Meteors are nature's fireworks, but mankind is catching up as the artificial shooting star project Sky Canvas attempts to recreate colorful cosmic showers. Using miniature satellites that shoot special alloy ball bearings, the showers can be created to order over any spot on Earth for both a spectacular fireball display and to help better understand how to dispose of space debris.
The Solar System is a very untidy place. Even after five billion years, it's still cluttered with debris from its creation – some on the scale of dwarf planets and others the size of dust motes. One particular source of debris are the comets that are periodically disturbed from their ancient nesting grounds in the Kuiper and Oort belt, only to plummet into the inner Solar System.
Some of these are captured by the mass of the giant planet Jupiter, causing them to return near to the Sun again and again in elongated elliptical orbits. Eventually, after many visits over thousands of years, the ice that make up the bulk of a comet sublimates away and all that is left is a trail of dust and rubble spreading along the entirety of the comet's orbit. If the Earth happens to intersect this orbit, these particles collide with the atmosphere and burn up, producing meteor showers at predictable times of the year.
Backed by Japan's ALE Company and other partners, Sky Canvas aims to create artificial meteors a bit closer to home. Instead of lassoing comets, the project uses a mini-satellite placed in a sun-synchronous orbit. That is, a high-polar orbit set at an angle and altitude that allows the satellite to fly over a spot on the Earth at exactly the same time each day. It's a technique used by spy satellites to ensure that their targets are always in full daylight while being photographed, but for Sky Canvas, it's to make sure the meteors arrive on cue.
To produce the bright plasma emissions caused by the heat of reentry that make meteors visible from the ground as streaks of light, the satellite carries up to 300 pellets one centimeter in diameter and made of special metal alloys. Exactly what these alloys are is confidential, but they include different elements to cause the artificial shooting star to burn in different colors.
Once in the proper orbit, the pellets are released when the satellite is still a distance away equivalent to over a third of the Earth's circumference from the target event or city. The pellets hit the atmosphere at about one second intervals over a period of roughly eight minutes. If weather over the target is poor, the satellite has an abort function to prevent spoiling the show.
These pellets will burn up over the target at an altitude between 60 and 80 km (37 and 50 mi) where they will glow with a brightness of magnitude -0.86 or about that of the star Aldebaran. This will make the artificial shower visible over an area 200 km (125 mi) in diameter at a cost of US$16,000 per meteor. The satellite itself will burn up in the atmosphere due to orbital decay in two to four years.
According to ALE, the artificial meteors can not only be used for entertainment purposes, but also for scientific research. Since the pellets are released in a controlled fashion, their incidence, velocity and materials are known. This makes them very useful to compare to natural meteors to understand more about their characteristics by providing a baseline for comparison. This will also help in better understanding the Earth's upper atmosphere as well as collecting data to better plan the disposal of space debris.
The first test of the system is expected in 2019 with the first display over Hiroshima, Japan in the middle of that year.
The video below introduces Sky Canvas.