Over the next two years, the James Webb Space Telescope (JWST) will fly through the dust and debris left in the inner solar system by Halley’s Comet.
Scientists are currently working on solutions to avoid a repeat of what happened in May 2022 when the $10 billion space telescope was damaged of a micrometeroid.
So don’t worry—it’s Halley’s Comet itself not will hit the Webb Telescope.
Although measuring 15 km by 8 km wide, it orbits the Sun every 75 years or so, Halley’s Comet is not expected to be back in the inner Solar System until 2061 when it will pass relatively close to Earth (and thus may be as bright as the brightest star Sirius).
Webb will probably be defunct by then, although one hopes humanity’s premier space observatory will last until the early 2040s.
Comets are made of dust, rocks and ice, so melt – and emit material – when they get close to the Sun. They leave streams of debris the size of grains of sand on their way in and out of the solar system, both before and after they wind around the sun.
Webb’s engineers expect about one meteoroid strike per month, but that can be greatly increased while the telescope is traveling through a meteor shower.
According to Nature NASA’s Meteoroid Environment Office at Marshall Space Flight Center in Huntsville, Alabama now calculates meteor shower forecasts for Webb’s engineers.
This could mean that Webb is maneuvered to point away from the incoming particles and thus avoid them hitting the mirrors. This means minimizing the time spent looking in the direction of orbital motion.
It’s a scenario that could become a live number both in May 2023 and again in May 2024 when Webb travels through Halley’s comet stream.
Halley’s Comet Stream is the root cause of two famous meteor showers experienced on Earth – May’s Eta Aquarids and October’s Orionids. Both produce about 20 “shooting stars” per hour – which are tiny particles of dust that hit Earth’s atmosphere and then release energy as light.
Webb’s huge 6.5 meter primary mirror consists of 18 hexagonal segments of beryllium gold and is fully exposed to deep space. One of the mirror segments, called C3, was struck by micrometeoroids between May 23 and 25, 2022. It caused permanent damage that cannot be repairedalthough it is hoped that this will not affect the image quality of the observatory.
Its primary mirror was also hit by four less measurable micrometeoroids, although they were all within the predictable range.
Micrometeoroids are an inevitable aspect of working in space, but Webb’s engineers are now reassessing how often its primary mirror will be hit—and what can be done about it.
Webb orbits the L2 point approximately one million miles/1.6 million kilometers from Earth.
Halley’s Comet was last seen in the inner solar system in 1986, and next year it will be at its farthest from Earth before it swings back toward the Sun. It is currently about 35 au distance (35 times the distance between the Sun and Earth), which is roughly the distance from Earth to the dwarf planet Pluto. It is currently in the constellation Hydra, but close to the bright star Procyon in the constellation Canis Minor.
It is the only known comet to the naked eye that can appear twice in a human lifetime. It has been observed every 75 years since 240 BC, but it was not until 1705 that the English astronomer Edmund Halley calculated that same bright objects kept returning to the night sky. He died 16 years before its appearance in 1758, which he had accurately predicted.
Wishing you clear skies and big eyes.
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