ESA Sentinel-1D delivers first high-resolution images
esa.int
esa.int
> Radar instruments can image Earth’s surface through clouds, precipitation, regardless of sunlight, making them particularly well suited for monitoring polar regions. The Sentinel-1C and -1D satellites also carry an Automatic Identification System (AIS) instrument – improving the mission capacity to detect ships and sea pollution. The Sentinel-1D AIS was also activated as the satellite passed over Antarctica capturing the presence of ships in these extreme areas.
A single image from Sentinel-1 won't give a height map directly, but a pair can using interferometry (InSAR), as the phase of the backscattered signal is also measured. With that you can derive something about the terrain. It's not super accurate though for absolute height maps.
And yes the signals pass through cloud and it works at night.
https://en.wikipedia.org/wiki/Interferometric_synthetic-aper...
[1]: https://www.earthdata.nasa.gov/data/instruments/srtm [2]: https://en.wikipedia.org/wiki/TanDEM-X
The core idea is that you send out pulses as you pass over the ground and then record the echoes. You can create an image by - for each pixel in the image - working out the response you would expect to receive back and correlating that with the actual responses you saw. That gives you a reflectivity value. You can do it in multiple polarisation to better distinguish things.
Check out this video they made if you want your mind blown: https://www.youtube.com/watch?v=rXCBFlIpvfQ
SARLink is a passive satellite backscatter communication system that uses existing spaceborne synthetic aperture radar (SAR) imaging satellites to provide connectivity in remote regions .. As the first technique for passively sending information bits from the ground to a SAR satellite — and with some SAR systems offering open-access data — this system could enable anyone to send information without expensive licenses or subscriptions.
Thus, it provides an accessible way of sending messages in areas without connectivity or in censored environments where active radio transmissions cannot be used. Furthermore, SARLink requires no modification of the satellite infrastructure.. We demonstrate our system using the European Space Agency (ESA) satellite Sentinel-1A, as the data is freely available and the system regularly images all the land on Earth .. a 5.5 ft by 5.5 ft modulating corner reflector could send 60 bits every satellite pass, enough to support low bandwidth sensor data and messages.https://en.wikipedia.org/wiki/Tobler%27s_second_law_of_geogr...
We had zoomable, downloadable images in the 90s, with bandwidth as the only constraint.
Now I've got 50x as many pixels and I'm forced to use a bookmarklet and 2 menus to be able to see it larger than my fingernail.
Chrome has a similar option, which also works on this site. I expect this might break a few pages, but Google Maps and OpenStreetMap work fine, with pinch zoom zooming the map when you do it on the map.
And frankly it's in the wrong place if you ask me.
Copernicus browser claims 10x10 meter pixels (which seems to be correct) but the actual resolution of the radar is supposed to be 5m-x-20m for the standard IW mode. I assume "high resolution" here means the data should have 5m x 5m resolution (Strip Map mode) which in Copernicus browser claims 3.5x3.5m pixels.