A conversation with a friend about NASA

The other day a very close friend and I were talking about re-entry for any manned mission entering the atmosphere. Anyone that reads my blog knows what my opinion is in regards to NASA. After having gone back and forth with my friend on the topic of the re-entry process of any object, manned or unmanned… I only have one question.

But, before I present my question, I want to point out that in the beginnings of NASA we are told that smashing into the atmosphere during re-entry can cause temperatures to rise above more than 5,000 degrees Fahrenheit (about 2,800 degrees Celsius). Not only does the exterior of the re-entry module reach above 5,000 degrees, but there are only a few inches of wall space between the exterior and interior of the cabin. Apparently NASA has developed a self consuming ablative heat shield that can withstand some pretty extreme temperatures (meaning that the heat experienced by the exterior of the object would not affect the temperature inside the object as it falls away from the craft).

But, don’t take my word for it… let’s ask NASA.

The initial conversation that I had with my friend was how I didn’t understand the mechanics of the heat shield they created and how it works so well. For example, in the above video the outside part is made of stainless steel. Stainless steel has a melting point of about 2,500 degrees Fahrenheit. Then, the honeycomb interior ablative heat shield in the video that is between the cabin and the stainless steel is nothing more than polymer fiberglass. Sadly enough, the melting point of this material also doesn’t even come close to being able to withstand 5,000 degrees (it has a melting point of about 2,200 degrees).

One other option that we are presented in the following video is pure silica-tiles (which again, sadly doesn’t have a melting point that reached 5,000 degrees). Although these tiles can withstand about 3,000 degrees, they were not used in the first video, but rather much later. Even still, that presents a problem.

The answer that finally clicked for me after having talked with my friend is the ceramic coating that was used. Apparently, NASA used a spray adhesive that was designed to melt away made of ceramic (which is pretty awesome considering the fact that it has a melting point of almost 6,900 degrees). If you spray enough of this stuff on and also consider the fact that re-entry time wasn’t anything more than a few minutes at most, this answer makes a lot of sense. However, the self consuming ablative heat shield in the first video was actually behind the stainless steel (notated throughout the entire first video with no mention of a ceramic outer layer). Again, the ablated material that was designed to dissipate upon re-entry in the first video was not on the outside of the stainless steel.  But, that is beside the point. Just for argument’s sake, let’s assume that the ceramic coating was applied in the first video. It very well could have been despite not being mentioned. Although I am still looking, the farthest back that I have been able to find this ceramic ablation in use by NASA only goes back as far as the early 1990’s.

This 1960’s document shows that re-entry exceeded the melting point of silica by more than 1,000 degrees. While this 1960’s document shows that the primary ablator  used during that time was 99.8% silica.

After having had this conversation with my friend and totally setting aside the conflicts that arise with re-entry (which was a lot of fun, because it made me evaluate and think, which is something I enjoy to do)… all it did was cause me to ask a new question.

Let’s assume that the stance my friend holds is the correct one.

With that, here is the question…

What happened to re-entry exceeding temperatures of 5,000 degrees Fahrenheit (about 2,800 degrees Celsius and above)?

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I guess they realized that such a temperature was a little too outlandish, so they dropped it down a bit. Who knows… it’s probably just me being ignorant. Good ol’ Nye or Tyson can probably solve it for us.

7ce

I am not claiming to have answers. I am presenting questions.

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2 thoughts on “A conversation with a friend about NASA

  1. First off, the re-entry heat of a max of 4,800 degrees listed in your link still places the heat experienced below what we are told from the 1960’s footage. If anything, this tells me that the Sci-Show don’t have their facts straight (which might make anyone want to evaluate giving them the time of day).

    Secondly, re-entry of any craft going 6.8 miles per second is exceeding speeds of 24,000 miles per hour. I would love to see a live test showing someone traveling that speed with zero atmospheric resistance then instantly be hit with a brick wall of resistance. Seems to me that the sudden shock of re-entry at that speed would create a deadly level of G-Force that exceeds 16 G. I haven’t actually done the math, but considering the fact that 9 G is considered deadly in some circumstances I find it hard to believe man could survive hitting the atmosphere at that speed. Let’s however assume that the Apollo 10 data is true, and they reached speeds of more than 24,000 miles per hour while crashing through the atmosphere. Considering this speed and the fact that they are no longer in orbit (gravity now playing a factor), please explain to me how they didn’t instantly hit the earth and die. The atmosphere is only about 150 miles high. And since they were traveling at 6.8 miles per second, they would have hit the earth in less than 17 seconds. But, for the heck of it, let’s assume they were quick witted enough to open up their shoot. Again, the instant jolt in an opposing direction at such speeds (assuming you have a shoot strong enough) would cause such high levels of G force that the persons inside the craft would be instantly killed.

    Final note: this article you sent was posted in 2006 with quotes like “still developing” and “plans for 2014“. As a result, this information in no way explains away the 1960’s claims of successful re-entry at those temperatures.

    So, with that… what did your link show me?

    Your link showed me that my official blog question was answered. The heat hasn’t actually changed. Instead, Sci-Show doesn’t have their facts straight. This still in no way negates the issues that are addressed in my blog post regarding the shielding techniques of the 1960’s against what is currently used today. If anything, you brought up another very valid point (smashing into the atmosphere at 24,000 miles an hour should be no problem at all, for the craft or its passengers while considering that there is only about 150 miles between them and ground zero).

    Furthermore, what are we doing spending trillions of taxpayer dollars between 2006 and 2014 to solve an issue that NASA seemed to have solved time and time again in the early 1960’s? They either already had it solved or they didn’t.

    But, I digress. Thanks for the input.
    I enjoyed the article.

    Space is fake.

    Like

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