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Comment: Re:Deliberately crippled (Score 1) 118

by Dr La (#46236853) Attached to: Google Earth's New Satellites

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.

Comment: Re:It is post-Columbian (Score 1) 170

by Dr La (#46034827) Attached to: Voynich Manuscript May Have Originated In the New World

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.

Comment: It is post-Columbian (Score 4, Informative) 170

by Dr La (#46033929) Attached to: Voynich Manuscript May Have Originated In the New World
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.

Comment: Climate research (Score 2) 366

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: http://www.bangor.ac.uk/news/full.php.en?nid=16781&tnid=0

Comment: Re:It is called stacking, and already done (Score 1) 101

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.

Comment: It is called stacking, and already done (Score 2) 101

by Dr La (#44897069) Attached to: "Synthetic Tracking" Makes It Possible to Find Millions of Near Earth Asteroids
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.

Comment: Re:Throwing spears Homo sapiens sapiens (Score 1) 208

by Dr La (#43779715) Attached to: Narrowing Down When Humans Began Hurling Spears

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.

Comment: Lousiest topic title ever (Score 1) 67

by Dr La (#43022691) Attached to: Russian Meteor Likely an Apollo Asteroid Chunk
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

Comment: Re:This IS important (Score 1) 68

by Dr La (#42614587) Attached to: No, Life Has Not Been Found In a Meteorite
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!

Comment: Re:This IS important (Score 1) 68

by Dr La (#42601243) Attached to: No, Life Has Not Been Found In a Meteorite
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.

Not only is UNIX dead, it's starting to smell really bad. -- Rob Pike

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