Monday, September 22, 2008
A. Feild / STScI / NASA / ESA
|An artist's conception shows the dwarf planet Haumea|
and its two moons, Hi'iaka and Namaka.
So just how many planets are there in our solar system anyway? Eight? Nine? Thirteen? Or thousands? Far from settling the question, the "Great Planet Debate" has revealed just how complex and interesting the question is.
The planethood question got more interesting this week with the naming of yet another dwarf planet, Haumea. It's traditional to name planets after mythological deities - and Haumea, the Hawaiian goddess of childbirth and fertility, follows that formula.
The football-shaped world was found by Caltech astronomer Michael Brown just after Christmas 2004 (which prompted its initial, unofficial nickname: "Santa"). Haumea's discovery was shrouded in a scientific controversy that Brown recaps in his Weblog. At the time, controversy surrounded its planetary status as well, because it added to a growing class of objects in the same general class as Pluto. Astronomers surmised that hundreds of Pluto-scale objects may lurk on the icy rim of the solar system's disk, known as the Kuiper Belt.
The controversy came to a head in 2005 when Brown's team found the object now known as Eris - a world like Pluto, only bigger and farther out. All this led the International Astronomical Union to agonize over where to draw the line on planethood. In 2006, the IAU came up with a definition aimed at putting the solar system's eight biggest planets in one class, and Pluto in a different class with Eris and other dwarf planets or "plutoids."
The Great Planet Debate has been simmering ever since. In August, astronomers held a teach-in on the subject at Johns Hopkins University's Applied Physics Laboratory, which is the base of operations for NASA's New Horizons mission to Pluto. One of the purposes of the meeting was to see how teachers were handling the planethood question.
Scientist (and parent) sees 'teaching moment'
The education angle literally hit home for planetary scientist Alan Stern - and not just because he's the principal scientific investigator for New Horizons.
"My own son was told by a teacher that an answer was wrong on a test about Pluto," Stern told me last week. According to the test, the "right" answer for the number of planets in the solar system was eight - but Stern said that August's installment of the Great Planet Debate proved that the question was still up for grabs, even among educators.
"It was clear at the end of the two and a half days that there was no consensus," he said. "We're in transition. I think that's a teaching moment."
Stern has long argued that the IAU's definition of planethood provided more confusion than clarification. "There's a lot of unhappiness with the IAU's solution," he said. "I didn't hear anybody say, 'Oh, I think it's the cat's meow.'"
He maintains that it's wrong to think about the solar system as if there were a sharp division between eight planets and everything else. Even dwarf planets are still planets - and in Stern's mind, they may be more representative of the planetary spectrum than the eight biggies.
"It's the most populous class of planets in the solar system," Stern said. "Pluto's no longer the misfit."
There's something about Haumea
The fact that the IAU is giving names to dwarf planets - Pluto, Eris, Ceres, Makemake and now Haumea - shouldn't make a difference in the debate, Stern said. In fact, it totally makes sense. "From our perspective, these are planets. They deserve names," he said.
Stern has often compared the definition of planets with the definition of rivers: Sure, there might be six great rivers in the world ... or are there 14? In any case, that doesn't mean you have to set the Maquoketa River or thousands of other streams apart as "dwarf rivers." Every river, great or small, has its own special appeal - and it's the same with planets.
In fact, Haumea may be one of the most endearing little planets out there: Caltech's Brown has said it's his "favorite object in the solar system," in part because of its fast, end-over-end spin, the elongated shape it has as a result, and also because of its tightly orbiting satellites (which have been named Hi'iaka and Namaka, after two of the goddess Haumea's children). Brown said additional bits of ice and rock were apparently struck off Haumea in a cosmic collision long ago and are now circling the sun in their own orbits.
New Horizons gets a transplant ... and Twitter!
Oodles of such oddities may well come to light when the New Horizons spacecraft makes its way through the Kuiper Belt, starting in seven years. Last week, the probe underwent a successful "brain transplant" that upgraded the onboard software. It's now more than a billion miles from Earth, flying toward Pluto at a rate of about a million miles a day.
You can keep up with the mission's progress via Twitter or Facebook. (In the wake of Phoenix Mars Lander's Twitter success, it seems as if every space mission nowadays is getting into social networking.)
New Horizons' team will be checking out the spacecraft's instruments over the next couple of months, and then put the probe back to sleep for another months-long nap. The first "dress rehearsal" for the Pluto flyby will be conducted next year, but there's still a long way to go before showtime in 2015.
Will the planethood debate be settled by that time? Stern won't be surprised if it isn't. After all, it took decades for scientists to settle the controversy over continental drift - and some are still going back and forth over the implications of climate change and evolutionary biology.
"This is not atypical," Stern said. "It's just one of the most visible topics on the table right now."
Using microscopic metal particles, scientists from the University of Wisconsin-Madison have found that plant-based sugar can be converted to gasoline to be used in current engines. The substance is cleaner-burning than petroleum-based gasoline and more stable than ethanol.
While a method to turn sugar to gas already exists, it requires extremely high temperatures which made the process less energy efficient. The new process converts the sugars to fuel in mere minutes by running a mixture of water and sugar over particles of the precious metals platinum and rhenium. The metal atoms break the chemical bonds in sugar and release oxygen, which leaves a mixture including carbon and hydrogen that can be used to make plastics or gasoline. Even the gas byproducts of the process can be used as a replacement for natural gas.
The scientists have only tested the process in laboratory setting, and before wide-scale use, the process faces the same problem as other biofuels: where to acquire the sugar. The process uses the simple sugar compound sorbitol, which is available but difficult to separate from biomass. “We would just intercept the sugar and go to gasoline,” said James Dumesic, the chemical engineer from the University of Wisconsin-Madison who led the study. “But there’s still a lot of work to do on how to go from cellulose to sugar.”
The metals used in the process are cost-prohibitive, but the researchers are unsure how much of the metal would be required for mass production. In the meantime they are studying how the metals react with the sugar in hopes to find cheaper metals that produce similar reactions.
Newly discovered bacterial alchemists could help save billions of plastic bottles from landfill. The Pseudomonas strains can convert the low-grade PET plastic used in drinks bottles into a more valuable and biodegradable plastic called PHA.
PHA is already used in medical applications, from artery-supporting tubes called stents to wound dressings.
The plastic can be processed to have a range of physical properties. However, one of the barriers to PHA reaching wider use is the absence of a way to make it in large quantities.
The new bacteria-driven process – termed upcycling – could address that, and make recycling PET bottles more economically attractive.
PET bugsAlthough billions of plastic bottles are made each year, few are ultimately recycled. Just 23.5% of US bottles were recycled in 2006.
This is because the recycling process simply converts the low value PET bottles into more PET, says Kevin O'Connor at University College Dublin, Ireland.
"We wanted to see if we could turn the plastic into something of higher value in an environmentally friendly way," he says.
O'Connor and colleagues knew that heating PET in the absence of oxygen – a process called pyrolysis – breaks it down into terephthalic acid (TA) and a small amount of oil and gas.
They also knew that some bacteria can grow and thrive on TA, and that other bacteria produce a high-value plastic PHA when stressed. So they wondered whether any bacteria could both feed on TA and convert it into PHA.
Bacteria hunt "It was a long shot to be honest," says O'Connor. His team studied cultures from around the world known to grow on TA, but none produced PHA. So they decided to look for undiscovered strains, in environments that naturally contain TA.
Analysing soil bacteria from a PET bottle processing plant, which are likely to be exposed to small quantities of TA, yielded 32 colonies that could survive in the lab using TA as their only energy source.
After 48 hours they screened each culture for PHA. Three cultures, all similar to known strains of Pseudomonas, accumulated detectable quantities of the valuable plastic.
The next step is to improve the efficiency of the process, says O'Connor. "A quarter to a third of each cell is filled with plastic – we want to increase that to 50 to 60%."
Less landfill Sudesh Kumar, a microbiologist at the University of Science, Malaysia, in Penang, is impressed with the study.
"There are many other systems that are economically more viable to produce PHA with better material properties," he says. "But Kevin's work offers an interesting novel approach to solve the problem of PET accumulation in landfill dumps."
But it is still unlikely that using the new approach alone will appeal to industry, O'Connor says.
"Working with this kind of environmental technology in isolation, the chances of success are reduced," he says. The best approach, he continues, would be to use the new bacteria as just one part of a bio-refinery capable of upcycling an array of waste products in an environmentally friendly way.
Soon, we’ll probably be seeing Lithium Iron Phosphate (LiFePO4) batteries being used in most electric cars and bikes. This new battery type is set to dominate the market. Based upon lithium ion technology, LiFePO4 batteries offer many advantages over lithium cobalt dioxide (LiCoO2) batteries which are commonly used in laptops, mp3 players and cell phones. In electric vehicles, LiFePO4 batteries offer greater range, power and safety.
LiFePO4 batteries also offer faster charging rates, and they provide full power until they are completely discharged. LiFePO4 chemistry is also environmentally friendly — it’s the least toxic of all the battery types.
LiFePO4 batteries were developed by Dr. John Goodenough at the University of Texas. These batteries have seen wide acceptance recently in Asian countries, but still have not made inroads in the U. S. marketplace. However, you can find these batteries being sold on eBay for electric bikes and scooters.
For electric vehicles and plug-in electric cars, the LiFePO4 batteries will typically perform well in temperatures up to 400-degrees F, last for 6 to 7 years at a charge-discharge cycle of over 3,000.
The biggest player in the LiFePO4 marketplace for electric vehicles, however, is A123 Systems that has teamed up with GM to develop these batteries for the Chevy Volt plug-in hybrid. Another big player is Lithium Technology Corporation who has been working with GM, Toyota and U. C. Davis to develop LiFePO4 batteries for all-electric and hybrid vehicles.
Here’s a list of all the advantages of LiFePo4 batteries:
- Safe technology — will not catch fire or explode with overcharge
- Over 2000 discharge cycles life compared to typically around 300 for lead acid
- Double the usable capacity of similar amp hour lead acid batteries
- Virtually flat discharge curve means maximum power available until fully discharged (no “voltage sag” as with lead acid batteries)
- High discharge rate capability, 10C continuous, 20C pulse discharge
- Unlike lead acid batteries, can be left in a partially discharged state for extended periods without causing permanent damage
- Extremely low self discharge rate (unlike lead acid which will go flat quite quickly if left sitting for long periods)
- Does not suffer from “thermal runaway”
- Can be used safely in high ambient temperatures of up to 60C without any degradation in performance
- Maintenance free for the life of the battery
- Can be operated in any orientation
- Does not contain any toxic heavy metals such as lead, cadmium, nor any corrosive acids or alkalies thus making LiFePO4 batteries the most environmentally friendly battery chemistry available
- LiFePO4 cells are of solid construction — there are no fragile/brittle plates made of lead which can be prone to failure over time as a result of vibration
- Can be safely rapidly recharged — when fully discharged can be brought to a state of over 90% fully charged in 15 minutes
WASHINGTON - Alice and Jeff Speck didn't have a car and didn't want one. But District of Columbia zoning regulations required them to carve out a place to park one at the house they were building.
It would have eaten up precious space on their odd-shaped lot and marred the aesthetics of their neighborhood, dominated by historic row houses. The Specks succeeded in getting a waiver, even though it took nine months.
Like nearly all U.S. cities, D.C. has requirements for off-street parking. Whenever anything new is built — be it a single-family home, an apartment building, a store or a doctor's office — a minimum number ofmust be included. The spots at the curb don't count: These must be in a garage, a surface lot or a driveway.
D.C. is now considering scrapping those requirements — part of a growing national trend. Officials hope that offering the freedom to forgo parking will lead to denser, more walkable, transit-friendly development.
Opponents say making parking more scarce will only make the city less hospitable. Commuters like Randy Michael of Catharpin, Va., complain they are already forced to circle for hours in some neighborhoods.
"Today I had an 11:30 meeting and I had to plan an extra hour just to park" said Michael, 49. It ended up taking him 40 minutes to find a metered spot.
Advocates counter that parking is about more than drivers' convenience; it can profoundly affect the look and feel of a city.
"Do you want to look like San Francisco or Los Angeles?" asked Donald Shoup, an urban planning professor at UCLA and author of "The High Cost of ." "New York or Phoenix?" (Shoup prefers San Francisco and New York — hard to park in but highly walkable.)
Parking requirements — known to planners as "parking minimums" — have been around since the 1950s. The theory is that if buildings don't provide their own parking, too many drivers will try to park on neighborhood streets.
In practice, critics say, the requirements create an excess supply of parking, making it artificially cheap. That, the argument goes, encourages unnecessary driving and makes congestion worse. The standards also encourage people to build unsightly surface lots and garages instead of inviting storefronts and residential facades, they say. Walkers must dodge cars pulling in and out of driveways, and curb cuts eat up space that could otherwise be used for trees.
"Half the great buildings in America's great cities would not be legal to build today under current land use codes," said Jeff Speck, a planning consultant. "Every house on my block is illegal by current standards, particularly parking standards."
Opponents also say the standards force developers to devote valuable land to parking, making housing more expensive.
Milwaukee, one of a small group of cities that has eased minimum parking requirements, did so because they were impeding redevelopment of struggling neighborhoods, said John Norquist, the city's mayor from 1988 to 2004.
Norquist, who today heads the Chicago-based Congress for the New Urbanism, described a lot that sat vacant for decades after a historic building burned down. The required parking made it unfeasible to build anything new there, he said. After officials relaxed the parking requirement, a thriving restaurant sprang up.
Some cities have switched directions altogether, replacing the minimum requirement with a cap on the maximum allowable number of parking spaces. London and San Francisco began making the shift decades ago. San Francisco is currently considering extending the new approach to more neighborhoods.
Activists say too much parking is required even in New York City, particularly outside Manhattan. In August, a coalition of environmental groups said existing parking minimums would boost traffic and cancel out much of the expected improvements from the city's green initiatives.
The D.C. proposal would eliminate minimum parking requirements with some exceptions. Caps on parking would also be established.
In old D.C. neighborhoods like Capitol Hill and Georgetown, where parking is scarce, opponents of the change fear that if new homes don't provide off-street spots, competition for on-street parking will worsen.
Ken Jarboe, a neighborhood leader from Capitol Hill, said the way to reduce traffic is to continue improving the transit system and to create incentives for people not to drive.
"Simply saying, 'Let's make it more painful to park — it doesn't get you where you want to be," Jarboe said.
But Harriet Tregoning, director of the D.C. Planning Department, said the city is already easy to navigate without a car. Nine out of 10 residents live within a quarter-mile of transit, and, according to census data, 12 percent of Washingtonians walk to work, Tregoning noted. More than a third of D.C. households don't have a car.
The Specks say they haven't regretted their decision to go car-free even after the birth of their son, Milo, in June. They walk to shops and parks in their neighborhood, and the baby's pediatrician is a short bus ride away. When needed, they can rent vehicles from Zipcar, a car-sharing service.
Adding a garage and a driveway to their house would have forced them to sacrifice the equivalent of a bedroom and their garden. They decided it was worth spending the time to get a variance, especially since they were applying for several other zoning waivers at the same time.
For a developer, however, seeking a variance may not be an option.
"If you're working off borrowed money, you're not going to wait nine months," Jeff Speck said.
As a result, developers of some recent D.C. projects have ended up with more parking than actually gets used, Tregoning said.
"We're forcing people to invest in spaces for automobiles rather than in spaces for people," she said. "There's no way to recover that use."