayed mostly the same. Bigger planets are considerably easier to find and the earth sized planets are harder to find, and this will stay mostly the same until some of the newer, more cutting-edge technology is put to use. Earth might have been bigger if Venus did not have such a powerful gravitational pull and had sucked up some extra mass, so some planets might have not have had a ‘Venus’ to do that, and had turned out too big for life, and some planets might have had a Venus and it drew too much mass to itself and the planet turned out too small for life. The number of possibly habitable planets may seem scarce because of all of these numbers, but most planets found so far are the ones much bigger and hotter than earth because they are the easiest to detect. Soon, big projects will be put implemented to help us locate the more life-promising planets that currently sit, just waiting to be found. Space is a vast place, and so is time. There likely many planets that can support life. Breakthrough Starshot, the new telescopes, and Starshade (a space device designed to deflect the light from a star for planet detection) may help us have a new perspective on space and space exploration, like Kepler did. Despite we as humans thinking we are so knowledgeable and advances, the truth is that there remains so much to be uncovered. I do not know what the future will bring, but I do know one thing for sure: There is something great out there, and in time we will find it.
DEFINITIONS & TERMS
Transit duration
This is the length of time that a planet spends orbiting a star.
Flux
This is any effect that appears to pass through or travel through a surface or substance.
Photometer
Photo means light, and meter means measuring device. This device has one sensitive square that measures how much light comes from a square.
Electromagnetic Radiation
This is the waves of the electromagnetic field.
Stellar Discs
Pancake or ring-shaped accumulation of matter such as dust, gas, asteroids or collision fragments that are in orbit around a star. Around young stars there are materials out of which planets may form.
Uniform
This is when there is the same thickness all across the surface of an object.
Solar System
A solar system only needs a star to be classified as a solar system, as “sol” means star.
Brown Dwarf
A brown dwarf is a type of star that occurs when a large enough planet has hydrogen moving fast enough that it collides and creates the chemical reaction that turns it into a star.
Newton
Measures force.
Millibar
Measures pressure. Thousandth of a bar.
Pascal
Also measures pressure.
BIBLIOGRAPHY
Allen, M. (September 20, 2018). What’s the Maximum Gravity We Could Survive?. Discover. Retrieved from: https://www.discovermagazine.com/the-sciences/whats-the-maximum-gravity-we-could-survive
F.J. Ballesteros, A. Fernandez-Soto, and V.J. Martínez.Astrobiology.May 2019.642-654.http://doi.org/10.1089/ast.2017.1720
Goldilocks World's. (n.d.). National Geographic. Retrieved from: https://www.nationalgeographic.com/astrobiology/goldilocks-worlds/
Horner J., Nicholson B., & Carter B. (January 5, 2015). What makes one Earth-like planet more habitable than another?. Queensland, Australia: The Conversation. Retrieved from: http://theconversation.com/what-makes-one-earth-like-planet-more-habitable-than-another-33479
One-on-one conversation with Brendan Wiebe, a high school physics teacher (Calgary Board of Education).
Wenz, J. (2020). Visit The Nearest 14 Habitable Exoplanets. Astronomy. Volume 48. 50-51.
Who’s Out There? Shreeve, Jamie (March, 2019). National Geographic. Washington DC, National Geographic Partners, LLC.
Wenz, J. (2020). Visit The Nearest 14 Habitable Exoplanets. Astronomy. Volume 48. 50-51.