terramex

10 ms·

91.
by terramex 5y ago
It preceeds this news, I've seen original post translated into polish two days ago. edit: here https://www.wykop.pl/wpis/64199473/translator-z-rosyjskiego-... and this was given as original source: https:&#x
92.
by terramex 5y ago
Dyson sphere would emit significant amount of infrared light but no visible light. Original Freeman Dyson's paper from 1960 was titled "Search for Artificial Stellar Sources of Infrared Radiation" https://sci-hub.
93.
by terramex 5y ago
I'm surprised that so many comments talk about "too many draws in classical chess problem" as just yesterday we just finished Tata Steel that was a terrific tournament with plenty of decisive games (84 out of 182) and even mo
94.
by terramex 5y ago
The biggest surprise for me is that organ transplant from animals had been attempted in the past, I was sure it had not been done yet. Apparently there was a newborn that lived for 21 days with baboon heart in 1984: https://en.wi
95.
by terramex 5y ago
Quantum efficiency is a ratio of how many electrons are created from typical photon hitting a detector. For optical instruments max value is 100% and is the ultimate reference - every photon gets converted into electrical signal. This is wh
96.
by terramex 5y ago
Final optical instruments were integrated in 2014, proposed launch date at the time was 2018. There was not enough time to think about any upgrades and cost was ballooning anyway. NIRCam has quantum efficiency of 70 to 90% depending on ligh
97.
by terramex 5y ago
No, cameras' resolution is limited by diffraction that is a function of mirror size. JWST achieves that diffraction limit in range between 2 to 28.5 micron where most of it observations will be performed. As for sensitivity, installed
98.
by terramex 5y ago
> As an additional challenge, the JWST observation schedule in the next 21-day period will not be known at the time of SK [station keeping] maneuver planning. A planned observation schedule one week ahead will be available, but the actua
99.
by terramex 5y ago
Momentum flap will bring average CoP closer to CoM but CoP will shift as JWST is rotated to point at different targets. Unwanted torque can be minimised by carefully choosing observations targets so it mostly cancels out but it cannot be do
100.
by terramex 5y ago
> That's a fixable design problem. You are right, it is fixable. It was fixed by adding active station keeping to the telescope. > Or you can rotate the telescope. There are limits on its rotation with respect to the Sun, dark si
101.
by terramex 5y ago
Here is a paper detailing metal reaction wheels failure modes going into detail on how charge was built up and solar influence on this process: https://www.esmats.eu/esmatspapers/pastpapers/pdfs/2017/bial
102.
by terramex 5y ago
> Some high priority scientific observations (GTO & GO) with the JWST are likely to be carried out during the commissioning period, since it is clearly desirable to begin to take science data as early as is technically feasible. >
103.
by terramex 5y ago
There are no plans at the moment because it is not even clear how long will current fuel supply last. NASA engineer today said "maybe 20 years, roughly speaking", my back-of-napkin math says that it could be up to 30 if everything
104.
by terramex 5y ago
> Some high priority scientific observations (GTO & GO) with the JWST are likely to be carried out during the commissioning period, since it is clearly desirable to begin to take science data as early as is technically feasible. >
105.
by terramex 5y ago
Actually LUVOIR will most likely have smaller 6 meter mirror to reduce cost and use lessons from JWST construction. It will be simpler design than JWST as it will use only 2 or 3 layer sunshield and no cryocooler (creating equipment that ca
106.
by terramex 5y ago
> It's like saying if you invent the first microscope, and discover bacteria, why bother with another one? Exactly, why bother with discovering millions of bacterias with 20 copies of the same microscope if for the same cost can bui
107.
by terramex 5y ago
> The reason Kepler ran out of fuel when it did was that it was expending more maneuvering fuel for attitude control because two of its four reaction wheels failed. Hubble and the ISS also had similar failures. And to calm down anyone af
108.
by terramex 5y ago
It matters a lot, L2 is unstable point so if it ventures beyond L2 there would be no way to bring it back and it would enter a heliocentric orbit. Communication between Earth and telescope would become impossible after some time as gimballe
109.
by terramex 5y ago
It will surely take plenty of engineering and calibration photos during that time. I don't think they will be published instantly because telescope operators want to make a 'wow' effect with first photos from JWST. Here is fi
110.
by terramex 5y ago
There is a bit of exaggeration, for example non-explosive actuators that needed to be released for sunshield to deploy have two redundant electric circuits for their deployment but are considered 'single points of failure' as comp
111.
by terramex 5y ago
Pressure from solar wind will constantly put some torque onto telescope as its center of pressure is offset from center of mass. This torque will be counteracted by reaction wheels but they have maximum rotation speed and need to be unloade
112.
by terramex 5y ago
Similar question was just asked during press conference and the answer was "telescope is cooling a bit faster than we simulated but it is not a significant difference, it might be ready one or two days ahead of current estimation"
113.
by terramex 5y ago
> Mike Menzel: 49 of the 344 single point failures remain and will remain throughout the mission. They are the same types of things on every mission, like propulsion. 15 are related to the instruments. https://twitter.com&#x2
114.
by terramex 5y ago
I've read that optical tracking/docking markers were added around mating ring that connected JWST to Ariane upper stage. It does not mean that docking to it will be easy but it was at least considered.
115.
by terramex 5y ago
It does use helium only as refrigeration fluid in closed cycle, it does not get depleted. Building a cryocooler capable of achieving so low temperatures without boiling helium off was a major hurdle in JWST development.
116.
by terramex 5y ago
Hubble needed to hide mirror because it is passing from sunlight into shadow every 47 minutes and mirror has to be protected from thermal stress. Also Earth emits some light even on night side that would interfere with observations. JWST&#x
117.
by terramex 5y ago
Not an IR astronomer, but enthusiast astrophotographer. As I understand it there is a bit of leeway in the sunshield. They added strips of "duct tape" going across layers to prevent potential tears from spreading and telescope can
118.
by terramex 5y ago
It has a docking ring for potential service mission.
119.
by terramex 5y ago
An article clearing it up a bit: https://www.autocar.co.uk/car-news/new-cars/renault-zoe-give... Matthew Avery, Euro NCAP board member and chief research and strategy officer at Thatcham, told Autocar: “Every few
120.
by terramex 5y ago
> On M1 Air there is pwm flickering which makes impossible to work with it According to table you linked M1 Air has PWM frequency of almost 120 kHz, which very high and well above headache and eye strain inducing frequencies.

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