Thursday, May 5, 2016

Criticisms of the Rare Earth Hypothesis

The Rare Earth hypothesis holds that one of the reasons scientists on Earth have not found other alien civilizations in our galaxy is that the combination of conditions of the Earth that make it suitable for complex life to ultimately form may be rare. Some factors on which the hypothesis is built include (but are not limited to) an orbit within a star system’s habitable zone, a large moon, plate tectonics, and an abundance of water. Each characteristic that contributes to the Earth’s ability to sustain life is then combined to form Peter Ward and Donald Brownlee’s Rare Earth Equation, which is an alternative version of the Drake Equation. The result is eleven total variables used to estimate the number (N) of planets in the Milky Way with complex life, or, as Ward and Brownlee put it, “the percentage of planets with worms.” Although the Rare Earth hypothesis is plausible, there are many parts that are impossible to test, making the theory questionable. In addition, there are multiple criticisms regarding certain parts of the theory, such as the idea that life only arises in the habitable zone of a star system, that Jupiter plays a protective role, and that rocky planets found within a habitable zone are rare.

Many of the criteria in the Rare Earth hypothesis cannot be tested. A few theories do exist that support that the Earth’s large moon, plate tectonics, and abundance of water are rare. However, current technology does not give scientists the ability to detect these features on planets in other star systems in the galaxy. Therefore, the possibility still stands that these characteristics exist on other planets similar to the Earth; we just may have not been able to detect their existence yet.

Technology also limits scientist’s ability to detect planets that are roughly the same size as the Earth, but the possibility that rocky planets form around stars also still stands. As a matter of fact, researchers have concluded that small rocky planets are likely to form around stars with “diverse elemental compositions,” and that the existence of these planets are not uncommon. Once these small planets are found, the next challenging step is classifying them. But scientists confirm that Kepler has found there are Earth-sized rocky planets out there in the galaxy, and that their compositions may also be chemically diverse.

In addition to discovering these planets, Kepler has also found Jupiter-like bodies relatively close to them. The Rare Earth hypothesis explains that Jupiter acts as a giant guardian from long period comets for the inner solar system planets; its gravitational pull slingshots these comets originating in the Oort cloud out of the solar system. The idea is that the presence of a body as large as Jupiter is beneficial to the development of life on the Earth and is also rare. There are two main problems with this theory, however. First, there is evidence that Jupiter sends short period comets from the asteroid belt flying towards the Earth and other inner solar system planets, which is ultimately dangerous for existing life. Second, the presence of a gas giant in a star system is not as uncommon as scientists may have thought, according to recent discoveries by Kepler and other research.

Although the Rare Earth hypothesis is a well-supported argument, there are still many criticisms. Parts of the Rare Earth hypothesis are used in the Rare Earth equation, which is used to estimate the number of planets in the galaxy with complex life. Unfortunately, many of the variables used are unable to be tested because of the limits of current technology. In addition, there is evidence that rocky planets within the habitable zone of a star system are not necessarily rare. The idea that Jupiter protects inner solar system planets has also been challenged due to recent Kepler discoveries. Overall, the Rare Earth hypothesis is convincing, but it still contains gaps like most other theories.
- Sara Jahanian

Monday, May 2, 2016

Colonizing the Moon

The closest astronomical body to Earth that people can one day colonize is the moon. For instance, the European Space Agency wants to establish a space village on the moon. Johann­-Dietrich W├Ârner specifically said a permanent moonbase would be appropriate at the 32nd Space Foundation’s National Space Symposium. He wanted the base to be located on the far side of the moon to further space research. For instance, the far side of the moon does not get affected by radiation from the Earth, so radio telescopes will be able to survey the skies with very little background noise.

Another useful thing about a moon base is that one can use it as a take­-off point to Mars. Because the moon has virtually no atmosphere and has very little gravity, it is much easier to take off from the moon. Also, by mining substances on the Moon, we can potentially make rocket fuel or the materials necessary to build a moon base. The materials mined from the moon can also help begin to build the station. By using materials from the moon, the cost of a base would drop significantly because countries would not need to bring everything from Earth.

A couple of things need to be considered when choosing a location for a moon base. The first thing people think of is sunlight. Scientists think that putting the base at the poles to maximize sunlight is one of the best options. However, even at the poles, there will be large temperature variations due to shadowing. One could avoid the effects of shadows by building the base high, but then it would be exposed to cosmic radiation. The solution then is to bury thebase, since the moon's surface has strong thermal insulation properties and it would protect the base from radiation. However, problems arise when scientists try to determine how to build it underground. The only way would be to use remotely controlled construction machines, or to crash the moon base into the moon. Given the potential for disaster if we try to crash a base into the moon, burying it would be the best option. So burying it would still be the best option. However, the base would run into a problem with the amount of solar power it can generate. So an alternate source of power would be needed. One possibility is thermoelectric generators. These would only be able to be used at night and have low efficiency, but they would be easy to maintain due to their simplicity. Another possibility is using a radioisotope thermal generator, a nuclear reactor, which offers greater efficiency and a compact fuel source. However, supplying these generators with radioactive power generators always pose a danger. A more creative idea is to transmit power from the international space station to the moonbase by microwave or laser. The International Space Station has 3,300 square meters of solar panels and it could make a huge contribution to the amount of power the moonbase needs.

The moon is one of the most viable places to colonize, and unlike other places like Mars, the moon can be traveled to within four days by a spacecraft. However, after saying all the facts, colonizing the moon is not an easy feat. Accomplishing this task would take a large amount of money, energy, and resources. Furthermore, the technology to make it cheap enough does not even exist yet. Until scientists find a way to transport people and materials, and build the space station, this idea will only be something people think about.

Sources:

- Tommy Sha

Friday, April 29, 2016

The History of Europa

Europa, one of Jupiter’s moons, has a diameter of 3,100 kilometers, which is about 20 percent smaller than that of the Earth’s moon. Almost all evidence indicates that Europa has an iron core, a rocky mantle, and a salty ocean lying under an icy shell. It orbits Jupiter every three and a half Earth days, and it is very nearly tidally locked with its planet, meaning that its orbital period is the same as its rotational period; one hemisphere of Europa constantly faces Jupiter. As with most planetary bodies, this moon probably formed with a rotation that was not originally synchronous. Over time, tidal torque would have slowed the spin so that it would be nearly synchronous with its orbit. It is generally thought that Europa has a synchronous orbit; however, Richard Greenberg, author of Unmasking Europa, claims otherwise. A non-synchronous orbit would help support the theory that there is a subsurface ocean. The asymmetry of Europa’s mass distribution would offset the tidal torque, and the surface would be separated from the interior by a layer of liquid. The strength of the tidal torque is uncertain, and theory alone does not reveal if Europa is truly tidally locked with Jupiter. Jupiter’s gravity is slightly stronger on the near side of the moon than the far side, so the magnitude of the gravity changes throughout the orbit. This push and pull of gravity stretches and relaxes the surface, and it is believed that this tidal action might cause volcanic or hydrothermal activity on the seafloor, supplying chemicals that could have generated life.

Between its discovery by Galileo and when the Pioneer and Voyager spacecraft passed by it, Europa was an unresolved point of light. However, by passing Europa’s light through a spectrograph, 20th-century scientists were able to infer the material that made up its surface. There were no instruments available to determine what would lie beneath the surface, and even now, it would be challenging to confidently determine the substances that lie within Europa unless scientists were to drill through the surface layer to see what lies underneath.

The presence of water was predicted long before Voyager or Galileo by Guy Consolmagno, who based this prediction on the theoretical models of how Jupiter’s moons form. These models suggest that Jupiter’s moons formed from a swirling cloud of dust and gas that surrounded the planet, just as the planets themselves grew in a similar cloud around the sun. As this Jovian “nebula” cooled, solid particles condensed out, and they gradually came together to form the satellite. The sequence of condensation determined the composition while internal heating separated the materials by density within each moon. Dense metal would sink to towards the center to form a core whereas lighter material would form the surface.

It is worth the cost and time to explore Europa as much as possible because there are still many features of it that remain a mystery. The combination of strong evidence of a subsurface ocean and the possibility of life should make exploring Europa a priority for future missions, and hopefully the mysteries of Europa will one day be revealed.

Sources:

Unmasking Europa: the Search for Life on Jupiter’s Ocean Moon by Richard Greenberg

Discovering Mars

For many years, humans have observed Mars and thought about whether we should eventually colonize it. NASA has sent several missions to land on Mars, and they are helping us to determine if we can actually inhabit this bare planet. The American spacecraft Viking 1 was the first to land on Mars, in 1976, and the first to transmit images from the Martian surface. What it found was a dusty and cold planet that we would have to terraform in order to make it inhabitable.

However, it is difficult to actually travel to Mars and explore it. The biggest hurdle is the amount of time it takes to reach Mars. When Mars is closest to Earth, it is about 38 million miles away. To determine a launch window for Mars, there are many factors to consider. About every 26 months, Mars and Earth are positioned such that the time needed to travel between the two is minimized. The length of a launch window depends on the type of launch vehicle that is selected. A given launch vehicle is associated with a set of parameters that must be optimized, such as the amount of mass that can be carried given a certain target velocity. For a mission to Mars, lift-off is usually scheduled before an ideal launch day, but there needs to be acceptable conditions for the launch vehicle. A launched vehicle utilizes both the orbital velocity of the Earth (about 18 miles per second) and the velocity achieved by its rockets to move swiftly towards Mars. As it moves towards the orbit of Mars, it trades some kinetic energy associated with the velocity into potential energy. When it finally reaches Mars’ orbit, it will slow down enough to allow orbit capture. The total travel time from Earth to Mars is 150 days. Even with this fast travel time, there is still the issue of how a manned mission will get back to Earth, because once we are on Mars, we have to wait for a Martian launch window before sending a rocket back. Thus it is important to plan early when to take off from Earth as that will determine the takeoff date from Mars to Earth, since Mars and Earth are constantly changing their positions from one another.

To learn more about Mars, it takes tremendous effort and time. However, it would be worth it if we can terraform it and transform the planet into something we can inhabit that is similar to Earth.

Sources:

Zubrin, Robert, and Richard Wagner. "From Kepler to the Space Age." The Case for Mars: The Plan to Settle the Red Planet and Why We Must. New York: Free, 1996. 19-20 & 87-91. Print.
http://athena.cornell.edu/mars_facts/sb_launch_window.html
- Minami Makino

Delaying Our Doomsday

The average lifetime of an intelligent civilization is one of the variables in the Drake Equation used to estimate the number of alien civilizations in our galaxy. Attaching a quantity to this variable invites not only scientists but also political philosophers into the discussion of our path to finding intelligent life. Because our species is the only intelligent society we know of, determining the average likelihood of intelligent species is mostly dependant on our single data set sample size: us.

One reflective question to ask with outward projection: How long are we going to survive as a species. This is widely disputed across the board, but I have a fairly optimistic point of view. The naturalistic argument is too frequently paired with an outdated anti-industrialist point of view. Too frequently, take a transcendentalist. After all, I consider myself a fan of pomp and convention. It is too late to assert that as humans all we need should be water, food, and love. This is no longer true with today’s size of population. We have a lot more problems to deal with-- but in many ways we have naturally developed infrastructure to match everyone’s needs.

But that’s besides the point. If we think of the progress we’ve made in creating a structure of peace, by the numbers, modern human civilization has been incredibly successful. Consistently, decade after decade, the rate of deaths attributed to war has consistently decreased. Compared with tribes in amazon in the 1900’s, of whom the death rates ranged from 20%-60% coming from murder, the 20th century Europe and U.S. tolled immensely less (around 1%), even including World War I and II. Moreover, since those times we only become even more exponentially peaceful. The death rate attributed to war in 2016 is far below 1% of the world’s population.

Under these statistics, I really believe that we are going to keep progress moving into more consistent eras of unparalleled peace. While many argue the fact that we know are living in a world with much more risk, given the threat of nuclear power-- I argue the opposite. We have been in possession as a global power of nuclear weapons well over 50 years and we haven’t had any type of imminent threat from nuclear war for some time now. In many ways, actually, the new level of peace in the twenty first century can be attributed to the possession of nuclear weapons and the threat of mutually assured destruction.

If we are going to assume, however, that intelligent societies generally will not self implode, going forward we have to think more critically about the fermi’s paradox. If it is indeed true that intelligent life doesn’t self-destruct then why haven’t we been visited by any civilizations that are indulging in their worlds of unforeseen scientific progress and peace as we predicted.
- Sean Moore








The Future of Traveling

Teleportation is everyone’s dream superpower. Instantly moving from one place to another would infinitely increase production and efficiency. But is it scientifically possible? Many scientist, including Professor Michio Kaku and Charles Bennett, think that teleportation is in fact possible, and happens at a quantum level. Quantum teleportation exists and is called quantum entanglement. This process connects atoms, similar to umbilical chords, and allows atoms to transmit information between each other even if they are far away. However, the information does not actually travel. The chunk of information just arrives at the destination without physically passing between them. This might not sound like much, but all objects are just sets of data--elemental abundances, atomic energy states, etc.-that one may use to reconstruct them. So by transferring these data from place to place and using them to reconstruct objects, we are in effect "teleporting" these objects.This teleportation is different from the Star Trek-style teleportation where atoms are converted to energy and then beamed to faraway locations. This style of teleportation is more like making a copy of the object in another place.

Another way of moving over large distances without actually travelling that distance utlizes wormholes, also referred to as Einstein Rosen bridge. Wormholes are tunnels connecting one point in spacetime to another. They can make locations that are actually billions of light years away much, much closer. They create holes in the fabric of spacetime and bend it so the two ends are next to each other. Wormholes sound very efficient and useful, but we may never attain the engineering ability to capture, enlarge, and stabilize wormholes. If wormholes exist, they exist on very small scales, in the quantum foam, where they constantly pop in and out of existence. Because these wormholes are so small, they are impossible to detect with current technology. But let's say we could detect them and capture them. Then we would need to apply a source of negative energy to open them up and make them big enough for human-scale objects to fit. But we currently know of no sources of negative energy. The physics behind wormholes, though it may be hard to admit, is simply not there.

Lastly, a small comment about hyperspace/hyperdrive. Getting a spaceship to travel a couple thousand times faster than the speed of light is very implausible. Teleportation, which on the other hand is much more plausible, is the method that I feel is most likely to be the one we use to travel large distances in short amounts of time in the future.

Sources:

Thursday, April 28, 2016

Home in the Void

The idea of space colonization has been explored in many ways over the past several years. Many individuals in the industry and scientific community have become fixated on the idea of Mars domes or underground caverns where humans would eke out an existence until it could be terraformed. Between where we are now and terraforming Mars, there is a very important step- maybe even an alternative- that we should consider. Free space settlements are those that are not terrestrially bound. This type of settlement would exist in the vacuum of space, which in itself presents a host of positives and negatives.

On the one hand, the fact that we are not terrestrially bound means that we do not have to worry about the hazards of the planet (or moon’s) surface. Cosmic background temperature stays relatively constant at -454 degrees Fahrenheit. The main problem we have with temperatures and building structures is not one extreme or another, but rather drastic temperature changes. The surface of Mars, for instance, varies immensely from -195 to 70 degrees depending on time of day, and this can cause stresses to equipment. Another advantage to living in free space is the relative lack of weather. Although there are bouts of cosmic radiation that surge through space, the surface of Mars is plagued by massive dust storms and other potentially dangerous weather. Living in free space would not limit us by location. We would have the added advantage of avoiding entry of another atmosphere, as well as the possibility of using centrifugal force to create artificial gravity. This would allow us to circumvent some of the problems with living in low-gravity environments, such as fertility and bone-density issues.

On the other hand, living below ground on a planet may be a way to avoid severe weather and temperature changes. Living on a planet may allow us to source more material locally, instead of sending everything up into space from Earth, which would save money. Conceding that living on a planet is not a bad idea, however, does not mean we should not build free space settlements. A space settlement could actually be a stepping stone for Mars missions, as it would be much cheaper to assemble and launch a rocket from space instead of from Earth.

What type of structures could we expect to be living in? Early on, colonists might live in small quarters, like the international space station. As we gain the ability to scale, either by making transportation to space much cheaper than it is now, or by using resources in space, we could build some really luxurious abodes. Bernal spheres, O’Neill cylinders and Stanford tori all rely on the same principle: spinning to create artificial gravity. The interior walls would, in theory be able to support human life, with conditions not too different from here on earth. These mega structures would be on scales of five to twenty miles, which is infeasible today, but in the future, it may be a better alternative than living in a Martian cave.

Sources:
- Krishna Rao