Mr. Bones

Tyrannosaurus rex on display at the American Museum of Natural History.

Barnum Brown was arguably the greatest fossil hunter of all time. Working for the American Museum of Natural History in New York, he had a career spanning more than 60 years. The museum boasts the largest collection of fossil dinosaurs in the world, thanks in large part to Brown’s collection efforts. Mr. Bones, as he was affectionately known by admirers, had his discoveries plastered on the front page of newspapers across the country and had been on so many radio programs and given so many lectures that he was considered one of the most famous scientists in the world during the first half of the twentieth century.

  Brown was completely dedicated to his work with the museum. One chilly December morning in 1898, Brown arrived at the museum as usual and by the time he had removed his coat he was called into Professor Osborn’s office. Osborn was the curator of vertebrate paleontology for the museum and wanted to send Brown on an expedition to Patagonia. Brown’s account from his journal follows: “Yesterday, about three hours before the Capac was to sail I was notified by Professor Osborn that arrangements had been made for me to go to South America. Four of the Dept. men packed up my kit and I took another with me home to pack up. Imagine getting an outfit together in three hours to go on a seven thousand mile journey, and be gone a year or more. Such is the life of a fossil man.”

  Brown embarked on the month-long sail to Punta Arenas, during which he was so taken with sea sickness that he was “…first hoping I would die, then afraid I wouldn’t”. He managed to survive the journey, and collected fossils for the next year and a half. Months would pass without word and at times the only evidence of Brown’s continued survival would be the shipment of tons of fossils back to the museum. Mr. Bones would face blizzards, evade quicksand, and even survive being shipwrecked near Tierra del Fuego before heading home. 

  Brown’s greatest discovery came in 1902. Brown and his team had been sent to the badlands of Montana to search through the Cretaceous rock beds of Hell Creek for Triceratops fossils, in particular an intact skull. This rugged terrain was explored by Louis and Clark and is known as the Missouri Breaks today. After supplying themselves at Miles City, Montana, they traveled by wagon for five days to Hell Creek where they made camp at the base of Mount Sheba. Before dinner on the first night, Brown found bone fragments that had fallen down the hill into the creek. After tracing them up the hillside to their point of origin, they started digging, first with plows and scrapers to remove the overlying sediment, then with dynamite when the sandstone became too hard. It would take two years to excavate, and in the end they left a hole that was nine meters long, nine meters wide and six meters deep. The surrounding rock was so hard that they removed everything in large stone blocks which were transported, first by wagon, then by train, back to the museum. The pelvis was massive—it’s block weighed over two tons and was too big to put on a wagon. Brown had to build a sled and drag it with a team of horses the 200 km back to Miles City. It turns out he had discovered the type specimen of Tyrannosaurus rex. A few years later, Brown would return to Hell Creek and discover another, even more perfectly preserved Tyrannosaurus rex which would allow the museum to fully characterize the dinosaur that has captured the imagination of so many in the hundred plus years since its discovery. This “favorite child” of Mr. Bones is still on display in the Museum’s Fossil Hall and speaks volumes about the incredible power of Tyrannosaurus rex, one of the largest carnivores to ever walk the planet.

Why Ice is Slippery

Ice has a hexagonal crystal structure, but what happens
at the surface boundary to make ice slippery?

Ice is a very common solid here on Earth yet one of the most puzzling. Take the seemingly simple question, “Why is ice slippery?”, for example. Common wisdom says that when you step on an icy surface the pressure melts the ice a little bit to create a thin layer of water that acts as a lubricant. It’s due to the unique property of water: the solid form is less dense than the liquid form. We take it for granted that an ice cube will float in a glass of water, but for most material the solid form would sink to the bottom. And because ice has a lower density it is also true that the melting point of ice is depressed as pressure increases. 
The theory goes that as you walk on ice the increase in pressure lowers the melting point of the top layer of the ice and it melts for a brief moment, then refreezes as you pass by. The problem with this explanation is that the effect is very small and would only reduce the melting point by a few hundredths of a degree at most. Yet ice is still slippery when its temperature is far below the melting point.
One possible explanation is that friction plays a part as well. The act of walking on ice creates friction which heats the ice to create a slippery surface. But the problem with this is that ice is still slippery regardless of whether or not you are moving. If you are standing still there is no friction, yet it’s still slippery.
A better theory is that ice has an intrinsic liquid layer. Water molecules at the surface remain unfrozen because there are no molecules above them to hold them in place. This was first proposed in 1859 by Michael Faraday who noticed that two ice cubes will fuse together if they are pressed against one another. Faraday’s explanation for this is that the liquid layers freeze when they are no longer at the surface. But even this theory is not quite correct. 
In 1996, a team led by Gabor Somorjai, a professor of chemistry at Lawrence Berkeley Laboratory, bombarded the surface of ice with electrons. By observing how they bounced off they were able to make an amazing discovery: What actually makes the surface of ice slippery are rapidly vibrating water molecules. These “liquid-like” water molecules do not move from side to side—only up and down. This is an important distinction. If the atoms moved from side to side, the layer would actually become liquid, which is what happens when the temperature rises above 0° C. It turns out that it is this “liquid-like” layer that makes ice slippery.

The Geology of Arches National Park

Landscape Arch, the longest arch in the park and the 

second-longest arch in the world.

Arches National Park contains more than 2,000 natural stone arches—the greatest concentration in the world. But this pales in comparison to the grandeur of the landscape—contrasting colors, textures and landforms unlike anything else on the planet. 
   Located above the Colorado River in southern Utah’s high desert, the park is part of an extended area of canyon country, sculpted by millions of years of weathering and erosion. 300 million years ago, inland seas covered the region. The seas filled and evaporated—29 times in all—leaving behind salt beds up to about 4,000 m thick in places which is known as the “Paradox Formation” today. Later, sand and material carried down by streams from the surrounding uplands buried the salt beds beneath thick layers which later became cemented into rock. Most of the formations at Arches are made of this red Entrada sandstone and tan Navajo sandstone that was deposited 150 million years ago.

Delicate Arch, the most famous of the over 

2,000 arches in the park.

   The salt beds, under tremendous pressure from the weight of the overlying sandstone, became unstable and began to flow. This movement caused the overlying rock to move and buckle. Some sections were thrusted upward into domes, while other sections dropped into the surrounding cavities. Vertical cracks developed which would later contribute to the creation of arches. 
   As the movement of salt deep underground shaped the surface, erosion carried away the younger layers of rock. Water seeped into the rock through cracks and washed away loose material and eroded weaker portions of the sandstone, leaving a series of free-standing vertical fins. Ice formed during colder periods would expand and put pressure on the rock, breaking off chunks and created openings. Many of the fins collapsed, but some that were harder and more resistant to the erosion survived to become the spectacular stone sculptures that we see today. 
   Although the park has timeless beauty, it is not indestructible. The same powerful forces that nature harnessed to carve these extraordinary arches will eventually tear it down. Wall Arch, a photographer’s favorite that was ranked 12th in size, collapsed in August 2008. Landscape Arch, which at 88 m is the longest arch in the park and the second-longest in the world, is facing a grim future at the destructive hands of gravity and erosion. Since 1991, three slabs of sandstone have fallen from the thinnest portion of the arch and the park has had to close the trail which passes beneath it to protect visitors from its eventual demise.

Alkali Metals in Water

Alkali metal are the Group 1 metals on the periodic table and include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs) and francium (Fr). All of the alkali metals are naturally occurring, but francium is exceedingly rare. These metals share similar chemical properties and are all highly reactive.

Fact vs. Fiction

I was looking around on the internet last night, searching for ideas for my next column when I found an article titled “50 Interesting Science Facts”. One of the items it listed was “If our Sun were just [an] inch in diameter, the nearest star would be 445 miles away.” Wow, I thought, that really illustrates the vastness of space pretty well. Maybe I could use it somehow. But I was a bit suspicious because the comparison didn’t use the metric system, and we all know that any scientist worth their NaCl uses the metric system! Also, it had a typo—the word “an” was omitted before the word inch. In my day-job I do a lot of proofreading and copy editing so typos always make me suspicious. What the heck, I thought, lets run the numbers and see if it checks out.

   According to NASA and Wikipedia, the diameter of the Sun is about 1,390,000 km, and the nearest star to us, Proxima Centauri, is 4.22 light years away, or 39,900,000,000,000 km (written as 3.99 x 10¹³ km in scientific notation). So if we divide the latter by the former, we find that the ratio of distance to diameter is 28,700,000 : 1, so if the Sun were one centimeter in diameter, the nearest star would be 287 km away. Sounds about right, but lets convert to American units to be sure. The number of inches in a mile = 12 in/ft x 5,280 ft/mi = 63,360 in/mi. So if we take our distance to diameter ratio, 28,700,000 and divide by 63,360 in/mi we find that, in fact, if the Sun were one inch in diameter the nearest star would be 453 miles away. Our “interesting fact” is off by eight miles, or about three percent! If they had just written that it would be about 450 miles away I would have no problem, but when you present information to three significant digits then it should be accurate to three significant digits.

   But now things get even more fun, because on the internet an incorrect fact gets propagated far and wide rather quickly. Doing a Google search on “If our Sun were just inch in diameter, the nearest star would be 445 miles away.” it turns out that I wasn’t the only one that thought it was an interesting fact, just the only one to check it. There were over 3,000 results that had the same incorrect information, and all but nine of them had kept the typo as well. Even a monkey can copy and paste I guess!

Google returns 3,010 search results for “If our Sun were just inch in diameter, the nearest star would be 445 miles away.”

   Good science requires attention to detail and willingness to question everything, and I want to encourage my readers to take the time to check details and ask tough questions. So instead of a quiz this week I have a challenge instead: find your own scientific “fact” that is incorrect and report it to me, either by e-mail (douglasclark@sbcglobal.net) or through my Facebook page (keyword weeklysciencequiz). If you find something, I’ll give you credit on an upcoming article. Happy hunting!

Jet Propulsion Laboratories

Located in the foothills of the San Gabriel mountains in Pasadena, JPL is NASA’s research laboratory that is managed by Caltech. JPL’s primary mission is space exploration using robotic spacecraft. This past weekend I had the good fortune of being able to attend JPL’s annual open house event, and I was pleasantly surprised by how many people were there, with lines of people waiting patiently to get into one of the 20+ exhibits. We were able to view 3D stereo images of Mar’s surface as well as watch a short 3D movie about the Earth. We were able to see how NASA missions are using JPL's infrared imaging technology to create incredible photos of distant stars and galaxies. We also saw how exoplanets are being discovered at an ever-increasing pace in an attempt to find other Earth-like planet in the cosmos capable of supporting life.

The Martian Science Laboratory rover (right) on display 

at JPL and in comparison with the Mars Exploration Rover 

(left) and Sojourner rover (center).

   There were several rovers on display, the most-impressive being the full-scale next-generation Mars Science Laboratory (MSL) rover. Named Curiosity, the MSL is scheduled to launch this fall and make a precision landing on Mars in August, 2012. Curiosity, with its array of scientific instruments, will be able to help assess whether or not Mars either now or at some time in its past is able to support microbial life forms.

   2011 is a very busy year for JPL. Besides Curiosity, in June JPL’s Aquarius satellite will be launched. Aquarius will map the salinity of the Earth’s ocean surfaces. This information will be used to improve our understanding of the oceans’ role in the water cycle by tracking how fresh water is exchanged between the atmosphere, sea ice and oceans. By measuring changes in ocean surface salinity, as well as melting ice and river runoff, Aquarius will provide new information about how freshwater moves around our planet which will help improve computer climate models as well as our understanding of worldwide ocean currents.

An artistic conception of Juno orbiting Jupiter.

   In August, NASA will launch JPL’s Juno explorer which will, by 2016, begin orbiting Jupiter to study the planet’s composition as well as gravitational and magnetic fields, and polar magnetosphere. Juno will look for clues about how Jupiter was formed: whether it has a rocky core, how much water is present deep within the atmosphere, and what the mass distribution is within the planet. Juno will also study Jupiter’s violent storms where winds can hit speeds of 600 km/h. With all the activity going on at JPL, we can be assured of many new discoveries in the near future which I look forward to covering in more detail as they occur.

Fusion's Future

This week we will wrap up our series on nuclear fusion by taking a look at one possible scenario for the future of fusion and how it could eventually play a part in ending our reliance on oil and natural gas.

The fusion reaction of two helium-3 atoms yields one
helium-4 atom and two protons plus energy.

   Even though nuclear fusion does not produce radioactive waste directly, it does produce neutron radiation which does require shielding. But some fusion reactions are aneutronic. One such reaction is a pure reaction of helium-3 where two He3 nuclei fuse to create one helium-4 nucleus and two protons. Since the protons are electrically charged, they can be contained by an electric or magnetic field. And it gets even better, because by containing these protons it would be possible to convert this energy directly into electricity, bypassing the need to heat water and create steam which runs through turbines which then powers electric generators.
   But there are some problems, the biggest of which is that helium-3 is virtually nonexistent here on Earth. Our closest source for helium-3 is on the Moon, which has sparked a new space race which may one day lead to mining on the Moon. China, Russia, India, Japan and Germany have all declared their intention to make it to the Moon with the intent of eventually mining helium-3 and bringing it back to use as fuel for fusion reactors here on Earth. NASA, too, is scheduled to be on the Moon by 2020 and to have a permanent base by 2024. And while NASA has not specifically come out and declared an intention to mine helium-3, it does have advocates of helium-3 mining in influential positions.
   The other problem is the extreme temperature required in order to begin a fusion reaction of pure helium-3, which is estimated to be six time hotter than the interior of the Sun. The only research facility currently doing successful helium-3 fusion reactions is at the Fusion Technology Institute at the University of Wisconsin-Madison, where they have been able to confine the reaction with a technology known as inertial electrostatic confinement (IEC). The benefit of IEC is that it doesn’t need a massive confinement structure—their experiment is table-top sized. It is estimated that we are 50 years away from creating clean fusion energy, but the potential advantages are so great there is no doubt that research will continue and possibly one day in the not-to-distant future clean energy will be more than just a dream.