Micrometeorites collide with James Webb at least 14 times: How much damage to the telescope's mirror?

November 18, 2022  21:11

Every spacecraft and telescope encounters micrometeorites sooner or later - it simply can't be avoided, so it is necessarily taken into account when building these instruments. The James Webb Space Telescope is no exception.

According to NASA, the telescope was designed to withstand a continuous bombardment of particles the size of dust moving at extreme speeds. Even during the construction of the telescope, its mirrors were subjected to a series of ground tests so that scientists understood how to strengthen them to stay in an L2 orbit.

Now during James Webb's work, micrometeoroids occasionally hit its mirror. However, NASA reports that the optical errors caused by these collisions are within normal limits and almost exactly as expected. This, at least, is evidenced by data from a study of 14 known micrometeorite impacts on the telescope's main mirror.

The only exception was an incident between May 23 and 25, when micrometeorites crashing into the mirror resulted in a minor but noticeable impact on the data.

These collisions went beyond simulations and experiments and caused more damage than researchers expected. Though even after such a problem, the telescope's optical performance still exceeds NASA's requirements by a factor of two.

Such serious collisions, according to experts, do not happen often and can be avoided. To that end, NASA plans to adjust the telescope's trajectory and observation plan so that it is as safe as possible from the risk of collisions with micrometeoroids. Although this may result in some limitations to observations of certain parts of the sky at different times of the year, the operation of the expensive telescope will be as safe as possible. One way or another, all planned areas of the sky and all objects of interest to scientists will be covered, but - in a different mode.

True, NASA noted that over time, collisions with micrometeorites - even despite all the measures taken - will still degrade the performance of the telescope mirrors. For now, however, James Webb has some safety margin.

The James Webb Space Telescope is a large space observatory, optimized for infrared wavelengths. The data obtained with this telescope will complement and extend the discoveries made by the Hubble Space Telescope.

Webb was launched on December 25, 2021. The original plan was for it to operate for five years after launch, but NASA hopes it will last 10 years and possibly longer. Unfortunately, the observatory will not last forever: although James Webb mainly runs on solar power, it requires other fuel to maintain its orbit and instruments, and its reserves are not unlimited. Moreover, collisions with micrometeoroids will also sooner or later render the telescope unusable.

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