Comments
Disastrous_Elk_6375 t1_j9z7xvx wrote
> "By subtracting the visible matter, we can calculate the presence of the dark matter which is in between," [Euclid project manager] Racca said.
This reminds me of this great nugget brought to us by the department of redundancy department:
The missile knows where it is at all times. It knows this because it knows where it isn't. By subtracting where it is from where it isn't, or where it isn't from where it is (whichever is greater), it obtains a difference, or deviation. The guidance subsystem uses deviations to generate corrective commands to drive the missile from a position where it is to a position where it isn't, and arriving at a position where it wasn't, it now is. Consequently, the position where it is, is now the position that it wasn't, and it follows that the position that it was, is now the position that it isn't. In the event that the position that it is in is not the position that it wasn't, the system has acquired a variation, the variation being the difference between where the missile is, and where it wasn't. If variation is considered to be a significant factor, it too may be corrected by the GEA. However, the missile must also know where it was.
TheCatLamp t1_j9z7ceu wrote
Euclid sounds so cool, it's a nice name for it.
Hope it does not actually find some non-euclidean geometric spaces in space, tho. That would be frightening.
jamjamason t1_ja0d04m wrote
Umm, you are living in a non-Euclidian space.
augugusto t1_j9z1we1 wrote
How large are Lagrange points? I think this one is going to L2. Isn't Webb also there?
valcatosi t1_j9z2ta7 wrote
The Lagrange points themselves are (theoretically) literally points. Zero spatial extent. The reason they're useful is that you can enter what's colloquially known as a "halo orbit" around them. Those orbits can be enormous - there's plenty of room for all the telescopes we could ever send.
t3hjs t1_j9z83n5 wrote
So If I understand you right, the satellites dont sit stationary on the exact point.
Instead they orbit around the point, and thats possible because there is a circle (ellipse?) you can draw around the Earth-Sun L2 point that is equipotential, due to the radially symmetric pull of the Earth-Sun (if radius is defined as a perpendicular to an axis straight through the Earth and Sun)
valcatosi t1_j9z9qz1 wrote
Yeah, that's essentially it. Here's an ESA presentation that goes into a little more detail, since as you've guessed it's slightly more complicated: https://www.esa.int/Enabling_Support/Operations/Libration_point_orbits
[deleted] t1_j9ze3v2 wrote
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rocketsocks t1_ja13kdl wrote
All of the "orbits" or pseudo-orbits at the Lagrange points are within a very large volume. At the Sun-Earth L1 and L2 points the typical orbit is a halo orbit or a Lissajous orbit which loops around the Lagrange point at a distance of typically a few hundred thousand kilometers (on a similar scale to the Earth-Moon distance). In a practical sense the volume available for spacecraft to use the points is so enormous that we are unlikely to run into any crowding constraints any time soon.
Seek_Treasure t1_j9zdvu2 wrote
It would be cool to have a non euclidean space telescope though
[deleted] t1_j9y3hnj wrote
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KnottaBiggins t1_ja0qmi4 wrote
Well, at L2 it won't be lonely - JWST is already there.
[deleted] t1_ja2w6yg wrote
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[deleted] t1_ja25mzu wrote
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tanman729 t1_j9zwrlx wrote
Didnt you just launch a new telescope NASA? you dont get another one until you finish that one!
[deleted] t1_ja2debs wrote
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marketrent OP t1_j9xwj1g wrote
Excerpt from the linked content:^1
>Cannes (France) (AFP) – For now, Europe's Euclid spacecraft sits quietly in a sterilised room in the south of France, its golden trim gleaming under the fluorescent light.
>But in a few months the space telescope will blast off on history's first mission to search for two of the universe's greatest mysteries: dark matter and dark energy.
>How will Euclid, which is named after the ancient Greek founder of the field of geometry, observe something that cannot be seen? By searching for its absence.
>The light coming from billions of years in the past is slightly distorted by the mass of visible and dark matter along the way, a phenomenon known as weak gravitational lensing.
>"By subtracting the visible matter, we can calculate the presence of the dark matter which is in between," [Euclid project manager] Racca said.
>To do this, Euclid has two main instruments, a 1.2-metre (four-foot) diameter telescope and the Near Infrared Spectrometer and Photometer (NISP), which can split infrared wavelengths not visible to the eye.
>
>Aiming to shed light on these dark secrets, the European Space Agency's mission will chart a 3D map of the universe encompassing two billion galaxies across more than a third of the sky.
>The third dimension of this map will be time -- because Euclid's gaze will stretch out to 10 billion light years away, it will offer new insight into how the 13.8-billion-year-old universe evolved.
>Partly what sets Euclid apart from other space telescopes is its field of view, which takes in an area equivalent to "two full moons", said David Elbaz, an astrophysicist at the French Atomic Energy Commission.
>This wide view will enable Euclid to locate massive structures like black holes that the Webb telescope cannot hope to find because its "field of view is too small", Euclid's project scientist Rene Laureijs told AFP.
>Only a few final tests remain before it heads to Cape Canaveral in the United States for a launch scheduled between July 1 and 30 on a SpaceX Falcon 9 rocket.
>Euclid was originally planned to get a ride into space on a Russian Soyuz rocket, but last year Moscow withdrew its launchers in response to European sanctions over its invasion of Ukraine, delaying the launch.
^1 AFP via France Médias Monde‘s RFI, 25 Feb. 2023, https://www.rfi.fr/en/science-environment/20230225-euclid-spacecraft-prepares-to-probe-universe-s-dark-mysteries