Posts Tagged ‘Speed’

How could Ilan Ramon’s Diary Survive the Fall from Space?

Payload specialist Ilan Ramon

A little while ago, the Israeli Museum in Jerusalem opened an exhibit featuring some of the torn, slightly burned pages of Col. Ilan Ramon‘s personal diary from the shuttle Columbia. Ramon was the payload specialist onboard STS-107 (the spaceshuttle “Columbia”) that disintegrated during re-entry from space, killing all 7 crewmembers onboard. The diary survived the re-entry and subsequent crash, and was found in a field next to Palestine, TX.

Ramon’s personal diary fell close to 37 miles (almost 60 km) through the extreme conditions of re-entry. Unlike its human owner, it has survived the process and is now being restored and presented to the public in the Israeli Museum in Jerusalem.

During the weeks and months after the Columbia disaster, pieces of the debris were still being collected from wide areas in Texas. small pieces of insulation that detached from the outer parts of the shuttle to pieces of the Astronauts’ space suits. In an article covering the subject on “Universe Today”, The Israeli Museum curator is quoted as saying that “There is no rational explanation for how it was recovered when most of the shuttle was not.” It is no wonder, then, that many are awe-struck at such an apparent miracle.

But is there, really, no rational explanation for the survival of the diary? None at all? I doubt that. And when I doubt, I check it out, which is exactly what I am about to do.

A thought (or two) about Hypotheses

The information about the Columbia disaster is available in many online and offline sources, but it is still very limited. We can guesstimate what happened to certain parts of the shuttle based on facts on the ground and what we already know from previous manned missions to space using the Columbia shuttle.

The general investigation I am about to embark on in this post is based on the material I have found online and my own personal knowledge, strengthened by facts from other missions and physical concepts. It is by no means complete, and I had no time (or resources, sadly) to do a full blown investigation into the full train of events that Col. Ramon’s diary went through. If you have any thoughts on the matter, or if you hold any factual data that will help hypothesize what it “went through” in the moments before hitting the ground, please share them in the comment section. I am very much willing to update and upgrade this hypothesis in light of new information or ideas (just make sure you base those on valid data, of course).

I try to support my guesstimates with valid data when I can, and use ‘extremes’ to get us a rough idea of how this discovery (and this ‘survival’ of such an item) is possible.

The Space Shuttle – Crew Quarters

The space shuttle is built to sustain its crew for days (and sometimes weeks) in space. It has sleeping bunks, restroom and shower, all located in the crew area in the “Mid Deck” (picture is taken from Space Shuttle News Reference (NASA), p 5-5):

According to ex-astronaut R. Mike Mullane, the mid deck also holds the crew personal lockers (“Do Your Ears Pop in Space”, R.  Mike Mullane, pg 135). We will remember this fact when we consider the process in which the Columbia disintegrated (keep reading).

Where was the Diary Located?

No one can know for sure (at least not from the published data that I’ve read) where the diary was located before the Columbia’s disastrous descent. However, there are a few facts we can be sure of:

  • The crew was about to come home; their personal items were, most likely, locked away in their personal lockers, that are located in the Mid Deck.
  • According to astronauts who were active in previous missions, a diary is sometimes put in the lower pocket of the flight suit. If the diary wasn’t locked away in Ramon’s personal locker, it is logical it was safely tucked into his flight suit pocket.  Flight suits are very durable and tolerate extreme heat and cold conditions.

Either way, it seems logical to assume that the diary was placed somewhere that kept it safe from the initial processes of re-entry and descent.

Temperature Variation

Unlike common belief, the intense heat on the wings and body of a space shuttle as it descends from Space is not caused by friction, but rather by ‘compression’. The big body of the shuttle compresses air molecules downwards so strongly that the air around the shuttle becomes dense and packed like plasma. At this point, the wing-edge temperature naturally rise, and can reach a temperature of about 1,400° Celcius (2,500° Fahrenheit).

After the initial temperature rises, the Columbia initiated a roll to the right, a maneuver that decreases its speed and the heat on its body. This maneuver was successfully performed, and following it were 10 minutes where the heat on the body of the shuttle reached its peak. From there, it started to cool down.

The temperature at these heights is extremely low, and the heat from the shuttle can dissipate relatively quickly.

Explosion vs. Disintegration

About 15 minutes after the Columbia entered the Earth’s atmosphere, pieces of debris were visibly shedding out of its body. But the Columbia did not explode, it disintegrated, and this difference is very important to understand what happened to the parts inside the shuttle.

Explosion and Disintegration are two very different processes.

Explosion is quick and “dirty”, resulting in a lot of damage to the individual parts. Disintegration is the breaking apart of the whole into individual, smaller, parts. It is usually slower, and gradual. The Columbia’s disintegration began about 10 minutes after re-entry and lasted until the massive body crashed on the surface. The various parts and debris were scattered over an enormous area, from eastern Texas to Western Louisiana.

The fact that the Columbia disintegrated, rather than exploded, has two main meanings for our investigation:

  1. The Columbia did not ‘explode’ all at once; it took time for the various parts to separate away from the main body while the shuttle was cooling down in descent.
  2. In an explosion, the parts heat up due to the exerted energy. When a body disintegrates, the parts separate away from the body without experiencing any sort of extra heat. If a piece was deep inside the shuttle, it wasn’t subjected for the intense heat from the plasma (during re entry). It would take it longer to be thrown-away and out of the body of the shuttle. It would, therefore, “spend” less time free-falling.

The objects inside the Columbia slowly broke apart and began a gradual free-fall to the ground, from varying heights, the largest of which is approximately 60 km above the surface of the Earth.

Disintegration = Change in Shape

The shuttle is designed and built for aerodynamic movement. From the nose, to the wings and tail, the purpose is to make sure its movement in the air is smooth and with as little drag as possible. This is meant to decrease drag and allow the pilot better control over the movement of the shuttle once it’s back inside the atmosphere.

Aerodynamic objects move very quickly through the air because of their shape. But Columbia began disintegrating about 40 minutes after initiating the ‘de-orbiting’ maneuver. Parts tore off its body, probably starting with the wings and tail (that ‘stick out’ of the body and are subjected to more heat and pressures). Once those pieces – and pieces of the outer hull – tore off, the Columbia lost its aerodynamic shape. From this point on, it will slow down dramatically.

Terminal Velocity of an Object

In reality, when an object falls from a certain height down to the ground, its velocity increases because of the pull of gravity. Air resistance, however, exerts a force upwards – “fighting” the downward acceleration. When both forces are equal, they both negate one another, and the object falls in a constant speed (without the effect of any acceleration). That speed is called ‘terminal velocity‘.

For example, a sky diver falling from 12,000 feet would stop accelerating (hence, would move at a constant speed) at about 200 kph (124 mph). If his parachute didn’t open, he would hit the ground at the same force that a motorcyclist going at 200kph would hit a cement wall in case of a head-on collision (don’t try this at home). The height, in the case of the speeding diary, is not a very good indicator as to the force it hit the ground with.

Terminal Velocity and the Falling Diary

Assuming the diary was protected during the initial stages of the disastrous descent (as I’ve already explained), it shouldn’t have fallen as fast as it may sound like. When we hear the height “60 km above ground”, it sounds as if the falling object would hit the ground at enormous speed (and force). That, however, isn’t the case, because of the terminal velocity.

It is very much possible that the diary was packed or partially protected during parts of the fall, stopped accelerating at the terminal velocity. The pieces continued to disintegrate as they fell, and at some point whatever ‘protected’ the diary disintegrated and exposed it to the full force of the fall. But by that time the conditions that existed at the beginning of the fall were considerably lessened.

Conclusion

  • Based on past missions and the structure of the Space Shuttle, we can safely assume the diary was encapsulated inside an item that protected it, either a closed locker or a sealed space suit pocket.
  • Air resistance (and the laws of physics) makes the speed of falling objects limited.
  • The diary was found in a damp field covered with soft leafs (provided a relatively soft landing).
  • Other pieces of debris survived the long extreme fall to Earth (see next section).

Based on all the above, it is a bit easier to see a logical trail of events that could lead to the survival of a paper diary. This isn’t a miracle; it’s a surviving piece of history in light of a horrible, disastrous space mission.

A bit of Realism (Other objects made it, too..)

So we’ve examined the situation, and saw that it’s not as unlikely as we might have first thought for such an item to survive the Columbia disaster. A lot of other debris have survived, including ‘sensitive’ materials such as CPU boards and pieces of cloth from the astronauts’ uniforms and rest area. But we also need to take into account the condition in which the diary was found.

According to the State of Israel Ministry of Public Security, which was responsible for the reconstruction and preservation of these pages, the diary was very hard to decipher. It was found wet, torn and crumpled in a muddy field (see picture). The efforts involved a lot of digitized reconstruction along with some measure of guesswork. Some of the text on the pages was simply incomprehensible.

That said, it is also important to remember that this is not the most “surprising” piece of debris that “survived” re-entry. If you want surprise, it is reported that a few worms survived re-entry and the fall to Earth. Yes, alive. A piece of crumpled, wet, torn paper, as emotional and touching as it may be (and I agree that it is), is hardly any competition to life forms surviving the fall to Earth.

This is no miracle.

Many thanks to Capn_Refsmmat for (again!) being the brevity King, and for asking questions that needed to be answered.

References and Resources

Related articles

Olympic Controversy: How does the “Space-Age Swimsuit” Work?

The Olympics Games are here (well, in Beijing) and everyone’s watching and trying to guess who will win a medal. But, apparently, even the Olympics is a source of scientific inquiry, and not just for geeks. The “Speedo” controversy raises some interesting points about the effect of a swimsuit on the swimmer, and the effect of physics in general as a consideration for the athletes. As we all know, specifically if you’ve been reading the other posts on this site, physics is everywhere, and it’s time we start making sense of it.

Many sites out there reiterate the controversy, but few actually explain what and why it is. In other words: What, really, is the effect of a swimsuit on a swimmer? Why would it give an “unfair advantage”? Can a “Space-Age” swimsuit help Michael Phelps reach his 8-medal dream?

Speedo LZR Racer Swimsuit Official Webpage

Speedo LZR Racer Swimsuit Official Webpage

Since this subject raises some controversy and doubt, I decided I should check it out. I went to Speedo’s official website and read through all their specifications for the Speedo LZR RACER swimsuit (the source of the controversy, and the one Michael Phelps is wearing) and examined each feature.

But First: Physics in a Nutshell

When looking at moving objects (like balls, or planes, or rockets, or swimmers), there are forces at work. The swimmer exerts force forward and spends energy “fighting” whatever other forces that might be applied in the opposite way.

In physics, in order to predict the speed or acceleration of a certain object, we can draw a rough schematic of the known forces that apply on the object. The sum of all the forces (forward, backward, up, down, diagonal, etc) is the final force.

For more on what a Force is, click here.

About Friction and Drag

In general, every moving object (unless it is in a vacuum, which is very hard to achieve) is affected by friction. The amount of friction depends on the material that the movement is performed on. Ice has a relatively low friction, while cement has a relatively high friction.

Drag is very similar to friction; it is a mechanical force (see above figure) that is exerted on a solid object moving through liquid. The interaction between the moving object and the liquid that it moves through creates a “backwards” force that slows that object down. That force is drag.

Drag depends on the shape of the object and its aerodynamic form. Bulky objects will “suffer” more drag and will be slowed down quicker. Slick objects will have less drag.

That’s why the dog (furry and bulky) can’t swim as fast as the shark (slick and aerodynamic). Poor, poor dog.

The Speedo LZR RACER’s Features, Explained

LZR Pulse:

The official website claims that the suit is made of “ultra lightweight, powerful and water-repellent” material, and that it reduces “muscle oscillation and skin vibration”, which in turn leads to “low skin friction drag”.

The LZR Pulse swimsuit claims to shape the swimmer’s body, forcing his (or her) muscles and skin into a bullet-shape aerodynamic structure that reduces the drag – and allows the swimmer to move faster while expending less energy.

The water-repellent feature of the swimsuit essentially causes it to have less interaction with the water. Since drag is caused by the interaction of the swimmer and the water, this feature will reduce the drag (and friction) even more.

Finally, as you could see in the video (embedded at the end of this post, produced by Speedo), the swimmers’ muscles oscillate — move back and forth quickly — while water is flowing at them.

This muscle-oscillation causes the muscles to change shape, which causes the aurodynamic property of the swimmer’s body to change also. In order to maintain the ideal aerodynamic shape, the swimsuit holds the muscles tightly and produces a slick, stable surface that reduces surface tension, increases the velocity of the water flow next to the body, and eases the movement of the swimmer.

LZR Panels

Speedo’s official website claims that the swimsuit has “ultra thin, ultra powerful, ultra low drag” panels that are embedded “at strategic points on the swimmer’s body”, which are meant to “deliver optimum streamlined shape and drag reduction”.

The Shape is one of the most important factors in drag reduction and the creation of an aerodynamic structure. As we said before, bulky objects are subjected to more drag (and more friction), and streamlined objects (like the shark) are subjected to less drag.

The main reason for this is the flows that are created from the movement of the object inside the liquid. Something very similar happens within winds (in case of a plane) or water (in case of Michael Phelps). The liquid flows either slow the swimmer down or make him (or her!) move more easily.

Aerodymanic flows on an airplane wing. Source: http://www.classicairshows.com/

Aerodymanic flows on an airplane wing. Source: http://www.classicairshows.com/

The above depends on the shape, and that’s what the suit claims to produce: A better aerodynamic shape for the swimmer’s body, depending on key areas that might usually produce more of a problem for such structure.

Core Stabilizer

The “internal Core Stabilizer” is, according to Speedo, like a corset; it “helps [the swimmers] maintain the best body position in the water for longer”.

The human body is not exactly aerodynamic in nature, and part of a swimmer’s training is to learn how to hold himself in the water so his body takes the best aerodynamic shape possible. Maintaining this position – specifically in the water – also takes energy from the swimmer. If, indeed, the swimsuit “holds the swimmer in a corset-like grip”, it can assist him (or her) in the effort to hold their bodies in the proper position, and help them spend that energy on gaining speed instead.

Bonded Seams

The LZR Racer claims to be the “first fully bonded swimsuit.” The problem with seams, usually, is that they have stitches. Stitches are adding mass and weight to the fabric (not only the string itself, but also the fact that stitches require folding the fabric, hence increasing the amount of fabric in that location), and they are also bulkier. Eliminating the stitches will make the suit lighter and without unnecessary ‘bulks’, thereby improving the aerodynamics.

Speedo claims that the LZR Racer has “Ultrasonic welded” seams. The seams are not ‘sewn’ but welded, which means that no string is used, and no folds are needed. Ultrasonic welding is a technique that uses high-frequency vibrations on a material under pressure to seamlessly bond two pieces together. The main feature of such technique is that no soldering material or any sort of glue is needed – hence no extra weight, folds or bulks are produced and the suit remains seamless and homogenous.

Ultra Low Profile Zip

This is nothing new; the zipper is “bonded into the suit”, which is common in all swimming suits to make sure that the bulky shape of a zipper doesn’t stand out of the overall shape of the swimmer’s body, and interrupts the water flows.

Unique 3D Three Piece Pattern

The claim on this feature is that the suit is “Dynamically engineered to optimise the shape of the swimmer” (all ye Americans – they mean ‘optimize’). This seems to be mostly a sales pitch; it’s not much different that their “Unique Core Stabiliser” (again, the British spelling).

Summary

Additional Side Note: In order to claim that the suit makes the records rather than the swimmer, or that there is a truly ‘unfair advantage’ for the swimmers who wear this suit, it’s not enough to just see the claims Speedo is making. What needs to be done is have Michael Phelps try out his world-record-breaking with this suit, and with a different suit; if there is an overwhelming difference in the results, perhaps there’s a cause for complaint from other swimmers. Seeing, however, the amount of records (and the overall achievements) in Michael Phelps’ athletic history, claiming that it’s the suit that makes the record might be doing some serious injustice to this obviously-talented swimmer.

All in all, the Speedo RZR Racer swimsuit looks absolutely beautiful, and its claims do fit with reality and physics. As to whether or not it is giving the swimmer an “unfair advantage”, I can’t judge, since I haven’t compared it to any other – perhaps similar – swimsuit in the market.

What I can say quite confidently, however, is that regardless of its features, the person wearing the suit needs to know what he (or she!) is doing. In other words, I could wear this suit ’till my face turns blue (which will probably happen pretty fast, judging from the ‘corset-like grip’) and I’d still never have gotten anywhere close to Michael Phelps’ (or any of the other Olympic swimmers) speed.

That said, I can also summarize this analysis by concluding quite confidently that this suit is, most definitely, better than the one originally worn by Olympic swimmers. They, by the way, used to swim nude.

YouTube Promotional Video

[youtube:http://www.youtube.com/watch?v=dvMdqvO3R9g]

Extra Resources:

Duckies and the Doppler Effect

You probably hear this every day, that weird phenomenon sounds makes when it whooshes you by quickly. In fact, the entire ‘whoosh’ effect – that ‘zzzzzzzzzzzhoooooooom!’ that seems all children are familiar with and use as a description for a passing car is a great hint that something is going on.

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We’re SmarterThanThat

The scientific method is all around you, and you use it without even noticing. Science can be fun, interesting and engaging; you don't have to be a nerd to enjoy understanding the world around you. Read More...

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