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Bolivian Salt Flats Aid Spacecraft Calibration

Zonk posted more than 6 years ago | from the wait-just-one-okay-wait-no-wait-i'll-get-it-wait-hold-on-okay-wait dept.

Space 98

PCOL writes "Salar de Uyuni is a vast plain of white salt in the mountains of Bolivia, with a total elevation range of less than 80 centimeters - the flattest place on earth. Beginning in 2002, geophysicist Adrian Borsa led a survey that resulted in precise GPS measurements of the salt flat. The flats will be used as a giant calibration device for satellite-based radar and laser altimeters on the CryoSat recovery mission so the spacecraft can more precisely monitor changes in the elevation and thickness of polar ice sheets and floating sea ice. 'Satellites can calibrate their altimeters by bouncing signals off the ocean surface .. because of atmospheric interference, tides and waves, there are uncertainties. Borsa says the salar, now so accurately mapped and with dry, clear skies, is about five times better than the ocean as a reference point.'"

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98 comments

Google Maps Link (5, Informative)

SeanTobin (138474) | more than 6 years ago | (#21548555)

Salar de Uyuni [google.com] in Google Maps.

Re:Google Maps Link (1)

boris111 (837756) | more than 6 years ago | (#21548833)

That area has some interesting geography. I wonder what that volcano looking thing [google.com] with a moat around it is to the east of the salt flats is?

wierd (1)

Bananatree3 (872975) | more than 6 years ago | (#21549143)

That definitely doesn't look like water to me. My best hunch is some form of geological outcropping (blue crystals?)

Either that or some sort of weird shrub.

Re:Google Maps Link (1)

X0563511 (793323) | more than 6 years ago | (#21552395)

Looks like glare. If you zoom in you get an image from another angle, and its salt like the rest of the flat.

Re:Google Maps Link (1)

schon (31600) | more than 6 years ago | (#21548909)

Salar de Uyuni in Google Maps.
Hmm.. anyone else get an overpowering craving for pretzels?

Re:Google Maps Link (1)

bennomatic (691188) | more than 6 years ago | (#21549967)

I never made it to Salar de Uyuni, but I spent some time in Bolivia, and it's one of the most amazing, diverse places I've visited. Anyone who wants to see Sorata [dimspace.com], a jumping off place for climbing 20,000 ft mountains, Rurrenabaque [dimspace.com], a town on the edge of the Bolivian arm of the Amazon river basin or Copacabana [dimspace.com], on the shores of Lake Titicaca, click away!

wow (-1, Troll)

Anonymous Coward | more than 6 years ago | (#21548561)

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i've got a bad feeling about this... (4, Funny)

User 956 (568564) | more than 6 years ago | (#21548565)

Bolivian Salt Flats Aid Spacecraft Calibration

Many Bolivians died to bring us this information.

Re:i've got a bad feeling about this... (0)

Anonymous Coward | more than 6 years ago | (#21548921)

Bolivian Salt Flats Aid Spacecraft Calibration

Many Bolivians died to bring us this information.
Really? Were they salt golems? And have we actually established that golems are alive? I thought they were basically religious artifacts. They can follow commands, but they can't actually think. They are more or less a fancy version of those automated welding machines in auto factories.

Re:i've got a bad feeling about this... (0)

Anonymous Coward | more than 6 years ago | (#21555693)

And many people were duped about global warming. Suddenly they will have to "recalculate" the thickness of polar ice sheets which of course won't be reported. Such as this: http://www.geotimes.org/aug07/article.html?id=WebExtra081607_2.html [geotimes.org]. As far as predicting things, right now we do not have the tools to really get a handle on global warming. But you can bet some people will get rich off it, like selling elixirs to naive people, but they will drink it down because it makes them feel good.

Evil Supergeniouses (2, Funny)

Protonk (599901) | more than 6 years ago | (#21548573)

How long until the League of Evil (or some such nonsense) invents a dastardly plan to mess with satellite location calibration by digging giant holes in the salt flats?

Hey. It's more credible than Goldeneye. :)

Re:Evil Supergeniouses (1)

Ziwcam (766621) | more than 6 years ago | (#21550211)

They won't have to. TFA (one of them, at least) mentioned that the area floods every 5 years or so, causing the salt to realign itself. I would imagine this changes the height, and the distribution of the high and low areas in the plane.

Re:Evil Supergeniouses (2, Interesting)

barakn (641218) | more than 6 years ago | (#21552755)

I've been there. It's already being mined for salt. Not only do they leave holes but they leave the salt in conical piles to dry out (the water table is quite close and actually pools on the surface in some locations).

Alternatives (3, Funny)

Anonymous Coward | more than 6 years ago | (#21548575)

Didn't anyone tell these guys about the Netherlands?

Re:Alternatives (2, Funny)

Anonymous Coward | more than 6 years ago | (#21549031)

Didn't anyone tell these guys about the Netherlands?
Yeah, but the Netherlands would probably make arrays to catch all of the energy being directed from space so that they could reduce their CO2 output even more. And that sort of defeats the purpose. Why would you make a fancy satellite to measure ice loss if the Netherlands is trying to stop it (both the radar calibration and the ice loss).

It's Saturday night (4, Interesting)

Dunbal (464142) | more than 6 years ago | (#21548617)

And I have probably had a bit too much to drink, so forgive the deeply philosophical question.

      When they mean that it's the "flattest place on Earth", do they mean that it conforms exactly to the curvature of the earth (thus not REALLY flat but earth shaped sort of flat), or is it FLAT flat, as in a chord across the curvature of the earth at that point...

      Sorry, just trying to work out the meaning of "flat" on a round planet... blame the rum.

Re:It's Saturday night (1)

Bl4d3 (697638) | more than 6 years ago | (#21548699)

Good question! The beer and snaps hasn't cleared out yet so I want to know it to.

Re:It's Saturday night (2, Informative)

Rolgar (556636) | more than 6 years ago | (#21548703)

Just a guess, but the note, "less than 80 centimeters variation," would indicate it follows the curve of the earth. If it were flat-flat, it would have a much larger variation than a meter.

Re:It's Saturday night (4, Interesting)

maxume (22995) | more than 6 years ago | (#21548819)

It is somewhat important that the article mentions the 80cm variation in terms of elevation.

In order to be straight line flat, the elevation would have to vary something like 200 meters, based on some rough calculations I did in trying to thing about this. Basically, I assumed that the salt flat is ~100km across, so the each edge is ~50km from the center, and would have an elevation given by the right triangle formed by the radius from the center of the earth and a 50km tangent line(the hypotenuse would be the elevation at the edge). (6300**2+50**2)**0.5=6300.198, subtract the radius, and you are left with 0.198 km, or ~200 meters). This is a simple model of the earth's shape, but it's within a factor of 3 or something.

Re:It's Saturday night (2, Informative)

Mantaar (1139339) | more than 6 years ago | (#21548725)

Well, OK. You've got an excuse for asking this, since you're drunk. There is no FLAT flat on the earth. The area still shows a horizon which means that it's EARTH flat and not FLAT flat:

http://www.google.com/search?&rls=hi&q=salar+de+uyuni&ie=utf-8&oe=utf-8 [google.com]

Re:It's Saturday night (1)

maxume (22995) | more than 6 years ago | (#21548857)

Please explain why a flat flat would not have a horizon.

Keep in mind that I might have had a few.

Re:It's Saturday night (5, Informative)

Mantaar (1139339) | more than 6 years ago | (#21548937)

Jesus effing Christ, everybody on this thread seems to be drunk.

Go to Wikipedia [wikipedia.org] and figure [wikimedia.org] it out yourself. Or better yet: go to bed and sleep. Look out of the window when you wake up tomorrow and try to find out why on earth you're not seeing the Chinamen in the far distance.

Re:It's Saturday night (1)

MiniMike (234881) | more than 6 years ago | (#21549535)

I hope for your sake he's not in China...

Re:It's Saturday night (0)

Anonymous Coward | more than 6 years ago | (#21549709)

Hey, Scots don't go nuts when called Scotsman, and the same with Nordics and Norsemen, so why should the Chinese? It's all good.

Re:It's Saturday night (1)

RR (64484) | more than 6 years ago | (#21550471)

Because Scots and Norse were not generally considered inferior to Anglos.

Because American racism means a 3rd-generation Japanese-American gets called a Chinaman.

Regarding the GPP: I work with immigrants, so I expect to see people from China when I wake up. Not recognizing that is an incredibly narrow-minded idea of what a modern Western society is like.

Re:It's Saturday night (2, Interesting)

Mantaar (1139339) | more than 6 years ago | (#21550725)

wheez! I seem to have forgotten the <sarcasm>tags</sarcasm>. I didn't expect this kind of statement to be percieved so badly - maybe that's because I'm European and afaik we didn't abuse Chinese laborers (at least not them!), so I don't have this perspective on that.

Disclamer: I'm a member of a people that had been enslaved for about 500 years and hence I know how it feels like when 50% of your ancestors died in liberation attempts and your petty nation is ridiculed by both the West and its former tyrants because of lack of economic progress and a culture they generally don't understand. Tell you what it feels like: just the same, as far as I can tell.

How do we get rid of racist statements just as mine a few posts ago? BFC: don't perieve them to be racist statements! Seriously, when a person wants to be treated as equal this person wants to be treated equally well or badly as every other person. At least I want to! Not like "ooh, he's the one, you know. We're not supoosed to say the XYZ-word when he's here. Better watch you're tongue". So I make jokes about Jews in front of my Jewish friends and they laugh because they know I'm not offending them I'm rather being sarcastic against a culture that allows those statements to be offending. When I said 'Chinamen' I wanted to (sort of) ridicule my post's parent's author by (sort of) descending to a level he (sort of) understands. Now notice that though I just said that, it's most likely untrue and this person is most likely a fairly intelligent person (he/she can operate a computer - and navigate to /. Heck I know a lot of people that can't!). That's called sarcasm. At least around here.

Re:It's Saturday night (1)

MiniMike (234881) | more than 6 years ago | (#21551865)

I work with people from China, India, Korea, France, (the list goes on), but I don't expect to see them outside my window when I wake up (unless I fell asleep at work and my snoring scared them all outside).

Poster below seems to be the only one with the correct interpretation- the comment was not about the use of the term 'Chinaman' (which I think is not considered derogatory everywhere) but about the 'out the window' comment. Now you have made me overanalyze the joke too, thanks.

Re:It's Saturday night (1)

TheThiefMaster (992038) | more than 6 years ago | (#21550965)

I don't know what you're drinking, but I interpreted "I hope for your sake he's not in China" as meaning that if he was then he would be able to see Chinamen outside his window, invalidating the argument.

Re:It's Saturday night (1)

flynns (639641) | more than 6 years ago | (#21550277)

Seriously. Also, Dude, 'Chinama' is not the preferred nomenclature. Asian-American, please.

Re:It's Saturday night (0)

Anonymous Coward | more than 6 years ago | (#21551223)

If that was satire, it was utterly brilliant. If it wasn't, you're a living example of how brain-dead political correctness is. Congratulations either way!

Re:It's Saturday night (0)

Anonymous Coward | more than 6 years ago | (#21551355)

Actually, it's a quote from The Big Lebowski [imdb.com]. And if you think that's brilliant, I highly recommend you watch the whole flick.

Re:It's Saturday night (1)

maxume (22995) | more than 6 years ago | (#21551299)

I meant a flat flat set down on top of the globe. There would still be a horizon.

Re:It's Saturday night (1)

Mantaar (1139339) | more than 6 years ago | (#21551679)

That's why I linked to the google search. One of the first hits is this beautiful picture [tripod.com] - if it was FLAT flat you'd see some mountains in the distance since you'd just have to see something that's not the salt lake. But you don't. In fact, you only see the sky. Really beutiful shot, btw.

Re:It's Saturday night (1)

maxume (22995) | more than 6 years ago | (#21553519)

You implied that a flat flat wouldn't have a horizon. I was hassling you about it. Clearly you meant that a flat flat wouldn't have a curved horizon.

Re:It's Saturday night (0)

Anonymous Coward | more than 6 years ago | (#21553975)

Of course there are actual flat places on earth. The earth is bumpy all over, it's not a perfect sphere. So it makes perfect sense to expect that there could be some FLAT flat parts. Most definitely not as large as those Salt Flats, but I can guarantee I could find (or at least make) a FLAT flat section of earth just by stepping outside my house, even if it's only a square-foot in size.

Re:It's Saturday night (4, Informative)

swillden (191260) | more than 6 years ago | (#21548787)

When they mean that it's the "flattest place on Earth", do they mean that it conforms exactly to the curvature of the earth (thus not REALLY flat but earth shaped sort of flat), or is it FLAT flat, as in a chord across the curvature of the earth at that point...

Flat in the sense that every point on the surface is equidistant from the earth's center of mass.

Re:It's Saturday night (4, Informative)

Deadstick (535032) | more than 6 years ago | (#21548905)

No. It means every point is at the same gravitational potential, and the equipotential surfaces are not spheres. Close, but different.

For example, Mt. Chimborazu in Ecuador, 21000 feet above the equipotential surface we call "mean sea level", is farther from the center of the earth than Everest at 29000 feet.

Bear in mind these are small differences: if you could make a perfect scale model of the sea-level surface the size of a billiard ball, it would be rounder and smoother than the ball.

rj

Re:It's Saturday night (1)

swillden (191260) | more than 6 years ago | (#21549213)

No. It means every point is at the same gravitational potential, and the equipotential surfaces are not spheres. Close, but different.

True in general because the earth doesn't have uniform density. Over an area as small as even the Bolivian salt flat, though, is the difference likely to be at all significant?

Re:It's Saturday night (1)

swillden (191260) | more than 6 years ago | (#21549249)

True in general because the earth doesn't have uniform density.

Sorry to reply to my own post, but I realized there's another issue, and it might be the more significant one -- the earth is closer to an ellipsoid than a sphere. Still I expect that over a small area a sphere is a *very* close approximation.

Re:It's Saturday night (4, Informative)

Deadstick (535032) | more than 6 years ago | (#21549621)

No, extremely small. Over an area that small, you can pretty well assume the equipotential surface is a sphere.

The reason for the flatness of salt flats is that the salt gets soupy in the rainy season, gravity smooths it out, and then the water evaporates out leaving a hard surface -- although if there's a substantial prevailing wind during the wet season, you get some deviations.

rj

Re:It's Saturday night (1)

phliar (87116) | more than 6 years ago | (#21553429)

Over an area as small as even the Bolivian salt flat, though, is the difference likely to be at all significant?

Yes. In fact, the article itself points out that there are bumps in the surface due to large rock formations a few km below the surface.

The surface of the ocean varies hugely from a sphere over the mid-oceanic ridges. Precisely mapping the sea surface height allows us to deduce the relief of the ocean floors. Check out the front cover picture of Mapping the Next Millenium: The Discovery of New Geographies by Stephen S. Hall.

Re:It's Saturday night (4, Interesting)

goodmanj (234846) | more than 6 years ago | (#21550279)

Bear in mind these are small differences: if you could make a perfect scale model of the sea-level surface the size of a billiard ball, it would be rounder and smoother than the ball.

Mind if be pedantic? Not quite true. The difference between pole and equatorial radii at sea level is 22 km. Add in the height of Mt Chimborazu and the depth of the ocean near the South Pole, and we find that Earth deviates from a sphere by about 33 km, and so it's spherical to within +/- 0.26%.

The Billiard Congress of America [pool-table-rules.com] requires billiard balls to be 2.25" in diameter, to an accuracy of +/- 0.005", or +/- .022%.

So, the Earth doesn't quite pass muster as a billiard ball.

"Give me a pool cue large enough and a place to stand, and I shall sink the Earth in the corner pocket." -- Archimedes Fats

Re:It's Saturday night (4, Interesting)

TimeTraveler1884 (832874) | more than 6 years ago | (#21548829)

Usually when anything of a GIS nature refers to something as "flat", it is in relation to the WGS84 [wikipedia.org]. My understanding is that geodetic systems basically project an perfect, elliptical sphere around the the gravitational center on earth. But I probably have had too much to drink myself so don't hold me to it.

Here's to spending way too much time playing with GPS! Cheers!

Re:It's Saturday night (1)

AikonMGB (1013995) | more than 6 years ago | (#21548991)

I suspect they mean flat as in it conforms to the curvature of the Earth. Having said that, my guess is that the areas they are dealing with are small enough that this curvature may be neglected.

Aikon-

Re:It's Saturday night (1)

White Shade (57215) | more than 6 years ago | (#21549021)

I have an unopened beer sitting in front of me, and I had the very same question, so don't blame the booze! ;)

Re:It's Saturday night (0)

Anonymous Coward | more than 6 years ago | (#21549955)

Sorry to humbly correct my dear geniuses here on /.
The Earth IS NOT round, spherically round. It is a Geode. So it is made like a 50 faces RPG dice for example.
So we have billions of flat areas that are all put together to create a Geode (not spherical) object. The Salias are almost exactly flat as you can just point a laser sight paralleled aligned with the line of the ground and it will reach the a sensor on the other side.

Re:It's Saturday night (0)

Anonymous Coward | more than 6 years ago | (#21550115)

You guys sure that's salt? This is Bolivia we're talking about...........

Re:It's Saturday night (0)

Anonymous Coward | more than 6 years ago | (#21555241)

heh... that's why it's so flat - people are always out there obsessively leveling it out with razor blades.

the calibration would've gone faster... (1)

SuperBanana (662181) | more than 6 years ago | (#21548633)

...if the Bolivian navy hadn't been on maneuvers in the South Pacific.

Re:the calibration would've gone faster... (1)

Scoldog (875927) | more than 6 years ago | (#21549023)

You're banana's mate.
 
Oh well, back to watching "What's My Fruit"

Don't be cruel (0)

Anonymous Coward | more than 6 years ago | (#21558691)

Don't be cruel. The Bolivian Navy is limited to lake Titicaca since they lost their seaboard, and they are still resented about it.

oblig simpsons quote (1)

timmarhy (659436) | more than 6 years ago | (#21548647)

"in the event of nuclear war, the bolivian salt flats will be designated nuclear whipping boy and have test nukes fired for calibration"

If it is used for Calibration right now... (2, Interesting)

Sique (173459) | more than 6 years ago | (#21548671)

... doesn't that mean that if anyone started mining the salt there, all navigational devices are hosed, because there is no normal anymore to calibrate them?

Wow (2, Funny)

moosesocks (264553) | more than 6 years ago | (#21548727)

"Salar de Uyuni is a vast plain of white salt in the mountains of Bolivia, with a total elevation range of less than 80 centimeters - the flattest place on earth. Beginning in 2002, geophysicist Adrian Borsa led a survey that resulted in precise GPS measurements of the salt flat. The


In other news, Adrian Borsa* has the most boring and tedious job on the planet.

*Or his grad students

And sitting in a cubicle isn't boring? (2, Insightful)

NotQuiteReal (608241) | more than 6 years ago | (#21548879)

lol, I appreciate the humor, and I am self employed, not even a cubicle worker.

While you are probably looking for a quick "Funny" rating, a serious look reveals that, sadly, doing a GPS survey of some god-forsaken salt flats probably *is* more exciting than many ordinary jobs.

50 years from now you will have forgotten what you did, but some geophysicist will be able to say "Oh, yeah, back in ought-two, I was part of a team that had an all expense paid trip to Bolivia to hang out and sample the local cervesas and take a few GPS readings. Yup all that data eventually put to rest that man-made global warming malarkey. God I hate this ice age."

Re:And sitting in a cubicle isn't boring? (1)

timmarhy (659436) | more than 6 years ago | (#21548975)

unlikely, surveying is a tidious boring fucker of a job. I'm betting it's boiling hot during the day and freezing at night.

he will be taking 100's of measurements and compiling a list of them, nothing exciting about it. I'll keep my comfortable chair and aircon thanks.

Re:And sitting in a cubicle isn't boring? (1)

BeeRockxs (782462) | more than 6 years ago | (#21551551)

It is pretty fucking cold at night, but not boiling hot during the day. When I was there I even wore my sweater.

And, from the headlines of 2010... (0, Troll)

nugneant (553683) | more than 6 years ago | (#21548733)

SALAR DE UYUNI, Bolivia -

In a video released today, Osama Bin Laden, leader of the Al-Qaeda terrorist organization, declared responsibility for the bucket brigade attack that left three dead, fifty-seven dehydrated, and hundreds of millions of satellites disoriented.

"The imperialist Western heathens launch their metallic eye to watch the honorable Allah undress", Bin Laden says in the video. "As Muslims, we must show the world that we will not tolerate this, or any other, act of Western aggression."

Muslim leaders remain divided on the issue. While Abdul Ackman Ackgrab Ackmeer Ackbeer Ackbar publically decried "any and all acts of violence in the honorable Muslim community", some, such as Abdul Rohammed Ackgrab Ackmeer Ackbar Abdul-Paula-Ackman, took a more neutral stance, saying under conditions of anonymity that "America cannot deny" the impact the hundreds of satellites had upon "the honorable Muslim community", and cited a Koran verse that, loosely translated, declares "none shall be higher than Supreme Allah". When asked about the potentially harmful effects of all that out-of-control metal pummeling the Earth, Mr. Abdul-Paula-Ackman had nothing coherant to say, though seemed generally ambivilant.

Small groups of Earnest Student Democrats have already formed in support of what they label the "honorable savages of the Middle East", and were seen against a police barricade decrying Israel, chanting "NO WAR FOR SALT".

Several despotic Palestine hoodlums could not be reached for comment.

seriously (-1, Troll)

Anonymous Coward | more than 6 years ago | (#21548743)

am i the only one here who would rather hear about the dude who finds something in a toilet bowl...

Nevar forget: Fact x Importance = News.

Using the Bolivian Salt flats (2, Funny)

philpalm (952191) | more than 6 years ago | (#21548853)

What? and Bolivia won't be able to charge anyone for this service? It is really unfair to this poor country to be used and exploited like a flat chested woman....

OP is Misleading (-1, Offtopic)

Anonymous Coward | more than 6 years ago | (#21548943)

Everyone knows the flattest surface on Earth is an Asian girl's ass.

Asian girls asses are a carpenter's dream. (-1, Offtopic)

Anonymous Coward | more than 6 years ago | (#21549863)

Flat as a board, and easy to nail.

Then again, Negro girls asses are a librarian's dream. Have a nice shelf, and easy to slide into.

Flatness? (0)

Anonymous Coward | more than 6 years ago | (#21549047)

Why don't they just use a flat patch of ocean, like the Sargasso sea? That's gotta be flatter.

The Great Salt Flats in Utah are flatter... (5, Interesting)

JRHelgeson (576325) | more than 6 years ago | (#21549089)

The dried Bonneville Salt Flats (open to the public) and its attached military only area called the Dougway Proving Grounds are the flattest place on earth. They have been used by the military for the past 40+ years to calibrate space and weapons systems. Pretty much every land speed record has been made at the Bonneville Salt Flats, including breaking the sound barrier. The variation of altitude is so minimal that it is within the accuracy of the measurement equipment used to calibrate altitude variations, but it has been certified to be less than 1 foot of elevation for every 10 miles.

And every year it gets 'reset'... The springtime runoff from the surrounding mountains will cover the entire salt flats with a perfect 1/2" of water. It is SO COOOL to go out there when there is a *PERFECT* sheet of water covering the salt, it looks like the worlds largest piece of glass. You can actually *SEE* the curvature of the earth. I have a picture of a much younger me 'walking on water' because it is so smooth you cannot tell that the water is only 1/2" (1.5cm) deep.

Working out on the salt flats, doing surveys, the survey crew would drive out 1 mile and hold up a survey marker. At five miles out we could not see them any more, we asked them to raise it up over their heads and we saw the marker rise up over the horizon like it was the sun coming up.

Because it is the worlds largest and flattest spot on earth, my father, an engineer in flight optics systems, has built optical calibration targets used by the military to calibrate autopilot systems, weapons guidance systems, terrain following radar systems, satellite optics systems and all that jazz for the military... which is why I grew up in Utah, am intimately familiar with the flats, and know without a doubt that my dad has worked on black projects that I hope someday he'll be able to tell me about (including flights into and out of the Janet terminal).

Re:The Great Salt Flats in Utah are flatter... (0)

Anonymous Coward | more than 6 years ago | (#21549269)

Salar de Uyuni: 12000 km2
Bonneville Salt Flats: 412 km2

Maybe in imperial units 412 is bigger than 12k, tho.

Re:The Great Salt Flats in Utah are *not* flatter (2, Interesting)

JRHelgeson (576325) | more than 6 years ago | (#21549781)

Oh yeah!?! Well, the Bonneville Salt Flats are 125452549094400.2 Square Millimeters!!! ahem...

If this is accurate (and it does appear to be), Bolivia is much, much bigger. You could lose Bonneville salt flats in Bolivia. I would also further speculate that both locations are equally flat as the salt will form a flat, equally distributed surface whenever it rains. I know from survey after survey that the Bonneville Salt Flats are within the margin of error for the measuring equipment to even detect variations in uniform surface 'flatness' where the margin of error is within 1' (30.48cm) altitude for 10 miles (16.09km) linear distance.

All my life I heard how they were the largest, flattest spot on the earth - so I assumed it was true because people from around the world went there to race.

Re:The Great Salt Flats in Utah are flatter... (2, Informative)

mad zambian (816201) | more than 6 years ago | (#21549457)

Minor correction. The most recent Land Speed records were set on the Black Rock Desert. Prior to this almost all of them were done on the Bonneville salt. From the Wikipedia article [wikipedia.org];
Richard Noble,
October 4 1983, Thrust2, 633.468mph (1019.47kph) Record stood for 13 years
September 25 1997, ThrustSSC, 763.035mph (1227.99kph) Sound barrier broken - (Mach 1.016)

Re:The Great Salt Flats in Utah are flatter... (5, Informative)

Anonymous Coward | more than 6 years ago | (#21549483)

As the other poster mentioned, the two locations have varying sizes.

You are looking at an area of 10,582 km (Salar de Uyuni) versus an area of 412 km (Bonneville Salt Flats).

In fact, you are most likely correct about the Bonneville Salt Flats having no more than 1 foot (30 cm) of elevation variation for every 10 miles (16 km), however, the Salar de Uyuni was found to have only 16 inches (40 cm) of variation over its entire surface. This is a huge area that dwarfs 10 miles. The Salar de Uyuni has also been stated by several places that it is, indeed, the largest flattest surface yet to have been found on earth.

Purely speculation on my end however, would be the reasons why the military would choose the Bonneville Salt Flats over the Salar de Uyuni. The military would most likely be testing equipment and technologies they don't want anyone else to get their hands one or are a type which are particularly politically sensitive, whereas other space or research agencies are more or less politically neutral comparatively. This allows other groups to test in an international (and further away) location that the military might find inconvenient due to both political and logistical reasons. Stating that because a lot of people do testing on the Bonneville Salt Flats is not evidence for it being the flattest. There are reasons to use it, simply because of its convenience and close location (it is in US compared to being in Bolivia) among other things.

Read more on the Bolivian Salt Flats (Salar de Uyuni).
http://dsc.discovery.com/news/briefs/20041206/flatearth.html/ [discovery.com]

Re:The Great Salt Flats in Utah are flatter... (1)

GaryPatterson (852699) | more than 6 years ago | (#21555095)

the Salar de Uyuni was found to have only 16 inches (40 cm) of variation over its entire surface

I assume you're not factoring in the few 'islands' dotted around the Salar de Uyuni.

It's a very interesting place to visit. My (now) wife and I went there in 2005 on our trip around South America. For two months of the year it rains steadily and the whole area floods to about 30-50 cm (going from memory here). The water evaporates for the next few months, leaving a bed of salt. We went there in the last few weeks of water evaporation, and when there's a few centimetres of water over the packed salt you get these incredible reflections.

The locals mine the salt, piling it in small mounds about a metre tall. The reflective surface makes these little mounds look just like diamond shapes hanging in the air around you. It's surreal.

Just before the road enters the area, some locals will try to sell you salt crystal formations in any size you like. We paid a few small coins for one that sits on my bookshelf, but once we were in we realised we could easily have found hundreds of crystals just as nice. Tourists, eh?

The islands dotted around the place are full of ancient coral fossils and the one we wandered around had a huge, freestanding arch you could walk under. It's clear that all this area was once sea bed, although I can't recall how long ago that was.

An amazing place, well worth visiting. The tour company we met in Potosi tried to rip us off (very dishonest, promising much, costing hundreds but failing to deliver) but the people in the local town (name escapes me at the moment) were very nice. Oddly enough they were the only town where people smiled that we saw in Bolivia. In Peru we saw poverty just as terrible but the people were generally far happier. Must be a local thing.

Pic of just how big the Bolivian flats are. (2, Informative)

danamania (540950) | more than 6 years ago | (#21550833)

As others have said, the size of the Bolivian salt flats is the thing here. And they're not just big in the sense that you can measure them as larger than bonneville, they're big as in "go to google earth and see the huge white splotch on south america" big.

http://www.danamania.com/tmp/salar.jpg [danamania.com] for a pic.

In other words... (4, Funny)

fahrbot-bot (874524) | more than 6 years ago | (#21549335)

Satellites can calibrate their altimeters by bouncing signals off the ocean surface .. because of atmospheric interference, tides and waves, there are uncertainties.

Ocean measurement have to be taken with a grain of salt, but these - oh wait.

Tag (4, Funny)

Hemogoblin (982564) | more than 6 years ago | (#21549377)

Only on Slashdot would a story about "calibration of equipment using saltflats" be tagged as ReallyFuckingCool. :D

Re:Tag (1)

MichaelSmith (789609) | more than 6 years ago | (#21550691)

Only on Slashdot would a story about "calibration of equipment using saltflats" be tagged as ReallyFuckingCool

But now the tag has gone. I didn't know they could be deleted.

Thats Strange... (0, Offtopic)

Elitist_Phoenix (808424) | more than 6 years ago | (#21549429)

Thats strange i thought the flattest thing on earth was my girlfriends chest

Re:Thats Strange... (0)

Anonymous Coward | more than 6 years ago | (#21549795)

Nope, you were thinking of your Mom.

Re:Thats Strange... (1)

Tablizer (95088) | more than 6 years ago | (#21549803)

Thats strange i thought the flattest thing on earth was my girlfriends chest

Perhaps she's not a girl.

And if she is, one way to change that is to knock her up. When she starts lactating, her breasts will get plump. (However, she won't let you touch them at that stage.)

From the More Than You Wanted To Know dept.
   

Re:Thats Strange... (1)

Elitist_Phoenix (808424) | more than 6 years ago | (#21550469)

Ahh i like ur thinking... I've been going with the up the bum no babies approach. But i could kill two birds with one stone, while enlarging her breast size i could also get a little butler (well in a couple of years anyways... u know when hes old enough to pull a cart) to carry my beer around. Also as another bonus i'd get the governments cash bonus for having a baby... to get more beer for him to pull around!! *Tents Fingers* Excellent

Re:Thats Strange... (1)

Tablizer (95088) | more than 6 years ago | (#21554485)

i could also get a little butler (well in a couple of years anyways... u know when hes old enough to pull a cart)

Warning: kids that cooperate are rare. The parent becomes a behavioral experiment to them, and they test every nook and crany of the experiment.
     

Re:Thats Strange... (0)

Anonymous Coward | more than 6 years ago | (#21555073)

And if she is, one way to change that is to...
lol. I thought that your pronoun was referring to his girlfriend being a girl. Not sure he wants to change that...

You girlfriend is a carpenter's dream. (-1, Flamebait)

Anonymous Coward | more than 6 years ago | (#21549891)

Flat as a board, and easy to nail. Plus she's like a 7/11. On every corner, and open all night. Kinda like my Negro girlfriend's ass is a librarian's dream. Has a nice shelf, and is easy to slide things into.

Similar calibration for imaging sensors too... (2, Interesting)

haut (678547) | more than 6 years ago | (#21549431)

I had a remote sensing professor at the University of Arizona that frequently took road trips with his students out to remote areas in Nevada to calibrate imaging sensors. For this, the absolute flatness isn't as important as the high reflectance of the dry lake beds they use. Here [arizona.edu] is more info.

Calibrating spy satellites (1)

AdamInParadise (257888) | more than 6 years ago | (#21550707)

Once I visited a military base that hosted large fields of well-known cereals and stuff. I was told those fields were used to calibrate spy satellites, since the size and "color" of those fields are perfectly known. I guess they use those flat areas as well.

I dont know... (0)

Anonymous Coward | more than 6 years ago | (#21552043)

This whole thing leaves a funny taste in my mouth.

Brain...exploding... (1)

RealGrouchy (943109) | more than 6 years ago | (#21552055)

Wait, I'm confused.

Did I just stumble onto a Bizarro-Slashdot where the Earth is flat and Intelligent Design is a sane, logical, evidence-supported theory?

- RG>

Envisats LRR (1)

Zoxed (676559) | more than 6 years ago | (#21554319)

> Satellites can calibrate their altimeters by bouncing signals off the ocean surface .. because of atmospheric interference, tides and waves, there are uncertainties. Borsa says the salar, now so accurately mapped and with dry, clear skies, is about five times better than the ocean as a reference point.'"

Sounds more complicated then Envisats LRR (mirror on spacecraft, bounce a land based laser off it and measure the round trip time: http://envisat.esa.int/instruments/lrr/ [esa.int])
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