Stories tagged Earth and Space Science

Dec
19
2007

Extreme volcanism may have put the kibosh on the Mesozoic: Unaware of their impending doom, dinosaur contemporaries frolic in the Late Cretaceous sea.
Extreme volcanism may have put the kibosh on the Mesozoic: Unaware of their impending doom, dinosaur contemporaries frolic in the Late Cretaceous sea.Courtesy Mark Ryan
The mass-extinction that signaled the end of the Cretaceous period, as well as the Age of Dinosaurs has long been blamed on an Earth-shaking collision with an asteroid that struck 65 million years ago near Chicxulub on Mexico’s Yucatan peninsula. Some scientists however have long argued that extreme episodes of volcanism around the same time played a significant if not major role in the event.

Now, a Princeton University paleontologist claims that evidence in the fossil record adds weight to the latter argument saying the volcanic activity that poured out massive amounts of toxic gases and the expansive flood basalts in India’s Deccan Traps may have been the real villain in the Mesozoic era’s demise.

In a recent presentation at the Geological Society of America, Gerta Keller explained that microfossils known as foraminifera show steep decline nearly half a million years before the Chicxulub asteroid event happened, and just when the Deccan event was beginning.

The volcanoes poured huge amounts of toxic gasses into the atmosphere, and flooded something like 600,000 square miles of south-central India with lava flows. To give you an idea of the magnitude of the outpouring, when Mount St. Helens erupted in 1980, the volcano unleashed a cubic kilometer of volcanic material. And the eruption of Mount Vesuvius that buried the city of Pompeii nineteen hundred years earlier had poured out something like 8 cubic kilometers. But the Deccan event is estimated to have produced 512,000 cubic kilometers!! Yikes!

Just prior to the end of the Cretaceous period, the Deccan eruptions would have released massive plumes of carbon dioxide and sulfur dioxide into the atmosphere – possibly ten times more toxic gases than generated by a meteor impact, according to one volcanologist. At any rate, it set off extreme global warming and acid rain, and significantly weakened the biosphere. When the asteroid arrived a half-million years later, the environment would have been ripe for collapse. Nearly thirty years ago, physicist Luis Alvarez and his geologist son, Walter, discovered the crater at Chicxulub, and claimed that asteroid that created it could be the one responsible for the dinosaurs’ demise. But Keller thinks it may have been a case of being in the wrong place at the wrong time.

"The Chicxulub impact could not have caused the mass extinction," she said, "because this impact predates the mass extinction and apparently didn't cause any extinctions."

Keller studied the sediments directly above and below the Chicxulub impact layer, in Mexico, Texas, and India, expecting to find evidence of a new bloom of plankton to fill the void left by a mass extinction. Instead, she found no significant change in the micro-marine environment.

"We cannot attribute any specific extinctions to this impact,” she said. But where she did find evidence of a new bloom was in strata that had been laid down 300,000 years after Chicxulub and just about the time when the output of the Deccan volcanoes would have been at its greatest.

In India, near the Bay of Bengal, about 1000 kilometers from the Deccan lava fields, Keller discovered two lava “traps” each with four lava layers. The telltale bloom of microfossils was found in nine meters of marine sediment located just above the lower trap, which marks the Deccan event’s climax.
"We've shown convincingly the mass extinction came about 300,000 years after the asteroid impact,” she said.

But what about the famous iridium layer found in the K-T boundary? If the Chicxulub impact didn’t produce it, then where did it come from?

Keller thinks a second asteroid impact – not the Chicxulub one- may have been responsible for laying down the worldwide iridium layer that divides the Cretaceous and Tertiary rock layers. Direct evidence of this later impact (such as a crater) has not yet been found.

But to add fuel to the fire –pun definitely intended- it may be that the iridium source isn’t even extraterrestrial at all. Volcanism could be another possible source of increased iridium in the rock layer. The Deccan eruptions were peaking right at the time of the dinosaurs’ demise and maybe that’s all that was needed to send them on their way into extinction.

At any rate, the case against the dinosaurs’ killer or killers is certainly not closed.

LINKS
Story at ScienceDaily
The Chicxulub debate on Gerta Keller's site
More on the Deccan Traps
More on the Deccan Traps Extinction Theory
The Cretaceous Extinction Event

Dec
12
2007

Rolling discovery: The Mars rover Spirit, similar to this NASA rover called Fido, has made an unusual discovery of clues to life on Mars because of a bad wheel.
Rolling discovery: The Mars rover Spirit, similar to this NASA rover called Fido, has made an unusual discovery of clues to life on Mars because of a bad wheel.Courtesy NASA
There’s nothing quite as deflating, figuratively, as a getting a flat tire. And what about if you’re a space rover on Mars, where there’s no shop to go to get your tire fixed?

That’s what NASA’s Spirit Mars rover has been dealing with since its right front tire went bad nearly two years ago. It didn’t go flat, but it’s quit turning forcing NASA to move the rover around in reverse ever since, trailing the stuck wheel behind.

But nearly a year later, that astronomic misfortune has led to an interesting discovery. Ruts carved by the bad wheel last May churned up a bright spot in the rover’s wake.

Rover guiders turned the craft back to the colorful streak for a closer look and discovered that the rock contains high levels of silica. Upon further investigation, however, another nearby rock cracked open that was jam-packed with silica.

You’re wondering what’s the big deal?

Well, on Earth high levels of silica occur only in two places: hot springs or fumaroles, which are environments near volcanoes where acidic steam rises through cracks in the ground. In each of those environments on Earth, water is present and the area is teeming with life forms.

NASA Mars researchers are terming the discovery, made through these very accidental means, as one of the biggest breakthroughs to discovering life forms could have existed on the Red Planet.

By the way, if the bad wheel isn’t enough of a problem for Spirit, it’s also been through a bad dust storm which has coated much of its solar panels with grit. Because of that, it’s only operating at about 30 percent power and rover operators will soon be driving it up a higher altitude for a rest and to have the panels wind-cleaned.

Dec
11
2007

Streaming space light: Satellites on NASA's Themis mission have discovered what may be some of the mysteries behind the northern lights. Charged particles from the sun are blasting through magnetic fields stretching out from Earth's upper atmosphere, bursting with the energy of a medium earthquake.
Streaming space light: Satellites on NASA's Themis mission have discovered what may be some of the mysteries behind the northern lights. Charged particles from the sun are blasting through magnetic fields stretching out from Earth's upper atmosphere, bursting with the energy of a medium earthquake.Courtesy NASA
I know the source of the energy that powers the Christmas lights in my home’s windows: the outlet on my wall. No surprises there.

But today scientists announced that they have found what they believe is the energy source behind the spectacular views that make up the northern lights. NASA’s Themis mission has used five satellites to track down this magical, astronomical phenomenon.

What’s been discovered is that charged particles from the sun are flowing through space and are twisted through magnetic fields that link Earth’s upper atmosphere to the sun.

The satellites were launched last winter and on one two-hour span of time, measured the particle flows while northern lights were shimmering over Alaska and Canada in March.

If you’ve ever seen the northern lights, you know how cool and magical they can look. But you really wouldn’t want to get too close.

The same satellites measured the forces flowing through the March light show and found that the charged particles were moving around 400 miles per hour. The movement and energy release of their passing through the magnetic field was about the same as a 5.5 magnitude earthquake.

Dec
10
2007

A meteor streaking across the night sky: The Geminid meteor shower peaks this week on the night of December 13-14.  Photo by Jeff Smallwood at flickr.com.
A meteor streaking across the night sky: The Geminid meteor shower peaks this week on the night of December 13-14. Photo by Jeff Smallwood at flickr.com.

The last big meteor shower of 2007 will hit this week, and it's expected to be a doozy! The 2007 Geminid meteor shower peaks on the night of December 13, though meteors may be visible any night this week. What's more, it's supposed to be the best shower of the year! (And I can attest from personal experience that most of the previous showers this year have been a disappointment.)

If you want to catch the show, here's what you do:

  • Head out before 10 pm local time.
  • Bring a lawn chair or sleeping bag.
  • Dress warmly. A thermos of hot chocolate is optional, but highly recommended.
  • Get away from city lights.
  • Set up chair or sleeping bag, and sit / lie down.
  • Look up.

That should do it. The shower will increase as the night goes on, reaching rates of about one meteor per minute by dawn. (Folks who don't want to pull an all-nighter are advised to go out after midnight.)

The meteors will appear to be coming out of the constellation Gemini, about half-way up the sky in the east. But they will be streaking all across the heavens, so you don't really need to be facing in any particular direction.

No special equipment is needed. Meteors are visible to the naked eye. In fact, using a telescope or binoculars will actually hurt your chances of seeing a meteor, as they focus your attention on a small area. You want to keep scanning the entire sky.

For more information on the Geminid meteors, go here.

For tips on meteor watching, go here.

And, as a special treat, both Jupiter and Saturn should be visible that night as well.

Dec
10
2007

A nice and tidy future: And, see, there are still trees!
A nice and tidy future: And, see, there are still trees!Courtesy NASA
Aren’t you tired of the rainforest already? Who’s with me on this? Who else is sick of tapirs and spider monkeys? Show me a tapir that can fetch a Frisbee, or a spider monkey that can be prepared in under five minutes and we’ll talk, but I don’t see those things happening any time soon. A don’t get me started on rainforest themed television! Please, people, as far as good TV goes, the rainforest was tapped out about ten years ago. National Geographic needs to move on, maybe get it self a new image (I’m thinking something along the lines of The O.C. That was a show I could get behind).

Wouldn’t it be good for everyone if there were a little (or a lot) less rainforest? I mean, think about this: in Minnesota, we have zero (0) rainforests, and an annual death-by-poison dart frog rate of zero (0). In Brazil, they have one (1) rainforest, and an annual death-by-poison dart frog rate of, um, greater than zero (>0). Do the math – that’s bad.

Well, good news is here at last: we’re winning! A new report by the World Wildlife Fund claims that not only can that great bastion of ho-hum, the Amazon rainforest, be defeated, but that it’s happening right now, faster than we had ever dared hope! 60 percent of the Amazon could be gone within 25 years!

The agents of deforestation have been hard at work for decades, but their progress has never been quite fast enough for me. See, they don’t hate the rainforest (not like I do, anyway), and their chopping and burning has been dictated by economic pressures for more agricultural land (primarily livestock pasture). Fortunately, it seems that the magic of climate change will be picking up the slack here.

The Amazon rainforest plays a significant role in absorbing carbon from the atmosphere. When it is slashed and burned (the preferred method for clearing more agricultural space) it not only releases lots of carbon, but it is then, of course, unable to absorb any more. The rising levels of CO2 in the atmosphere then contributes to climate change, which, it is believed, will lower rainfall rates in Amazonia over the course of the next several decades. The lower rainfall will then result in more forest fires. It’s what they call a “delicious circle.”

These are exciting times we live in! What do you all think? Does anybody have any other ideas on how we could hurry the destruction of the rainforest along? Be creative! Have fun! Like, maybe we could all buy a piece of teak furniture, and then throw it away to make room for… our new teak furniture! Or we could try re-branding the rainforest – I’m thinking something along the lines of “the tropical painforest,” or “the land of root canals and dead puppies.” The second one doesn’t have quite the same ring as “painforest,” but I like how it gets right to the point.

So? Any ideas?

Nov
30
2007

Where's the lightning?: I can't see any lightning in this picture, but recent magnetic antenna data shows that Venus has regular lightning flashes in its dense atmosphere.
Where's the lightning?: I can't see any lightning in this picture, but recent magnetic antenna data shows that Venus has regular lightning flashes in its dense atmosphere.Courtesy NASA
With a name like Thor, any mention of lightning and thunder jumps off the page (or computer screen) demanding my immediate attention.

So I was locked into yesterday’s account that the European Space Agency’s Venus Express has confirmed the theories astronomers have had for years, that lightning strikes on Venus.

Lightning is one of the factors considered in the evoluntionary process that could have “sparked” life into inorganic materials. But weather and climate conditions on Venus today suggest that the window of supporting life forms has been long shut on the planet.

But the finding of lightning has electrified the weather forecasts for Earth’s solar system neighbor. Previously, astronomical meteorologists had figured that Venus had a long, boring forecast of strong, steady winds for the next 400 years.

Venus Express, which has been orbiting Venus for nearly two years now, used a magnetic antenna to pick up the planet’s lightning activities.

So if you had a strong enough telescope to see a lightning flash on Venus, how long would you have to count until you hear the ensuing thunder clap? Talk amongst yourselves to come up with the answer.

Nov
27
2007

Mars Rovers
Mars RoversCourtesy NASA/JPL-Caltech
About this time last year it was springtime on Mars. The two rovers had survived winter but a large, planet wide dust storm threatened to deplete their source of energy. To survive, both rovers were put into survival mode for several months. The both came through OK but because their solar panels are coated with dust, they do not have the energy they used to. Another winter is now approaching so both Rovers need to find a spot to maximize their solar gain.

Preparing for a long Mars winter

Spirit spent last winter on the sunny side of a hill called "Winter Haven" (click to see panorama) This winter Spirit is heading north toward an extra steep slope on "Home Plate". Right now it is stuck in what appears to be loose soil.

Rovers are showing their age

Spirit is having trouble getting around because one of its wheels doesn't work. It needs to go backwards, dragging its bad front wheel. Opportunity has a wheel that cannot steer. Its instrument arm is arthritic due to a bad motor in its shoulder. Opportunity is also blind in its infrared "eye" because of too much dirt on its lens. Both rovers are having problems with their grinding tools (RAT).

Mars rover's mission extended again

The twin rovers landed on the surface of Mars in January, 2004. Mission planners expected that it would only take a few months before dust coated the rovers' solar panels so thickly that they wouldn't be able to generate power any more. But the Martian weather had a trick; dust devils and wind gusts came by often enough to keep the solar panels relatively clear of dust. Without the loss of power looming, the rovers have been able to keep going, and going, and going. UniverseToday

Catch up on news about the Mars Rovers

Nov
26
2007

Ichnology takes a step forward
Ichnology takes a step forwardCourtesy Mark Ryan
There have been a couple of recent reports about new prehistoric tracks being discovered. The first was the report from Montana of what could be a rare footprint Tyrannosaurus rex. A second discovery involves some 315 million year-old reptile tracks found

recently in New Brunswick in Canada,

The two discoveries are the latest in the science of Ichnology, a specialized branch of paleontology that studies the trace fossils of prehistoric creatures. Trace fossils can be anything that the behavior of an ancient creature has left in the fossil record, such as footprints, borings, burrows, eggs, coprolites etc., anything besides its dead remains. Gene made a recent post about burrowing dinosaurs. The burrow dug by the dinosaur would be classified as a trace fossil. But the bones found at the bottom of the burrow would not.

But since the Object of the Month for November here at the Science Museum of Minnesota is fossil animal tracks, I thought I’d muse a bit about them, specifically dinosaur tracks, a favorite subject of mine.

Dinosaur trackway near Morrison, Colorado
Dinosaur trackway near Morrison, ColoradoCourtesy Mark Ryan
The first recorded dinosaur trackway came to light in 1802 when Pliny Moody, a 14-year-old farm boy, in South Hadley, Massachusetts plowed up a slab of red rock containing several three-toed footprints. Dinosaurs hadn’t even been imagined yet, so the tracks were attributed to giant birds –Noah’s Ravens– as the local doctor called them. Of course, he wasn’t far off since today’s birds are considered descendents of dinosaurs.

Three decades later, Reverend Edward Hitchcock who was president of Amherst College became fascinated with the tracks and started to collect them in earnest. Between 1836 and 1865 he amassed huge numbers of fossil tracks that today make up the world’s largest collection and are held in the newly completed Amherst College Museum of Natural History in Amherst, MA. Hitchcock did extensive study of the trace fossils for the rest of his life, and was the first to classify them into a Linnean system that is still used today. He even made large stony books of the prints by binding together slabs of complementing casts and molds. But in the end, he just couldn’t reconcile his religious beliefs with the evidence the tracks presented and went to his grave still holding on to his belief that they had been made by giant birds.

In 1858, the world’s first nearly complete dinosaur skeleton (Hadrosaurus foulkii) was discovered on John Hopkins’ farm in Haddonfield, NJ and put on public display at the Academy of Natural Sciences in Philadelphia. It was the start of the public’s fascination with dinosaurs that continues to this day. Unfortunately, as more and more dinosaur bones were found, the interest in their tracks diminished.

But in the past two decades new interest in fossil footprints has flared up as scientists begin to realize their value in determining dinosaur behavior. Luckily, dinosaur footprints are extremely abundant, and can be found as single prints or as trackways, sometimes hundreds of yards in length. One trackway in central Colorado called the "Dinosaur Freeway" is suspected to continue for hundreds of miles into New Mexico!

Fossil footprints can give scientists insight into a creature’s behavior revealing such information as locomotion, stride and speed, foot and leg anatomy, chronology, ecology, and geographic distribution.

The tracks are found, generally, in three forms: casts, true prints, and underprints. A cast is formed when the original imprint is filled with sediment that hardens into rock. True prints form when the animal leaves a direct imprint in the ground surface it steps on. Underprints are created when the weight and pressure of the dinosaur’s foot causes it to press into layers beneath the thin ground it steps on. Underprints usually don’t contain the detail of foot structure that a true print will sometimes reveal.

Because skeletal remains are seldom found along with tracks, it’s nearly impossible to say which exact species created them, so thanks to Edward Hitchcock fossil footprints have their own classification. The reverend’s original classifications contained genera such as Grallator, Eubrontes, and Anomoepus, but new names continue to be added as new tracks are uncovered. Take for instance, Dr. Phil Manning’s above mentioned recent discovery of a large therapod footprint. Because of its size and structure and the location it was found, it can be speculated that the trackmaker was a Tyrannosaurus rex. But because it’s not certain that that’s the case, the track would be attributed to a T-rex but would be called a Tyrannosauripus, a genus name meaning “tyrant lizard foot”. Dr. Manning could make it more specific by add a species tag resulting in something like Tyrannosauripus manningnensis.

In general, tracks are described by the size and shape of the footprint, the number and arrangement of digits, claw and heel marks, interdigital webbing and skin impression.

Some well-known tracksites in the United States include St. George Dinosaur Discovery Site in Utah, the Red Gulch tracksite in Wyoming, Dinosaur Ridge in Colorado, Dinosaur Valley State Park in Glen Rose, Texas, Clayton Lake State Park in New Mexico, and of course, Dinosaur State Park in Rocky Hill, Connecticut.

MORE INFO

Glen Kuban’s great dinosaur track info site
Dinosaur Trackers Research Group – Dr. Martin Lockley
Tracks of swimming dinosaur
Walk like a dinosaur; the study of emus
Raptor tracks show group behavior

Nov
25
2007

This is how the moon feels: all the time now.
This is how the moon feels: all the time now.Courtesy Wikimedia commons
The product of a brief and fateful union between the earth and “a body as big as Mars” in the back alley of the solar system, our moon has never quite come to grips with its lack of a present father figure With a distant mother and no siblings, the Moon has no true peers to turn to, and has always had to reassure itself that, someday, definitely someday, it would find a moon just like it, a friend and comrade that it could finally relate to.

Unfortunately, the social workers of the galaxy, astronomers, have recently had to bear the bleak news to the Moon that it is, at best, an ”uncommon moon”, and that the chances of it ever finding its soul mate are “pretty sucky.”

Most moons were either formed simultaneously to the formation of their planets, or were trapped by a planet’s gravity at some point. Our moon was probably created thirty to fifty million years after the formation of the solar system by a massive impact between Earth and a Mars-sized body (the impact would have tossed enough material into “circumterrestrial orbit” to form the Moon). These sort of moon-creating knock-ups, if you will, leave a cloud of telltale dust in a star system, allowing scientists a general idea of which moons were created that way. By examining how many star systems have this dust could, astronomers have determined that it is likely that only 5 to 10 percent of moons (at most) share a similar origin to ours.

This was an understandably crushing revelation for the Moon. It remains in a gray mood, despite the consolations of people around the world, many of who have insisted that it is “still pretty.”

Nov
15
2007

Rosetta: It didn't want to cause any trouble. All it wants to do is chase comets.
Rosetta: It didn't want to cause any trouble. All it wants to do is chase comets.Courtesy Wikimedia commons
Just in case you were concerned, the planet earth isn’t about to get creamed by an asteroid.

Oh? You weren’t concerned? Never mind.

Apparently, last week the Minor Planet Center was just about to release an emergency warning that a large, extra-terrestrial body was just about to pass a hair’s breadth from the earth – it should have skimmed by about 3,500 miles away. That’s creepily close, when we’re dealing with space.

Fortunately (for our stress centers, I guess) a clever Russian scientist actually took the time to look at the nearly earth-bound mass, and to track its trajectory, and realized that it was, in fact, the European, comet-chasing probe, Rosetta. Rosetta is about the size of a utility van (with wings), and we are quite safe from it.

So, thanks to one plucky Russian astronomer, the world is safe again. You all still have a pretty good chance of getting hit by cars tomorrow, though, or by dead birds falling from the sky. Or of choking on something you thought would be harmless, like pudding.