Welcome to the Slashdot Beta site -- learn more here. Use the link in the footer or click here to return to the Classic version of Slashdot.

Thank you!

Before you choose to head back to the Classic look of the site, we'd appreciate it if you share your thoughts on the Beta; your feedback is what drives our ongoing development.

Beta is different and we value you taking the time to try it out. Please take a look at the changes we've made in Beta and  learn more about it. Thanks for reading, and for making the site better!



Google Earth's New Satellites

Dr La Re:Deliberately crippled (118 comments)

It will merely be a customer of DigitalGlobe - one of many, including the US government.

Not that the US goverment needs DigitalGlobe's images. After all, the NSA has a fleet of its own satellites with far better image resolution capability than the DigitalGlobe effort.

In fact, the US Government relies heavily on DigitalGlobe imagery. After the optical component of the Future Imagery Architecture (FIA) program that should have replaced the aging KH-11 Keyhole/CRYSTAL satelites was scrapped, it left the NRO (the NSA has nothing to do with optical reconaissance) with limited high-res imaging capabilities. For a while they had only 3 operational KH-11 optical reconnaissance satellites left in orbit: two new recent launches have expanded this to 5 recently but one of these is over 17 years old and will likely soon be deorbitted, bringing it down to 4: hardly a "fleet". Lawmakers have been holding off NRO requests for more optical satellites with the argument that it is better to buy time on DigitalGlobe satellites.

about 7 months ago

Voynich Manuscript May Have Originated In the New World

Dr La Re:It is post-Columbian (170 comments)

L'Anse aux Meadows.

Just a single example of European knowledge in the Americas that predated Columbus.

Irrelevant. The pictures in the Voynich manuscript are clearly not 11th century Norse but depict 16th century west European clothing and equipment and classic constellations.

Everything points to it being post-Columbian.

about 8 months ago

Voynich Manuscript May Have Originated In the New World

Dr La It is post-Columbian (170 comments)

The radiocarbon date of 516 +/- 18 yrs bp only dates the time of life of the goats who's skin was used for the parchment. It does not date the construction of the book persé. It was not unusual at that time to use old parchment.

The manuscript contains several depictions that are clearly European: figures in European clothing, European equipment (e.g. a cross-bow) and some pages with Western (not indigenous American) constellations (e.g. Capricorn, the Balance).

So it is very clear, if it indeed shows American plants, that it must be post-Colombian and old parchment was used.

about 8 months ago

Clam That Was Killed Determining Its Age Was Over 100 Years Older Than Estimated

Dr La Climate research (366 comments)

What was the point of examining this individual animal?

It was part of research into climate change over the past 1000 years. The oxygen isotopes in carbonates in clam shells provide information about climate at the time the shell layer was formed. See:

about 10 months ago

"Synthetic Tracking" Makes It Possible to Find Millions of Near Earth Asteroids

Dr La Re:It is called stacking, and already done (101 comments)

It's worth keeping in mind, though, that you don't publish CalTech papers and get time on the Palomar 200" by being a dim-witted slacker.

True. I think their presentation of things is more the result of current publishing demands: useful or even innovative is not good enough anymore to get your paper through, it needs to be "new" and "never done before" instead of an innovation on an existing technique.

Still, I find the complete lack of any reference to even the words "track & stack" weird, given that tracking & stacking is common practise in imaging faint asteroids. Maybe not when you use a 5-meter telescope, but with with smaller instruments it is often done. I have used the technique myself o faint asteroids and much-used astrometry packages like Astrometrica have a standard option for it.

about a year ago

"Synthetic Tracking" Makes It Possible to Find Millions of Near Earth Asteroids

Dr La Re:It is called stacking, and already done (101 comments)

Small addition: the technique is called "track & stack" when employed on moving objects. Most existing astrometric software can do it.

about a year ago

"Synthetic Tracking" Makes It Possible to Find Millions of Near Earth Asteroids

Dr La It is called stacking, and already done (101 comments)

The more sensitive camera and the algorithm to empirically find the correct direction and speed of movement of a not-known asteroid are new.

The method of overlaying multiple short images so that the asteroid is a pinpoint additive composite of multiple images and the stars become trails is not new.

The latter technique is called "stacking" (a word existing for quite a long time and meaning the same as their "synthetic tracking"). It is regularly done to image and get astrometry on faint objects, when speed and direction of movement are already known (e.g. in follow-up observations on a Near earth Asteroid that already has some observations over the previous hours/days and hence a preliminary orbit). That part is really not new, and there is no need to invent new terminology ("synthetic tracking") for it.

Frankly, it is weird that the authors nowhere mention "stacking" as an existing technique that is often used in imaging faint asteroids. It suggests they did not investigate whether their "new" technique is really that new. Yes, they innovate on it, but they did not invent a completely novel technique.

about a year ago

New Moons of Pluto Named Kerberos and Styx; Popular Choice 'Vulcan' Snubbed

Dr La Re:can a non-planet have moons? (194 comments)

A number of asteroids have moons (most well known pair: (243) Ida and Dactyl). So moons are clearly not restricted to planets.

about a year ago

700,000-Year-Old Horse Becomes Oldest Creature With Sequenced Genome

Dr La No: Welcome to PLEISTOCENE Park (69 comments)

Pleistocene Park, not Pliocene Park.

The Plio-Pleistocene boundary is at 2.6 million years ago. With 700 000 yrs, this Horse is Middle Pleistocene (the Lower-Middle Pleistocene boundar is at 780 000 yrs ago).

about a year ago

Narrowing Down When Humans Began Hurling Spears

Dr La Re:Throwing spears Homo sapiens sapiens (208 comments)

The general consensus is that Homo sapiens neanderthalis did not use throwing spears and it was the Homo sapiens sapiens who did this innovation.

There is no such consensus at all.

For the bow and arrow: yes. For throwing spears: no.

The 350 000 yrs old Schöningen (Germany) wooden spears, which predate Homo sapiens, are finally balanced with the center of balance at 1/3rd of their length. They have the balance and shape of an Olympic throwing javelin. Experiments with replica's show they are indeed quite suited as throwing spears.

The weak point of this new study is that it actually does not differentiate impact marks from thrusting from impact marks from throwing. It merely assumes that traces of a stone tip equate a throwing spear. And in placing the earliest evidence in an early H. sapiens context in S-Africa, it overlooks evidence elsewhere in a non-sapiens context.

Neandertals in Eurasia for example did haft stone points to pieces of wood: we know this because stone points with remnants of birch tar have been found (e.g. at Campanello, Italy). There is also the find of a wild ass vertebra from Um el Tlel in Syria with a Levallois stone point deeply embedded in it. In addition: a throwing spear does not have to be stone-tipped.

about a year ago

Russian Meteor Likely an Apollo Asteroid Chunk

Dr La Re:No surprise... (67 comments)

(I don't know where the 5200 number in the summary comes from but IAU's Minor Planet Center knows of only 4803) .

There is a disparity between their summary table (which lists 4803) and the full table of orbital elements of all Apollo's they (the MPC) provide. The latter counts 5203 objects

about a year and a half ago

Russian Meteor Likely an Apollo Asteroid Chunk

Dr La Lousiest topic title ever (67 comments)

Yay, what a surprise: "likely an Apollo"...[sarcasm] gosh, that is unexpected! [/sarcasm]

Given that the vast majority of objects in earth-crossing orbits are Apollos, that is hardly a surprising conclusion. It would have been much more interesting if it was an Aten - much less of those around. Or a comet fragment

87% of asteroids in earth-crossing orbits are Apollos. 13% are Atens. Then there is a n unknown quantity of cometary objects

about a year and a half ago

No, Life Has Not Been Found In a Meteorite

Dr La Re:This IS important (68 comments)

That SNC meteorites are from Mars was a main stream notion in meteoritics already well before the ALH 84001 "fossil" announcement. It was NOT with the ALH 84001 announcement that that link was first made. The first suggestions date from 1979. For ALH 84001 it is somewhat different: it initially had been misidentified as a diogenite (because its composition is mostly low-Ca pyroxene) and was found to be a SNC-related meteorite in 1994 (two years before the ALH 84001 "fossil" announcement). Its oxygen isotope fractionation is very similar to SNC's.

True, there are a few scientific dissenters about a Martian origin for SNC meteorites but they are few. Their main problem is to explain what the parent body of these meteorites is if it is not Mars. It needs to be a large differentiated body with active volcanism in the past, volcanism still active less than 1 billion yrs ago (which points to a body of planetary size). It needs to have posessed an atmosphere quite similar in noble gas composition as that measured on Mars by the Viking probes, and another clue is the similar chemical composition of the Mars surface and these meteorites. The Oxygen Isotopes moreover show that this parent body cannot be the earth-moon system, and they also differ in this from HED meteorites (linked to Vesta), as do their "young" crystalization ages.

The idea that scientists worldwide would engage in a 'conspiracy' just to save the face of a US President is ridiculous by the way. Many scientists studying ALH 84001 and other Martian meteorites are not even American - we foreign scientists don't give a rats arse about the reputation of your former President!

about a year and a half ago

No, Life Has Not Been Found In a Meteorite

Dr La Re:This IS important (68 comments)

The controversy about ALH 84001 was not that it is from Mars (that is pretty much agreed upon): the controversy was about nanofossils purportedly discovered in this meteorite.

about a year and a half ago

No, Life Has Not Been Found In a Meteorite

Dr La Re:This IS important (68 comments)

The problem is to recognize them: Mars and Moon meteorites stand out in the lab by their composition. Earth meteorites just look like, well, any common stone on the earth surface. So an analysis will say: "nope, it is just a terrestrial rock, not a meteorite".

A fresh fallen one will have a fusion crust, but it might be dismissed a a weathering crust.

about a year and a half ago

North Korea's Satellite Is Out of Control

Dr La This topic is sensationalist FUD (450 comments)

The OTP ought to cut severely in the hyperbole. There is very little (read: no) "bad news" in all of this. Most of what is brought up is FUD aimed at fooling people to think the North Koreans "failed" again (as crazy commies should). Truth is: this time they didn't.

1) Tumbling does not increase the changes of a collision at all. It is completely irrelevant for the collision danger whether a satellite tumbles or not;

2) Tumbling does not really influence the orbit (only in the final stages of decay it does). Indeed, it is completely unclear what is meant by a "stable orbit" here. ALL satellite orbits decay over time, so NONE of them is "stable". Probably, it is meant to imply that the Korean satellite has no reboosting capability. That is probably part of the design (many simpler satellites have no reboosting capability).

Yes, maybe the Koreans have no control over the attitude of the object. But that doesn't matter much: nothwithstanding Korean claims of it being a "weather satellite" this was probably never meant to be a truely functioning satellite.

The fact is that the North Koreans managed to successfully bring an object into earth orbit this time, and that in itself is an achievement. Whether you like them or not (and I don't like the North Koreans), those are the facts. No amount of spin and hyperbole about "danger" and "bad news" can take away that fact. This is all simply FUD.

about 2 years ago

North Korea's Satellite Is Out of Control

Dr La Re:X-37B timing? (450 comments)

They are in completely different orbits: so no.

about 2 years ago

Amazon and Google Barred From UK Government Cloud

Dr La The Patriot Act is the problem (79 comments)

The problem is simply that Amazon and Google servers in the US fall under the US Patriot Act. This means that the US Government ALWAYS has access to the hosted files, if it wants. It is not possible for a company and foreign government to negotiate on this: Amazon and Google are bound by US law.

Of course, as a government you don't want another other government to have complete access to anything you put in the cloud. And in some countries (e.g. the Netherlands where I live) it is explicitly forbidden to host privacy sensitive information (e.g. medic records) on systems that have servers outside of the country in question for exactly this reason.

about 2 years ago



Unpatched software and no antivirus at Diginotar

Dr La Dr La writes  |  about 3 years ago

Dr La (1342733) writes "On request of the Dutch government an independant company (Fox-IT — no relation to the TV network whatsoever) investigated the situation at Diginotar, the hacked Dutch company at the center of the fraudulent SSL certificates scandal. The report contains some amazing observations. While the company is active in the internet security business, Diginotar was extremely sloppy regarding it's own security to internet threaths.

The report ( mentions that:

a) No antivirus software was present on Diginotar's servers;
b) "the most critical servers" had malicious software infections;
c) The software installed on the public web servers was outdated and not patched;
d) all servers were accessible by one user/password combination, which was "not very strong and could easily be brute-forced".

Diginotar did appear to have run a firewall though."

US Delta rocket crashes in Mongolia

Dr La Dr La writes  |  more than 4 years ago

Dr La (1342733) writes "Two metal objects, one cylindrical and a smaller round one, which crashed near Buren Soum in the Tuv province of Mongolia on 19 February , are parts of an American Delta II rocket stage (nr. 35939, 2009-052C) that launched the military STSS Demo 1 & 2 satellites in September 2009. The largest of the two objects is 7.5 meter long and has the serial number "02728" on it. Pictures of both objects can be seen here

The Delta II rocket in question launched a military satellite duo, parts of the STSS program, intended for space-based detection and tracking of missiles.

The fall of the rocket stage was followed by amateur satellite trackers in the months leading up to the February 19 decay over Mongolia. Based on their final orbit determinations just hours before the decay, the decay must have occured near 3:32 UTC on February 19."

Two satellites collide in space

Dr La Dr La writes  |  more than 5 years ago

Dr La writes "SpaceFlight Now breaks the story about a collision between two satellites on Tuesday 11 February. The satellites were a commercial Iridium satellite (providing satellite telephone service) and a defunct Russian Kosmos satellite.

Amateur satellite sleuths at the list were quick to deduce that it concerned Iridium 33 (Norad #22675) launched in 1997 and Kosmos 2251 (Norad #24946) launched in 1993. The collision occured at 16:56 GMT (11 February) over the arctic of Northeast Siberia, at 98.156 E, 72.462 N, 788.58 km (490 mile) altitude.

The collision resulted in a large amount of fragments, which will gradually disperse and form a band of debris at about 800 km altitude, the operational altitude of many satellites. They will not endanger the International Space Station, as this orbits at a much lower altitude (about 350 km)."

More debunking of the USA 193 satellite shootdown

Dr La Dr La writes  |  about 6 years ago

Dr La writes "Following close on Oberg's defense of it in IEEE Spectrum, which was recently covered on /., the online Bulletin of the Atomic Scientists has published an essay by Harvard astrophysicist Yousaf Butt with a very critical view of the official reasons given for the shootdown of the failed USA 193 spy satellite.

Butt filled a request through the Freedom of Information Act and obtained the report featuring the re-entry model and analysis that was used. And found it to be flawed and on closer look not quite supportive of the alledged 'danger' of the re-entry of USA 193's hydrazine fuel tank. The report is very cautious and it's authors already note that some of the model assumptions are not realistic. Importantly, it shows that even with these assumptions maintained, much of the tank's titanium outer layer will ablate according to the model (remember how Oberg denied this in his essay?!), leaving only a very thin outer shell 1/5th or less of the original thickness. This assumes uniform ablation (which is not realistic).

Butt argues that when more realistic assumptions are made, this suggests the tank would likely have been destroyed upon reentry. The implications are that the 'danger' was very small indeed. And hence the 'concern' given in the official reasoning behind the shootdown, overstated.

You can read the essay here, and it includes a link to the report pdf.

The essay highlights (taken verbatim from the essay introduction itself):
  • A NASA study on the survivability of USA-193's hydrazine fuel tank used an oversimplified model, leading to an overly optimistic assessment of the tank's survival.
  • But even this study showed how the tank would have burned up when reentering the atmosphere.
  • Therefore, Washington's contention that the tank would have hit the ground intact, posing a health hazard, seems questionable.

Another thing to note is that the tank was not completely filled with fuel, but 76% filled. That turns out to be an important factor in the assessment of what would have happened to the tank upon reentry."


Dr La has no journal entries.

Slashdot Login

Need an Account?

Forgot your password?

Submission Text Formatting Tips

We support a small subset of HTML, namely these tags:

  • b
  • i
  • p
  • br
  • a
  • ol
  • ul
  • li
  • dl
  • dt
  • dd
  • em
  • strong
  • tt
  • blockquote
  • div
  • quote
  • ecode

"ecode" can be used for code snippets, for example:

<ecode>    while(1) { do_something(); } </ecode>