I was confused for a minute on how it's both _geostationary_ and _over Europe_ -- you can't be geostationary if your orbit is not over the equator!
Turns out[1] the MTG-S1 satellite is in fact geostationary and parked at exactly 0°00'00"N 0°00'00"E (off the coast of Ghana), 42164 km up from the center of Earth, it's just pointing at Europe at an angle.
But you are right, [1] confirms "0° longitude".
[1] https://user.eumetsat.int/resources/user-guides/mtg-in-opera...
Presumably it's an intentional choice to put it at such a round number, rather than any scientific benefit over it being, say, 10km west or east.
[0] A few sites give 10km as a standard minimum separation for geostationary satellites. That theoretically allows a thousand of them in the 100km cube, but I am guessing a lattice of them every 10 km in all 3 dimensions would not be manageable.
But some geostationary satellites are close enough so that there can be failover without adjusting receiving antennas on the ground.
So you can of course keep them dense around the equator. Probably very close down to hundreds of meters (if not less) if you coordinate the station keeping. After all the forces that push or pull the satellites out of orbit (tidal forces and particle streams) should be very similar for close neighbours. Problem is that you have to share the bandwidth of the up- and downlink then because the dishes of the groundstations cannot focus so sharply.
Given that, and redundancy put aside, one bigger satellite with more payloads would usually be cheaper than two smaller ones without any disadvantages.
Is there a way to list what's all in geostationary orbit (either stationary at the equator, or at which longitudes they commonly cross through the equator)? Edit: found https://en.wikipedia.org/wiki/List_of_satellites_in_geosynch... (geosynchronous is a superset of geostationary). The closest is H2Sat at 0.5°. Article notes: "Some of these satellites are separated from each other by as little as 0.1° longitude [or] approximately 73 km". Trickier than keeping them apart is apparently getting a narrow enough communications beam width. /edit.
How long until we can see this ring above the equator from the ground? Although I guess the thickness would rival Saturn's rings and we would probably not be able to make it out even if the sats were shoulder to shoulder. We do see satellites from the ground when the sun hits them right, but those are typically around 1000x closer
In other words, it is
> "The Infrared Sounder on MTG-S1 is the first hyperspectral sounding instrument in geostationary orbit."
https://www.esa.int/Applications/Observing_the_Earth/Meteoro...
Is there a more technical article describing this hyperspectral instrument somewhere? It sounds pretty novel.
edit: Also, I'm now confused about the ESA's claim to be "the first", because
> "In 2016, the Chinese Meteorological Agency (CMA) launched the Geostationary Interferometric Infrared Sounder (GIIRS), to be the first hyperspectral sounder in geostationary orbit"
https://www.aos.wisc.edu/aosjournal/Volume38/Loveless_PhD.pd... (PhD thesis of David M. Loveless (2021))
I think you might have misread the title, "Europe’s first [...]"
> Is there a more technical article describing this hyperspectral instrument somewhere?
https://space.oscar.wmo.int/instruments/view/irs has an short overview
Then this document provides an introduction (+ details) about the MTG-IRS program in general: https://user.eumetsat.int/s3/eup-strapi-media/MTG_IRS_L2_ATB...
No; I'm quoting the esa.int article verbatim. The eumetsat.int article qualifies "...over Europe", but the esa.int does not. I suspect esa.int is just mistaken.
The IRS seems 4km and sentinel 4 8km if I read it correctly. The cool thing is that it is stationary unlike other sentinel satellites and can actually be used for now casting. No clue how infrared sounding performs with cloud cover.
In fact, I have nothing but respect for any agency that makes free and public access to earth observation data a priority, regardless of how janky their API is.
Are there any other standout national agencies you've dealt with?
And, have you seen any degradation recently with NOAA data? NGS has always impressed me, but I've been worried about their future lately.
Are you looking at sentinel 1 or sentinel 2
I think esa.int is probably one of the more popular .int domains on HN: https://news.ycombinator.com/from?site=esa.int
• World Health Organization - https://who.int
• NATO - https://nato.int
• Council of Europe - https://coe.int
• Mercosur - https://mercosur.int
• African Union - https://au.int
• EFTA - https://efta.int
(Not real affiliation but still: I added a domain to that page at some point)
But I guess this is what you get when these things get away from technologists.
(In Fortran 66, variables didn't have to be declared. They would be integer if they began with I, J, K, L, M, or N. Otherwise it would be floating point [REAL, in Fortran parlance]. To this day it's why for loops usually use "i". With the bonus joke that God is real unless declared integer.)
for example, the US has stopped sharing weather data with canada.
Citation needed. Most weather data from NWS is required by treaty to be disseminated through WMO compliant methods. The Metsat data is transmitted unencrypted from the GOES sats. I don’t believe they even have the capability to encrypt it. It’s only DoD weather data that’s not being widely disseminated, AFAIK.
I don't know if that is still in effect. Google "Did the US stop sharing weather data with Canada?" or ask your favorite LLM that provides references for its answers for more information.
If that was not the question, can you provide more detail?
Perhaps earth's spherical shape gives an advantage to the satellites in both cases ?