Author: alfredprah

Astrobiology, The Future.

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Space Travel

I am still trying to decide whether my admiration for Elon Musk is because of his electric vehicles (S-3-X-Y) or his passion for space exploration. The topic of space exploration leads me to a scientific field I would like to talk about briefly, Astrobiology. Wikipedia defines Astrobiology as “an interdisciplinary scientific field concerned with the origins, early evolution, distribution, and future of life in the universe.” I am not an Astrobiologist but I do know that what is keeping professionals in the field awake at night is the question of whether extraterrestrial life exists, and if it does, how humans can detect it. To do this, Astrobiologists make use of molecular biology, biophysics, biochemistry, chemistry, astronomy, physical cosmology, exoplanetology and geology to investigate the possibility of life on other worlds. They also try to recognize biospheres that might be different from that on Earth.

Thanks to the use of high level automated systems for space missions, space exploration has become easier. According to Wikipedia, these high level automated systems “yield benefits such as lower cost, less human oversight, and ability to explore deeper in space which is usually restricted by long communications with human controllers.” How much progress have we made in determining whether extraterrestrial life exists? Ever since landing on the moon, Mars has been a focal point of modern space exploration. According to Aerospace.com, “Mars exploration is a long-term goal of the United States. NASA is on a journey to Mars, with a goal of sending humans to the Red Planet in the 2030s.” NASA and its partners have sent landers, orbiters, and rovers to help it increase its knowledge about the planet.

It is worth mentioning that only three countries have human space programs (China, Russia and the US). It costs a lot to have such a program! Additionally, there is more competition between these countries than is healthy. Even though the International Space Station (ISS) is a massive collaboration between five space agencies (Nasa, Roscosmos, Japan’s Jaxa, the pan-European agency ESA and the Canadian Space Agency), we have a powerful and resourceful country like China trying to ride solo. As a matter of fact, it is reported that “in 2006, Beijing reportedly tested lasers against US imaging satellites in what appeared to be an attempt to blind or damage them, and US lawmakers later banned cooperation between Nasa and China’s state agency.” But I am hopeful that the ISS is strong and resourceful enough to embark on many more groundbreaking missions.

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Extremophiles 101

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Extremophiles produce some of the color at the Grand Prismatic Spring

Wikipedia defines “an extremophile as an organism that thrives in physically or geochemically extreme conditions that are detrimental to most life on Earth.” This means that if extremophiles were your classmates, they will totally be the cool kids in the class. Not only are extremophiles able to survive in extreme conditions; actually, many of them wouldn’t survive in supposedly “normal, moderate environments.”

What are some of these extreme conditions? Examples are highly acidic systems, highly alkaline systems, low temperatures, high temperatures, extreme UV radiation and high salinity, among others. What piques my interest as well as that of many Astrobiologists, is the fact that some of these environments that these extremophiles survive on are similar to those known to exist on other planets. This means we could have a good idea of how to prepare for some of the planets that we may someday explore, or to even decide if visiting the planet is a reasonable expedition in the first place.

Of all the extremophiles, Thermophiles are my favorite. As a matter of fact, I  am planning a trip to the Yellowstone National Park because of this organism. These organisms produce some of the color at the Grand Prismatic Spring in the park! Wikipedia defines a Thermophile as “an organism that thrives at relatively high temperatures, between 41 and 122 °C (106 and 252 °F).” Many thermophiles are archaea. “Archaea” refers to microbes that have no cell nucleus, and the first observed archaea were extremophiles, living in harsh environments such as hot springs and salt lakes.

Exoplanets 101: Does the earth have a twin?

potential habitatable planets

Potential Habitable Planets

An extrasolar planet is a planet that orbits a star that’s not our sun. Even though these planets can be recognized, and their sizes measured, they are light years away so it would take astronomers thousands of years to reach these extrasolar planets. To detect these planets, scientists use either one of two methods: doppler and transit.

The doppler method measures the star’s wobble. The wobble is caused by the force of gravity from exoplanets themselves, pulling the stars in different directions during their orbits. Measuring the wobble also makes it possible for astronomers to measure the planet’s mass. The greater the wobble of the star, the greater the mass of the exoplanet.

The transit method: after observing a star over a period of time, astronomers sometimes notice a faint dimming of its light. This dimming is probably caused by a planet orbiting past it. Taking note of the “size of the dim” through the transit method gives away the size of the planet. The doppler technique gives astronomers the mass of the exoplanet, and the transit method gives them the radius/physical size.

Combining the results, astronomers are able to calculate the density of the exoplanet. The value of the density of the planet is then used to determine the kind of planet that has been discovered. Ie, is it a rocky planet like earth or a gaseous, giant planet like Jupiter? A gas giant like Jupiter has a low density, and a rocky metallic planet like earth has a high density.

What will it take to find a planet like earth? There is a difference between being earth-sized and being earth-like. Astronomers have discovered hundreds of planets that may be the same size as our earth but a planet must be at the right distance from its  star, to have the right conditions where liquid water could exist on its surface. We are not entirely sure of what the atmospheres on these earth-like planets may be like, or whether these earth-like planets actually have atmospheres but we are excited to discover what could be our very own twin planet!

The Sun – the heart of our solar system

the sunn

Planetary System

The star at the center of the solar system plays a special role for us here on earth. It was formed about 4.5 billion years ago, in the Orion spur (in the milky way galaxy). It was born from the collapse of a cloud and dust called the “solar nebula”. It then condensed into a burning ball of gas, called the sun.

What makes the sun the heart of our solar system?

  1. Its magnetic field
  2. Its gravitational pull.

The sun’s magnetic and gravitational impacts are largely due to its size. It is large enough to hold the solar system intact, it is about 100 earths wide, and it could theoretically fit all 8 planets nearly 600 times. Additionally, it contains about 99.8% of all the mass in the solar system.

If you are guessing that this is why planetary bodies orbit it, you are right. Because of its mass, it has a great pull on the fabric of space, creating a gravitational force that causes nearby bodies to be drawn towards it. Without this pull, the other planets will vanish into deep space.

The magnetic field of the sun is called the heliosphere, and it encapsulates the entire solar system. It protects the planets form harmful cosmic radiation. It is caused by the sun’s plasma, and it causes the pushing of particles towards its poles.

Will the sun last forever? Unfortunately not. It is expected to collapse into a white dwarf in about 6.5 billion years, after it runs out of its hydrogen fuel. That’s such a depressing thought. I hate to imagine what will happen to our existence as a result of this. Maybe we should think of ways to refuel the sun? Or maybe we should just refrain from worrying about things we cannot change. In the meantime, let’s enjoy the sun’s magnetic field, gravitational pull and vast amounts of energy.

Radioactivity 101. Is the sun radioactive?

sun radio

sun spots and solar flares

Chemical reactions occur because atoms strive for stability. Just like the outer electrons require a certain number of electrons to become stable, the nucleus requires a certain number of protons and neutrons to achieve this stability. The decomposition (breaking down) of the nucleus to achieve this stability is what we call Radioactive Decay. An unstable nucleus can be referred to as a Radionuclide.

Why do atoms decay in the first place? Each nucleus contains protons and neutrons. If there are too many or too few of the neutrons, the core of the atom becomes unstable, leading to the decay of the radionuclide. 

How do we measure the rate of decay? We measure this by measuring the time it takes for exactly one-half of the radioactive substance’s nucleus to decay.  There are three types of decay, and each one is based off the radiation emitted through radioactivity. The three types are: alpha, beta or gamma decay. Our very own sun emits gamma rays, but unlike that of unstable nuclei, its rays are from solar flares.

 

Retrograde Motion simplified.

the path of mars

The path of Mars, as viewed from the Earth.

         Retrograde motion is the apparent backward motion of a planet caused by its being lapped by another planet, or vice-versa.1  These two planets are usually on two different orbits, a larger one and a smaller one, and they move around the sun in the same direction (eastward). The planet on the smaller orbit moves faster than the planet on the larger orbit. When the two planets on different orbits do overlap, and align with the sun, either one of the planets sees the other planet as moving in the opposite direction. However, this is only an apparent motion, as the planets are truly moving in the same direction. This apparent motion is what we call “retrograde motion.” The period between two retrogradations is the synodic period of the object/planet.2 A practical example of retrograde motion is the motion that when you pass a car on the freeway. The car being passed appears to move backwards relative to you. Alternatively, you can experience this by standing side by side with a friend, and having them. walk forward slowly. Now walk forward at a faster speed and watching your friend, think about how they are moving relative to you. At first, they move away, then as you pass them, they appear to be moving backward relative to you – even though they are still walking forward. Ancient Greek astronomer Ptolemy in 150 AD believed that the Earth was the center of the Solar System and therefore used the terms retrograde and prograde to describe the movement of the planets in relation to the stars, and the names have remained since then.3

Historical Astronomers in Context

1. Isaac Newton: 25 December 1642 – 20 March 1726/27.

2. I admire Isaac Newton (12/25/1642-03/20/1726) a whole lot and here is why:

He was modest enough to build on the work of Kepler’s law, instead of making his own from scratch. Through his work, we were able to have a deeper understanding of gravitation and its effect on planetary motion; The principia which he first published on 5 July 1687 and later in 1713, is what gave him the international recognition that has lasted till present day. In this publication, he talked about how the results of his findings conclude that indeed there is a gravitational attraction. Because he could not indicate the cause of gravity at the time, he described his findings as “hypotheses non-fingo.”

 

3A.  In 1699, French settlers moved into Mississippi and Louisiana.

  • Louisiana was named in honor of French King Louis XIV.
  • It became a French territory in 1682 when Rene-Robert, Cavalier de La Salle claimed the area.

1648 marked the end of Thirty years’ War.

  • This was a war fought primarily between 1618 and 1648.
  • It resulted in the German population being reduced to about half its size.

 

3B.   A famous author named Voltaire lived from 21 November 1694-30 May 1778.

  • He was a polygenist. He suggested that each race had entirely separate regions. Because of his beliefs which were considered to be somewhat abnormal at the time, his work as a prolific writer was well-publicized.

 

4. Learning this helped me to realize the progression of events over the years. Through this historical context, I was able to develop some sort of timeline of astronomical events which served as a foundation for what we know in the present day.

Can we travel at the speed of light?

speed of light
Light’s speed

How fast is light? Nothing on earth is known to move faster, and in my opinion, we are actually very fortunate to be able to measure it. Aside the fact that light enables us to see, I am appreciative of it even more because if it were to get any faster by any stretch, astronomers would have to build new technology to measure its speed. This speed of light is known as the cosmic speed limit and even at the age of twenty-two, I am yet to experience anything more rightfully named. Why is It so hard for us to travel at the speed of light? The reason is that as you propel an object faster and faster, its relative mass compared to when the object is at rest, increases. This means that not only do we increase the speed object; we end up increasing the object’s mass as well, eventually resulting in an infinite mass which requires an infinite amount of energy to move it.