What NASA is really saying about the space rock hitting the Webb telescope

Yes, tiny rock particles hit the Webb telescope. No, the mission almost failed.

You may have read misleading headlines emphasizing that the James Webb Space Telescope – the most powerful observatory ever built – has suffered permanent damage. That’s a bit of a cherry on a new 55-page report that describes the instrument’s excellent scientific performance over the past six months, as engineers prepare and test unprecedented cosmic observation capabilities.

The Webb telescope, overall, is in excellent condition. Here’s what you should know about observatory conditions that will revolutionize our understanding of the cosmos.

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What do scientists conclude about the state of the Webb telescope?

NASA and its collaborative partners, the Canadian Space Agency and the European Space Agency, concluded that Webb – even after micrometeroids (small rock particles often the size of dust) hit and caused “significant irreparable changes” to one of the 18 telescopes. gold-plated hexagonal mirror — “fully capable of achieving the invention he made.”

Most importantly, they expected Webb to exceed expectations. “Moreover, almost overall, JWST’s science performance was better than expected,” the Webb scientists wrote.

“JWST’s science performance is better than expected.”

Why is Webb expected to excel? Its mirrors are cleaner than needed to fulfill their lofty scientific goals. Its guidance system, which locks on and tracks targets, is better than necessary. And its overall performance in seeing objects clearly is better than requirements.

And if that wasn’t good news enough, Webb scientists have concluded that the ship has limited enough fuel to help carry out its mission to 20 years. (The telescope used less propellant than planned to arrive at the outpost about 1 million miles from Earth.) Initially, NASA hoped the instrument would last five years, and the agency was initially pleased to learn that it would operate with adequate propellant for more than 10 years. year.

With the peak performance of the Webb telescope, astronomers plan to:

• Take a peek at the stars and galaxies that formed more than 13 billion years ago, just a few hundred million years after the Big Bang. “We’re going to see the first stars and galaxies that ever formed,” Jean Creighton, astronomer and director of the Manfred Olson Planetarium at the University of Wisconsin-Milwaukee, told Mashable last year.

• See the cosmos in infrared light, which allows us to see much more of the universe. Infrared has a longer wavelength than visible light, so light waves more efficiently penetrate cosmic clouds; light does not often collide and is scattered by these solid particles. Ultimately, Webb’s infrared vision could penetrate places the legendary Hubble Space Telescope could not reach.

• Peek into distant exoplanets: Webb telescope carry special equipment, called a spectrometer, which will revolutionize our understanding of this distant world. The instrument can decipher what molecules (such as water, carbon dioxide and methane) are in the atmospheres of distant exoplanets – whether they are gas giants or smaller rocky worlds. Webb will see exoplanets in the Milky Way galaxy. Who knows what we will find?

How bad is the damage to Webb?

As you have read above, the telescope as a whole is in very good condition.

During the six months scientists prepared the $10 billion telescope for the highly anticipated science operation, researchers detected six impacts from micrometeroids. Indeed, they expect about one hit every month. “Inevitably, every spacecraft will encounter micrometeoroids,” the report said. Of the six hits, five had a negligible effect.

However the impact that occurred between 22 and 24 May was strong enough to cause, as noted above, “significant irreparable changes” in any of Webb’s 18 hexagonal mirror segments (segment C3). Fortunately, the observatory’s mirror – which collects the faint light from the cosmos very far away – is quite large at over 21 feet wide. This means most telescopes are unaffected.

The image on the right shows the bright area (bottom right of the mirror) where the micrometeroid hit the Webb telescope, eventually changing the mirror’s surface.
Credit: NASA/ESA/CSA

“However, the effect is small at the full telescope level because only a small part of the telescope area is affected,” the Webb scientists wrote.

What’s more, after the strike, Webb’s engineers worked to make minor adjustments to the mirror alignment, which limited small imaging errors. (Such errors are to be expected because the telescope is hovering slightly in space.) “Webb’s ability to sense and adjust the mirror’s position allowed partial correction of impact results,” NASA said earlier. “By adjusting the position of the affected segment, engineers were able to partially cancel out the distortion.”

What risks impact telescopes in the future?

Only time will tell whether these impacts are rare, or perhaps more common than the Webb scientists think.

“It is not yet clear whether the May 2022 collision to segment C3 was a rare event (i.e. an unlucky initial strike by a high-kinetic energy micrometeoroid that statistically might only occur once every few years), or whether the telescope might be more susceptible to damage by micrometeoroids than modeling predicts. pre-launch,” the report concluded.

If it turns out that Webb is at a higher risk of damage, NASA and its Webb partners could consider minimizing how much time the telescope peeks at where there are more micrometeroids flying through space, or pointing the telescope away during certain meteor showers.

For now, however, the telescope is poised to succeed.

“With its revolutionary capabilities, JWST has embarked on the first scientific discovery in years,” the report concludes.

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