Talk:South Atlantic Anomaly

Sources

• NYT
• NYT
• TimesLive AniRaptor2001 (talk) 00:43, 11 February 2010 (UTC)

Is this what caused the Bermuda Triangle?

If all of the computer failures that resulted in losses of multiple computer-guided vehicles, then couldn't the Bermuda Triangle be just a concentration of said failures? I shall look into record patterns of this anomaly. — Preceding unsigned comment added by Maxzutter (talk • contribs) 18:49, 3 February 2012 (UTC)

Previous discussions without headers

An image to illustrate this would be useful. The last paragraph makes reference to "figures below" which aren't.

Is this backwards?

Is it me or is this article backwards? i.e. the SSA is the van allen belts, caused by the magnetic field. Shouldn't that be the SSA is the magnetic field.... it caues the van allen belts to move etc.

Backward or not depends on your viewpoint.

I am not a geoscientist and was indeed hoping that something real about the SAA was in Wiki. I worked thru a contractor at NASA for several years as an EE, and issues with the Hubble Space Telescope (HST) involving radiation from the SAA were nontrivial for us.

The limit of my understanding is that there is *something* in the South Atlantic basin that affects Earth's magnetic field enough to warp the Van Allen belts. The effect is that low earth orbit (LEO) satellites like HST pass through a pulled-down edge of the Van Allen belt often--almost once per orbit on average. Low-earth equatorial orbits largely avoid this, while geosynchronous orbits are not only equatorial but higher than the Van Allens (verify?), so they are subjected to general space radiation but not the concentration that Earth's magnetic field has created in the Van Allens.

The excess radiation (gamma-photon-x-ray) due to the SAA fouls up many processes and ages electronics prematurely. Thus, for example, good old micropower CMOS integrated circuits can experience "single event upsets" (SEUs) that can cause systems to go bonkers and require extra design precautions, such as very simple "watchdog" timers that reset the system if they aren't "petted" frequently. New ultrasmall transistor memory locations in VLSI and like devices are also susceptible to SEUs because the capacitors that form the instruction bit storage are small enough to be flipped by the charge that a single gamma ray can induce.

What I was looking for was speculation or better as to what the physical phenomenon that manifests as the SAA actually is. I read somewhere that the name refers to magnetic compass errors, gravimetric irregularities, radar altimeter discrepancies, or some such that coincide spatially with the later-discovered (?) Van Allen issues. I suppose evidence for a hypothetical Mars-sized asteroidal ferrous masscon in the mantle associated with formation of the Moon a few billion years ago would be tough to dig up. Literally.

Compared to this, the Wiki discussion of the K-T boundary debate is rigorous.

Your turn.

Radiation?

I'm confused. Why would an annomaly in the magnetic sphere cause sattilites to experience more radiation? Could someone clarify that in the article? Thanks! Schwael 17:02, 30 June 2006 (UTC)

Argus connection

Was there the anomaly before the Argus? And was it also this much radiating?

Can it be, that the anomalous radiation is still the remnant of a nuclear weapon test?

Can it be, that the magnetospheric hole, that makes inner van-Allen belt getting near ground, was caused by that?

propaganda

Both the argus and south atlantic anomaly wikipedia articles appear to be whitewash, expecting us to take the usa's word for there being no link between the two. On issues involving unethical behaviour by powerful entities wikipedia is not a useful resource. Even without state sponsored edit wars the number of people who swallow their own government's propaganda outnumber by far other wikipedia editors. According to wikipedia operation argus was a harmless science experiment with no ethical issues or lasting effects. I doubt this is the truth of the matter. 2001:8003:6E1E:A600:6725:C395:14C0:FC9F (talk) 21:35, 27 October 2018 (UTC)

It may not be backwards... but is the Magnetic Field reversing...?

I first heard of the concept of field reversal in a quote Graham Hancock attributed to Albert Einstien in "Fingerprints of the Gods".

Earlier this year, I was channel surfing and came across a documentary on Discovery, or NatGeo. It talked about the fact that every so many hundreds of thousands of years, there is a magnetic field reversal, just as I had read so long ago. It mentioned that the SAA may be symptomatic of this, as it seems to be getting steadily larger and more chaotic.

Some information can be found here: http://www.crystalinks.com/earthsmagneticfield.html

CrusherV 00:12, 17 December 2006 (UTC)

Continental outlines?

Can someone update the maps to overlay continental outlines? It'd be nice to see exactly where the SAA is.

Also, 0.3 degrees a year means that it travels all the way around the earth in about 1200 years, correct? It might be interesting to search the literature for recurring events, especially in the area of the SAA, which have 1200-year cycles. --Scott McNay 06:34, 1 March 2007 (UTC)

Operation Argus

What does the comment about Operation Argus have to do with the rest of the article? 65.113.40.130 23:41, 2 May 2007 (UTC)

I agree with 65.113.40.130, I removed the statement from there and added it as "see also" Javit 10:49, 28 May 2007 (UTC)

And I removed the link to it in the "See Also" section. For future reference to those who will read this, the notion that any action of man caused this magnetic anomaly is a physical impossibility. --76.224.71.159 09:38, 2 October 2007 (UTC)

Insufficient explanation

The SAA is produced by a "dip" in the Earth's magnetic field at that location, caused by the fact that the center of Earth's magnetic field is offset from its geographic center by 450 kilometers (280 miles).

This is insufficient to explain the anomaly, since by itself it implies that there should also be a North Pacific Anomaly. There isn't. Elaboration required. --76.224.92.141 17:31, 26 August 2007 (UTC)

Answering various questions

On 26 Aug 2007 User:76.224.92.141 noted: This is insufficient to explain the anomaly, since by itself it implies that there should also be a North Pacific Anomaly. There isn't.

This is true. There's no north pacific anomaly. That's because the inner van Allen belt is furthest from Earth's surface over the north Pacific. The belt is symmetric to the Earth's magnetic axis, which is both tilted and offset from the rotational axis.

About the whole Operation Argus thing: Yes, Operation Argus (and later Operation Starfish) did pump a great number of charged particles into the van Allen belts. This caused a temporary increase in the size and intensity of the SAA. The SAA had returned to its pre-test intensity levels by 1967.

Going way back to the first question at the top of the page, it asks: "Is it me or is this article backwards? i.e. the SSA is the van allen belts, caused by the magnetic field. Shouldn't that be the SSA is the magnetic field.... it caues the van allen belts to move etc."

No, the article isn't backward. Earth's magnetic field is not caused by the particles trapped in the van Allen belts. Earth's magnetic field is caused by the dynamo effect resulting from the rotation of Earth's liquid iron core. The magnetic field traps energetic protons and electrons from the solar wind in the van Allen belts. The SAA is not the magnetic field. The SAA is shaped by the magnetic field.

The real experts on the SAA are folks in the Applied Engineering Technology Directorate at the Goddard Spaceflight Center. Look at the literature for articles by E. C. Stassinopoulos and others from AETD for more on the SAA.

BillGawne 18:46, 14 November 2007 (UTC)

History?

There is no discussion of history, when was the SAA discovered and how? I know that Sergey N. Vernov studied the east-west asymmetry of cosmic ray readings along the equator with a ship in 1949. 71.231.42.134 (talk) 17:24, 14 August 2008 (UTC)

Basic questions

There are a few basics from the ground that aren't really addressed in this article which would be interesting.

• Is there any detectable effect on compass needles for people simply sailing the South Atlantic?
• Is the area associated with more aurora australis, and have people in South America noticed an increase as it has moved in?
• Do the major South American cities with their extensive power grids have any tendency to slow the local movement of the region?
• The anomaly works with trapped particles from a Van Allen belt. Does this mean that its intensity will diminish if it grows larger?

Note: as the "leaky bucket theory" of the aurora was long since disproved (see article); there can't be any strong contact between the Van Allen belt and the atmosphere - but this still leaves me wondering whether the rate of leakage of what does exist is significant and proportional to the area of closest proximity.

Wnt (talk) 04:15, 5 March 2010 (UTC)

Some answers, an animation that might help

I am writing up a section on Van Allen belt radiation for my own wiki. No citations yet, but I can informally answer your questions. You will have to read some literature and do some physics to really understand the SAA. A good starting place is the book "The Space Environment and its Effects On Space Systems" by Vincent Pisacane, AIAA Press, 2008.

The SAA was discovered by the same team of scientists that discovered the Van Allen Belt in 1958, led by Dr. James A. Van Allen of the University of Iowa. The SAA was an anomalously high radiation count over part of the orbit of the Explorer satellite, though at the time the existence of the Van Allen Belt itself was quite an anomaly, until they thought it through. The SAA occurs where the lowest McIlwain L shells in the Van Allen Belt come closest to the upper atmosphere of the earth. You can see an animation of the L shells here on my own wiki. Note how the inner L shell ( L=1.1 ) comes close to the surface over Brazil. A band the width of that narrow region, running all the way around the magnetic equator of that shell, can contain radiation particles for a very long time. The parts of the L shell north and south of that band cannot contain particles - they would collide with the earth.

The characteristics of the magnetic field that cause the anomaly are measurable on the earth, affecting the declination and inclination measured by compasses. The magnetic equator runs along the SAA, so in the middle of it, compass needles are level and have zero inclination. They still have nonzero declination, and point away from true north.

The particles in the belt have no measurable effect on compasses. Particle currents are tiny compared to the currents in the earth's core that generate the magnetic field that channels the SAA.

Power lines and power grids are pairs or triplets of wires, typically AC, with no net current. They generate no measurable magnetic fields kilometers away - they would have no effect on the global magnetic field, or on the SAA.

KeithLofstrom (talk) 07:51, 14 July 2010 (UTC)

Direction of motion: SAA and the Earth core spin

The article currently states: "The highest intensity portion of the SAA drifts to the west at a speed of about 0.3 degrees per year, and is noticeable in the references listed below. The drift rate of the SAA is very close to the rotation differential between the Earth's core and its surface, estimated to be between 0.3 and 0.5 degrees per year."

The Earth rotates West-to-East. The Earth core is (also according to the references given in the article) spinning somewhat faster than the surface. That is: faster towards the East. So if the Earth magnetic field, produced in the core, is drifting relative to surface just because of this differential rotation, it should be drifting eastward on the surface. The SAA drift is towards the *West*. Even if the absolute values are similar, the two effects are in opposite directions: +0.3 and -0.3 degree per year -- claiming a direct connection between them seems hasty. Unless there is a reliable source for the connection claim.

Also, it should likely be "differential rotation" or perhaps "rotation difference", not "rotation differential".

129.194.8.73 (talk) 16:08, 10 August 2010 (UTC)

I'm sure I can find some reliable sources if that is what is required. However, it most certainly is moving in parallel with the core - it's generally accepted now that the anomaly is caused by convection currents in the outer core which happen to be the "wrong" way around in this area compared to the rest of the surface. I just came to this article after it came up somewhere else and was surprised to nee no coverage at all of this. I'll try to develop that area with sources but it will have to wait, time to get to work now. Quantumsilverfish (talk) 04:07, 18 January 2012 (UTC).

the early failures of the Globalstar network's satellites.

Since the satellites exceeded their design life, it wasn't exactly an 'early' failure. Actual, in-place measurements predicted late failure, but that turned out not to be the case because of late radiation damage. —Preceding unsigned comment added by 218.214.18.240 (talk) 12:11, 28 January 2011 (UTC)

Antiprotons found in SAA: New Article

http://www.technologyreview.com/blog/arxiv/27058/?p1=blogs <excerpt>: But, like most spacecraft in low Earth orbit, PAMELA must pass daily through the South Atlantic Anomaly, a region where the Van Allen Radiation Belts come closest to the Earth's surface. It's here that energetic particles tend to become trapped. So if any antiprotons are caught up in the mix, that's where PAMELA ought to find them.

Now the PAMELA team has analysed the 850 days of data, looking only at the times when the spacecraft was in the South Atlantic Anomaly (about 1.7 per cent of this time).

Lo and behold, these guys found 28 antiprotons. That's about three orders of magnitude more than you'd expect to find in the solar wind, proving that the particles really are trapped and stored in this belt. <end excerpt> I'll leave this to others to decide if this should be added to the article. Ghaller (talk) 14:47, 4 August 2011 (UTC)

another source to integrate

• Davis, Jason (Jan. 26, 2012). "Guest Post: Jason Davis: Solar flares from Skylab". Planetary Society. {{cite web}}: Check date values in: |date= (help) ---Scientists had figured out that the best indication of an impending flare was an uptick in X-rays, as measured by one of the two detectors on the ATM (Skylab Solar Telescope Array). If a significant increase was observed by the system, an alarm would sound to alert the crew. Unfortunately, there is another phenomenon in low-Earth orbit that causes an increase in X-rays: the South Atlantic Anomaly.… When Skylab passed through the Anomaly, the station's X-ray detectors often triggered false alarms. This was problematic because capturing solar flares required a lot of high-speed film, a finite resource in the era before digital cameras. Pete Conrad explains it best in one of his communications with Mission Control on day 18:

"Hey Houston, I think you guys have got to put those...Anomaly passes, all of them, on our pads. If that ever happens out of station contact, we're going to come over the hill minus about 300 frames of film." --- thought this would be good to include in some manner. Smkolins (talk) 13:03, 29 January 2012 (UTC)

Location and drift of the "highest intensity portion of the SAA"

If a reader wants to know where the SAA is currently centered, they won't be able to find out from this article.

In the current image in the article (ROSAT_SAA.gif), it's hard to pin down where the "highest intensity portion of the SAA" is; plus, the image has a vague date of "1990s," so there are up to 24 years' worth of drift not reflected in the image.

This news article states that the SAA is over Brazil. Is that accurate?

Ideally, the article would contain an image that shows how the center of the SAA has drifted over time, and a table showing how its latitude and longitude have changed over time. If this data is linear, people could make valid extrapolations about its future position. 199.46.199.230 (talk) 00:57, 28 January 2014 (UTC)

Another affected satellite?

From ISRO AstroSat page here [1] ..."During the first orbit, there was a difficulty in detecting this Crab Nebula as the satellite happened to pass through the SouthAtlantic Anomaly (SAA) region when Crab was in the field of view. SAA avoidance zone was deliberately kept wide to protectthe instruments, and detectors were switched off in this interval during the initial days of Astrosat operation."

References

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ESA's "Swarm probes weakening of Earth’s magnetic field"

Could you please add some info on this to the article?

I added this to 2020 in science#May:

ESA reports that its Swarm satellite constellation is being used to better understand the mysterious South Atlantic Anomaly whereby the magnetic field has lost around 9% of its strength on a global average over the last 200 years in large area. They are investigating the processes in Earth's core driving these changes, which have caused technical disturbances in satellites and may be relevant to a potential geomagnetic reversal, and found that the anomaly could split up into two separate low points.

--Prototyperspective (talk) 11:11, 14 June 2020 (UTC)

References

Where's the actual measurement data?

In this whole article there is no hard data at all in terms of electromagnetic measurements. It doesn't even say if the anomaly features greater electromagnetic intensity from the surrounding background norm or diminished electromagnetic frequency in the anomaly region. How about some solid numbers? — Preceding unsigned comment added by 2405:6582:8580:C00:613F:E0B0:709B:A3A5 (talk) 06:27, 25 August 2020 (UTC)

Links to other languages not shown in Portuguese article

(The issue below seems to be global and not specific to this article). — Preceding unsigned comment added by Osoriosp (talk • contribs) 14:42, 30 October 2021 (UTC)

In the web version, links to other languages are shown in the left column. But not in the Portuguese version of this article, so I can´t navigate from the Portuguese to English or Spanish version, for example. The opposite path is available. Any idea on how we could fix this? In the Android app version, there is no problem. — Preceding unsigned comment added by Osoriosp (talk • contribs) 13:59, 30 October 2021 (UTC)