Fireballs vs. eyeballs

On 17th June 2012 Anders Helstrup was skydiving using his wingsuit. In one of the jumps something very unexpected happened, and his two helmet mounted camera confirmed it: A rock fell from the sky, just past Anders towards the ground. There was no one or nothing above him that could have dropped it. He contacted some geologists and meteorite experts, and an investigation was under way. The videos were analysed and the area was searched, but the only conclusive proof for a meteorite, the meteorite itself, was not found. We know that a few meteorites fall over populated areas on Earth every day, often unnoticed. Relatively slow fireballs may be fainter than the full moon and still drop meteorites, and they may be very hard to see in the glare of the sun or behind clouds. A sonic boom could be mistaken for thunder or human activity. Considered the many million cameras now in use worldwide, one is occasionally bound to capture something extremely unlikely. So however unlikely a near hit of a meteorite is, it is certainly a possibility. Due to its extreme low probability, it’s naturally the last pick of all the thinkable actual possibilities. A number of scenarios were considered, but all apparently failed to explain what is seen in the video. We were left with scenarios that we were unable to find possible solutions for against something that fits but is extremely improbable, though possible. We seemed to get no further, and we decided to go public with what we had and at the same time invite anyone to have a go at the puzzle. The story was announced here on the web pages of the Norwegian Meteor Network, where we expressed our hope that it would go viral and scrutinised for something that we might have missed, and the result was beyond our expectations.
Stein

Let’s get straight to the conclusion. The good news: The crowdsourcing was a success. The bad news: There is no meteorite. It was a rock accidentally packed into the parachute. But how? It was a scenario considered from the beginning and it kept haunting us until the time we went public, as Anders told in the TV interview. Despite much effort, we saw no way to reconcile this scenario with the videos. The rock was clearly falling from well above the parachute. It did not seem to accelerate as if released from the parachute. It fell several seconds after the parachute had fully deployed. So what did we miss? The riddle quickly cracked under the pressure of the numerous fresh eyes now looking at the problem. Several people were able to point out the important clue that made the pieces fall into place.

We think we can reconstruct what happened: A pebble, a few cm in size at most, was accidentally caught inside the parachute at the landing site after the previous jump. Then the parachute was packed on a clean floor and the pebble was not noticed. Then Anders made the jump with the stowaway. This is a wingsuit dive and he’s travelling fast northwards at an downward angle of approximately 40 degrees. When he releases the parachute, the wind catches it and it shoots out to the south of him. The parachute is held back by the cords, but the pebble is not. The pebble is now increasingly getting further south and further above Anders. However, the parachute then slows Anders down, he makes a 250 degree clockwise rotation and at this moment the pebble happens overtake him. It had now been falling for a few seconds and was no longer accelerating much.

The exact details are somewhat unclear, but it doesn’t matter. It has been demonstrated that a pebble brought by the parachute can appear falling rapidly, not accelerating much, above the parachute a few seconds later. It doesn’t matter that a long chain of events that usually don’t happen is required when the alternative hypothesis is a passing meteorite. All of these events were orders of magnitude more probable and the presence of Occam is quickly felt. The pebble was shot out and then Anders was overtaken by it. This is the possibility that we had completely missed all this time. An adaptation of Linus’s law, after the creator of Linux, applies: Given enough eyeballs, all mysteries are shallow.

Are we disappointed? The ultimate prize would be a meteorite, but frankly, we had been faced with a mystery for nearly two years, we went public, and thanks to an incredible crowdsourcing effort the mystery was solved beyond reasonable doubt in just a few days. That’s amazing.

We are tremendously thankful for all those who engaged in this. The creativity has been outstanding and much appreciated. Special thanks go to Dr. Phil Metzger for his ballistics analysis.

It turns out that during the many hours of calculating the path of the object we were closer to the answer than we were aware of. Ironically, “calculus” is the Latin word for “pebble”.

14 thoughts on “Fireballs vs. eyeballs

  1. Good that the case is closed now (and in a way that many – including myself – had suspected all along). But you could have had the same outcome years earlier by just releasing the video right away – perhaps without the exact site of the jump, so no one could snatch the meteorite from you, in case there really had been one …

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  4. After all this time we now got the proof that there were only a prebble flying past the camera lens…opps, I guess my mistake… :)
    After all the video have encouraged many people to solve the puzzle. Thanks to everyone that have been involved and had different opinions along the way!
    There would have been a really cool thing if a meteorite had been discovered, but I’m glad that we finally have found a more likely explanation:)

    Once again thanks to all the helping people out there. Interesting to see how problems can be solved like this one. I’m impressed by people who don’t give up unless they get to the bottom of things!

    And must the prebble R.I.P.

    • Har sekvensene som viser fallskjermen folde seg ut blitt analysert nøye. Det jo fort gjort å fokusere på stenen som faller :-)

      På videoene som ligger på Youtube, kan det virke som om er “noe” som roterer og beveger seg mot høyre når skjermen åpner seg.
      Hadde vært brillefint å kunne analysere originalvideoen før den har vært igjennom kvalitetsforringelsen via Youtube :-)


      1/1g

      • Ja, det har vært undersøkt uten funn. Bakoverkameraet viser åpninga, men sola gjør det litt vanskelig å se noe smått. Feilen som har blitt gjort, er å anta at det som detter ut ved åpning, vil falle ned med en gang, mens det som antakelig har skjedd her, er at steinen har “blitt igjen” bak og over, og så har tatt igjen Anders etterpå. Det er i hvert fall mulig, og bare muligheten trumfer umiddelbart en meteoritthypotese sjøl om det ikke blir funnet direkte bevis.

        • Det er i filmen fra *fremoverkameraet* når Anders titter opp som jeg synes at jeg se noe bevege seg mot høyre.
          Vil anta at stenen kan blitt “fanget opp” av fallskjermen ved landing ( skjerm har blitt dratt bortover bakken ), og at den da har lagt seg i en “lomme”. Dette kan kanskje forklare hvorfor den ikke ble oppdaget ved pakking av skjerm. Det tar jo litt tid før skjermen har åpnet seg 100%, og en eventuell “lomme” med en sten er åpen slik at stenen kan bli frigjort. Hvis åpning av skjermen også gav stenen en horisontal bevegelse ( slik det kan se ut på videoen – hvis det er en sten jeg ser ), vil sekundene det tar før den oppnår maks fallhastighet stemme bra med når sten passerer Anders i videoen.

          • Jeg klarer ikke se det du viser til. Antakelig kan Anders svare best på om den kan henge igjen i ei lomme og så falle ut. Jeg ville imidlertid i det tilfellet forvente at steinen synlig aksellererer.

          • Hei Helge,
            Dersom objekter blir fanget i fallskjermen i forbindelse med landing vil det samle seg “i toppen” av fallskjermen da den normalt bæres opp-ned frem til pakking. Dette vil naturligvis kunne forekomme. Ved pakking holdes skjermen først opp-ned (mens det ryddes i duk og liner) før den legges på et gulv og komprimeres og foldes før den legges i en bag. Ved komprimering/folding benyttes bryst/knær/armer og et eventuelt objekt ville blitt liggende nær toppen av fallskjermen, skjult bak noen få lag med materiale/duk. Enkelte påstår at “bøss i skjermen” kan bli liggende i skjermen opptil flere hopp på rad. Andre hevder at det som eventuelt ville være fanget i skjermen ikke ville blitt utløst ved åpning i det hele tatt (grunnet åpning kun i front av cellene)…

            Jeg har gjort en del forsøk og pakket småsten inn i skjermen med vilje. Jeg mener fremdeles at et gruskorn på 3 cm er i øvre sjikte av hva som vil være mulig å pakke inn ubemerket…større objekter ville bli oppdaget…

            Av alle hoppere jeg har snakket med i etterkant av episoden er det ingen som tilsynelatende kan forstå at “et så stort objekt” vil kunne bli pakket inn ubemerket. Antar at Dr. Metzgers analyser er korrekte og at objektet virker større enn i virkeligheten – en optisk illusjon?

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