[HN Gopher] Guide stars found as Euclid's navigation fine tuned
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Guide stars found as Euclid's navigation fine tuned
Author : raattgift
Score : 43 points
Date : 2023-10-05 15:18 UTC (7 hours ago)
(HTM) web link (www.esa.int)
(TXT) w3m dump (www.esa.int)
| yardshop wrote:
| > Loopy star trails show the effect of Euclid's Fine Guidance
| Sensor intermittently losing its guide stars
|
| https://www.esa.int/ESA_Multimedia/Images/2023/10/Loopy_star...
|
| Now that's some beautiful Glitch Art!
| dylan604 wrote:
| You can achieve similar on terra firma. Go way out to the
| boonies away from city light pollution. You'll be in nature
| with all of the critters that entails, but hopefully the flying
| types. Set up your camera to frame just the night sky. Set it
| for long exposure focused at infinity. Place a dim light source
| near the camera but out of frame. Black lights work wonderfully
| well. As the night progresses, all sorts of flying insects will
| swarm your camera rig at random heights. As they fly around
| during the exposure, you'll end up with a very similar look.
| dotancohen wrote:
| In the fine article, all the trails have identical paths.
| dylan604 wrote:
| i said "similar". besides, mine cost pennies compared to
| what the image in TFA cost. you get what you pay for.
|
| or, set up the same rig minus the light, and then give the
| rig a shake while the shutter is open. much less random in
| the streaks.
| yardshop wrote:
| I like your idea, I could do it right in my front yard, but
| what I like about the image in the article is the very nice
| proportions and exact repetitions of the curves and even the
| little dove-head figure, and the fact that it was entirely
| unintentional. Added bonus that it cost millions and millions
| and involved over the top equipment and time and distance!
| dylan604 wrote:
| >I could do it right in my front yard
|
| Great! I'm coming over next week with all my gear! Closest
| place for me is 4 hours away. It is my motivating factor of
| trying to buy a car again.
| dtgriscom wrote:
| You can actually do useful astrophotography by slightly mis-
| focusing an SLR and wobbling it around. Each bright star will
| leave a trail, changing in brightness and color as the
| atmosphere twinkles.
| greggsy wrote:
| This makes me wonder, do extra-solar space probes need to adjust
| their star charts to account for a change in their related
| location, or is the change negligible?
| wolfram74 wrote:
| As others have noted, depends on which stars you're using as
| reference points. We've done some interesting long-distance
| parallax stuff at the demo scale, new horizons took some
| pictures last year to that effect.
|
| https://www.nasa.gov/solar-system/nasas-new-horizons-conduct...
| dylan604 wrote:
| Have you ever seen the 3D views of where stars in the
| constellations are in relation to each other? These kinds of
| videos are something that I think really helps esoteric
| concepts become much more widely understood, and I'm constantly
| jealous of them from the position of going to school vs "back
| then" when I was in school.
|
| Here's Orion:
|
| https://www.youtube.com/watch?v=lD-5ZOipE48
| icegreentea2 wrote:
| If you knew you were going extra-solar, you would want to pick
| guide stars with minimal/immeasurable parallax over the scale
| traveled. A naive worst case scenario would be not negligible.
| For example, Proxima Centuri has a measured stellar parallax
| (from Earth - so across a 2AU distance) of ~0.8 arcseconds. We
| were able to measure that parallex from the ground by the mid
| 19th century.
|
| Abusing small angle approximations, that implies that each
| ~arcsecond of shift you encounter could potentially mislocate
| you by ~2AU...
| dylan604 wrote:
| close enough for horseshoes, on a cosmological scale. pretty
| much a ringer!
| Y_Y wrote:
| "We'll fix it in the first patch"
|
| Programming for astronomy is famously difficult, since you're
| always pushing the boundaries one way or another. That said the
| problem domain is fairly well specified and (as the article
| shows) usually well models. Mr. Feynman going to Washington
| showed what treating astro like office software can do, but it's
| a shame when an expensive project gets a fleshwound from
| something predictable.
|
| See also: what JAXA launched and x-ray satellite that couldn't
| stop spinning, or that notorious kerfuffle converting pounds-
| force-hogsheads into metric that sent a very expensive item off
| into oblivion.
| cratermoon wrote:
| I've noted, unscientifically, space flight problems are now
| largely about software bugs. Rarely is the hardware the root
| cause, with notable exceptions like the first SpaceX Starship
| flight. That tracks for me, as software "engineering" is a long
| way from any other engineering discipline, including aerospace.
|
| > that notorious kerfuffle converting pounds-force-hogsheads
| into metric that sent a very expensive item off into oblivion.
|
| I feel compelled to chime in here and point out there was far
| more at fault than a units conversion error. "A critical flaw
| was a program management grown too confident and too careless,
| even to the point of missing opportunities to avoid the
| disaster."
|
| https://spectrum.ieee.org/why-the-mars-probe-went-off-course
|
| Look at program management in the aerospace industry and you'll
| see software treated as an afterthought, or poorly managed and
| tested. It seems developing space-worthy software is still
| largely a work in progress.
| kwentine wrote:
| > It arrived smoothly at Lagrange point 2, focussed its telescope
| mirror and captured its first mesmerising test images. It soon
| became clear, however, that the mission was experiencing some
| hiccups.
|
| Did anyone else wonder if Advent of Code had begun early this
| year ? ;)
| bloopernova wrote:
| What a wonderful sci-fi headline.
|
| "Guide Stars Found as Euclid's Navigation Fine Tuned"
|
| (I included it here in case the headline is changed)
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