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Ion Propulsion Engine: What is it and Why do We Care?

For the past hundred years, all rockets have been powered using a traditional combustion engine design. But recently, scientists have been researching and a testing an entirely new design. The ion propulsion engine.

Rockets are able to fly because of Newton’s Third Law—for every action there is an equal and opposite reaction. Gaseous hydrogen or methane is burned and expelled through the nozzle toward the ground and the equal-opposite force on the rocket propels it upward. Ion propulsion engines use the same principle, but in a completely different way.

A chamber filled with gaseous xenon is electrified—bombarded with electrons—, creating and ionized plasma of electrons and positive xenon ions. The ions are attracted to and accelerated by two electrode grids, an anode grid for the positive ions and a cathode for the electrons. The net-neutral-charge plasma is then expelled to create thrust.

There are obviously many differences between the two designs and each have their pros and cons. For example, xenon is very light and compact and the ionization process allows for a much longer engine run time and much more powerful thrust than a combustion engine, these being the main motivations for ion propulsion. However there is one considerable drawback. Ion propulsion builds thrust very gradually, whereas combustion creates a lot of thrust very quickly. For the most part, this is not a huge deal. But when it comes to making quick maneuvers to avoid obstacles or correcting trajectory, it becomes a problem. Also, it takes a lot of energy to ionize the gas, which is produced by solar panels on the rocket. But for extended trips, especially those in the future that may travel beyond the sun’s reach, solar panels can’t keep up with such a high energy demand.

For the first issue, some scientists have proposed a dual engine: ion propulsion for long term travel with a backup combustion system for short bursts of extra thrust. As to the energy problem, it’s been suggested to use nuclear energy instead of solar. Of course, both solutions have problems of their own, but for now they’re the most reasonable ones.

My personal opinion is a combination of the two: use nuclear energy to power the ionization and use any excess heat produced by the fission process for quick maneuvers. This way, there is no need for an additional complex section of the rocket for an alternate combustion engine. Also, if the key goal for now is to reach mars, the nuclear reactor could be used to power  the settlement of the first group to land there, before they are able to set up solar farms.

So far, only a couple spacecraft using ion propulsion have actually been launched, all of them being space probes. But soon enough the first ion propelled rocket will be built and ready to traverse among the stars.

Fusion and Fission: How Can Both Produce Energy? Breakthrough Junior Challenge Video

This is my submission to the breakthrough Junior Challenge 2023, a competition where students from all across the globe create a video explaining a topic in math, physics, or the life sciences. The winner receives a $250,000 scholarship as well as a $50,000 cash prize to the teacher of his choice and a $100,000 science lab for his school.

Video transcript:

How can nuclear fusion and nuclear fission both produce energy when they are opposite reactions?

That’s a great question!

First, here’s a little clue: the fusion of small atoms and the separation of large atoms both increase the stability of the atoms involved. Keep that in mind.

Ok, so the key lies in the atomic mass defect, which goes like this: protons, neutrons, and electrons each have a specific mass. So when you combine a certain number of them to form an atom, you would expect the mass of the atom to be the sum of the masses of all the particles in the atom. But in fact, the atomic mass is slightly less than that sum. This is because atoms are more stable than the individual particles, meaning an atom requires less energy to exist than those particles. 

The difference in energy is called nuclear binding energy and is the amount of energy necessary to split an atom’s nucleus. As atomic mass increases, the binding energy (BE) increases, because the atom becomes more and more stable, meaning it requires less and less energy. Therefore, when you fuse two small nuclei, the new, large nucleus needs less energy than both of the small ones, and the excess is released.

Now, you’re probably thinking: if fusion produces energy, shouldn’t that mean fission only consumes energy?

Not exactly. See, BE only increases to a certain extent. Iron-56 is the most stable element and has the maximum BE. Elements larger than iron begin to decrease in BE, because the strong force—which holds the nucleus together—has less of a pull on the particles near the edge of the nucleus, making it unstable. So when a heavy, unstable element is fissioned into lighter, more stable ones, the BE is increased and energy is released.

Thus both reactions produce energy because they both increase the stability and therefore the binding energy of the atoms involved.

Saving the Mission with Fusion

On December 7, 1995, NASA’s Jupiter probe, of the Galileo mission, entered Jupiter’s atmosphere at 47.4 kilometers per second, about 29.5 miles a second or over 106.03 thousand miles an hour, making it the fastest man-made object of its time. As NASA expected, it immediately began to burn through the carbon phenolic heat shield. This is a process called ablation, meaning simply that the outside material was made so that it would be burned at a controlled rate, absorbing the brunt of the heat, and protect the ship itself. What NASA didn’t expect was that the heat would be over double the temperatures of the sun’s surface; the probe measured over 28,000 degrees Fahrenheit. Atoms were split and plasma was formed. The plasma decimated the probe’s heat shield, nearly destroying it.

The tests that NASA had preformed were flawed, because they lacked a heat source great enough to truly test the limits of the shield. For a long time they used lasers, high powered jets, and basically anything hot enough to disintegrate the heat shield, but as we’ve seen, this wasn’t quite enough. However, recently two people, Eva Kostadinova from Auburn University and Dimitri Orlov who works on a fusion reactor in San Diego, have come up with a solution. They’ve began shooting small carbon phenolic pellets into plasma filled fusion reactors, called tokamaks, to test the current heat shield and other potentially better materials. 

Fusion reactors are certainly notmade for this purpose; nuclear fusion is an atomic reaction of, essentially, smashing atoms into each other to create a chain reaction of other atoms fusing to each other. Physicists say this bring virtually unlimited electricity, making it accessible anyone in the world.

Though it cost them over half a million dollars for merely one day of these tests, it could keep them from wasting the half a billion dollar planetary probe that they are working to protect. It may not seem like a big deal, but NASA is currently scheduling a similar trip to Venus, the DAVINCI+ mission, for the next few years and are determined not to make the same mistake again. After the semi-failed attempt in Jupiter, NASA realized how much more they could learn if they’d had a lighter, more efficient heat shield that didn’t take up over half of the weight of the entire probe, which could have been used for vital equipment.

SpaceX to Cheapen Space

Space travel and exploration is extremely expensive. One major reasons why space isn’t open to the public yet is due to cost—specifically having to throw away every rocket that is used. But Elon Musk and SpaceX are changing that.

Because launching rockets is so expensive and delicate, the business launching them makes sure that it is as reliable and durable as possible. This only makes the launch cost more, making the company realize that they should make the cargo as light and efficient as possible, to ensure that they can pack enough for the trip to be worth the risk and cost. But this also leads to more expensive rockets.

Compare these rockets with a modern passenger airplane. The cost to fuel an airplane is about 30-50 percent of the entire cost. Contrast that to less than 1 percent of the total cost to launch a rocket is for the fuel—and it certainly isn’t lower because it needs less fuel. Depending on the rocket, they can use anywhere from 1-4 million pounds of fuel for one trip, whereas a plane on a 10-hour flight uses only 250 thousand pounds. So, if it isn’t the fuel, it has to be just the extremely high cost of the rocket itself.

SpaceX was founded in 2002 with the main goal of bringing everyday civilians into space. However, Elon Musk knew that this would be impossible as long as every flight needed a new, tens-of-millions dollar rocket. So he started fixing it. In 2015, SpaceX managed to successfully land their rocket the Falcon 9 on its boosters, and after only a little bit of maintenance, they were able to reuse those boosters. Since then, that has been the standard modus operandi for SpaceX; over 85 percent of the Falcon 9’s launches uses recycled boosters. But it didn’t end at there. According to The New Atlantis, “SpaceX has also begun recovering payload fairings—the nose cones atop the rockets—saving about $6 million per reuse.”

Elon Musk is confident that with these new improvements, they will be able to place a man on mars in, at most, ten years. SpaceX is continuing to increase the amount of reusable parts and sections and won’t stop until they can fully reuse every rocket they launch, regardless of wether they make it to mars soon or not. And every single one of these improvements is lowering the price of a ticket to space. Though it may still seen like a lot, Elon Musk says their newest, most reusable rocket, Starship, could launch for a mere 1 to 2 million dollars. This isn’t only proving that civilian space travel is possible; it suggests that it could be much sooner than most people expect.

Works Cited:

https://www.thenewatlantis.com/publications/walmart-but-for-space

https://futurism.com/the-byte/elon-musk-mars-ten-years

Shedding Some Light on Black Holes

Some people are under the impression that black holes are the absence of matter, that they are void of color because they cannot absorb light, simple because it is called a black hole. This is utterly false. Quite the opposite is true, in fact. According to NASA, a black hole is “a star ten times more massive than the sun squeezed into a sphere approximately the diameter of New York City.” 

Another misconception about black holes is that the gravitational pull around one sucks  in anything and everything around it. While this is partly true—anything that falls into its center instantly gets squished, but more on that in a second—, black holes actually have the same gravitational pull as the star that it once was. It definitely seems like it sucks in every object in its pull, seeing as how nothing could get remotely close to it while is was a live star, but it is the exact same. Except in the center.

When a black hole is created, the dead star gets compressed into almost infinite density. This is the center, and it is called a singularity. From here to a few miles out, the gravitational pull is so strong that it does pull in everything around it. Don’t get confused here—a couple miles is completely different from the entire gravitational pull, which would probably be a couple million miles depending on the black hole. Because the density of the center is near-infinite, a strange phenomenon happens while the star is collapsing. It is a thing that I still don’t fully understand called the event horizon. As the star compresses, the escape velocity—the speed at which an object would have to travel at to “escape” the black hole’s gravitational pull—increases. So the event horizon occurs when the escape velocity exceeds the speed of light. From what I understand, this means that the event horizon is just the part of a black hole’s surface that doesn’t let anything—including light, since Einstein’s theory of special relativity says that the speed of light is the fastest something can travel through space—out.

Let’s say for a second, that, somehow, you manage to fall—or more accurately, get sucked into—a black hole. As I mentioned, you would never escape. The extreme gravity, which is also almost infinite at the center or event horizon, would instantly stretch you vertically and compress you horizontally because of a process that scientists legitimately call spaghettification. Of course we don’t actually know what would happen since it never actually has happened. But scientists expect that the way you would perceive space and time would be completely different.

Although a person has never had an encounter with a black hole, scientists have seen and created advanced simulations of stars entering black holes. You may be surprised to hear that though some get ripped to shreds, there have been several instances of the star entering, warping and being slightly compressed, but managing to exit the gravitational pull fully intact.

Works Cited:

To learn more about black holes in general, visit:

https://science.nasa.gov/astrophysics/focus-areas/black-holes

https://solarsystem.nasa.gov/news/1068/10-questions-you-might-have-about-black-holes/

https://stardate.org/astro-guide/black-holes-0

To learn more about a black hole’s event horizon, visit:

https://www.space.com/black-holes-event-horizon-explained.html

To learn more about and see simulations of when a star nears a black hole, visit:

https://screenrant.com/when-star-gets-close-black-hole-explained/amp/

Dune: to Read or not to Read?

Shortly after the Ducal family Atreides arrives at the desert planet of Arrakis, called Dune, they find themselves caught by their political opposition, the Baron Vladimir Harkonnen. They are then forced to fight through the barren waste land that surrounds them, and fit in with the native culture, as the Duke’s son, Paul Atreides, soon to be known as Muad’Dib, slowly finds his place again.

Though not as action packed as our 21st century novels, Frank Herbert’s 1965 sci-fi series, Dune, quickly became a classic through its original writing style and sense of wonder. It is one of the first books to use what writers call “Third person true omniscient” since it shows each scene from multiple characters eyes and thoughts at once giving it the sense that every character is the main protagonist. Herbert’s completely new universe uses a mixture of futuristic technology and ancient magics, and combines fantasy suspense with political schemes for power and control. This universe became a classic for the ingenious creativity in the technology and scientific advancements, which eventually inspired the desert planet of Tatooine in A New Hope. However, although being a great novel in general, there were a few issues, in my opinion. The plot is not noticeably established until about two thirds in, making it seem go on chapter after chapter with little to no progress, even through the most intense scenes. Because it is an absolutely original world, the amount of new information can, at times, become a bit much to process. As previously said, the writing style is one of a kind, but this can cause some confusion from the slightest difference in compound sentence structure to the immediate change in character viewpoint. It is quite obvious that Herbert did not want much action. Several scenes had potential to escalate, and they did, but as a background to a different a character’s viewpoint.

Over all, Dune is absolutely worth reading, even with the few issues it arguably has. So, if you happen to have 12 hours of free time and don’t mind a book mostly based around political schemings of a fictitious universe, then this may be your cup of tea. Or for those who have already read it, your spice coffee.