Landsat proved the power of remote sensing | Hacker News Reader

Landsat proved the power of remote sensing

spectrum.ieee.org

40 pointssohkamyung16 comments

Very useful and powerful technology. By using Landsat images you can even detect water leakages from buried water pipelines [1],[2]. Processing the satellites images with advanced techniques like AI can also reveal something that oblivious from the plain sight [1],[3].

[1]Satellite Leak detection:

https://github.com/3springs/satellite_leak_detection

[2]Leak Detection from the Buried Water Transmission Pipeline Using Landsat 8 Satellite Images:

https://www.researchgate.net/publication/305990869_Leak_Dete...

[3]The powerful technologies making your future (better):

https://venturebeat.com/2022/05/12/the-powerful-technologies...

To me the most impressive detail about Landsat is that, on the first one, the main camera failed, predictably, and all its results came from a sort of "back-up" camera whose creator had to fight tooth and nail to get lofted.

That the USA essentially gives out free remote sensing data to the entire globe, is actually incredible.

Even with landsat as free competition, the cost of remote sensing data is exceptionally high.

> That the USA essentially gives out free remote sensing data to the entire globe, is actually incredible.

Indeed, in the documentation for the Nigerian Gas Flare Tracker in 2019 I wrote the following:

> “I keep being impressed by NOAA’s and NASA’s openness. That they provide unfettered access to such an amount and quality of data sources and even their own time to answer questions for the benefit of foreign citizens (Spanish, British, and Nigerian) stands in contrast with the attitude of other agencies like the European Space Agency (ESA) and the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfart, DLR). I must admit that the USA does such things better.”

> https://sentido-labs.com/en/library/#gft-2018

That project uses NOAA’s VIIRS data to monitor gas flaring in Nigeria, and is used by the National Oil Spill Detection and Response Agency of the Nigerian Ministry of the Environment.

I have zero background in this area, just following the rabbit hole -- there seems to be open access to ESA's Sentinel missions: https://scihub.copernicus.eu/

Is this any good?

Hey, thanks for this link, it looks interesting but I’ll have to find out what kinds of measurements they provide. The User Guide seems to have a complete list:

https://scihub.copernicus.eu/userguide/

Then they have more details in their Technical Guides, for instance this one for Sentinel-5P: https://sentinels.copernicus.eu/web/sentinel/technical-guide...

There are several interesting things there, like CH₄, SO₂, etc. They also include data derived from “Suomi-NPP VIIRS Clouds” which is the NOAA instrument used by the Gas Flare Tracker, matched to the ESA data.

Here is the Sentinel-3 OLCI Technical Guide: https://sentinels.copernicus.eu/web/sentinel/technical-guide...

It would be great news if they changed their policies in these years.

(A couple of minutes later, checking while writing this comment...) Oh... “Please login to access our services...” Ok, I might take a look at it later.

Thanks anyway for the link, I might have seen a previous version of this page but I don’t remember seeing the detailed product (measurements) list. It does look more promising that it used to.

Meanwhile in USA: “The VIIRS Nightfire (VNF) digital data access will be transitioned to restricted access for organizations that have approved data user license agreements with EOG. Commercial users can also be approved, but will be expected to make annual payments to cover a portion of the VNF program costs.” https://eogdata.mines.edu/products/vnf/

The ESA is just as open as nasa, and the freely available Copernicus images benefit US citizens as well. This pissing contest that you try to start is ridiculous. Americans and Europeans are very happy with each other in this regard.

I’m sorry I wasn’t clear: the last paragraph quoting the current conditions for using the VIIRS Nightfire data, where as you correctly note the conditions of use are similar, is a change that happened afterwards. I should have written “Meanwhile in USA, things have changed: ...”.

During the years when I worked on the Oil Spill Monitor and Gas Flare tracker, from 2013 to 2019, NOAA gave the data completely without conditions: anyone could go to the Suomi-NPP website and just download the CSV files without login or anything else, and not just the current one (the satellite does one pass per night over the whole world) but also historic data.

Now things have converged, and your statement that "ESA is just as open as NASA" is, at least when comparing the Sentinel vs. the VIIRS Nighfire data, absolutely correct.

The Sentinel data is excellent, and spans several satellite platforms and a huge number of modalities. In some significant cases (surface deformation, imaging spectroscopy, for example) Sentinel surpasses (current!) NASA data. (I use both in various projects.)

In general there are a lot of trades, including ground sampling distance, temporal revisits, and spectral coverage. So it’s good to have options.

Both NASA and ESA do exceptionally well at offering free data for science purposes. All the NASA science data, Earth and otherwise, is free.

People think of this data as a camera that’s pointed at a target, but that’s not how it works now. There are calibration and inversions that have be done to transform the observed electromagnetic data into physically-relevant quantities.

I’m not a commercial user, but it is possible that there are charges for some commercial purposes, or for niche applications that require high volumes or low latency. (Although many missions offer near real time feeds for free as well as slower calibrated feeds.) The data egress costs are a concern for NASA Earth science…I don’t remember the specific numbers but they have been increasing rapidly.

Do they have an archive of different datasets they offer. I'd be curious but to see if their are any that pique my interest particularly.

Start at: https://search.earthdata.nasa.gov/search

Problem is, there are a lot of missions at this point: https://svs.gsfc.nasa.gov/30065

It’s easy to get confused. If you are a potential science user, be sure to get in touch with another savvy user in your domain, or with someone from the instrument team, before you write it up.

> Even with landsat as free competition, the cost of remote sensing data is exceptionally high.

And yet strangely enough remote sensing companies apparently struggle to make a profit, at least as I understand it.

It's not only the USA, European citizens also pay for freely availabe earth observation data via the Copernicus program. It includes optical multispectral, radar, and hyperspectral images with weekly coverage.

Wow that article is about what my dad did at Purdue in the 1970s!

Apparently my mom helped him with the color “printouts”. They would print out Rs Gs and Bs and my mom would color them in on the printout and they would tape it all on the wall and take a color picture of the wall with a regular old camera.

From my dad: "I was the only one left at LARS @ 3 or 4 in the morning on May 25, 1972 when I displayed the first ERST/LANSAT, but nobody knew where in the US the image was taken, so I went to my car in the parking lot (the gold Pontiac T37) and brought in my road map from my glove compartment and by 5 am I had identified the location of the first ever ERST/LANDSAT image that later was known as the Lake Texoma frame :)"

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