SPACE
How far above Earth does Space begin?
Exploring the Boundaries of Space: Where Does Outer Space Truly Begin?
Republication from our Sister Web: www.aviationnepalnews.com by Karan Bhatta
There is the Karman line- a proposed boundary 100 kilometers above the ground where FAI defines “space begins.” The United States of America dubbed anyone an astronaut when they’d inched past the 50-mile 80-kilometer mark. Whenever a spacecraft, after its voyage into the cosmos, is brought back to the Earth, its entry into Earth is marked at 400,000 ft, roughly 121 kilometers. Given that as soon as your eyes inch upwards of ground, you see Space- from the point you observe the lowest hanging helicopters to the seemingly suspended moon to the furthest galaxies- and that there are so many different proposed markers of Earth and Space, one is bound to ask the question, “Where does “space” really begin?”
The farthest reaches of outer space from where humans have observed light streaking into the home, that is, the Earth, is from some galaxy that is some 13 billion light years away. And this, the farthest we’ve observed in Space, is what astronomers call to be the edge of “the observable universe” (Places like these are often dubbed as “deep space”). There are others who believe that the universe might as well be harboring Space that is infinite in its course- a multiplicity of universes whose numbers benumbs thought. On the opposite spectrum, there are balloon flights that are sometimes inching toward the edge of Space.
With so many ideas of “space” ranging from “outer” to its “edge” or “deep space,” “where reality is “space “?” is a question to ponder.
Definitions of Space
Various terms have derived out of the womb of “space” itself: there was the famous “Space race” between the US and the USSR which saw the putting up of humans in Space and on the moon; we have what astronomers experience “space sickness” during their adaptation to weightlessness in Space, there’s the rather encompassing term called “aerospace” which collectively refers to the atmosphere and outer Space, “airspace”- the Space above a country’s territory which it controls, “interstellar space” that serves as the place where raw materials for star formation or galaxy formation brew and a plethora of other terminologies.
But in order to ensure that we’ve got a bearing on these terms, we need to examine what the definitions of “space” really are and where they come from.
Karman Line
The Fédération Aéronautique Internationale (FAI), whose English translation renders itself as “World Air Sports Federation,” proposed that the Karman line- a region of Space that lies 100 kilometers above the Earth’s surface to be the boundary between the Earth and Space. It is the FAI that determined the records set by Yuri Gagarin when he first took to Space, and it is this very body whose proposed limit of 100 kilometers is thought to be a boundary, with some people claiming that this boundary is an “imaginary” at best.
Karman, who was a brilliant mathematician and set boundaries in other areas of physics too (Born–von Karman boundary conditions), thought that above 100 kilometers, the aerodynamic forces were too heavily dominated by astronautical forces:
“This is certainly a physical boundary, where aerodynamics stops, and astronautics begins, and so I thought, why should it not also be a jurisdictional boundary? … Below this line, Space belongs to each country. Above this level, there would be free Space.”
A few positions differ from the Karman line as a boundary that defines “space.”
But there are people who dub this proposed idea to be a “folk theorem,” and this proposal of a “Karman line” isn’t backed up by a peer-reviewed “published article,” which has to be ratified by many scientists working on the particular field to find common ground. If you tread 80 kilometers above the Earth’s surface, the US will deem you to be an “astronaut”- someone who’s been to Space.
One might as well argue that going to Space would consist of escaping the Earth’s atmosphere. Some observations, particularly of the geocorona- the luminous glow of the outermost layer of the Earth (exosphere)- reveal the Earth’s atmosphere extending to 100,000 kilometers.
If we take this number as the reference, the International Space Station (located some 400 kilometers upwards of the Earth) would have to be renamed. As observations have revealed that the geocorona extends further than the surface of the moon, we might have to ponder whether we’ve really been to “Space” as most people think “space” to be devoid of Earthly qualities like the atmosphere.
Factors Affecting the Boundary of Space
Space begins where Earth ends. Or so it is generally thought. There are also the connotations of “vacuum-ness” that “space” is supposed to harbor. Before the Michelson-Morley experiment, the luminiferous aether was thought to be pervading through “space,” allowing the possibility of light to propagate.
Gravity
There are a variety of factors that affect the boundary of Space. We tend to think of Space as a place that harbors “zero gravity.” After all, the pictures of astronomers floating about in Space or astronauts training in zero-gravity conditions are galore. But gravity isn’t truly “zero” anywhere. Even in Newtonian mechanics, gravity is inversely proportional to the square of the distance.
Even when the moon is so far out from the Earth, it is still clinging to the Earth’s gravitational pull. So “zero-gravity” is virtually non-existent. The apparent “floating” of the astronauts is because they are accelerating around the Earth at the same speed that the space vessel is accelerating-much like the case of how a lift would behave if it was boxed within a lift shaft.
Atmosphere
One another yardstick that might help adjudicate the boundary of Space might be when the Earth’s atmosphere ends. But the outermost layer of the Earth does extend to thousands of kilometers from the Earth’s surface. The Earth’s magnetosphere extends to even longer stretches, gliding the various charged particles to the magnetic poles and creating weather phenomena such as aurora borealis. But “space” tourists generally only fly as high as the International Space Station and sometimes much lower- in sub-orbital regions, aka Karman line.
Aerodynamic flight, a Piloting perspective
One other concept that is related to atmosphere and setting a definition of “space” in some ways would be considering what Theodore von Karman himself pondered: at what altitude would planes find it difficult to fly?
There is a reason that “airplanes” fly in “the air” compared to “rockets” that veer off into “space.”
The wings of the aircraft are designed in such a way that they take advantage of the pressure difference between the top of the wing and the bottom of the wing: allowing the air pressure underneath the wing to thrust an aircraft upwards.
The US Military and the National Advisory Committee on Aeronautics believe that it is around 80 kilometers or so above the Earth’s surface that the aerodynamic forces are no longer useful.
The case for Atmospheric drag
The National Aeronautical Space Administration uses the 122-kilometer boundary that marks Space while admitting a space vehicle to the Earth. It is generally thought that at around the 122-kilometer mark, the atmospheric drag on spacecraft becomes almost as high as four times that of “aeronautical drag.” Think of the raindrops: if it were not for the atmospheric drag, a raindrop falling from the sky would be as high as 550 m/s, enough to become lethal.
Going around the Earth
There are two approaches a satellite can take while being in a stable orbit around the Earth: one is a “circular” orbit, and the other is an “elliptical” one. Without propulsion, the lowest a satellite can revolve around the Earth is at an altitude of 93 miles. And the lowest altitude from the Earth that an elliptically revolving satellite can be has been observed to be around 80 miles.
Exploration of Space
The exploration of Space gave us a rather imperceptible picture of the Earth from Voyager I as it was heading out of the Solar System. The picture is famously known as the “Pale Blue Dot” and comes with a rather marvelous caption:
Look again at that dot. That’s here. That’s home. That’s us. On it, everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every “superstar,” every “supreme leader,” every saint and sinner in the history of our species lived there-on a mote of dust suspended in a sunbeam.
There are some more brilliant pictures in Space we’ve been able to patch up-not least the image of a black hole or an astonishing nebula. But Space itself is so vaguely defined, and there is a multiplicity of regions in Space with their own names and bear the prefix “space.”
Interplanetary Space
Voyager I, the space probe that took the sounds of classical music and pictures of Earthly qualities, has been in Space for more than 45 years and traversed a distance which is 150 times the distance between the Earth and the Sun. It was the first probe to make it across the interplanetary Space (the Space between the planets) of our Solar System and head towards interstellar Space, making it the most distant thing that humans have sent to Space.
There are some plans for the colonization of Mars and other planets- all of which will require interplanetary travel. Given that humans tend to suffer from reduced bone density while traveling in Space for prolonged periods of time, interplanetary Space will be tough to master unless we have significant changes to the duration of space travel- which according to current space technology, would take about nine months.
There are some space probes that have been recently sent to study objects in interstellar Space- ranging from Lucy to study the Gas Giants of our Solar System,
Interstellar Space
It takes about 500 seconds or roughly 8 minutes for light from the Sun to reach the Earth. The light from the next closest star to the Sun, Proxima Centauri, takes about 4 light years. Given that light travels at a speed of 300,000 kilometers per second and Voyager I travels at 15 kilometers/per second, it is clear why it will be exorbitantly difficult for any probe to reach a different Solar System and reveal details of exoplanets like Voyager did for planets of our Solar System.
But telescopes based on Earth are getting better, more capable of revealing the interior of distant galaxies and stars. And so are spectroscopic techniques used to make sense of data captured from telescopes. These techniques, which are getting more polished with time, are expected to reveal information about interplanetary stuff such as “nebulae,” which coalesce together to form stars.
Intergalactic Space
The spaces between galaxies are even greater than interstellar spaces. To put this in numbers, it would take 5 million years for light from one galaxy to reach another. And 5 million years is a conservative estimate. But given how big galaxies are, two galaxies are much closer to one another relative to their size. Also, galaxies tend to be present in clusters. This is one of the reasons why galaxy mergers are more or less a given. Two galaxy clusters might be billions of light years distant from one another.
It might be fair to say that for the foreseeable future, whatever intergalactic exploration we do will take place with the help of a telescope.
Conclusion
The universe is so big that Blaise Pascal, while musing about the vast emptiness between astronomical objects we conceive of as “space,” said,” The eternal silences of these empty spaces frightens me.” Given the overwhelming size of the cosmos and the furthest reaches of Space, it might be very difficult to come up with a valid definition of “space.” If “nothingness” is what we think of as “space,” we might have to redo our definitions. As Laurence Krauss puts it, even empty spaces have virtual particles popping in and out of existence.
With billionaires such as Elon Musk and Jef Bezos setting their sights on “space exploration,” it will be useful to have a clear definition of where “space” really begins. But in order to determine “where” Space begins, we might also have to delve deeper into “what” Space really is. The FAI has released a statement saying that “compelling evidence” suggests lowering the Karman line from 100 kilometers to 80 kilometers. Whether that will be done or whether the various organizations such as the FAI, NASA, and all other countries will unite on a universally accepted answer to how far above Earth Space begin is something for posterity.
Frequently Asked Questions
What is outside of Space?
We’d all like to have a bird’s eye view of how Space was from a vantage point outside Space itself. In a cosmos where we’ve been confined to the remits of Space, we don’t really have a non-spaced view of the intestines of Space. There is a scientific view that the matter/anti-matter annihilation is taking place far beyond where our telescopes have poked at.
Others believe that there might be a universe with different values of cosmological constants as we know it. And such a place might be deluged with “space” that is very different from our current understanding of this term.
When certain Zen masters painted a picture, they thought that a painting wasn’t supposed to be occupying the whole of a canvas: they thought of leaving certain spaces around the picture un-daubed with colors because they conceived the universe in its wholeness- a picture can only exist with relation to its Space- a sort of “emptiness” or “nothingness” or “empty space” that we are cloaked around.
What is Space made of?
Outer Space is not completely empty. There are gaseous molecules or even atoms of solids that are remnants of previous supernovae explosions, galore. There might be as many as 1 electron per cubic centimeter in interstellar Space.
But when we are talking about what the “fabric” of Space itself is made out of, we have a lot of differing ideas. String theory posits that there might be as many as 11 dimensions that are currently hidden from our view, and the fundamental particles as we think of them might be different. This might change our perception of “space” forever. Other theoreticians say that Space, which for all practical purposes is empty, is a soup of virtual particles popping in and out of existence for a very short period.
What was the first thing in Space?
There are various sources which point at totally different things, one of them towards a V-2 rocket by the name of MW 18014 while the other one claims that Bumper-WAC was. But both of these answers have a point of commonality: the two of these spacecraft were of German origin. The first of these is claimed to have been launched in 1944 while the latter one was launched in 1949. The heights to which these reached are also different. The MW18014 climbed 176 meters high while the Bumper WAC reached 393 kilometers.
How was Space created?
How Space was created is something that is still something that no one has a definitive answer to. Given the observations from the Hubble Space Telescope, we’ve discovered that the universe is flying apart-in, that the distant galaxies are getting more distant, and that in trillions of years or so, the galaxies might have been blown so further apart from one another that traces of galaxies outside one’s own might also have vanished.
If you extrapolate this into the past, it definitely implies that the galaxies and other stuff of matter must have, in the past, been close together, like a dense ball- something akin to fitting in everything you have in a suitcase. There are people who posit that this dense ball would have been small enough to fit in a pocket. And a definitive event scattered the bones of this extraordinarily dense matter in all directions.
But what was the view of this dense matter from the outside is something not known. And what caused the spluttering of something so dense is unknown too. We know it did explode with a Bang, but What Banged to bring forth “space” and “time” into existence is something that we hope is answered in the future.
Which was the first living thing in Space?
The first living beings in Space were fruit flies. The fact that these flies are close to humans on a genetic level and proliferate across multiple generations within a single human lifespan means that they’re excellent for conducting space research bordering on chances of survival during spaceflight. The first fruit flies were sent to speed in rockets that cut across the Karman line in less than 200 seconds. During their flight back, they were recorded alive, making them not simply the first organisms in Space but the first organisms to go to Space and make it back to Earth alive.
They were far ahead of the first dog to have made it to Space, Laika, and even the first human to make it to Space. As a part of experimenting with more complex life forms and observing what toll space flight takes on their bodies, a lot of mice, dogs, guinea pigs, and monkeys died as a part of the space exploration.
Does Space have a beginning or end?
It is a commonly held view that Space and Time were created simultaneously about 14 billion years ago in an event known as the “Big Bang.” So in that sense, Space did have a beginning. But what circumstances led to the “bang” itself is something that still has no conclusive answer.
The Conformal Cyclical Cosmologists think that the currently observable universe is part of a never-ending cycle of creation and destruction. Roger Penrose, who came up with this idea, believes that after the universe gets astonishingly big and hopelessly boring with all the stars and galaxies and the eventual black holes that eat them phased out with Hawking radiation, therein will lie the seeds of the “Next Big Bang.”
Extrapolating his understanding of the past means that the currently observable universe was born out of the ashes of a previously blazing universe. A continuum of universes, each with its own epochal time frame extending to “aeons” is what Roger has postulated, though he believes that much work needs to be done before his theory can be credibly accepted.
A sentiment that was echoed in James Joyce’s Ulysses comes into mind:
“To reflect that each one who enters imagines himself to be the first to enter whereas he is always the last term of a preceding series even if the first term of a succeeding one, each imagining himself to be first, last, only and alone whereas he is neither first nor last nor only nor alone in a series originating in and repeated to infinity.“
What came first, Space or time?
Before the theory of relativity came about, “time” was thought to be a universal meter that ticked off, unhurriedly, or un-sluggishly, on its own accord, unscathed, on its own rhythm that neither ebbed nor flowed but on a constancy, ticked off as steadily as one could imagine. It took the genius of Einstein to link what was thought of as independent properties: “space” and “time.”
So time couldn’t have fostered or come into existence with the presence of Space- the wholeness of “spacetime” would be broken if we could pick the birth of one before the other. In places of extremities such as Black Holes where the Space is warped at mind-bending speeds, time is thought to come to a halt- at least for observers outside the black hole. The lighter an object, the more wispily the fabric of Space around it contorts and ticks off quicker.
When was the first death in Space?
There have been many disasters that have taken the lives of astronauts and cosmonauts alike. Vladimir Komarov, the first Russian to go to Space on two different occasions, died while returning from a spacecraft, making him the first to lose his life on a spacecraft. But his death occurred after his parachute failed to open while he was on his way to the Earth. So it can’t be technically called a “death in space.”
There has only been one recorded instance of a death in Space. And that was during the Soyuz 11 mission, where three cosmonauts by the name of Georgy Dobrovolsky, Vladislav Volkov, and Viktor Patsayev lost their lives while on the way to Earth after having visited the World’s First Space Station, Salyut I. The three were on their way back after spending 23 days in Space- a record-breaking amount of time then. And on their way back, the cabin had depressurized, which led to the asphyxiation of the crew.
What is below the Earth in Space?
When Stephen Hawking was once asked about the “time” before the Big Bang, he said that it was akin to reaching the North Pole-the flag bearer of north-ness, getting beyond it, and asking where the North was. With “upwardness” being defined as things we see above the horizon, we tend to think of “below” as harboring things very different from above.
But if we do away with the parochiality of being on the Earth and gazing upwards and floating in Space, the distinctions between up and down would melt, like that of a person’s muddled sense of direction after (s) he’s inched past the directional poles of the Earth.
In simpler words, the ups and the downs, the above and the below, the lefts and the rights of the Earth have the same sort of stuff. The distribution of matter around the universe is homogeneous to a particular degree.
What is the origin of Earth in Space?
Over the centuries, it was thought that the Earth and other planets were merely pieces that were broken out of the Sun. Later on, different scenarios came to light. One of them is known as the accretion hypothesis. According to this theory, billions of years ago, the region around the Solar System occupied by the planets was rich in dust and gas- raw materials for the formation of planets. When these coalesced, the planets were formed.
References
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