Posted September 4, 2015

An artificial meteor shower

A Japanese company called Star-ALE thinks it can create record-breaking fireworks: it wants to imitate a meteor shower by throwing pellets from a satellite. It is currently raising money to develop a prototype. Many blog postings and news articles mention the possibility that such a light show could illuminate the opening ceremony of the 2020 Olympic Games in Tokyo. But it's not clear if this is Star-ALE's intention, let alone if the Olympic Committee would spend 8 million dollars on a product that doesn't even exist yet.

But is it possible? Can man imitate a beautiful celestial event like a meteor shower? Well, in a way it has been done. Many times in the past a satellite has come down, disintegrated in the atmosphere and partly or wholly burned up. Here are two stunning examples, one of which probably looks a lot like what Star-ALE  has in mind.

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How will the company achieve this in a controlled fashion? Lena Okajima, the founder and CEO of the company, who is also an astronomer, says the idea is to launch a satellite carrying about a thousand pellets to an altitude of 400 to 500 km and releasing the pellets to have them descend and burn up.

All of this could be a hoax but it's interesting to assume it's not, and think about how it could be done. Having the pellets light up is the least of our concerns. Anything you drop from a 400 km orbit is going to burn, as it enters the atmosphere at about 7.5 km per second. It should be relatively easy to design those pellets in such a way that they burn long enough to be seen, but burn up in time and do not reach the ground. Also, let's believe Ms. Okajima that she can optimize the secret mix of chemicals to burn as bright as a third magnitude or even a first magnitude star (all very well visible to the naked eye, the last category even in the presence of city lights). In the next video, note how the animated artificial meteor shower looks like the satellite debris shower in the previous video.

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But how about delivering the pellets where you want them? Apparently the satellite itself is supposed to continue in its orbit. At least one source says [http://www.sott.net/article/298321-Meteor-to-mark-your-birthday-Japanese-start-up-hopes-to-launch-its-own-shooting-stars] it's expected to come down only after a few months. So it's not as if  the craft goes down with the pellets. (If it did, parts of it could reach te ground, causing unacceptable risk.)

So the pellets need to separate from the spacecraft. The latter must stay up, the former have to more or less hit a target. That's the really hard part. If you separate early - say a couple orbits in advance - you can do it smoothly but your cloud of pellets will spread way out and a very small imprecision may cause you to miss the target altogether. If you separate late, you need to create a big difference in velocity between satellite and pellets and you have to use some kind of cannon. If you do that it will be hard to control the remaining satellite.

The specifics of all this depend on many more factors, such as the exact altitude, the mass of the satellite and of the pellets, and many uncertainties make the operation even more difficult such as the weather.

So it will be very interesting to see if Ms. Okajima can find the money to develop and launch her prototype. If she does and succeeds, there will no doubt be billionaires and organizers of big events who will pay her handsomely to perform this new form of art. We can't wait.


About Herbert Blankesteijn

Herbert Blankesteijn is a technology journalist from the Netherlands who has written for many prominent Dutch newspapers. He presented and directed television and radio programmes and has 10 books to his name. Herbert is interested in nascent fields such as 3D printing, drones, robotics and the private space business.