By Jim Gerard
Well, not too long. Only two weeks. And it's not winter yet: not until the Sun reaches the Winter Solstice at 9:47 am on Monday, December 21. But the point is that the OLC will only get occasional updates through the holiday season. Most of the INSPIRE staff will be with family over the holidays, and we know that you have some great plans as well. We hope you use this time to go back into the Discover section and find some activities to catch up with. Make them a present to yourself. Share them with your families and friends. Remember, if you want to apply for a Summer STEM Experience, the points you earn will play a role in the selection process! The OLC will be back at full speed on Monday, January 4 (Perihelion Day), 2010.
From all on the INSPIRE team to everyone in our virtual community, the very best wishes for a joyous holiday!
(And if you want to track Santa, check out the NORAD site!)
Friday, December 18, 2009
Thursday, December 10, 2009
2009: An Online Year of Milestones
By Jason Townsend
As our turkey comas wear off from Thanksgiving and the chilled air of December settles in, a New Year looms around the corner. 2009 held many large events for NASA.gov. Almost 392,000 people watched the LCROSS impact video live on NASA.gov with 5.4 million visitors simultaneously looking at the NASA.gov Web site, the second-largest online event in our history. We also set a new bandwidth record during the LCROSS impact with data transfers of over 75.5 gigabits per second spread among live video and the Web site. All-told during the LCROSS impact event, we moved a total amount of data equal to over 85 terabytes or about the equivalent of 127,327 CD's.
NASA.gov also set milestones with the Hubble Space Telescope Servicing Mission during STS-125. In addition to all the normal online activities that any shuttle mission usually garners, astronaut Mike Massimino captivated space enthusiasts around the world via Twitter by sending the first tweet from space. His Earth-shattering tweets also managed to amass @Astro_Mike over a million followers on Twitter, rivaling the likes of Ashton Kutcher. Additionally, the launch of STS-125 also resulted in our fourth-largest online event in NASA.gov history.
NASA delved deeper into our enthusiastic group of followers on Twitter by hosting 'Tweetups' where Twitter users learn about our programs and speak with astronauts. Thus far, Tweetups have been held at the Jet Propulsion Laboratory in Pasadena, California, NASA Headquarters in Washington, D.C. and at the Kennedy Space Center in Florida. Demand for attending the Tweetup to learn about STS-129 and view the launch of the Space Shuttle from Florida culminated with the filling of our 100 registration slots, plus all the spaces on our wait-list, in less than twenty minutes.
Other ground was broken in NASA's online communications with this fall's Operation Ice Bridge campaign, which featured an unprecedented level of near-real time coverage across cyberspace with tweets on Twitter, Webisodes on YouTube, photos on Flickr, and a blog on NASA Blogs. This precedent-setting social media coverage exceeded all expectations and is something that we hope to repeat in the years ahead.
Another large online event for NASA.gov was the launch of the Ares I-X Development Test flight. While lasting just a few minutes, the intrigue of the new rocket and it's successful test launch showed sustained interest in the days leading up to the launch, even after the first launch attempt was scrubbed.
Now that we've talked about some of our online highlights from 2009, what other NASA events interested you from throughout the year?
As our turkey comas wear off from Thanksgiving and the chilled air of December settles in, a New Year looms around the corner. 2009 held many large events for NASA.gov. Almost 392,000 people watched the LCROSS impact video live on NASA.gov with 5.4 million visitors simultaneously looking at the NASA.gov Web site, the second-largest online event in our history. We also set a new bandwidth record during the LCROSS impact with data transfers of over 75.5 gigabits per second spread among live video and the Web site. All-told during the LCROSS impact event, we moved a total amount of data equal to over 85 terabytes or about the equivalent of 127,327 CD's.
NASA.gov also set milestones with the Hubble Space Telescope Servicing Mission during STS-125. In addition to all the normal online activities that any shuttle mission usually garners, astronaut Mike Massimino captivated space enthusiasts around the world via Twitter by sending the first tweet from space. His Earth-shattering tweets also managed to amass @Astro_Mike over a million followers on Twitter, rivaling the likes of Ashton Kutcher. Additionally, the launch of STS-125 also resulted in our fourth-largest online event in NASA.gov history.
NASA delved deeper into our enthusiastic group of followers on Twitter by hosting 'Tweetups' where Twitter users learn about our programs and speak with astronauts. Thus far, Tweetups have been held at the Jet Propulsion Laboratory in Pasadena, California, NASA Headquarters in Washington, D.C. and at the Kennedy Space Center in Florida. Demand for attending the Tweetup to learn about STS-129 and view the launch of the Space Shuttle from Florida culminated with the filling of our 100 registration slots, plus all the spaces on our wait-list, in less than twenty minutes.
Other ground was broken in NASA's online communications with this fall's Operation Ice Bridge campaign, which featured an unprecedented level of near-real time coverage across cyberspace with tweets on Twitter, Webisodes on YouTube, photos on Flickr, and a blog on NASA Blogs. This precedent-setting social media coverage exceeded all expectations and is something that we hope to repeat in the years ahead.
Another large online event for NASA.gov was the launch of the Ares I-X Development Test flight. While lasting just a few minutes, the intrigue of the new rocket and it's successful test launch showed sustained interest in the days leading up to the launch, even after the first launch attempt was scrubbed.
Now that we've talked about some of our online highlights from 2009, what other NASA events interested you from throughout the year?
Wednesday, December 9, 2009
Fewer Southeastern Tornadoes Occur Following Dry Falls and Winters
By Gretchen Cook-Anderson
Perhaps Dorothy, from the famed film Wizard of Oz, should have hoped for a fall or wintertime drought. According to findings from a NASA-funded study published last June in Environmental Research Letters , dry fall and winter seasons in the southeastern United States mean it is less likely that Southern twisters will develop in springtime to sweep anyone off their feet.
Using rainfall data from NASA satellites, rain gauge information, and NOAA’s Storm Prediction Center tornado record dating back to 1952, University of Georgia meteorologists Marshall Shepherd and Tom Mote and Purdue University climatologist Dev Niyogi discovered a statistical tendency for drought-ravaged fall and winter seasons to pave the way for “below normal tornado days” in spring seasons that follow.
“This is conceptually similar to what Bill Gray’s been doing for more than 25 years when he predicts how active the hurricane season will be based on African rain,” said Shepherd, the study’s lead author, of the Colorado State University’s pioneer hurricane season forecaster.
They culled data from Northern Georgia and other parts of the southeast, but Shepherd and his colleagues believe their findings may have relevance for other regions. The new study also adds to the body of related work Shepherd and Niyogi are ushering, including their study earlier this year in the aftermath of Atlanta’s spring 2008 twister that linked urbanization and drought to tornado activity.
For Shepherd in particular, there’s no place like home when considering the geographical focus of much of his meteorological research. “Science is my proverbial yellow brick road,” explained Shepherd. “It’s taken me down some fascinating paths, especially in learning more in recent years about tornado phenomena in my own backyard.”
Perhaps Dorothy, from the famed film Wizard of Oz, should have hoped for a fall or wintertime drought. According to findings from a NASA-funded study published last June in Environmental Research Letters , dry fall and winter seasons in the southeastern United States mean it is less likely that Southern twisters will develop in springtime to sweep anyone off their feet.
Using rainfall data from NASA satellites, rain gauge information, and NOAA’s Storm Prediction Center tornado record dating back to 1952, University of Georgia meteorologists Marshall Shepherd and Tom Mote and Purdue University climatologist Dev Niyogi discovered a statistical tendency for drought-ravaged fall and winter seasons to pave the way for “below normal tornado days” in spring seasons that follow.“This is conceptually similar to what Bill Gray’s been doing for more than 25 years when he predicts how active the hurricane season will be based on African rain,” said Shepherd, the study’s lead author, of the Colorado State University’s pioneer hurricane season forecaster.
They culled data from Northern Georgia and other parts of the southeast, but Shepherd and his colleagues believe their findings may have relevance for other regions. The new study also adds to the body of related work Shepherd and Niyogi are ushering, including their study earlier this year in the aftermath of Atlanta’s spring 2008 twister that linked urbanization and drought to tornado activity.
For Shepherd in particular, there’s no place like home when considering the geographical focus of much of his meteorological research. “Science is my proverbial yellow brick road,” explained Shepherd. “It’s taken me down some fascinating paths, especially in learning more in recent years about tornado phenomena in my own backyard.”
Thursday, December 3, 2009
Tripping the Boundary Layer - Part 2
By Wayne Hale, JSC, Manager Space Shuttle Program
If we are to design future hypersonic aircraft and spacecraft, we need to understand this phenomenon in a very specific way. Precisely controlled data collection is required. That is what is going to happen on the next shuttle flight.
Here is a picture of the apparatus as it was being installed on Discovery in the Orbiter Processing Facility:
The older tiles have grayed with repeated flights, new tiles are shiny black, and the green painted aluminum skin is where tiles are yet to be installed. The wires hanging down are for the instrumentation. The black tile in the center of the picture has a quarter inch ridge down the middle of it, oriented crosswise to the airflow; that is our controlled trip mechanism.
If this experiment is successful, there are two more iterations with larger steps on the test tile.
Funny how it seems so simple, but it takes so much planning!
If we are successful, a better understanding of the transition will lead to a prediction capability. This will make it possible to design the engines and aircraft for the next leap forward in aircraft!
Tuesday, December 1, 2009
Tripping the Boundary Layer - Part 1
By Wayne Hale, JSC, Manager Space Shuttle Program
As I start this series, it occurs to me that "tripping the boundary layer" could be an article on social change - maybe I'll do that.
But for today it is an engineering subject. So buckle your seatbelt and hold your hat, we are off on an adventure in rocket science!
Aviation has been driven by the desire to fly higher and faster. Great strides have been made, especially up to the middle 1960's. But for the last few decades aircraft have been at a plateau in terms of speed and altitude. With the exception of rocket powered X planes, the boundary of high performance jets has been just faster than Mach 3 and up to about 100,000 ft. Even though there is the perennial dream of hypersonic transports carrying passengers across the globe in a fraction of today's aircraft, we don't seem to be advancing on that dream.
Part of the problem is we don't understand how to avoid tripping the boundary layer. There is precious little data at hypersonic speeds, and computer simulations are no good without data and the formulae derived from data to predict these things: garbage in; garbage out.
So, to start this discussion off, let us define the terms. (What the dickens are we talking about?)! What's a boundary layer and what does it mean to trip one?
In aviation, the boundary layer is a thin film of air closest to the wing, body, or engine of an aircraft. At the molecular level, the air immediately adjacent to the airplane is dragged along with the plane. Infinitesimally farther away, the air is being carried along at some fraction of the speed of the airplane, and at a longer way away from the airplane, the air is not moving at all, or at least not being dragged by the airplane. That distant air is called the "free stream" and the close by air - which is affected by the passage of the aircraft - is called the boundary layer. Typically aerospace engineers consider the boundary layer to be that close in part of the air that is being dragged along by the passing of the aircraft at a speed of 5% or more of the airplane. These boundary layers are thin, inches or fractions of an inch. They are important because the boundary layer causes most of the drag and most of the heating when an airplane is in flight.
Boundary layers, like all fluid flows, is either laminar or turbulent. Laminar flow is smooth, turbulent flow is, . . . well, . . . turbulent. You can see a good youtube video of this here:
http://uk.youtube.com/watch?v=NplrDarMDF8
And there is a really good wikipedia article on turbulence here: http://en.wikipedia.org/wiki/Turbulence
So why is all of this important? Exactly at this time there is a large effort by many companies and government agencies to develop hypersonic aircraft. NASA has even sponsored a couple of test flights. The problem, as it is for all types of aircraft flight, is drag and heating. When the boundary layer over the wings or in the engine is laminar, there is low drag and low heating; and when the boundary layer is turbulent, drag and heating increase dramatically. All boundary layers can be "tripped" or transition from laminar to turbulent flow.
In some of these experimental aircraft the engines [called SCRAM jets for Supersonic Combustion Ram jet engines] have only operated for a fraction of a second or a very few seconds. Why? Because the designers do not know how to cool them; they don't understand when or whether the boundary layer inside the engine is turbulent or laminar.
In some of these experimental aircraft, the engine begins to melt as soon as it is turned on; hence the extremely short operating times.
This is no good for a hypersonic passenger aircraft which might carry a hundred people from New York to Tokyo in a couple of hours.
Why do we not understand this phenomenon? Because it cannot be recreated in a wind tunnel or other experimental apparatus. The wind tunnels that have long enough flow durations to study this phenomenon run only up to about Mach 6. These hypersonic engines need to perform at Mach 8 or 10 or 12. There are "wind tunnels" that operate at high Mach numbers but only for fractions of a second; not long enough to understand the way in which a boundary layer works.
No aircraft fly that fast, missiles can achieve it briefly, but there is one platform that spends a serious amount of time flying through the atmosphere at speeds above Mach 6:
Its the space shuttle.
Tomorrow I'll talk about an experiment that will be on the next shuttle flight. An experiment which will study tripping the boundary layer.
With this knowledge, the designers just might be able to make a major advancement toward hypersonic passenger aircraft.
To hold your attention until my next post, here is a true story:
Around 1900 a young graduate student in physics was trying to do research on a problem that could earn him a doctorate degree. He started out studying the transition from laminar to turbulent flow in fluids. After months of work and study, he concluded that this problem was too hard. He would concentrate on an easier subject: atomic physics. His name was Niels Bohr and he won the Nobel prize for physics in 1922 for his work in quantum mechanics. And he was right; turbulence is harder. And we don't understand it yet.
As I start this series, it occurs to me that "tripping the boundary layer" could be an article on social change - maybe I'll do that.
But for today it is an engineering subject. So buckle your seatbelt and hold your hat, we are off on an adventure in rocket science!
Aviation has been driven by the desire to fly higher and faster. Great strides have been made, especially up to the middle 1960's. But for the last few decades aircraft have been at a plateau in terms of speed and altitude. With the exception of rocket powered X planes, the boundary of high performance jets has been just faster than Mach 3 and up to about 100,000 ft. Even though there is the perennial dream of hypersonic transports carrying passengers across the globe in a fraction of today's aircraft, we don't seem to be advancing on that dream.
Part of the problem is we don't understand how to avoid tripping the boundary layer. There is precious little data at hypersonic speeds, and computer simulations are no good without data and the formulae derived from data to predict these things: garbage in; garbage out.
So, to start this discussion off, let us define the terms. (What the dickens are we talking about?)! What's a boundary layer and what does it mean to trip one?
In aviation, the boundary layer is a thin film of air closest to the wing, body, or engine of an aircraft. At the molecular level, the air immediately adjacent to the airplane is dragged along with the plane. Infinitesimally farther away, the air is being carried along at some fraction of the speed of the airplane, and at a longer way away from the airplane, the air is not moving at all, or at least not being dragged by the airplane. That distant air is called the "free stream" and the close by air - which is affected by the passage of the aircraft - is called the boundary layer. Typically aerospace engineers consider the boundary layer to be that close in part of the air that is being dragged along by the passing of the aircraft at a speed of 5% or more of the airplane. These boundary layers are thin, inches or fractions of an inch. They are important because the boundary layer causes most of the drag and most of the heating when an airplane is in flight.
Boundary layers, like all fluid flows, is either laminar or turbulent. Laminar flow is smooth, turbulent flow is, . . . well, . . . turbulent. You can see a good youtube video of this here:
http://uk.youtube.com/watch?v=NplrDarMDF8
And there is a really good wikipedia article on turbulence here: http://en.wikipedia.org/wiki/Turbulence
So why is all of this important? Exactly at this time there is a large effort by many companies and government agencies to develop hypersonic aircraft. NASA has even sponsored a couple of test flights. The problem, as it is for all types of aircraft flight, is drag and heating. When the boundary layer over the wings or in the engine is laminar, there is low drag and low heating; and when the boundary layer is turbulent, drag and heating increase dramatically. All boundary layers can be "tripped" or transition from laminar to turbulent flow.
In some of these experimental aircraft the engines [called SCRAM jets for Supersonic Combustion Ram jet engines] have only operated for a fraction of a second or a very few seconds. Why? Because the designers do not know how to cool them; they don't understand when or whether the boundary layer inside the engine is turbulent or laminar.
In some of these experimental aircraft, the engine begins to melt as soon as it is turned on; hence the extremely short operating times.
This is no good for a hypersonic passenger aircraft which might carry a hundred people from New York to Tokyo in a couple of hours.
Why do we not understand this phenomenon? Because it cannot be recreated in a wind tunnel or other experimental apparatus. The wind tunnels that have long enough flow durations to study this phenomenon run only up to about Mach 6. These hypersonic engines need to perform at Mach 8 or 10 or 12. There are "wind tunnels" that operate at high Mach numbers but only for fractions of a second; not long enough to understand the way in which a boundary layer works.
No aircraft fly that fast, missiles can achieve it briefly, but there is one platform that spends a serious amount of time flying through the atmosphere at speeds above Mach 6:
Its the space shuttle.
Tomorrow I'll talk about an experiment that will be on the next shuttle flight. An experiment which will study tripping the boundary layer.
With this knowledge, the designers just might be able to make a major advancement toward hypersonic passenger aircraft.
To hold your attention until my next post, here is a true story:
Around 1900 a young graduate student in physics was trying to do research on a problem that could earn him a doctorate degree. He started out studying the transition from laminar to turbulent flow in fluids. After months of work and study, he concluded that this problem was too hard. He would concentrate on an easier subject: atomic physics. His name was Niels Bohr and he won the Nobel prize for physics in 1922 for his work in quantum mechanics. And he was right; turbulence is harder. And we don't understand it yet.
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