Software patch fixes Euclid space telescope navigation bug The European Space Agency's Euclid space telescope is back to normal and will resume its mission, thanks to a software update that was required after its navigation sensors mistakenly identified solar ray signals as stars. Launched in July, the billion-euro observatory designed to study dark energy and dark matter, …
It's like humanity's version of window shopping for real estate we can't afford and will never inhabit. "Look, dear, that galaxy looks cosy. Too bad it's several billion light-years away and we're stuck here on Earth!" Sure, let's map a third of the sky, hoping to understand dark energy and matter. All while we can't even locate our car keys on a regular basis. It's truly the cosmic equivalent of licking windows at the most expensive store in the universe, knowing we won't be buying or even touching a thing. But hey, at least we can dream about the stars while we trip over our own feet here on solid ground.
I'm curious. Hubble had its issues, but detecting its position in space was not one of them.
I haven't heard that JWST has any issues like that either.
So, how is it that this telescope does ? Isn't satellite positioning a known science now ? What did they change on this one to make it not work like the others, and why ?
I would have thought that Science shares knowledge like that. Apparently not.
I'm a bit disappointed about this.
There's no such thing as a solved problem when it comes to unique instruments. Hubble and James Webb both also have fine guidance sensors that do a similar job, but obviously they don't share identical hardware for either the sensors themselves or the systems feeding them light and doing the actual pointing. Hubble has three separate FGS (two have been replaced since launch), which combined would make up nearly half the size and mass of Euclid if it used the same system. James Webb has its FGS combined with a near infrared instrument. Euclid has its FGS combined with a visible light instrument.
Suggesting that they just made up their own new idea without bothering to ask anyone else is just silly. Of course knowledge is shared and they used the same principles as in other telescopes. But that doesn't mean they could just blindly copy the exact solution from Hubble even if they wanted to. The exact issue isn't being shared as far as I can tell, but it appears to be something along the lines of having underestimated how sensitive the CCD in the VIS instrument is to protons in cosmic rays and the solar wind, so it struggles to identify guide stars when activity is high. No amount of knowing the principle of how to aim a telescope is going to help when the problem is with the specific hardware used in a unique instrument that has never been in space before.
Could this have been solved before launch by doing better simulations? Maybe. But as the ESA explain, the whole point of the commissioning phase is to find and fix issues like this, and since they've successfully done so with a simple software patch, it's really not a big problem.
And how much fuel did it use up by all that repositioning?
Probably little to nothing directly, as the changes look pretty minor in absolute terms (hunting around the immediate field of view, not doing pirouettes - which would have probably seen the FGS fighting with the coarse sensors and any inertial instrumentation), so the wandering we've seen was probably all done with reaction wheels.
Of course if the wheels are now wound up a bit, the first "unwind" or desaturation event (which will burn propellant) will come sooner. But it doesn't seem like it will have a significant impact on mission lifespan.
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