Seeing Earth from outer space

https://pudding.cool/2017/10/satellites/

by callumlocke • 9 years ago

55 19 9 years ago

isostatic• 9 years ago

Really good, although this line annoyed me

"Communications satellites allow you to access the internet from your cell phone, or make a call to the other side of the world."

No, that's what towers and undersea fibres do. I work with satellites - they're a right pain when you're trying to use tcp over a bean with a >1sec delay and trying to deliver broadcast quality pictures for the ten, andthey're expensive when you're using a fixed station on the back of a truck, but we only use those from random places in the middle of nowhere where there's no 3G coverage.

99.99% of two-way communication traffic does not pass through a satellite, and tre portion that does keeps decreasing. Even 10 years ago a live video with someone in NZ would probably be bounced off not one, but two satellites, before arriving in London. Now it will take a fibre to singapore and then through Suez to France and into London that way.

Satellites are great at broadcasting to many people, andfor reaching the middle of nowhere where there's limited infrastructure. They aren't a normal means of communication though.

fnwx17• 9 years ago

Wait, there's an undersea cable from NZ to Singapore to the Suez Canal? How many of these are in the world? The only ones I knew where UK to US.

simonh• 9 years ago

Enjoy. https://www.submarinecablemap.com/

Per Isostatic's point, Ive not worked with satellite comms but did work on tracing financial transaction links all over the world. It al went by cable and I remember having the conversations about why we didn't use satellites. The latencies are terrible. In yet another life I spent some time working in Saudi Arabia, the compound had a satellite internet connection and it was terrible. The bandwidth itself was fine, but the delay between clicking something and getting a response was painful.

The main problem is that most current satellite communications goes to geosynchronous birds that are a long way out from earth. The low earth orbit constellations companies like SpaceX are working on should mostly avoid the latency issues because the hop up to the satellite and back down again should be only a couple of hundred klicks instead of the 35,000 km plus, about three earth diameters, out to GTO.

hycaria• 9 years ago

It's even crazier when you know their size, yet they still manage to find them in a whole ocean and to grab the repeaters for maintenance.

Robotbeat2• 9 years ago

Most of this is due to satellites being in geosynchronous orbit, which is ~40,000km away. This trend will likely slow or even reverse a bit once the big LEO constellations are launched (some are being launched at ~400km altitude).

25ms local ping times (eventually 10ms as the 340km altitude constellations launch) near-term and long-distance pings actually better than fiber. And with enough throughput to actually make a difference vs fiber.

Robotbeat2• 9 years ago

A lot of cellphone connections in Africa and rural locations generally are backhauled by satellite.

tones411• 9 years ago

Well done!

Sujan• 9 years ago

Does scrolling back up to see something from before work for anyone reliably? For me it always skips things, so if I scrolled over something (which happens quite quickly while reading as there only seems to be a very small "sweet spot") I can't really go back to it...

dEnigma• 9 years ago

Scrolling works, but the website nonetheless is downright unusable for me. Clicking on links only works every fifth time or so and I constantly get WebGL errors and am asked to reload the page.

pmontra• 9 years ago

It works very well on Firefox, Android 7.1.1. I didn't check on my desktop yet.

muxator• 9 years ago

Android 7.1.2, Firefox 56: it always skips for me, too.

weavie2• 9 years ago

Let's not forget this image of Earth from outer space : https://en.wikipedia.org/wiki/Pale_Blue_Dot

mxuribe2• 9 years ago

I'd never seen/heard of this! Its cool, though humbling...reminds me that we're so small.

weavie2• 9 years ago

Conversely, there are approximately 7 * 10^27 atoms in the human body and only 10^24 stars (estimated) in the known universe. So it some ways, we are also very big.

devkn0t• 9 years ago

I'm having some visual bugs in the 3D rendering of the Landsat Satellite in Firefox Desktop. It looks like a problem with the depth test or the culling.

mrguyorama• 9 years ago

This article is fairly lightweight from an information standpoint, but interesting nonetheless. Particularly because of a project I've been working on recently.

The Flight Simulator community works very hard to improve the massively extendable Flight Simulator X system, and part of that includes creating better scenery to fly around in. The gold standard for flight simulator scenery is "Photoreal", where you lay pictures from satellites over geographic elevation data to make beautiful vistas and allows you to do things like navigate purely by following real world roads and landmarks. Unfortunately, freely available satellite imagery is often resolution as low as 30 meters per pixel, making low level flying a smeary, indistinguishable mess. This prompts the community to turn to reverse engineering Google and Microsoft APIs and breaking Terms of Service agreements in order to use their 0.3 meter per pixel images.

The part that angers me is that, as an American, my government has signed off on using potentially billions of dollars developing, deploying, and utilizing highly advanced imagery satellites, and likely can reach inches per pixel. Despite paying for all these satellites and their use, as well as a giant datacenter in Utah, I have no way of utilizing these photos.

I believe that free access to high resolution satellite imagery would be a public good, and many first world governments have the ability to create such a thing. They could easily distribute 0.2 meter per pixel images without compromising any sort of national security

llccbb• 9 years ago

Though not the resolution of WorldView (~50 cm), Landsat 8 can get you 15 m resolution if you use pan sharpening. ESA's Sentinel 2 can get 10 m true-color natively. Both these are free to use and Landsat images are public domain. Copernicus data is copyright under ESA, but they are fairly permissive.

Over the US there is abundant true-color aerial imagery at resolutions of 1 meter that is freely available from USGS/USDA. I suspect there may be similar datasets over parts of Europe.

Not trying to say these will solve all the problems you mention or that scraping Google's tile server is specifically amoral, but the state of free satellite imagery is better than it has ever been (haven't even talked about weather satellites capturing images every 15 minutes!).

On the topic of defense contractors operating these high resolution satellites and not sharing the data -- It isn't really true that you have no way of utilizing these images. They are almost all available for purchase, albeit at a very steep price. If you are interested in the Arctic/Antarctic you can apply for free access to insane amounts of high-resolution data over the high latitudes. Granted this is probably not the area you are interested in. You can also apply for grants directly with Digital Globe if I remember correctly.

In many cases the satellite operators can't make every strip available because they are mission-oriented. Where the satellites are imaging can often be classified information. Recognize that these aren't civilian satellites. They are DoD contractors. Just because you can perceive the amount of data that exists by looking at Google Maps doesn't mean it is for you. Consider all the the National Geospatial Agency collects under funding from your taxes and the mere crumbs that ever get let through to the public.

I am all for citizen access to very high resolution satellite products, but from my experience it would be better to establish a new federal program that operates in that way. More stability in that sense and less potential for access to suddenly be revoked. If we can re-establish the mindset in DC that federally operated science programs and open data are beneficial to every american then we will be much better off in the long run.

Seeing Earth from outer space

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