New research looking at micrometeorites literally microscopic bits of meteorites, particles of rocks and metals from space that fall to Earth shows that about
5,200 tons of this cosmic debris settles onto the ground every year. 5.2 million kilos per annum, or about 14 tons per day. At
least. That s equivalent to the mass of a garbage truck every day.
Oof.
Also, this is very wee stuff, smaller than a millimeter in size and some smaller than the width of a human hair. There s no reason to panic . It slows from interplanetary speeds to basically 0 way up in the atmosphere and then drifts down to the ground. It s no danger, and in fact is quite welcome, since it tells us a lot about what s going on in space.
The material collected was found on Walnumfjellet, a peak in the Sør Rondane mountain range on the coast of Antarctica, about 4,000 km south of South Africa. This range of peaks reaches roughly 3,000 meters high, and the summits ice-free. Dating techniques show that the area the material came from has been exposed for at least 870,000 years.
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Spherules about the width of a human hair found on a mountain in Antarctica tell a story of a large impact from a 100-meter wide asteroid some 430,000 years ago. Credit: Scott Peterson / micro-meteorites.com
The debris pieces found are called
impactites, minerals made upon impact. They re spherules some 100 to 300 microns wide (a human hair is about 100 microns in diameter, or about a tenth of a millimeter). When I first saw them I thought they resembled tektites, dark glassy material blasted off the ground in a big impact. The huge energy and heat released upon impact melt soil into glass, which gets thrown into the air, cools, and
It s quite small, standing about half a meter high and with a mass of just 1.8 kilograms (so it weighs about 1.5 pounds in the lower gravity of Mars). The fuselage is a rectangular box about the size of two hefty hardcover books stacked on top of each other (20 x 14 x 16 centimeters) and it contains the avionics, the electronic systems that control the craft.
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Schematic of the Mars drone copter Ingenuity. Credit: NASA/JPL-Caltech
The lift is provided by a pair of counter-rotating carbon fiber blades (one spins clockwise, the other counterclockwise) stacked on top of each other. They span about 1.2 meters and will rotate at an amazing 2,400 RPM, which on Mars means the tips will be moving at 0.7 times the local speed of sound! The atmosphere of Mars is around 0.6% the pressure of Earth s at sea level, and that thin air means the blades have to work much harder to get Ingenuity airborne.
A lens bends the path light takes (this is called
refraction), so that a photon that would otherwise miss your camera gets directed into it. Again with a rain analogy: A raindrop that falls a meter away from you misses you, but if you could deflect (refract!) the path of that drop a little bit while it s still up high, it ll be aimed right at you, and you get wet.
In the case of the Terrascope, the lens is actually Earth s atmosphere. When light moves from one medium to another (like air to water, or space to air), its path bends a little bit. The amount it bends depends on the angle it enters and the stuff (what we usually call the
But even then it didn t act like a comet. No carbon monoxide, carbon dioxide, or dust was seen, which are very common in comets.
On top of all that, it was brightening and dimming with a regular period, indicating it wasn t spherical (and as it tumbled we saw a different geometry reflecting sunlight back to us). That s common enough, but it must have been a really weird shape to explain the extreme change in brightness seen, either shaped like a pancake or a cigar!
Lots of attempts were made to explain it. It s a hydrogen iceberg (unlikely). It s a fractal snowflake (cool, but also unlikely). It s a spaceship (no).