Salt Lake City from LandSat

Radiogal writes: "A great view of the area from NASA! See olympics.gsfc.nasa.gov." This is about all of the Olympics you're going to see on the web. :)

All right!

[CounterZer0]

Now we can pick out EXACTLY which targets to choose </sarcasm>
Pictures like this are a real neat use of satellites, even if they don't serve very much 'purpose' (well, in this case). Wonder what it would cost to set up a stream of this view during the olympics? Would that violate any 'single broadcaster' agreement? :)

Re:All right!

[TwP]

Now we can pick out EXACTLY which targets to choose

Now, I know you meant that comment as a joke, but it was in poor taste.

The satellites used to take these photos are in low earth orbit. This means they complete one orbit in roughly two or three hours. You really can't get a live video feed covering one geographic region for an extended period of time. Sorry :(

Re:All right!

[robsimmon]

At least two of the satellites involved--Terra [with the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument] and Landsat 7 [with the Enhanced Thematic Mapper plus (ETM+)]--have an orbital revisit of once every 16 days. Due to the field of view, low resolution data - 250 km per pixel (MODIS) - is produced every day or so. Medium resolution (15 meters per pixel, ETM+) every 16 days (well, maybe 9). IKONOS, which provides 1 meter data, is a commerical mission, and I don't know the specifics, but the revisit time is even less frequent.

http://earthobservatory.nasa.gov/Library/AM1/ [nasa.gov]
http://earthobservatory.nasa.gov/Library/Landsat/ [nasa.gov]

and in response to the target remark, we are no longer allowed to post labelled satellite images of NASA centers.

More cool related imagery (shameless plug): http://earthobservatory.nasa.gov/Newsroom/BlueMarb le/ [nasa.gov]

I can see my house from here!

[Anonymous Coward]

Who's that guy going into my house?

More content coming Friday

[minervaz]

There will be more content coming up on the site on Friday afternoon -- zooms from space into the various sites around Salt Lake City.

What surprises me...

[A_Roche]

,and it shouldn't, is the degree of detail they have with those things..We have all heard of the 'mythical' "Tell you which way the coin landed" cameras, but you don't get to see them. I won't get to go to the Olympics, so this is noce to get to see where they will be.

From the air

[flikx]

you can't see all the filth that I trudge through at the university of utah on a daily basis.

You can't see much from space this week.. the temperature inversion is awful. You can't even see our beautiful mountains.

Temperature Inversions

[swillden]

You can't see much from space this week.. the temperature inversion is awful. You can't even see our beautiful mountains.

For any of you who are wondering what flikx is talking about:

The Salt Lake Valley is surrounded on the east and the west by tall mountains, and the exits from the valley on the north and south are relatively narrow. The effect is almost like a big bowl. Fairly frequently during the winter a pocket of warmer air gets trapped in the bowl underneath a layer of cold air. This situation is called a temperature inversion.

The problem with this situation is that the cold air acts like a lid on the valley, trapping all of the smog produced by cars, refineries, factories, etc. When this situation persists for more than a few days it can get pretty bad. Not L.A. kind of bad, but thick enough that it does ruin the view, and bad enough that use of wood-burning stoves and fireplaces are disallowed to help keep us from exceeding EPA regulations on particulate matter (and we still do, at times). The haze stays high enough that it doesn't really affect people, just the visibility.

Unfortunately, after several weeks of record cold, but quite clear, weather, an inversion began a few days back, and there's no telling how long it will persist. Up in the mountains at the ski resorts where the downhill events are will be clear and typically beautiful, but the medals plaza, skating rinks, hockey, etc. will be shrouded in brown smog.

Too bad, really, but there's nothing to be done. A good snowstorm will both scrub the haze from the air and has a good chance of breaking the inversion, so that's our best hope. There is a storm on the forecast for Friday morning, which would be perfect. The view of the mountains from the valley is absolutely spectacular when the air is clear.

Re:Temperature Inversions

[Conor]

A temperature inversion occurs when a layer of cold air is trapped below a layer of warmer air. Thus the air temperature increases with altitude, which is not usually the case. This is often due to a high pressure region in the winter, which traps the air close to the ground. Since the cold air is less bouyant than the warm air above, the normal convection process stops working and a build-up of pollutants occurs. A strong horizontal wind is needed to clear out the cold, dirty air from the city.

Re:Temperature Inversions

[namespan]

Not L.A. kind of bad

I don't know about that. Having lived in LA for 2 years and near SLC for a long time, my judgement is that it DOES get "LA kind of bad" sometimes. "Hazy Shade of Winter" must have been written for Utah between November and March.

The only difference is LA is hazier in the summer, and Utah is hazier in the winter. Solution: live in So. Cal in winter, Utah in Summer. Yep.

Very Cool

[Danious]

The parent site for these images, NASA Earth Observatory is very cool, it's got some incredible pictures, and you can generate your own animations from their datasets! I've just watsted 2 hours and several 100Mb of my employers time/band-width on it :-) Damn, now that code is going to be late, time for another coke infusion...

Hubbel telescope

[Perdo]

Hubbel was myopic at launch because the design was barowed from a late seventies recon sattelite. Hubbel was perfect for earth surface imaging... Now with 1 meter imaging available on the web to the public, and hubbel being what was possible in the late seventies, how good is current earth imaging? Better than anyone that wants to not live paranoid is willing to belive.

Re:Hubbel telescope

[Hoi Polloi]

That is why I flip the bird to the sky at the same time everyday. "Resolve THIS!"

Re:Hubble telescope

[Caractacus Potts]

The Hubble telescope was myopic because of a 1.3 millimeter error on a piece of test equipment used to make the primary mirror. The construction of the mirror was flawless, but it just happened to be the wrong shape. I've never heard about it being based on a recon design from the 70s, that's sounds pretty iffy.

Here's a short summary: Why The Hubble Space Telescope Went Wrong [uoguelph.ca]

Re:Hubble telescope

[Perdo]

First, how did the Hubbell end up being "myopic". There is a short, quick answer. The optical system used by the Hubbell was designed to operate in the near field where the wavefront from a point source in object space would have a sag across the telescope aperture of several wavelengths, quite large compared to the desired level of correction of the optical system. The Hubbell application, however, for sources at optical infinity, called for a telescope designed for plane parallel wavefronts from object space. The Hubbell optical system was a "borrowed" design. The design was borrowed undoubtedly to "save money", a favorite exercise of the "almost technical" managers of that era.

The technical management of two groups of people had to fail to enable construction of the original "myopic" Hubbell telescope. The government group which contracted with the supplier had to overlook the rather obvious short fall of the borrowed design. Second, the supplier, who had performed the design originally for near field operation, either overlooked the design shortfall or, more likely, had lost the organizational technical legacy of the original design team which would have stopped or attempted to stop the Hubbell "borrowed design" project before it started.

The design criteria for the original optical design for the telescope was based on imaging features on the surface of the earth from a low earth orbit reconnaissance satellite. The potential performance of surveillance systems of this type had been detailed in JOSA in the mid 60s. The performance limitation of an imaging system in earth orbit was shown by Hufnagel of Perkin Elmer to be the modulation transfer function (MTF) of the atmosphere which veils the surface of the earth as viewed from space. In his paper Hufnagel performed trades which related performance to altitude and diameter of the optical system. To achieve the nominal 1 microradian resolution which he projected would require a nominal 2 meter diameter optical system. It is a small step from this fact to the requirement to have a telescope with a customized figure for near field operation. The 2.5 meter aperture used would have to operate at or very near it's diffraction limit of 0.5 microradian to achieve the performance as limited by the atmosphere. To achieve very near diffraction limited performance the optical figure would definitely have to be adjusted to accommodate the large sag, spherical input wavefront.

The production of optics generally requires the building of tooling, test jigs and test plates to insure that the finished product has been correctly produced. The development, building and testing of this tooling is a major part of the expense of producing optical systems. This was, apparently, a major "cost saving" envisioned for the original Hubbell project. The tooling for a telescope designed to operate in the near field was employed to build a telescope to view stars at optical infinity. During initial operation of the Hubbell after being deployed into orbit it's designed-in "myopic" condition was discovered.