Europe's Euclid telescope launches to figure out dark energy, the universe, and everything Euclid, an advanced telescope built by the European Space Agency to study the nature of dark energy and dark matter, blasted off into space aboard a SpaceX Falcon 9 rocket on Saturday. The rocket launched from Cape Canaveral in Florida at 1112 ET (1512 UTC) carrying the 4.5-metre-tall (15 foot) instrument packed tightly in its …
Everyone and their dog is hoping for something, anything, which might illuminate the unseeable darkness - perhaps Euclid will the one to pull back the veil.
There are more theories surrounding dark matter than you can shake a gravitational wave detector at, and very much a wild-west frontier gold rush; dark matter may be anything from a WIMP, axion, graviton, photonic mass, a creature from the black dimension or maybe not exist at all.
Much kudos to the winning theory, and yah-boo-sucks to the plucky losers in the race to discover what keeps galaxies from flying apart like shit off a fan.
I for one, have my shiny sixpence down on gravity being time, time being an illusion, and lunchtime doubly so.
There are more theories surrounding dark matter than you can shake a gravitational wave detector at, and very much a wild-west frontier gold rush; dark matter may be anything from a WIMP, axion, graviton, photonic mass, a creature from the black dimension or maybe not exist at all.
But this is why it's fun. I gain a couple of pounds, I can blame it on dark matter instead of pizza & beer. Dark energy is the logical complement to solar panels, which can currently only exploit light energy. Or just the way our current understanding of physics can account for a lot of the way the universe seems to work, except those pesky dark bits. Maybe it's all in the barrier around our universe, and we'll find out as we get closer to hitting the wall. Or there'll be an 'aha!' moment that fixes physics and enables fun stuff like FTL travel or anti-gravity.
Yeh, programming error in the simulation. I'm just hoping whatever extradimensional entity playing our god-sim doesn't get bored and turn it off, or pick the 'natural disaster' option. But still fascinating to read about. We kinda need it to explain reality, and that explanation mostly holds together. But that theory relies on a lot of stuff existing that we've not been able to find, yet. And if it doesn't exist, it's kind of back to the drawing board for reality. Or at some point, maybe we'll be able to add 1kg of dark matter to our FOOF order on a chinese e-commerce site.
> more theories surrounding dark matter than you can shake a gravitational wave detector at
I still think someone got the decimal place wrong doing the original sums and DM (and by extension DE) are all a colossal mistake.
One thing I still can't wrap my head around is when they say "X" is (say) 5 billion light years away - well it was went the light left that spot but everything is moving, so it's not there now and it was also probably not at that distance when the light left as the Earth is also moving.......yeah I guess it is all relative.
The actual L2 isn't stable
So regardless it will need maneuvering fuel and to have some kind of de-orbit plan once it runs out.
(I am pretty sure they figured this one out already)
I understand most Lagrange orbits are often of the 'spinning a weight on a string' (aka 'halo orbit') variety [or similar]. Some have very unusual patterns to maintain stability.
Wikipedia has some interesting info on Lagrange points.
"Just how big is L2?"
It is a theoretical point, the JWST is near it, but as Douglas Adams pointed out "Space is big, I mean RELLY BIG. You might think it is a long way down the road to the chemists, but that is just peanuts compared to space", so hoperfully there will be enough space* for both of them.
*Did you see what I did there? 'Space' and 'space'? Oh never mind, I'll just talk amongst myself. You youngsters have no sense of fun.
L2 is a very precise point where the gravity of earth and the sun cancel out. Problem is that point varies over time due to the tiny effects of the rest of the orbital systems (the moon, jupiter, mars, etc), so nothing stays *at* the L2 point, they orbit it. The orbits are also unstable and need station-keeping to ensure they stay there.
James Webb's L2 orbit varies by half a million kilometres for example. Gaia is also there, as was Herschel and a few others - the decommissioned ones get placed into a heliocentric orbit, however if they were to fail they would eventually fall back to Earth, but would take a number of years to do that.
There's a cool animated gif that shows the gravity wells and where you're balancing an object that demonstrates how unstable it is.
https://upload.wikimedia.org/wikipedia/commons/d/d0/Lagrangian_points_equipotential.gif
The James Webb telescope is already at L2
Also Spektr-RG (Russian-ESA collaboration X-ray/gamma-ray telescope) and Gaia (ESA spacecraft getting very exact measurements of the positions, motions, and distances of about a billion stars). All three spacecraft stay roughly opposite the sun in the sky, but can wander around dozens of degrees from that point. Every few months, they have to apply small maneuvers to stay "balanced" at L2, similarly to how you might move to keep a yard/metre-stick balanced on your palm.
Anyway... the spacecraft in question have lots of room to play in; there's no risk of a collision.
(I'm aware of all this because my day job is with the asteroid surveys. In images, these objects are about the same brightness and have motions similar to near-earth asteroids. So we have to keep track of them, plus some spacecraft in lower Earth orbits. We've had a few instances where spacecraft were "discovered" and briefly thought to be asteroids... in fact, I'm currently in the process of adding Euclid and its Falcon 9 booster to the list of objects we check.)
Bill Gary: I'm aware of all this because my day job is with the asteroid surveys.
Recent APOD: https://apod.nasa.gov/apod/ap230630.html
"Are asteroids dangerous? Some are, but the likelihood of a dangerous asteroid striking the Earth during any given year is low. ..."
This asteroid survey?
This was one of those rare launches that I got to see the live stream while it was actually live. I'd just gone onto the the BBC News website and saw the main headline lining to their live coverage, clicked on it and the countdown was at about T-00:01:40. And even after all this time, it's not only exciting watching the launch, the coverage SpaceX offer of their launch, especially on board is still about the best out there and I got to the absolutely most exciting bit, a successful landing of the first stage on a barge at sea! That landing still impresses me even if it does happen successfully pretty much every damn time! It still feels like science fiction :-)
I can't wait to see the piccies from Euclid (or it didn't happen :-))
And even after all this time, it's not only exciting watching the launch, the coverage SpaceX offer of their launch, especially on board is still about the best out there and I got to the absolutely most exciting bit, a successful landing of the first stage on a barge at sea! That landing still impresses me even if it does happen successfully pretty much every damn time! It still feels like science fiction :-)
It's a funny old world. When I was a kid, launches were a rare and exciting event, and in B&W. Now, they're kinda routine. Still impressive to watch, especially with the telemetry allowing us to watch more of the launch process. The launches I don't get to watch live I can also watch via Scott Manley's summary. Exciting times in the space industry, both with actual launches and all the stuff being tested. And then of course there's the news and papers coming from all the new instruments that have been launched.
I'm seriously skeptical about the whole dark matter/energy thing. Those (and cosmic inflation come to that) remind me of the ancient geocentric model and the way it accumulated epicycles because it just didn't fit the facts without.
Don't know what will come along yet. MOND fits on the scale of a galaxy, but not larger I'm told.
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