Skydiver records incredibly rare event as falling meteoroid nearly hits him

A meteoroid streaking through the sky is always a spectacular sight, and it's rare to capture one on video. Yet, according to a story on Norway's NRK.no, skydiver Anders Helstrup managed to do the next-to-impossible: he caught one on video in broad daylight, after it had burned out.

When a meteoroid enters Earth's atmosphere, it's travelling so fast that it compresses the air in front of it, heating the air until it glows in the bright streak of light that we call a meteor. The friction with the atmosphere causes the meteoroid to slow down, so that it eventually enters its 'dark flight' — the point where it's still falling through the sky, but it's not moving fast enough to produce the meteor trail. Essentially, it just becomes a rock that's free-falling towards the ground, going about 300 kilometres per hour, tops. Also, the rock itself is so cold to its core from being in the depths of space that, although the outer layers can heat up as the air around it heats up, as soon as it enters its dark flight phase, it immediately cools down again.

This is apparently what Helstrup encountered back on June 17, 2012, when he went skydiving with the Oslo Parachute Club near Østre Æra Airport, in southeastern Norway. The video below, from the Norwegian Broadcasting Corporation, tells the story (with subtitles). Pay particular attention when the video reaches 1 minute 54 seconds.

While it's natural to think that this was something else, and even Helstrup himself was fairly skeptical of the meteoroid explanation at first, geologist Hans Amundsen, from the Natural History Museum in Oslo, is sure that this rock originated from space.

"It can't be anything else," he told NRK. "The shape is typical of meteorites — a fresh fracture surface on one side, while the other side is rounded."

Amundsen added that the fracture surface indicates that it was likely part of a larger meteoroid that exploded far above where Helstrup was skydiving. How could Helstrup and the other skydivers have missed this? Meteors, fireballs and bolides (the bright lights caused by meteoroids, in order of brightness) are very easy to pick out during the night. During the day, though, with the bright sun sky, it's much more difficult (but not necessarily impossible).

By the way, if the terminology gets a little confusing: the solid piece of matter is called a meteoroid (or asteroid if it's big enough), which causes the bright meteor trail as it streaks through the atmosphere, and when it's found on the ground, it's a meteorite.

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Could this have been faked? Possibly. Phil Plait, from Slate's Bad Astronomy blog, mentions a few possibilities, but even he leans more towards the idea that this is real. The main points: it doesn't look digitally added to the footage and the rock was just moving too fast, relative to Helstrup, for it to have been tucked into his chute, or dropped from the plane (which happened to be beneath him at the time), or thrown/dropped by another skydiver. Also, he links to a pretty thorough analysis of the video by Steiner Midtskogen, of the Norwegian Meteor Network (with a rough English translation).

So, given that this is most likely real, that's pretty amazing! Even more amazing is the timing of the whole event. If Helstrup had jumped just a bit later, he'd have completely missed it. If he'd jumped a little big sooner, it would have cut him in half (says Amundsen in the video). As it is, he leaped out of the plane at just the right moment to record an incredibly rare event!

"It has never happened before that a meteorite has been filmed during dark flight," Amundsen told NRK. "This is the first time in world history."

All that's left now is to find the resulting meteorite. They've been searching for nearly two years now, and with no luck yet, they're turning to the public for help. Helstrup has started up Project Dark Flight, which is currently on YouTube, but should have its own website soon.

UPDATE: (April 8): Well, it turns out that our 'meteoroid' had a much more terrestrial and mundane origin. Thanks to the incredible crowd-sourcing campaign that resulted from the Helstrup and Midtskogen going to the public with the story, the added eyes and minds came up with the solution to the puzzle: It was just a rock. A small pebble, around a few centimetres wide, that was accidentally packed into his parachute.

It wasn't a hoax, though. Just a case of mistaken (and hopeful) identity. After gathering together all the new information that sprouted from the campaign, Midtskogen, who appeared in the original video, wrote up a new post on his blog, which details the conclusions and how they think it happened. So, while it is, technically, still possible to capture a 'dark flight' meteoroid on camera, because it would have slowed down enough by that point to be flying at terminal velocity, rather than the 11-17 km/s it entered the atmosphere at, in this case, that's not what happened.

So, while this conclusion is disappointing — since it would have been very cool if it really was a meteoroid — science still wins out, due to the diligence of the researchers in doing all they could to find out the truth, and coming clean with that truth when they reached the final conclusion. Kudos to them, and yay, science!

(H/T to NRK.no)

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