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NASA Will Land InSight on Mars With Cunning -- and Lots of Cork (wired.com)

On Monday, November 26th, NASA will attempt to land the InSight spacecraft on Elysium Planitia, a vast plain just north of the Martian equator. If NASA is successful, InSight (short for Interior Exploration using Seismic Investigations, Geodesy, and Heat Transport) will be the first mission to investigate Mars' deep interior with thermal probes and seismometry, an approach scientists think will address questions about the red planet's formation and composition. But first, the spacecraft must land. From a report: Getting to Mars is hard, but NASA engineers consider entry, descent, and landing -- the seven-minute period in which mission planners are helpless to intervene, due to the tremendous distance between Mars and Earth -- the riskiest sequence in the entire mission. Here's how NASA plans to pull it off.

For InSight, the action will begin Monday, November 26th at around 11:47 am PT (2:47 pm ET). That's when the lander is slated to hit the top of Mars' atmosphere, at an altitude roughly 43 miles above the planet's surface. On contact, the spacecraft will be blazing along at a not-so-cool 5500 meters per second. That's 12,300 miles per hour. At those speeds, the primary concern for NASA's engineers is friction. Mars' atmosphere, which is roughly 100 times thinner than Earth's, plays a vitally important role in InSight's arrival: Bleeding the spacecraft of its kinetic energy. Yet the atmosphere poses a significant threat, as well. The resistance it exerts on InSight's heat shield, a 419-pound enclosure composed primarily of crushed cork, will drive the temperature of the protective barrier to temperatures greater than 2,700 degrees Fahrenheit -- hot enough to melt steel.

70 comments

  1. Re: More fake space missions from NASA by Anonymous Coward · · Score: 0

    Well, maybe not, but we will certainly probe Uranus!

  2. We should cancel NASA's budget... by Grog6 · · Score: 0

    And give it all to SpaceX.

    They are actually accomplishing something, besides cost overruns.

    We made heat shields that did a much harder job in the 60's, bringing Astronauts home; this is something harder?

    LOL.

    The SLS is overbudget, behind schedule, and will need Billions of dollars to finish.

    What has NASA done since the 60's?

    Fucked up the concept of a Reusable Space Plane to the point we lost Two Sets of Astronauts for Trivial reasons, and are riding to the Space Station with Russia, maybe?

    It should be disbanded, and restarted by new people.

    --
    Truth isn't Truth - Guliani
    1. Re:We should cancel NASA's budget... by Anonymous Coward · · Score: 4, Interesting

      And give it all to SpaceX.

      Which is funded by NASA.

      Slashdot commenters seem to forget that the entire reason SpaceX didn't go bankrupt after the third failure of the Falcon-1 is that NASA believed in them and stepped in to fund them to design and build the Falcon-9, at a time when nobody else in the world saw anything in them other than a fringe company that tried to make a rocket and failed.

      If you're asking what NASA has accomplished since the 60s: well, this is one thing.

      Without NASA there would be no SpaceX.

    2. Re:We should cancel NASA's budget... by DontBeAMoran · · Score: 1

      It should be disbanded, and restarted by new people.

      Give the contract to Hollywood, they have decades of experience with reboots. Coming in 2021: NEONASA.

      --
      #DeleteFacebook
    3. Re:We should cancel NASA's budget... by Ol+Olsoc · · Score: 1

      And give it all to SpaceX.

      They are actually accomplishing something, besides cost overruns.

      We made heat shields that did a much harder job in the 60's, bringing Astronauts home; this is something harder?

      How's your Chemtrail research coming along?

      --
      The shepherds did so well protecting the flock that the sheep no longer believed that wolves existed.
    4. Re:We should cancel NASA's budget... by andydread · · Score: 5, Interesting

      We made heat shields that did a much harder job in the 60's, bringing Astronauts home; this is something harder?

      If you understand the process of EDL on Mars then yes. It's much harder to land spacecraft on Mars than on Earth. It would be better if Mars did not have an atmosphere. The problem is that Mars has just enough atmosphere to where you have to deal with it during EDL. This means you need a good heat shield that problem is basically solved like you said. Because the atmosphere on Mars is so thin it's difficult to slow down the spacecraft unlike on Earth. This requires some atmospheric gymnastic for the spacecraft to perform during EDL in order to slow the aircraft down in the atmosphere of Mars down to ~1000Mph in which case a supersonic parachute is deployed. As you can imagine deploying a parachute that has to be extremely light yet handle 8000+ pounds of load at 1000Mph is no small task. However given that Mars atmosphere is so thin the parachute alone will only slow the load down to 200 Mph. What do you do then?? Well retro rockets have to kick in and slow the craft down to landing speed but it's not that simple, you have can't land the load with retro rockets because the massive amount of dust will be all over the newly delivered load. So you need to use retro rockets in a sky-crane configuration attached to the sky-crane that will lower the load down to the surface from the sky-crane then detach the sky-crane and fly it away so the landing site is not disturbed. And you have to do this with a very delicate science laboratory on wheels and get it there on one piece with out any shock damage what-so-ever.

      See here for more information

    5. Re:We should cancel NASA's budget... by Anonymous Coward · · Score: 0

      > give it all to SpaceX. They are actually accomplishing something, besides cost overruns.

      Bullshit. SpaceX accomplishes NO scientific missions, NASA does.

      And why would you want to give taxpayer's money to a commercial enterprise (that is by definition supposed to be financially self-sufficient)? And then also restart NASA... so how would that new NASA be financed?
      My advice to you: inform yourself and think it through as to avoid spouting nonsense and embarrassing yourself.

    6. Re:We should cancel NASA's budget... by Anonymous Coward · · Score: 2, Informative

      It appears they're not using a sky crane for this landing.
      https://www.youtube.com/watch?v=C0lwFLPiZEE

    7. Re:We should cancel NASA's budget... by Anonymous Coward · · Score: 0

      Thank you for the informative article.

    8. Re:We should cancel NASA's budget... by Anonymous Coward · · Score: 0

      They are doing science every single day, and applying it (engineering), to turn around and do it all again. They're spending enormous sums to advance the state of human knowledge and capability and providing commercial services on top of it. Elon Musk has stated many times that he has goals beyond being SpacefedeX, and those goals aren't magically achieved without the use of scientific experiment.

      Not science, my ass.

    9. Re: We should cancel NASA's budget... by Anonymous Coward · · Score: 0

      NASA gives most of that tax payer money to external entities that actually make the stuff or run the projects on behalf of NASA. Most of those entities do still seem to be "mission first". A few (Boeing, Lockheed Martin) seem to be more into the "maximize executive bonuses" first with regards to especially their government services (defense, NASA...), cost-plus and sole source contracts, etc.

      Cynical view? Certainly a jaded one now.

    10. Re:We should cancel NASA's budget... by serviscope_minor · · Score: 1

      They are actually accomplishing something, besides cost overruns.

      I guess I imagined all those rovers that NASA successfully landed on Mars.

      What has NASA done since the 60's?

      You mean apart from Hubble, many mars rovers, Dawn, Kepler, the X43, and a bunch of other stuff?

      Fucked up the concept of a Reusable Space Plane

      Firstly, space is hard. Secondly, the shuttle had one of the best safety records of all rockets. If you look at the number of passengers lost versus the number carried it did very well.

      --
      SJW n. One who posts facts.
    11. Re:We should cancel NASA's budget... by drsquare · · Score: 1

      SpaceX is expecting to bleed off 99% of energy by atmospheric braking with its Mars rocket. It might be thin but it can still be useful.

    12. Re:We should cancel NASA's budget... by DanDD · · Score: 1

      NASA didn't want SLS, Congress did.

      After the disaster that was the Lockheed X-33, NASA crafted a competition between private companies to launch cargo to the ISS. SpaceX and Orbital (now Northrop) won.

      NASA basically funded and fueled the development of SpaceX.

      So instead of venting at NASA, turn your anger and frustration to Congress.

      --
      "Every time I see an adult on a bicycle, I no longer despair for the future of the human race." - H. G. Wells
    13. Re:We should cancel NASA's budget... by mentil · · Score: 1

      Couldn't the payload land with a fairing that's only deployed once the dust settles? Et voila, no dust on the payload. You could probably even use a soft fairing (e.g. vinyl bag) that unzips or whatever, if you need to save on weight..

      --
      Corruption is convincing someone that the selfless ideal is the same as their selfish ideal.
    14. Re:We should cancel NASA's budget... by andydread · · Score: 1

      Couldn't the payload land with a fairing that's only deployed once the dust settles? Et voila, no dust on the payload. You could probably even use a soft fairing (e.g. vinyl bag) that unzips or whatever, if you need to save on weight..

      Actually the Mars Pathfinder(MER) rover mission EDL sequence is basically what you described. see here for the video animation with explanation it's quite informative.

      For comparison here is the video with explanation of the Mars Curiosity(MSL) EDL sequence.
      Here is the full animation complete with cruise stage without narration or explanations.

      Also notice in the MER video how they still keep the retro rockets away from the landing site.

  3. Mars EDL is hard. by Anonymous Coward · · Score: 5, Informative

    Thus far, NASA is the only organization to have much luck with Mars EDL.

    There were a series of Soviet probes in the 1960's and 70's, but the only one to live on the surface was Mars 3, and then only for 20 seconds before it stopped. They also had two probes in the late 1980's, Phobos 1 and 2, but both quit before successfully landing on Phobos. Also their Phobos-Grunt mission in 2011 failed. They did have some luck with flyby missions however.

    Likewise Europe's Beagle 2 lander was never heard from again after it touched down on Mars. However the orbiter portion of the mission worked. Europe's 2016 Schiaparelli lander attempt also failed before touchdown and was never heard from again.

    NASA had the first full lander success (beyond a few seconds of operation) with Viking 1 and 2 in 1975. Since then they've had a few failures such as the Mars Climate Observer and Mars Polar Lander, but many successes too, even including rovers. NASA seems to be the only space exploration organization adept at landing probes on Mars and making them work. That's no guarantee however, and there are many, many things that can go wrong, some of them unpredictable.

    Mars EDL is hard.

    1. Re:Mars EDL is hard. by Anonymous Coward · · Score: 4, Informative

      The term "EDL" is not said anywhere but your own comment, so it would help if you defined what "EDL" meant at the beginning of your text or even write the long non-acronym version in your comment title. Otherwise everyone who's not a space enthusiast has to look up the acronym to know what it means.

      E.D.L. = Entry, Descent, and Landing.

  4. Re: Mars? by Anonymous Coward · · Score: 0

    The risk is too high. You can success 10 times and still fail at 11th time.
    Also. The space exploration haven't evolved too much since human stepped on moon, unlike the space race era.

  5. Re: More fake space missions from NASA by mermeid007 · · Score: 1

    Oh look. A Mars mission with an excellent chance of success, well-planned, by NASA. Whoda thunk it? Detractors will of course point at any detail gone wrong because they don't want NASA to succeed. smh.

  6. Re: More fake space missions from NASA by Anonymous Coward · · Score: 0

    So, is earth also flat or you are not that stupid.

  7. Re:Mars? by Geoffrey.landis · · Score: 5, Insightful

    Wow, didn't we already landed there like 20 years ago first time?

    Viking, 1976: 42 years ago.

    Should be easy with current tech?

    Easier, perhaps. But not easy.

    NASA's been successful with Mars landings since the loss of Polar lander, and that was 20 years ago. But Mars landings are not easy. For the entire planet Earth, the success rate for missions to orbit or land on Mars is 50% successful, 50% not; with the most recent failure the ESA Schiaparelli EDM lander. So, don't take Mars landings for granted.

    Or it was all massive BS and a lot of Photoshop?

    You know, that isn't really funny, because millions of people actually believe that shit. There really doesn't seem to be any possible satire conspiracy theory so extreme that people don't believe it.

    --
    http://www.geoffreylandis.com
  8. video by necro81 · · Score: 5, Informative

    Lockheed Martin has produced an animation of the entry descent and landing. Go ahead and watch it, once, then forget about it. It unfortunately is not nearly as informative as, say, the 7 Minutes of Terror video from Curiosity, or the whimsical bounce landing from Spirit and Opportunity.

    1. Re:video by necro81 · · Score: 3, Interesting

      It took some more searching, but here's an InSight EDL video from JPL

    2. Re:video by schweini · · Score: 1

      Nothing will ever beat the sheer crazyness of the Curiosity landing - I know that very smart engineers came up with that procedure as the optimal way to land the thing .... but it just seems so much like something some 5 year old came up with in a fever dream. So awesome!

    3. Re:video by wonkey_monkey · · Score: 1

      How did they even test it? It is pretty astonishing. I mean, just look at how many tries it took SpaceX to get booster landing right.

      --
      systemd is Roko's Basilisk.
    4. Re:video by Anonymous Coward · · Score: 0

      "I will" this, "I will" that. I don't get why NASA insists on pretending these things are intelligent and like giving them their own fake Twitter account.

  9. Re:More fake space missions from NASA by Geoffrey.landis · · Score: 1

    I assume that the AC here thinks that he is being witty.

    tens of millions of people believe this, though.

    --
    http://www.geoffreylandis.com
  10. Just wait a few years by Anonymous Coward · · Score: 0

    If this doesn't work it isn't a big deal. They just have to wait a few more years and SpaceX can send somebody to walk over and place a seismograph on Mars by hand.

  11. Reentry Heating Not Primarily Due to Friction by Anonymous Coward · · Score: 2, Informative

    Reentry heating is primarily caused by rapid compression of the air caused by the speeding vehicle. A bottle of aerosol gets cold when its contents are released and decompressed. Well, the reverse process of compression causes heat to be emitted. And that's what causes most of the heating during reentry, not friction.

    https://en.wikipedia.org/wiki/Atmospheric_entry

    1. Re:Reentry Heating Not Primarily Due to Friction by DontBeAMoran · · Score: 1

      That's an excellent idea. The next landing probe will be equipped with two dozens bottles of aerosol.

      Thank you, Anonymous Coward.

      Signed,
      NASA.

      --
      #DeleteFacebook
    2. Re: Reentry Heating Not Primarily Due to Friction by Anonymous Coward · · Score: 2, Interesting

      Actually, an ablative heat shield cools itself by the evaporation of the heat shield material.

    3. Re:Reentry Heating Not Primarily Due to Friction by religionofpeas · · Score: 1

      bottle of aerosol gets cold when its contents are released and decompressed

      and the phase change

  12. Mars again? by Anonymous Coward · · Score: 0

    NASA has had much success at exploring Mars. But what about some of the other rocky planets? Why do they only get flybys or orbitals?

    BepiColombo is heading for Mercury, but that's a European-Japan joint mission. It'll be another orbital. Nothing is currently around Venus, let alone trying to land there again. What, is Venus owned by the Russians and Mars by the U.S.?

    I'm sure the challenges of putting a lander on Mercury, let alone Venus, are very large. But won't we learn more by doing those missions, than by putting yet another lander on Mars?

    1. Re:Mars again? by Anonymous Coward · · Score: 0

      Whoops, Akatsuki orbital from Japan is currently around Venus. My apologies on posting before searching thoroughly.

    2. Re:Mars again? by Anonymous Coward · · Score: 1

      NASA has had much success at exploring Mars. But what about some of the other rocky planets? Why do they only get flybys or orbitals?

      Budget.

      NASA's budget is quite small, and NASA only gets to use a fraction of that on planetary probes, with the preponderance consumed by congress-mandated SLS and ISS manned programs.

      Let NASA shut down the SLS, and spent that money on landers, and you'll see them dropping landers on the other rocky planets.

      They do also plan this hopper lander for Titan.

  13. What is Winter Sunlight? by Anonymous Coward · · Score: 0

    For this reason, God sends them a powerful delusion(operation of wandering)(planet) so that they will believe the lie.
    Working of Error

  14. Microbial contamination? by phayes · · Score: 1

    NASA likes to try to force requirements on others that they don't apply to themselves.

    Commercial crew MUST have less than a failure rate of less than 1/270 (loss of Mission -- not necessarily loss of crew) but Shuttle could fly with an estimated chance of failure and crew loss almost 10 times worse.

    CCS needs to have multiple test flights but SLS 1b will be deemed to be safe to put astronauts in on it's first flight (just like the Shuttle).

    When Space-X was planning on sending a Dragon to Mars using Falcon Heavy, there were many cries from experts at Nasa that Space-X would be contaminating Mars with terrestrial microbes (leaving aside the fact that Space-X is planning on sending humans to Mars within 15 years if all goes well at which point it'll be a moot point).

    I'd be interested in just what precautions NASA has taken to make sure that the crushed cork CANNOT have any microbes that could contaminate Mars. Or is this yet another case where Nasa won't apply it's rules to themselves...

    --
    Democracy is a sheep and two wolves deciding what to have for lunch. Freedom is a well armed sheep contesting the issue
    1. Re:Microbial contamination? by Anonymous Coward · · Score: 0

      NASA likes to try to force requirements on others that they don't apply to themselves. Commercial crew MUST have less than a failure rate of less than 1/270 (loss of Mission -- not necessarily loss of crew) but Shuttle could fly with an estimated chance of failure and crew loss almost 10 times worse.

      That's a little unfair. The reason that commercial crew has such strict requirements is because of the shitstorm that hit NASA from every direction after the shuttle failures.

      Early NASA was allowed to fail sometimes-- when John Glenn launched, nobody could guarantee that the Atlas booster would even work; it certainly had enough failures. But somewhere in the process, the public got the idea that NASA should never every fail.

      CCS needs to have multiple test flights but SLS 1b will be deemed to be safe to put astronauts in on it's first flight (just like the Shuttle).

      Nope. First SLS mission is EM-1, an un-astronauted test mission.

      When Space-X was planning on sending a Dragon to Mars using Falcon Heavy, there were many cries from experts at Nasa that Space-X would be contaminating Mars with terrestrial microbes (leaving aside the fact that Space-X is planning on sending humans to Mars within 15 years if all goes well at which point it'll be a moot point). I'd be interested in just what precautions NASA has taken to make sure that the crushed cork CANNOT have any microbes that could contaminate Mars. Or is this yet another case where Nasa won't apply it's rules to themselves...

      NASA has a very rigorous planetary protection protocol, which, yes, the Insight Lander (including the heat shield) is subject to. The heat shield is easy, actually: it can be heat sterilized. Planetary protection is much harder for the actual electronics, but, yes, it is required, and there is a separate office-- independent of the mission office-- that monitors that it is done.

    2. Re:Microbial contamination? by Cochonou · · Score: 2

      Probably by using the same bioburden reduction technique that most of the instruments on this mission go through: dry heat microbial reduction.

    3. Re:Microbial contamination? by phayes · · Score: 1

      Many thanks, very informative.

      However, the presentation is essentially how to sterilise surfaces, assemblies and instruments which seems poorly adapted to ensuring that a reconstituted biological insulator (crushed cork) which will end up degrading on Mars is as sterile as they claim. I may be off base but Nasa's proven tendency to absolve itself of inconvenient rules it wants others to apply now makes many doubt their application.

      --
      Democracy is a sheep and two wolves deciding what to have for lunch. Freedom is a well armed sheep contesting the issue
    4. Re:Microbial contamination? by Agripa · · Score: 1

      When NASA found that the Space Shuttle's main engines returned with cracked turbine blades, they redefined this from a failure to a maintenance issue. But if the Merlin engines in SpaceX's Falcon 9 return with cracked turbine blades, it is a failure.

    5. Re:Microbial contamination? by Agripa · · Score: 1

      That's a little unfair. The reason that commercial crew has such strict requirements is because of the shitstorm that hit NASA from every direction after the shuttle failures.

      NASA did this before the Shuttle failures.

      NASA holds other parties to a higher standard than NASA and NASA's contractors. Things which are considered failures if others do them are maintenance issues for NASA.

  15. SpaceX by Anonymous Coward · · Score: 0

    Why don't they just ask Musk? He will have a colony on Mars soon. Right after he finishes his tunnel and offers a $35k electric car. So very soon.

    1. Re:SpaceX by Anonymous Coward · · Score: 0

      It is unlikely SpaceX lands humans on Mars before the 2030's. This NASA probe is landing in a few days. That is a gap of a decade and a half. SpaceX aren't even planning unmanned landings until the mid 2020's.

    2. Re:SpaceX by Fly+Swatter · · Score: 1

      Whoosh.

  16. Re:Mars? by Ol+Olsoc · · Score: 5, Funny

    p>You know, that isn't really funny, because millions of people actually believe that shit. There really doesn't seem to be any possible satire conspiracy theory so extreme that people don't believe it.

    Stanley Kubrick filmed the fake moon landings, but he was such a perfectionist he made NASA go to the moon to do it.

    --
    The shepherds did so well protecting the flock that the sheep no longer believed that wolves existed.
  17. Re:More fake space missions from NASA by Ol+Olsoc · · Score: 1

    I assume that the AC here thinks that he is being witty.

    tens of millions of people believe this, though.

    A little bit of exaggeration there Geoffrey?

    Yes there are some people who are genuine kooks, and will believe anything but the truth.

    But there are a lot more who just troll for the LuLz.

    Gotta remember that the best way to deal with the trolls, is to laugh with them. And the best way to deal with the kooks is to give them even crazier shit to believe.

    That said, I have to get heading off through the Pizzagate tunnels to Area 51 (that pedophile stuff was just a cover story for Elon Musk's real purpose, a boring tube, to provide a safe transit for the idle elite when the meteorite they have known about for 20 years hits the earth), and where Oblama hides his Kenyan Birth certificate, and he and Hellery are meeting with the Illuminati in the warehouse where the chemtrails and poison vaccines are stored. Wake up America!

    --
    The shepherds did so well protecting the flock that the sheep no longer believed that wolves existed.
  18. At least. Maybe more [Re:More fake space missi...] by Geoffrey.landis · · Score: 1

    I assume that the AC here thinks that he is being witty.

    tens of millions of people believe this, though.

    A little bit of exaggeration there Geoffrey?

    Nope. Tens of millions, and probably more.

    --
    http://www.geoffreylandis.com
  19. Oh, I Know! by Anonymous Coward · · Score: 0

    EDL stands for "Extraderrestrial Landing".

  20. This is not Hollywood EDL by Anonymous Coward · · Score: 0

    This is not simple matter of parachuting and cushion. The weight of the spacecraft may at 38% of its total weight in Earth, but the mass is still the same regardless. There is matter of minimizing impact shocks and vibrations too

  21. Does NASA time these for the holidays? by Anonymous Coward · · Score: 0

    Obviously orbital mechanics is the primary factor BUT it seems a lot of the Mars craft have arrived in the holiday season.

  22. Re:More fake space missions from NASA by GameboyRMH · · Score: 2

    Of course the public are interested, especially with 4K televisions, just think of looking at beautiful, awe inspiring 4k footage of the Moon every day, as the astronauts explore more and more of it.

    Meh, if you've seen one dusty gray crater you've seen 'em all.

    --
    "When information is power, privacy is freedom" - Jah-Wren Ryel
  23. How does the heat shield actually work though? by Anonymous Coward · · Score: 0

    They make a point to mention the cork in the title, then again in the article but no mention of why it works. Is it soaked in something?

    1. Re:How does the heat shield actually work though? by Anonymous Coward · · Score: 0

      Cork burns, but the carbon layer it produces becomes a heat insulator, until the carbon layer itself burns off, and then the it burns the next little layer or the cork.

      I have heard, but I have not checked that some early heat shields in the manned space programs where made of cork. Maybe on the Russian side?

  24. Re:Mars? by K.+S.+Kyosuke · · Score: 1
    --
    Ezekiel 23:20
  25. The Martian atmosphere is essential by aberglas · · Score: 1

    It is used to slow down from some 5,000 m/s to a few hundred. If Mars had no atmosphere it would require a huge amount of fuel to do that slow down.

    The only issue is that the atmosphere is so thin that the last bit of slowing does need to be done with rockets. But it is 90% with heat shield and 9% with parachute.

  26. Re:Mars? by Ol+Olsoc · · Score: 1

    Like this?

    By golly, it is!

    --
    The shepherds did so well protecting the flock that the sheep no longer believed that wolves existed.
  27. Dude, stop by Anonymous Coward · · Score: 0

    100 times thinner

    Just stop.

  28. First Tesla, now Honda? by OrangeTide · · Score: 1

    First a Tesla Roadster is launched into space, and now NASA has landed a Honda Insight.

    These car ads keep upping the ante.

    --
    “Common sense is not so common.” — Voltaire
  29. Re:2,700 degrees F -- hot enough to melt steel,unl by Anonymous Coward · · Score: 0

    At only 400 F the strength derating for steel is 0.90. And at 930 F structural steel is down to 0.50. A damage structure is unlikely to be able to handle double the maximum rated load, and will collapse.

    Twisting and flexing metal creates localized heat significant enough to metal small areas, even if the ambient temperature is not nearly enough. (because air is a poor conductor of heat, it means hot spots can build up easily).

    If you're interested in seeing a similar effect in action, go to YouTube and check out videos of a friction welder in action. It simply rubs bits of metal together enough to get it cherry red hot to bright yellow hot (2800 F), without any jet fuel required.

    Honestly, if a structural engineer looks at this scenario, they would conclude that the buildings were unlikely to collapse from the impacts and fires. The heat and impact alone should not have resulted in collapse of the twin towers. But several factors that wouldn't have been part of a typical engineering analysis occurred, and there is no way the hijackers could have planned for things like the fire proofing material to crack and dislodge in the impact. Luck was on the hijacker's side, so maybe all that praying to Allah paid off.