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How Far Is It To The Edge Of The Universe?

Artist's logarithmic scale conception of the observable universe. Galaxies give way to large-scale... [+] structure and the hot, dense plasma of the Big Bang at the outskirts. This 'edge' is a boundary only in time.

If you were to go as far out into space as you can imagine, what would you encounter? Would there be a limit to how far you could go, or could you travel a limitless distance? Would you eventually return to your starting point, or would you continue to traverse space that you had never encountered before? In other words, does the Universe have an edge, and if so, where is it?

Believe it or not, there are actually three different ways to think about this question, and each one has a different answer. If you consider how far you could go if you:

    • left today in an arbitrarily powerful rocket,
    • considered everything that could ever contact us or be contacted by us from the start of the hot Big Bang,
    • or used your imagination alone to access the entire Universe, including beyond what will ever be observable,

You can figure out how far it is to the edge. In each case, the answer is fascinating.

We often visualize space as a 3D grid, even though this is a frame-dependent oversimplification when... [+] we consider the concept of spacetime. In reality, spacetime is curved by the presence of matter-and-energy, and distances are not fixed but rather can evolve as the Universe expands or contracts.

ReunMedia / Storyblocks

The key concept to keep in mind is that space isn’t how we normally conceive of it. Conventionally, we think about space as being like a coordinate system — a three-dimensional grid — where the shortest distance between two points is a straight line, and where distances don’t change over time.

But both of those assumptions, so thoroughly good in our everyday lives, fail spectacularly when we begin looking at the larger-scale Universe beyond our own planet. For starters, the idea that the shortest distance between two points is a straight line falls apart as soon as you start introducing masses and energetic quanta into your Universe. Because spacetime is subject to curvature, which the presence of matter and energy is the cause of, the shortest distance between two points is inherently dependent on the shape of the Universe between those points.

Instead of an empty, blank, three-dimensional grid, putting a mass down causes what would have been... [+] 'straight' lines to instead become curved by a specific amount. In General Relativity, we treat space and time as continuous, but all forms of energy, including but not limited to mass, contribute to spacetime curvature. If we were to replace Earth with a denser version, up to and including a singularity, the spacetime deformation shown here would be identical; only inside the Earth itself would a difference be notable.

Christopher Vitale of Networkologies and the Pratt Institute

In addition to that, the fabric of spacetime itself does not remain static over time. In a Universe filled with matter and energy, a static, unchanging Universe (where distances between points remain the same over time) is inherently unstable; the Universe must evolve by either expanding or contracting. If Einstein’s General theory of Relativity is correct, this is mandatory.

Observationally, the evidence that our Universe is expanding is overwhelming: a spectacular validation for Einstein’s predictions. But this carries with it a series of consequences for objects separated by cosmic distances, including that the distance between them expands over time. Today, the most distant objects we can see are more than 30 billion light-years away, despite the fact that only 13.8 billion years have passed since the Big Bang.

The farther a galaxy is, the faster it expands away from us and the more its light appears... [+] redshifted. A galaxy moving with the expanding Universe will be even a greater number of light years away, today, than the number of years (multiplied by the speed of light) that it took the light emitted from it to reach us. But we can only understand redshifts and blueshifts if we attribute them to a combination of motion (special relativistic) and the expanding fabric of space (general relativistic) contributions both.

Larry McNish of RASC Calgary Center

When we measure how distant a variety of objects are from their physical and luminous properties — along with the amount that their light has been shifted by the Universe’s expansion — we can come to understand what the Universe is made of. Our cosmic cocktail, at present, consists of:

  • 0.01% radiation in the form of photons,
  • 0.1% neutrinos, an elusive, low-mass particle almost as numerous as photons,
  • 4.9% normal matter, made mostly of the same stuff we are: protons, neutrons, and electrons,
  • 27% dark matter, an unknown substance that gravitates but neither emits nor absorbs light,
  • and 68% dark energy, which is the energy inherent to space that causes distant objects to accelerate in their recession from us.

When you combine these effects together, you get a unique and unambiguous prediction for how far it is, at all times past and present, to the edge of the observable Universe.

A graph of the size/scale of the observable Universe vs. the passage of cosmic time. This is... [+] displayed on a log-log scale, with a few major size/time milestones identified. Note the early radiation-dominated era, the recent matter-dominated era, and the current-and-future exponentially-expanding era.

E. Siegel

This is a big deal! Most people assume that if the Universe has been around for 13.8 billion years since the Big Bang, then the limit to how far we can see will be 13.8 billion light-years, but that’s not quite right.

Only if the Universe were static and not expanding would this be true, but the fact is this: the farther away we look, the faster distant objects appear to speed away from us. The rate of that expansion changes in a way that is predictable based on what’s in the Universe, and in turn, knowing what’s in the Universe and observing how fast objects expand tells us how far away they are. When we take all of the available data together, we arrive at a unique value for everything together, including the distance to the observable cosmic horizon: 46.1 billion light-years.

The observable Universe might be 46 billion light years in all directions from our point of view,... [+] but there's certainly more, unobservable Universe, perhaps even an infinite amount, just like ours beyond that. Over time, we'll be able to see more of it, eventually revealing approximately 2.3 times as many galaxies as we can presently view.

Frédéric MICHEL and Andrew Z. Colvin, annotated by E. Siegel

This boundary, however, is not an “edge” to the Universe in any conventional sense of the word. It is not a boundary in space at all; if we happened to be located at any other point in space, we would still be able to detect and observe everything around us within that 46.1 billion light-year sphere centered on us.

This is because that “edge” is a boundary in time, rather than in space. This edge represents the limit of what we can see because the speed of light — even in an expanding Universe governed by General Relativity — only allows signals to travel so far over the Universe’s 13.8 billion year history. This distance is farther than 13.8 billion light-years because of the Universe’s expansion, but it’s still finite. However, we cannot reach all of it.

The size of our visible Universe (yellow), along with the amount we can reach (magenta). If we... [+] accelerated at 9.8 m/s^2 for approximately 22.5 years and then turned around and decelerated for another 22.5 years, we could reach any galaxy within the magenta circle, even in a Universe with dark energy, but nothing outside of it.

E. Siegel, based on work by Wikimedia Commons users Azcolvin 429 and Frédéric MICHEL

Beyond a certain distance, we can see some of the light that was already emitted long ago, but will never see the light that is being emitted right now: 13.8 billion years after the Big Bang. Beyond a certain specific distance — calculated (by me) to be approximately 18 billion light-years away at present — even a signal moving at the speed of light will never reach us.

Similarly, that means that if we were in an arbitrarily high-powered rocket ship, all of the objects presently contained within this 18 billion light-year radius would be eventually reachable by us, even as the Universe continued to expand and these distances continued to increase. However, the objects beyond that would never be reachable. Even as we achieved greater and greater distances, they would recede faster than we could ever travel, preventing us from visiting them for all eternity. Already, 94% of all the galaxies in the observable Universe are beyond our eternal reach.

As vast as our observable Universe is and as much as we can see, it’s far more than we can ever... [+] reach, as only 6% of the volume that we can observe is presently reachable. Beyond what we can observe, however, there is certainly more Universe; what we can see represents only a tiny fraction of what must be out there.

NASA, ESA, R. Windhorst, S. Cohen, and M. Mechtley (ASU), R. O’Connell (UVa), P. McCarthy (Carnegie Obs), N. Hathi (UC Riverside), R. Ryan (UC Davis), & H. Yan (tOSU)

And yet, there is a different “edge” that we might want to consider: beyond the limits of what we can observe today, or even what we can potentially observe arbitrarily far into the future, if we run our theoretical clock towards infinity. We can consider how large the entire Universe is — the unobservable Universe — and whether it folds in on itself or not.

The way we can answer this is based on an extrapolation of what we observe when we try to measure the spatial curvature of the Universe: the amount that space is curved on the largest scale we can possibly observe. If the Universe is positively curved, parallel lines will converge and the three angles of a triangle will sum to more than 180 degrees. If the Universe is negatively curved, parallel lines will diverge and the three angles of a triangle will sum to less than 180 degrees. And if the Universe is flat, parallel lines will remain parallel, and all triangles will contain 180 degrees exactly.

The angles of a triangle add up to different amounts depending on the spatial curvature present. A... [+] positively curved (top), negatively curved (middle), or flat (bottom) Universe will have the internal angles of a triangle sum up to more, less, or exactly equal to 180 degrees, respectively.

NASA / WMAP science team

The way we do this is to take the most distant signals of all, such as the light that’s left over from the Big Bang, and examine in detail how the fluctuations are patterned. If the Universe is curved in either a positive or a negative direction, the fluctuation patterns that we observe will wind up distorted to appear on either larger or smaller angular scales, as opposed to a flat Universe.

When we take the best data available, which comes from both the cosmic microwave background’s fluctuations and the details of how galaxies cluster together on large scales at a variety of distances, we arrive at an inescapable conclusion: the Universe is indistinguishable from perfect spatial flatness. If it is curved, it’s at a level that’s no more than 0.4%, meaning that if the Universe is curved like a hypersphere, its radius is at least ~250 times larger than the part that’s observable to us.

The magnitudes of the hot and cold spots, as well as their scales, indicate the curvature of the... [+] Universe. To the best of our capabilities, we measure it to be perfectly flat. Baryon acoustic oscillations and the CMB, together, provide the best methods of constraining this, down to a combined precision of 0.4%.

Smoot Cosmology Group / LBL

If you define the edge of the Universe as the farthest object we could ever reach if we began our journey immediately, then our present limit is a mere distance of 18 billion light-years, encompassing just 6% of the volume of our observable Universe. If you define it as the limit of what we can observe a signal from — who we can see and who can see us — then the edge goes out to 46.1 billion light-years. But if you define it as the limits of the unobservable Universe, the only limit we have is that it’s at least 11,500 billion light-years in size, and it could be even larger.

This doesn’t necessarily mean that the Universe is infinite, though. It could be flat and still curve back on itself, with a donut-like shape known mathematically as a torus. As large and expansive as the observable Universe is, it’s still finite, with a finite amount of information to teach us. Beyond that, the ultimate cosmic truths still remain unknown to us.

In a hypertorus model of the Universe, motion in a straight line will return you to your original... [+] location, even in an uncurved (flat) spacetime. The Universe could also be closed and positively curved: like a hypersphere.

ESO and deviantART user InTheStarlightGarden

Follow me on Twitter. Check out my website or some of my other work here.

Ethan Siegel Ethan Siegel

I am a Ph.D. astrophysicist, author, and science communicator, who professes physics and astronomy at various colleges. I have won numerous awards for science writing since 2008 for my blog, Starts With A Bang, including the award for best science blog by the Institute of Physics. My two books, Treknology: The Science of Star Trek from Tricorders to Warp Drive, Beyond the Galaxy: How humanity looked beyond our Milky Way and discovered the entire Universe, are available for purchase at Amazon. Follow me on Twitter @startswithabang.

Source: How Far Is It To The Edge Of The Universe?

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Have Scientists Found Source Of Mysterious Hum?

It’s been blamed on everything from high-pressure gas lines to low-frequency earth tremors to submarine communications, but so far researchers have been unable to pinpoint the source of a loud, mysterious humming sound that people around the world have reported hearing.

Now science has an answer. Maybe.

Unofficially known as the Hum, the sound is a droning noise that has been heard from Southampton and Leeds in England to Bondi, Australia, and even Seattle, Wash. While people in a few regions have complained about the intermittent humming for decades, residents in other places have only recently reported hearing it. And for some, the din is unbearable.

LISTEN: The Hum heard in Terrace, British Columbia. (Story continues below.)

                                         

“It’s a kind of torture; sometimes, you just want to scream,” Leeds resident Katie Jacques told the BBC. “It’s hard to get off to sleep because I hear this throbbing sound in the background.”

The humming has also been driving residents of Southampton batty, prompting scientists there to search for a source, which has led to a new theory involving the male Midshipman fish that lets out a distinctive drone when searching for a mate, The Telegraph reported.

LISTEN: The “humming” sounds of male Midshipmen.

                                            

Yet despite widespread media coverage, there is scant evidence to back up the hypothesis. The reports appear to be based on comments made last week by Dr. Ben Wilson, a Scottish Association for Marine Science (SAMS) scientist who said only that it was possible that fish were causing the throbbing sound.

“It’s not beyond the realms of possibility,” Dr. Wilson said, according to local publication the Daily Echo. “There are certainly ‘sonic fish’ in the north Atlantic and the approaches to the English Channel.”

This theory is not without precedent. Researchers from the University of Washington’s Marine Biology program said last year that Midshipmen fish were to blame for Seattle’s humming problem. Scientists speculated that the calls of the fish in Washington State could be reverberating off of boat hulls and buildings.

But while researchers in Seattle had studied the possible link between the fish and humming, no such research has yet been conducted in England. A statement released by SAMS on Friday attempted to clarify the quotation:

Ben did suggest to the Daily Echo reporter how he might record the noises (by putting a microphone into a condom, sealing it and dropping into the water), but he hasn’t received an audio file yet. Perhaps someone would like to take up the task. Or perhaps a media organization would fly Ben and his equipment south to listen to the hum in situ. Fish might be then ruled in or out.

 

Source: Have Scientists Found Source Of Mysterious Hum?

Everyone Missed An Apollo 11 Mistake, And It Almost Killed The Astronauts Returning To Earth

Neil Armstrong and Buzz Aldrin raise the American Flag on the Moon, with the shadow of the Lunar Module (where the camera is mounted) seen in nearby. The astronauts might not have successfully returned to Earth, however, if the procedure used to jettison the fuel from the Service Module had let it come into contact with the Command Module. (NASA/ullstein bild via Getty Images)

Even from our perspective in 2019, 50 years later, humanity’s achievements from July, 1969, still mark the pinnacle of crewed spaceflight. For the first time in history, human beings successfully landed on the surface of another world. After a 380,000 km journey, the crew set foot on the Moon, walked upon it, installed scientific instruments, took samples, and then departed for Earth.

Three days after leaving the Moon, on July 24, 1969, they splashed down in Earth’s oceans, successfully completing their return trip. But during Apollo 11’s return to Earth, a serious anomaly occurred: one that went undetected until after the crew returned to Earth. Uncovered by Nancy Atkinson in her new book, Eight Years to the Moon, this anomaly could have led to a disastrous ending for astronauts Armstrong, Aldrin and Collins. Here’s the story you’ve never heard.

This NASA image was taken on July 16, 1969, and shows some of the thousands of people who camped out on beaches and roads adjacent to the Kennedy Space Center to watch the Apollo 11 mission Liftoff aboard the Saturn V rocket. Four days later, humanity would take our first footsteps on another world. Four days after that, the astronauts successfully returned to Earth, but that was not a foregone conclusion. (NASA / AFP / Getty Images)

This NASA image was taken on July 16, 1969, and shows some of the thousands of people who camped out on beaches and roads adjacent to the Kennedy Space Center to watch the Apollo 11 mission Liftoff aboard the Saturn V rocket. Four days later, humanity would take our first footsteps on another world. Four days after that, the astronauts successfully returned to Earth, but that was not a foregone conclusion. (NASA / AFP / Getty Images)

According to our records, the flight plan of Apollo 11 went off without a hitch. Chosen as the mission to fulfill then-President Kennedy’s goal of performing a crewed lunar landing and successful return to Earth, the timeline appeared to go exactly as planned.

  • On July 16, 1969, the Saturn V rocket responsible for propelling Apollo 11 to the Moon successfully launched from Cape Kennedy. (Modern-day Cape Canaveral.)
  • Only July 17, the first thrust maneuver using Apollo’s Service Propulsion System (SPS) was made, course-correcting for the journey to the Moon. The launch and this one corrective burn were so successful that the other three scheduled SPS maneuvers were not even needed.
  • Only July 19, Apollo 11 reached the Moon, flying behind it and entering lunar orbit after a series of thrust maneuvers from SPS.
  • On July 20, the Eagle (lunar module) undocked from the Columbia (command and service module), made a powered descent, and landed on the Moon’s surface.
Astronaut Edwin E. "Buzz" Aldrin Jr., Lunar Module Pilot, stands near a scientific experiment on the lunar surface. Humanity's first landing on the Moon occurred July 20, 1969, as the Lunar Module code-named "Eagle" touched down gently on the Sea of Tranquility on the east side of the Moon. The Lunar Module, completely intact before the ascent stage is launched, can be seen in full beside the planted American flag. (NASA/Newsmakers)

Astronaut Edwin E. “Buzz” Aldrin Jr., Lunar Module Pilot, stands near a scientific experiment on the lunar surface. Humanity’s first landing on the Moon occurred July 20, 1969, as the Lunar Module code-named “Eagle” touched down gently on the Sea of Tranquility on the east side of the Moon. The Lunar Module, completely intact before the ascent stage is launched, can be seen in full beside the planted American flag. (NASA/Newsmakers)

Getty

  • After 4 hours setting up, astronauts Armstrong and Aldrin left the lunar module to explore the lunar surface, performing an extra-vehicular activity (EVA) for a total of 2.5 hours, deploying scientific instruments, collecting samples for return, and famously planting an American flag.
  • On July 21, after just 21 hours and 36 minutes on the Moon, the ascent engine fired, bringing the Eagle back to dock with Columbia, and returning astronauts Aldrin and Armstrong to the Command and Service Module with astronaut Collins.
  • On July 21, the SPS thrusters fired, returning the Command and Service Module to Earth, with the lone mid-course correction coming on July 22.
  • And on July 24, re-entry procedures were initiated, returning the Apollo 11 crew to a safe splashdown in the Pacific Ocean.
This artist's concept shows the Command Module undergoing re-entry in 5000 °F heat. The Apollo Command/Service Module was used for the Apollo program which landed astronauts on the Moon between 1969 and 1972. An ablative heat shield on the outside of the Command Module protected the capsule from the heat of re-entry (from space into Earth's atmosphere), which is sufficient to melt most metals. During re-entry, the heat shield charred and melted away, absorbing and carrying away the intense heat in the process. (Heritage Space/Heritage Images/Getty Images)

This artist’s concept shows the Command Module undergoing re-entry in 5000 °F heat. The Apollo Command/Service Module was used for the Apollo program which landed astronauts on the Moon between 1969 and 1972. An ablative heat shield on the outside of the Command Module protected the capsule from the heat of re-entry (from space into Earth’s atmosphere), which is sufficient to melt most metals. During re-entry, the heat shield charred and melted away, absorbing and carrying away the intense heat in the process. (Heritage Space/Heritage Images/Getty Images)

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It all sounds so simple and straightforward, which obscures the real truth: for every one of these steps, there were hundreds (or more) potential points of failure that everyone involved needed to guard against. That final step alone, which returned the astronauts from their presence around to Moon — after journeying back to Earth — was one of the most crucial. If it failed, it would lead to certain death, similar to the demise of the Soviet cosmonaut Vladimir Komarov.

Successful re-entries after a journey to the Moon had already taken place aboard NASA’s Apollo 8 and Apollo 10 missions, and Apollo 11 was expected to follow the same procedures. At the danger of becoming complacent, this step, in many ways, already seemed like old hat to many of those staffing the Apollo 11 mission.

This schematic drawing shows the stages in the return from a lunar landing mission. The Lunar Module takes off from the Moon and docks with the Command and Service Module. The Command Module then separates from the Service Module, which jettisons its fuel and accelerates away. The Command Module then re-enters the Earth's atmosphere, before finally parachuting down to land in the ocean. (SSPL/Getty Images)

This schematic drawing shows the stages in the return from a lunar landing mission. The Lunar Module takes off from the Moon and docks with the Command and Service Module. The Command Module then separates from the Service Module, which jettisons its fuel and accelerates away. The Command Module then re-enters the Earth’s atmosphere, before finally parachuting down to land in the ocean. (SSPL/Getty Images)

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Re-entry, in principle, ought to be straightforward for the astronauts returning from the Moon. The Command and Service Modules first needed to separate, with the astronauts inside the Command Module and the Service Module being jettisoned. Once safely away, the Command Module would re-orient itself so that the heat shield was in the forward-facing position, prepared to absorb the brunt of the impact of re-entering Earth’s atmosphere while protecting the astronauts inside.

At the proper moment, when the atmospheric density was great enough and the external temperatures and speeds were low enough, the parachute would deploy, leading to a gentle splashdown in the Pacific Ocean approximately 5 minutes later, where the astronauts could then be safely recovered.

Although there are no known photographs of the Apollo 11 Command Module descending towards splashdown in the Pacific Ocean, all of the crewed Apollo missions ended in similar fashion: with the Command Module's heat shield protecting the astronauts during the early stages of re-entry, and a parachute deploying to slow the final stages of descent to a manageable speed. Shown here, Apollo 14 is about to splash down in the oceans, similar to the prior missions such as Apollo 11. (SSPL/Getty Images)

Although there are no known photographs of the Apollo 11 Command Module descending towards splashdown in the Pacific Ocean, all of the crewed Apollo missions ended in similar fashion: with the Command Module’s heat shield protecting the astronauts during the early stages of re-entry, and a parachute deploying to slow the final stages of descent to a manageable speed. Shown here, Apollo 14 is about to splash down in the oceans, similar to the prior missions such as Apollo 11. (SSPL/Getty Images)

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It sounds so routine. But of the innumerable things that could go wrong, one of them was entirely unexpected: the possibility that the Service Module, scheduled to break apart and safely burn up in Earth’s atmosphere, could accidentally have a piece of its debris collide with the Command Module, ruining re-entry and killing the returning astronauts on board.

The plan to avoid it was simple: the Service Module, post-separation, would perform a series of thrust maneuvers to take it safely away from the re-entry path of the Command Module. By shifting the Service Module to a significantly different trajectory, it wouldn’t even re-enter at the same time as the Command Module, but would skip off the atmosphere this time. The re-entry of the Service Module should have only come much later, after performing another orbit (or set of orbits) around Earth.

Both the Command Module and the Service Module from Apollo 11 followed the same re-entry trajectory, which could have proved fatal to the astronauts aboard the Command Module if a collision of any type had occurred. It was only through luck that such a catastrophe was avoided.

Both the Command Module and the Service Module from Apollo 11 followed the same re-entry trajectory, which could have proved fatal to the astronauts aboard the Command Module if a collision of any type had occurred. It was only through luck that such a catastrophe was avoided.

NASA

But that didn’t happen at all. To quote from Nancy Atkinson’s book, pilot Frank A. Brown, flying about 450 miles (725 km) away from the re-entry point, reported the following:

I see the two of them, one above the other. One is the Command Module; the other is the Service Module. . . . I see the trail behind them — what a spectacle! You can see the bits flying off. Notice that the top one is almost unchanged while the bottom one is shattering into pieces. That is the disintegrating Service Module.

Fortunately for everyone, none of the debris resulting from the Service Module’s re-entry impacted the Command Module, and the astronauts all arrived safely back on Earth.

The crew of Apollo 11 — Neil Armstrong, Michael Collins, and Buzz Aldrin — in the Mobile Quarantine Facility after returning from the surface of the Moon. The U.S.S. Hornet successfully recovered the astronauts from the Command Module after splashdown, where the crew was greeted by President Nixon, among others. (MPI/Getty Images)

The crew of Apollo 11 — Neil Armstrong, Michael Collins, and Buzz Aldrin — in the Mobile Quarantine Facility after returning from the surface of the Moon. The U.S.S. Hornet successfully recovered the astronauts from the Command Module after splashdown, where the crew was greeted by President Nixon, among others. (MPI/Getty Images)

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How could this have occurred?

There was a fault in how the Service Module was configured to jettison its remaining fuel: a problem that was later discovered to have occurred aboard the prior Apollo 8 and Apollo 10 missions as well. Instead of a series of thrusters firing to move the Service Module away from the Command Module, shifting it to a different trajectory and eliminating the possibility of a collision, the way the thrusters actually fired put the entire mission at risk.

The problem was that there were two types of thrusters on board the Service Module: the Minus X RCS jets and the RCS roll jets. And while the roll jets fired in bursts in an attempt to stabilize the Service Module, the Minus X jets fired continuously.

The Reaction Control System, visible towards the center-left of the image, consists of two types of thrusters that control both acceleration and orientation. With the original flaw, the thrusters fired in a pattern that put the Command Module at risk. Had those two modules collided, the astronauts on board would have had a failed re-entry, killing all three passengers.

The Reaction Control System, visible towards the center-left of the image, consists of two types of thrusters that control both acceleration and orientation. With the original flaw, the thrusters fired in a pattern that put the Command Module at risk. Had those two modules collided, the astronauts on board would have had a failed re-entry, killing all three passengers.

NASA

In the aftermath of Apollo 11, investigators determined that the proper procedure for avoiding contact would be to properly time the firing of both the roll jets and the Minus X jets, which would lead to a 0% probability of contact between the two spacecrafts. This might seem like an extremely small point — to have the Minus X jets cut out after a certain amount of time firing as well as the roll jets — but you must remember that the spacecraft is full of moving parts.

If, for example, the fuel were to slosh around after the Service Module and the Command Module separated, that could lead to a certain window of uncertainty in the resultant trajectory. Without implementing the correct procedure for firing the various jets implemented, the safe return of the Apollo 11 astronauts would have to come down to luck.

This NASA picture taken on April 17, 1970, shows the Service Module (codenamed "Odyssey") from the Apollo 13 mission. The Service Module was jettisoned from the Command Module early, and the damage is clearly visible on the right side. This was to be the third crewed Apollo mission to land on the Moon, but was aborted due to the onboard explosion. Thankfully, the flaw in the jettison controller had been fixed, and the Service Module posed no risk to the astronaut-carrying Command Module from Apollo 13 onwards. (AFP/Getty Images)

This NASA picture taken on April 17, 1970, shows the Service Module (codenamed “Odyssey”) from the Apollo 13 mission. The Service Module was jettisoned from the Command Module early, and the damage is clearly visible on the right side. This was to be the third crewed Apollo mission to land on the Moon, but was aborted due to the onboard explosion. Thankfully, the flaw in the jettison controller had been fixed, and the Service Module posed no risk to the astronaut-carrying Command Module from Apollo 13 onwards. (AFP/Getty Images)

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Fortunately for everyone, they did get lucky. During the technical debriefing in the aftermath of Apollo 11, the fly-by of the Service Module past the Command Module was noted by Buzz Aldrin, who also reported on the Service Module’s rotation, which was far in excess of the design parameters. Engineer Gary Johnson hand-drew schematics for rewiring the Apollo Service Module’s jettison controller, and the changes were made just after the next flight: Apollo 12.

Those first four crewed trips to the Moon — Apollo 8, 10, 11 and 12 — could have all ended in potential disaster. If the Service Module had collided with the Command Module, a re-entry disaster similar to Space Shuttle Columbia could have occurred just as the USA was taking the conclusive steps of the Space Race.

View of the Apollo 11 capsule floating on the water after splashing down upon its return to Earth on July 24, 1969. If the Command Module and the Service Module had collided or interacted in any sort of substantial, unplanned-for way, the return of the first moonwalkers could have been as disastrous as the Space Shuttle Columbia's final flight. (CBS Photo Archive/Getty Images)

View of the Apollo 11 capsule floating on the water after splashing down upon its return to Earth on July 24, 1969. If the Command Module and the Service Module had collided or interacted in any sort of substantial, unplanned-for way, the return of the first moonwalkers could have been as disastrous as the Space Shuttle Columbia’s final flight. (CBS Photo Archive/Getty Images)

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Atkinson’s book, Eight Years to the Moon, comes highly recommended by me if you’re interested in the behind-the-scenes details and rarely-told stories from the Apollo era. Inside, you’ll find many additional details about this event, including interview snippets with Gary Johnson himself.

If Armstrong and Aldrin — the first two moonwalkers — were to perish before returning to Earth, the United States already had a presidential address drafted for such a purpose. We may chalk it up to good fortune that the following words never needed to be spoken:

In their exploration, they stirred the people of the world to feel as one; in their sacrifice, they bind more tightly the brotherhood of man.

In ancient days, men looked at the stars and saw their heroes in the constellations. In modern times, we do much the same, but our heroes are epic men of flesh and blood.

Others will follow, and surely find their way home. Man’s search will not be denied. But these men were the first, and they will remain the foremost in our hearts.

Follow me on Twitter. Check out my website or some of my other work here.

Ethan Siegel Ethan Siegel Contributor

I am a Ph.D. astrophysicist, author, and science communicator, who professes physics and astronomy at various colleges.

 

Source: Everyone Missed An Apollo 11 Mistake, And It Almost Killed The Astronauts Returning To Earth

The Microseconds That Can Rule Out Relative Time! — Lucid Being

The Microseconds That Can Rule Out Relative Time! According to Albert Einstein’s Theory Of Special Relativity, your time and my time are different, subject to and conditional to the question of your speed of movement and my speed of movement. The speed in which we are moving toward each other or the speed in which […]

via The Microseconds That Can Rule Out Relative Time! — Lucid Being

5 Mysterious Things In Mars Caught On Camera By Nasa – Top 5s Finest

If you thought planet Earth was the only place where life existed, then you are quite mistaken. There’s life on Mars, though at a microbial level. Admittedly, there has been a lot of back and forth from NASA and some alien hunters on the truth of this. As the debate rages on, at Top 5’s finest, we show you 5 Mysterious Things In Mars Caught On Camera By Nasa! Lets begin!

1. Star Destroyer From Star Wars Conspiracy theorists really shocked earthlings on this one in 2015 when they ‘saw’ the Star Destroyer from Star Wars on Mars. Though NASA is usually silent on such matters in a way that adds speculation to the theory that they are covering up proof of an alien civilization, this one they had to respond. One of their scientists working on the Mars Curiosity Project, dispelled this when he stated that mars could support life, but only at a microbial level. I know…It’s a bummer for all those planning to move there. Scientists attribute this seeing of objects on Mars to a mind trick they call Pareidolia. Tell that to the alien hunters if you dare!

2. Barack Obama’s Face This one is quite funny…but must be included: Barack Obama’s head….Really? In 2005, UFO experts zoomed on a rock that appeared, in a strange way, to look like Obama’s head. The image was caught by NASA’S Spirit Rover which had been stuck on Mars, without signal, since 2009 and started being active in 2010. The rock from which the image was taken is believed to be part of a statue. Scott Waring of the UFO sightings blog says that it is a full statue, buried from the shoulders. Some cheeky alien hunter must have digitally altered the image and cleaned it up using a computer program and claimed to have found Obama’s face! Very naughty indeed.

3. The Classic “Face on Mars” If you don’t know it yet, the Face on Mars shocked the world in 1976. Its fame is evident by the television, movies and books that have been written about it. Unlike most photos taken from space and used by alien conspiracies, this one was not quickly dismissed. It was thought, by at least at the time, that the face on Mars could be a potential alien relic. NASA was quite quick to refute the assumptions stating that the illusion was created by shadows and a light. The public could hear none of it but held to the fact that it was an alien civilization. In 1998, more details were taken on the Face of Mars and it was confirmed to be just an optical illusion.

4. An Alien Skull (Perhaps Bigfoot) In the alien hunter’s world, this is called an alien skull. It is no ordinary alien skull but is one that looks like Bigfoot. All the speculation arose from the YouTube channel Paranormal Crucible where they wrote, “Strange artifact found by the rover, appears to resemble a large skull, obviously alien in nature…”The speculation is that it could be Bigfoot or a bizarre Martian creature. Who knows? Maybe we will find out in 20 years later from now.

5. “Marshenge” You must have guessed the source of this name by now! Does the Stonehenge from Wiltshire, England ring a bell? At this point, It must have crossed your mind that the Stonehenge from Britain was first built by aliens who were first living on Earth! Too late! The alien hunters had already proposed that. The experts don’t agree. Science shows that natural processes can cause rocks to form in circles. The author of UFO Investigations Manual agrees. He said that it was quite a huge leap of imagination to compare “Marshenge” with the likes of Stonehenge.

With the mystery that lies in Mars, there’s really no way of knowing what these really are. They could even be random stones cast by marsquakes- you know, the equivalent of earthquakes. Background Music: Kevin MacLeod ~ Seventh Seal : https://www.youtube.com/watch?v=-PqKa…

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