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Showing posts with label Imagery. Show all posts
Showing posts with label Imagery. Show all posts

A History of the Landsat Science Satellite

Landsat 1 • Landsat 2 • Landsat 3 • Landsat 4 • Landsat 5 • Landsat 6 • Landsat 7 • Landsat 8

From the Beginning

“The Landsat program was created in the United States in the heady scientific and exploratory times associated with taming the atom and going to the Moon,” explains Dr. John Barker. In fact, it was the Apollo Moon-bound missions that inspired the Landsat program. During the early test bed missions for Apollo, photographs of Earth’s land surface from space were taken for the first time.






“This photography has been documented as the stimulus for Landsat,” explains Dr. Paul Lowman, who proposed the terrain photography experiment for the last two Mercury missions, the Gemini missions, and the Apollo 7 and 9 missions.


Thor-Delta rocket prepared to launch Landsat 1, 1972.
Thor-Delta rocket prepared to launch Landsat 1, 1972.

In 1965, director of the U.S. Geological Survey (USGS), William Pecora, proposed the idea of a remote sensing satellite program to gather facts about the natural resources of our planet. Pecora stated that the program was “conceived in 1966 largely as a direct result of the demonstrated utility of the Mercury and Gemini orbital photography to Earth resource studies.”


While weather satellites had been monitoring Earth’s atmosphere since 1960 and were largely considered useful, there was no appreciation of terrain data from space until the mid-1960s.
So, when Landsat 1 was proposed, it met with intense opposition from the Bureau of Budget and those who argued high-altitude aircraft would be the fiscally responsible choice for Earth remote sensing.


Concurrently, the Department of Defense feared that a civilian program such as Landsat would compromise the secrecy of their reconnaissance missions.
Additionally, there were also geopolitical concerns about photographing foreign countries without permission.


In 1965, NASA began methodical investigations of Earth remote sensing using instruments mounted on planes. In 1966, the USGS convinced the Secretary of the Interior, Stewart L. Udall, to announce that the Department of the Interior (DOI) was going to proceed with its own Earth-observing satellite program.


This savvy political stunt coerced NASA to expedite the building of Landsat. But, budgetary constraints and sensor disagreements between application agencies (notably the Department of Agriculture and DOI) again stymied the satellite construction process.
Finally, by 1970 NASA had a green light to build a satellite. Remarkably, within only two years, Landsat 1 was launched, heralding a new age of remote sensing of land from space.


The Landsat satellite record stretches from 1972 to the present. This gallery includes all Landsat images published on the Earth Observatory, Visible Earth, and Landsat Science web sites from all seven Landsat satellites (Landsats 1-8, Landsat 6 failed to achieve orbit). All of the images are in the public domain and may be used with attribution. The correct attribution for imagery obtained from this site is:


“Landsat imagery courtesy of NASA Goddard Space Flight Center and U.S. Geological Survey” or “USGS/NASA Landsat”





More History

 












Learn about the Landsat Legacy project        Landsat Science



Digital Town Planning by Night




“Here!” exclaimed Jebediah as he nosed his schooner onto a fan of fertile loam. Come sundown, a makeshift corral encircled his livestock, and by Sabbath eve, the crown of a crude barn rose above the neighboring hummock.


Next spring, a steady procession of ships yielded a healthy crop of farmhouses. Wagon wheels burned a double track to the river landing, where itinerant capitalists soon repurposed a cluster of spartan shacks:


Dispell ill humours at Rodger’s Saloon!

 Satisfy your homestead needs with Trusty Mercantile!

 Every fifth horseshoe free at The Irony!


Forthwith straightened and graded, Main Street ran east to west, land astride platted into tidy rectangles. Soon, Washington and Jefferson joined in parallel, crossed at even intervals by perpendicular First, Second, and Third Streets.


A crystal in saturated solution, this grid grew: shooting southeast into open country along Telegraph Road, doglegging left around Miller’s Swamp, and crossing the river at Monroe Street Bridge, which lensed the opposite shore into a different orientation…


And so on, until some time ’round the Depression, when town planners discovered:
Oh my golly, curves! By George, a city block doesn’t necessarily need to be a rectangle, right? And, three way intersections, yeah, they’re pretty darn tootin’ okay…


Thereafter, new streets came, but in more pear-shaped and less grid-like arrangements than before.
Now, to Yours Truly, nirvana is a sunny day, strolling well-worn sidewalks past the wide-windowed storefronts of an old downtown. Some people might call me a Main Streetaholic – I’ve been known to scour maps for quaintness, and on a road trip, I’ll happily choose the Byzantine route just to experience the charms of a bygone Broadway.

And I thought I knew about every one between Ukiah and Scotts Valley.


Until, out of the blue, a friend informed me: “I’m moving to Graton!
Graton…? California? Uh… Why? Up came the Street View, and there, west of Santa Rosa, it was: a pocket-sized downtown decorated by a handful of adorable “Old West”-style buildings. OMFG.


What other treasures had I missed?!


I made these maps to help me find out.


Above is San Francisco, and below, New York, Washington DC, Los Angeles, Tokyo, and five other interesting metros:


Tokyo
Tokyo
New York
New York
Paris
Paris
Los Angeles
Los Angeles
Washington DC
Washington DC
Chicago
Chicago
Berlin
Berlin
Boston
Boston
London
London
That’s every public street, colored by the predominant orientation of itself and its neighbors, thickened where the layout is most “grid-like” – to use an old-school woodworking metaphor, it’s as if we brushed some digital lacquer over the raw geographic transportation network data to make the grain pop.


For the detail-oriented, these are 100%-algorithmic images generated from MapZen’s Migurski-inspired October 2014 OpenStreetMap Metro Extracts as follows. First, we assign each linear street segment a compass-heading-based tone from a modified sinebow, where a 90 degree directional difference corresponds to a full color revolution, so that roads at right angles to each other have the same hue. Then, to render each point on the map, we use Proximatic, my custom high-performance k-NN engine, to calculate the length-weighted average of the colors assigned to the nearest 500 meters of street, keying render weight to the local degree of parallelism/orthogonality (derived in a similar mod-90° vector space), with rolloffs for outlying roads and territory.
Pan and zoom via Vladimir Agafonkin’s excellent Leaflet viewer, and click the “Acme” button for a more conventional map of the current view, kudos to Poskanzer.


Lots of stories in there: of cities waxed, towns waned, territory absorbed, and terrain negotiated (or, ala San Francisco, ignored completely).


Enjoy, and I’ll see you in the grids!       Data Pointed

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