We often hear about gravity being different on other planets--the Moon is an oft-cited example of how weaker gravity makes you weigh less. But did you know that gravity actually varies on our own planet?
There's this thing called a geoid. It sounds like something out of a sci-fi story, but it's quite real. The geoid is a map of the Earth's gravitational field. And since gravity impacts things like sea level and currents, it's important to understand how it varies.
Luckily, those crafty Europeans came up with the GOCE (Gravity field and steady-state Ocean Circulation Explorer) satellite, which has painted the clearest picture yet of the geoid. With its variations exaggerated, it makes the Earth look like a giant potato. The variations come from unevenness in earth's mass and shape. Its wobbly surface represents what shape the oceans would take without current, wind, or tide to move them. The satellite also studies ocean circulation and the movement of ice.
This information is particularly important to understanding sea level rise. Scientists predict that, on average, sea level will rise 3 feet overall by 2100. But those three feet will be distributed differently throughout the world, and studying that distribution is pretty complicated. There's the impact of the geoid and of gravity from large ice sheets, but winds and water circulation, water temperature, salinity, meltwater from ice sheets, rainwater runoff, and land changes all leave their marks.
Some of these changes redistribute water (ex. geoid), others add to the volume of seawater (ex. temperature increases), and still others modify the land's height relative to the water (ex. land changes, such as sedimentation and oil extraction). Some changes leave a lasting impact (ex. meltwater from glaciers), while others can vary by the hour or the season (winds).
By developing this most-accurate-to-date geoid and ocean circulation model, researchers have created a picture of sea level at its natural state and modeled some of the processes that alter that state, so that we have a reference point for understanding many of the less-defined factors in sea level rise. And that, my friends, will help us better anticipate and plan for the changes ahead.
Plus it's just kinda cool to see how the Earth is really shaped, huh?
Courtesy NASA/JPL-Caltech Yesterday NASA's Stardust spacecraft performed a final burn with its main engines which effectively ended the life of NASA's most traveled comet hunter. Called a "burn to depletion", the procedure will help to answer the question of how much fuel Stardust had left in its tank. While it sounds like running your snow blower until it runs out of gas to store it for the summer, this was an important test as no one has invented an entirely reliable fuel gauge for spacecraft. Part of the process of approximating fuel use is looking at the history of the vehicle's flight and how many times and for how long its rocket motors have fired.
Stardust's burn to depletion is expected to be useful especially because the spacecraft has been proverbially "running on empty" for a long time. Stardust has been in space for over 11 years and has flown past an asteroid (Annefrank), collected particle samples from a comet (Wild 2) and returned them to Earth in a sample return capsule in January 2006. Then, after these primary objectives, it was then re-tasked to perform a flyby of comet Tempel 1, a task it completed last month.
Before the burn to depletion Stardust pointed its antenna at Earth and sent information on the burn as it happened. The command ordering the rockets to fire was sent for 45 minutes, but the burn lasted just 146 seconds. 20 minutes after the engines burned out, Stardust's computer commanded its transmitters to turn off. Without fuel to power the spacecraft's attitude control system, Stardust's solar panels will not remain pointed at the sun. When this occurs, the spacecraft's batteries are expected to drain of power and deplete within hours.
Its a fitting end to a very impressive mission for NASA.
The crew of the Space Shuttle Discovery recently received a “wake-up call” from “Captain Kirk” of the “Star Trek” series. NASA piped in the opening theme from the original “Star Trek” series. It came complete with a custom monologue read by William Shatner, who played the legendary character in the series. However, the quest is a bittersweet one for the team. This is the final trip for Discovery. Source of article - Space shuttle crew gets wake-up call from Captain Kirk by Newsytype.com.
Declaring 'These are the voyages of the Shuttle Discovery'
CNN states that an interesting wake-up call from Earth came to those on the Space Shuttle Discovery from the International Space Station. Discovery got a Houston broadcast that had William Shatner reading the “Star Trek” television series opening monologue at 3:23 a.m. on March 7. ”Captain Kirk” read the monologue with different words added to it. The original songs still played:
"Space, the final frontier. These have been the voyages of the Space Shuttle Discovery. Her 30 year mission: to seek out new science. To build new outposts. To bring nations together in the final frontier. To boldly go, and do, what no spacecraft has done before."
NASA tune contest used
The “wake up call” for astronauts is a song picked by the public. A NASA tune competition is done to pick this. Almost every NASA quest in history has had a “wake up” tune played. Generally the NASA officials or family members of the astronauts picked the songs out though. Original music was submitted while people could also vote on popular songs when the voting started many years back. Versions of the “Star Trek” monologue were submitted by bother William Shatner and Patrick Stewart while the “Star Trek” theme has been really important to many. There has already been voting for the next quest. On April 19, the STS-134 will launch.
The final Discovery mission
This is the last quest in space for the Shuttle Discovery. Discovery and the team of Shuttle Quest STS-133 will land at Cape Canaveral on Wed, March 9, and the spacecraft can be retired. Two final shuttle missions are scheduled for April and July, in accordance with the Washington Times, that could be the final flights of the Endeavour and the Atlantis, respectively. While NASA works on other spacecrafts, the space flight will only be done with “space ferry” crafts that private businesses build and operate after the shuttles are done.
NASA Song Contest
History of NASA Wake up Songs
Buzzketeers, it's a big problem.
A ginormous, hulking, frozen, messy problem.
See, here in St. Paul, we've had a very snowy winter. (As of today, it has been the seventh snowiest winter on record. And the snow season isn't over yet.) When the City plows the streets, they have to put the snow somewhere. And one of the places they put it is the parking lot of the St. Paul Saints Midway Stadium, on Energy Park Drive.
Courtesy Liza Pryor
The 550-spot parking lot is completely -- and I mean COMPLETELY -- covered with snow. It's 30, even 50, feet deep. And it goes from Energy Park Drive north to the train tracks, and from the stadium west to the end of the property. It's impressive, peeps.
Courtesy Liza Pryor
And here's the problem, friends: the St. Paul Saints season opener is May 8th. And there's no way all this snow is going to melt before then. Baseball needs its parking lot back.
So how can we get rid of the snow? Trucking it away isn't an option, and minimal use of fossil fuels is a good thing. Buzzers, it's time to go all Mythbusters here and submit your ideas. If you've got a good one, you might get to see it in action.
Courtesy NASA/JPL-Caltech/UMDThe following is from a listserv I am on that I thought was interesting.
On February 14, NASA's Stardust-NExT (New Exploration of Tempel 1) mission will encounter Comet Tempel 1, providing a unique opportunity to measure the dust properties of two separate comets (Wild 2 and Tempel 1) with the same instrument for accurate data comparison. The encounter will also provide a comparison between two observations of a single comet, Tempel 1, taken before and after a single orbital pass around the sun.
NASA's Stardust spacecraft will fly within 200 kilometers (about 124 miles) of Comet Tempel 1 on February 14, 2011, at about 8:36 p.m. Pacific Standard Time.
NASA's Deep Impact mission observed Comet Tempel 1 in the summer of 2005, as the comet was inbound toward the Sun on its approximately 5.5-year orbit between Mars and Jupiter. Deep Impact's primary mission was to deliver a special impactor spacecraft into the path of Comet Tempel 1. The spacecraft -- and many ground-based observers -- observed the impact and the ejected material. Scientists were surprised the cloud was composed of a fine, powdery material, not the expected water, ice, and dirt. The spacecraft did find the first evidence of surface ice on the surface of a comet instead of just inside a comet.
The Stardust-NExT mission is a low-cost use of an in-flight spacecraft redirected to a new target. Prior to its tasking for Tempel 1, the Stardust spacecraft successfully flew through the cloud of dust that surrounds the nucleus of comet Wild 2 in Jan. 2004. The particles of cometary material and gathered during this flyby were then returned to Earth aboard a sample return capsule which landed in the Utah desert in January 2006.
The monthly JPL "What's Up" video podcast (above) features the January Quadrantids, which is a meteor shower that peaks in the morning hours of Tuesday January 4th. It's a good night with no moon, and while the shower will look best for our friends in Europe, if it's clear and you are awake, you should be able to spot it between and below the big and little dippers.
I thought it interesting that the meteor shower was named after a constellation that has been demoted. You're not alone Pluto - that International Astronomical Union is a cold-hearted bunch.
Generally interested in meteor showers? Here's a meteor shower calendar.
Courtesy xkcdThe current Mars rovers are, not surprisingly, still on Mars. The surprising bit is that one, Opportunity, is still operating, nearly seven years after landing. The other, Spirit, is stuck, possibly in a hibernation mode, and could "wake up" during the Martian summer solstice , this coming March. It’s pretty incredible that these rovers operated so long after they landed – in Opportunity's case 20 times longer and counting.
And, orbiting above the rovers is the Odyssey spacecraft, which last week broke the record for longest-working spacecraft at Mars. The previous record was set by NASA's Mars Global Surveyor, which orbited Mars from 1997 to 2006.
And amidst all this history, a little under a year from now, the Mars Science Laboratory Curiosity will be launched and is scheduled to land in August 2012. Curiosity is also a rover, but is larger than either Opportunity or Spirit. Its mission is to assess whether Mars ever was, or is still today, an environment able to support microbial life.
Courtesy splorpGather ‘round, Buzzketeers, so that I might tell you all a story.
“What story,” you ask?
Is it the one about the little blond girl who is killed by bears for breaking and entering? No, not that story.
Is it the one about the boy who killed an acromegalic man by cutting down the tree that held his fort? No, it’s not that story either.
Could it be the story about the little Blood member who couldn’t tell the difference between a wolf and her own grandmother, and was subsequently devoured by that very wolf? Oh, I wish it were, but it’s not that story.
No, the story I have for you all is even more enduring and horrifying than all of those. It is the story of biodiversity, and how it will freaking destroy you if you mess with it.
Sure, snort dismissively if you must, but you’ll soon be singing a different tune. A sad tune about how everything you ever knew and loved has been taken away from you.
“But how can a concept—and a boring concept like “biodiversity”—hurt me?” Ah, see, but what you don’t know can hurt you. You’re like the little blond girl, screwing around in a house that belongs to bears. She might not have known that it was a bear house (although it’s hard to imagine that she could have missed all the signs), and yet she was destroyed. So listen up.
You see, all biodiversity is is the degree of variation of living things in an ecosystem. Lots of biodiversity in an ecosystem, lots of different things living there. Little biodiversity in an ecosystem, few species living there. And biodiversity includes all forms of life, from your vampire bats and hagfish, to your streptococcus and your slime molds.
At the moment, biodiversity on the planet is on its way down. Lots of the things we do these days make life harder for other species, until there are very few or none of them left. And, sure, no one wants to see a panda get hit by a train, or watch an eagle being run over by road grading equipment, but who cares about the smaller, grosser stuff, like algae or germy things? We could probably do with a few less of those, right? Right?
Wrong, Goldilocks! An attitude like that is bound to get you turned into bear meat.
And here’s where my story begins (again)…
Once upon a time, long, long ago, everything died.
Well, not everything-everything, but pretty well near everything. It was called “the Permian extinction” (we’ve talked about it on Buzz before: here), and more than 90% of all marine (water) species and 70% of all terrestrial (land) species on the planet went extinct. It was way worse than the extinction that would eventually kill off the dinosaurs, and it took the planet a lot longer to recover from the Permian extinction.
What caused the Permian extinction? Oh, you know, a lot of stuff. Probably a lot of stuff. See, while we can more or less say that the dinosaurs were killed off by a giant space rock, it’s harder to say what did in the creatures of the Permian period. After all, the Permian ended almost two hundred million years before the extinction of the dinosaurs. But people have plenty of good guesses: maybe a few smaller space rocks hit the planet, maybe massive volcanic eruptions in what would become Asia kicked dust and poisonous gas into the atmosphere, maybe the oceans suddenly released massive amounts of methane… probably it was a combination of these things and more, and the extinction probably happened in waves before the planet became a good place to live again.
But here’s another straw for that dead camel’s back: the algae died. Not all of it, but lots and lots of the algae died. But why, and why did it matter? After all, it’s just algae.
Scientists aren’t sure exactly what cause so much alga—microscopic plant-like ocean life that turns sunlight into food—to die, but it looks like a sudden rise in the levels of sulfur in the oceans might have had something to do with it. It could be that there was an explosion in the population of sulfur using, hydrogen-sulfide releasing bacteria in the oceans, which would poison the algae.
In any case, there was a large die off of the sort of species we don’t give a lot of thought to. And what happened? The bear meat hit the fan!
Because they turn so much sunlight into so much food, algae act as the basis for most marine food chains. When the algae were gone, photosynthetic bacteria took its place to some extent, but the bacteria were a poor substitute, and the oceans were left with much, much less food. Also, algae produce a significant amount of the planet’s oxygen, and their absence would have created atmospheric changes as well.
This alone might have been enough to cause extinctions, and combined with the other natural calamities of the end of the Permian, it’s no wonder there was such a massive extinction event.
What a good story, eh? Now, if someone asks you what’s so great about biodiversity among the slimier and more boring species, you can just repeat this post, word for word. Or you can repeat this, the short version, word for word: “Because, Mom, if the algae die, we’ll be left choking and crying among the ruins of humanity for the rest of our short lives. And happy birthday.”
The University of Minnesota's Institute on the Environment has made some great movies examining what they call "big questions."
Big question: Feast or famine?
IonE's first Big Question asks: How do we feed a growing world without destroying the planet?
Big question: Is Earth past the tipping point?
Have we pushed our planet past the tipping point? That's a critical issue the IonE explores in our second Big Question video.
Big question: What is nature worth?
Plants, animals, even entire ecosystems are disappearing. So what? "What is Nature Worth" offers a three-minute look at what we’re REALLY losing – and what we can do about it.
Interesting problems, right? If you're intrigued, and want to know more about the folks posing the questions and trying to find the solutions, jump over to Future Earth.
This past week on November 17th, the Leonid Meteor Shower sent meteors streaming down on Earth. "Shooting stars," or meteors, are actually bits of debris in space that burn up upon entering the earth's atmosphere at high speed. Technically, the meteors don't run into the Earth, the Earth runs into the meteors.
The trail of debris in space that the Earth encounters every November 17th was laid down by the comet Tempel-Tuttle. The comet orbits the sun and has made many orbits, laying down a trail of dust and debris on each pass. The comet was first recorded in the year 1366 and has an orbit period of 33 years.
This year was not a spectacular show. The peak, the time when earth passes though the densest part of the trail, only produced about 20 meteors per hour. There have been spectacular years when the Leonids produce meteor storms. These tend to occur every 33 years and there can be thousands of meteors per hour. The next storm probably won't be until around the year 2042.
This year, it was cloudy at my home so I "observed" the shower in a completely different way. I listened to it.
Let me explain.
The US Air Force runs the Space Surveillance Radar in Kickapoo, Texas. There's a lot of junk in space and when the government is flying multimillion dollar craft up there they want to keep them safe. Twenty-four hours a day the space radar puts out 800 kilowatts of continuous wave power at 216.98 Mhz. It sounds like a steady tone on a receiver. The primary mission is to monitor everything in orbit. It can detect objects as small as 10 centimeters orbiting at up to 30,000 km above earth. The radar works by having the signal bounce off objects and reflect the signal back to a number of listening stations.
During a meteor shower, meteors streak through the atmosphere and create a trail of ionized dust. The radio signal reflects off this trail and we can hear the signal of the radar change. Space Weather Radio, a private group, has a listening station set up by Stan Nelson on the roof of his house a couple hundred miles away in Roswell, NM. Space Weather Radio streams the signal over the web and you can listen in. During a meteor shower, you can recognize meteors by the sound.
I recoded for an hour and successfully heard the signature sound of meteors streaking through the atmosphere. For sure a cool experience on an otherwise cloudy night.